InSight

InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport)

Lander    Spacecraft    Launch    Mission Status    Sensor Complement    Ground Segment    References 

 

InSight is a NASA minisatellite lander mission, designed to give the Red Planet its first thorough checkup since it formed 4.5 billion years ago. It is the first outer space robotic explorer to study in-depth the "inner space" of Mars: its crust, mantle, and core. Studying Mars' interior structure answers key questions about the early formation of rocky planets in our inner solar system - Mercury, Venus, Earth, and Mars - more than 4 billion years ago, as well as rocky exoplanets. InSight also measures tectonic activity and meteorite impacts on Mars today. 1) 2) 3) 4) 5)

The lander uses cutting edge instruments, to delve deep beneath the surface and seek the fingerprints of the processes that formed the terrestrial planets. It does so by measuring the planet's "vital signs": its "pulse" (seismology), "temperature" (heat flow), and "reflexes" (precision tracking). This mission is part of NASA's Discovery Program for highly focused science missions that ask critical questions in solar system science.

JPL, a division of Caltech in Pasadena, California, manages the InSight Project for NASA's Science Mission Directorate, Washington. Lockheed Martin Space, Denver, built the spacecraft. InSight is part of NASA's Discovery Program, which is managed by NASA's Marshall Space Flight Center in Huntsville, Alabama.

First Interplanetary CubeSat: The rocket that will loft InSight beyond Earth will also launch a separate NASA technology experiment: two mini-spacecraft called MarCO (Mars Cube One). These suitcase-sized CubeSats will fly on their own path to Mars behind InSight. Their objective is to relay back InSight data as it enters the Martian atmosphere and lands. It will be a first test of miniaturized CubeSat technology at another planet, which researchers hope can offer new capabilities to future missions.

If successful, the MarCos could represent a new kind of data relay to Earth, getting news of a safe landing — and any potential problems — sooner. InSight’s success is independent of its co-passengers.

InSight Science Goals: The InSight mission seeks to uncover how a rocky body forms and evolves to become a planet by investigating the interior structure and composition of Mars. The mission will also determine the rate of Martian tectonic activity and meteorite impacts. The InSight mission has two major goals, each with several science investigations, designed to help uncover the process that shaped all of the rocky planets in the inner solar system.

1) To understand how rocky planets formed and evolved, InSight will study the interior structure and processes of Mars by determining:

- The size of the core, what it is made of, and whether it is liquid or solid.

- The thickness and structure of the crust.

- The structure of the mantle and what it is made of.

- How warm the interior is and how much heat is still flowing through.

2) InSight will figure out just how tectonically active Mars is today, and how often meteorites impact it. For this, it will measure:

- How powerful and frequent internal seismic activity is on Mars, and where it is located within the structure of the planet.

- How often meteorites impact the surface of Mars.

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Figure 1: Left: Artist’s rendition showing the inner structure of Mars. The topmost layer is known as the crust, underneath it is the mantle, which rests on a solid inner core. Right: Measuring the pulse of Mars by determining the level of tectonic activity (impact of meteorites) on Mars (image credit: NASA/JPL-Caltech)

Why Mars? — Previous missions to Mars have investigated the surface history of the Red Planet by examining features like canyons, volcanoes, rocks and soil. However, signatures of the planet's formation can only be found by sensing and studying its "vital signs" far below the surface.

In comparison to the other terrestrial planets, Mars is neither too big nor too small. This means that it preserves the record of its formation and can give us insight into how the terrestrial planets formed. It is the perfect laboratory from which to study the formation and evolution of rocky planets. Scientists know that Mars has low levels of geological activity. But a lander like InSight can also reveal just how active Mars really is.

Some background:

Starting next year, scientists will get their first look deep below the surface of Mars. That's when NASA will send the first robotic lander dedicated to exploring the planet's subsurface. InSight will study marsquakes to learn about the Martian crust, mantle and core. 6)

Doing so could help answer a big question: how are planets born? - Seismology, the study of quakes, has already revealed some of the answers here on Earth, said Bruce Banerdt, Insight's principal investigator at NASA/JPL (Jet Propulsion Laboratory), Pasadena, California. But Earth has been churning its geologic record for billions of years, hiding its most ancient history. Mars, at half the size of Earth, churns far less: it's a fossil planet, preserving the history of its early birth.

"During formation, this ball of featureless rock metamorphosed into a diverse and fascinating planet, almost like caterpillar to a butterfly," Banerdt said. "We want to use seismology to learn why Mars formed the way it did, and how planets take shape in general."

A Planetary CT (Computed Tomography) Scan: When rocks crack or shift, they give off seismic waves that bounce throughout a planet. These waves, better known as quakes, travel at different speeds depending on the geologic material they travel through.

Seismometers, like InSight's SEIS instrument, measure the size, frequency and speed of these quakes, offering scientists a snapshot of the material they pass through. "A seismometer is like a camera that takes an image of a planet's interior," Banerdt said. "It's a bit like taking a CT scan of a planet."

Mars' geologic record includes lighter rocks and minerals — which rose from the planet's interior to form the Martian crust — and heavier rocks and minerals that sank to form the Martian mantle and core. By learning about the layering of these materials, scientists can explain why some rocky planets turn into an "Earth" rather than a "Mars" or "Venus" — a factor that is essential to understanding where life can appear in the universe.

A Fuzzy Picture: Each time a quake happens on Mars, it will give InSight a "snapshot" of the planet's interior. The InSight team estimates the spacecraft will see between a couple dozen to several hundred quakes over the course of the mission. Small meteorites, which pass through the thin Martian atmosphere on a regular basis, will also serve as seismic "snapshots."

"It will be a fuzzy picture at first, but the more quakes we see, the sharper it will get," Banerdt said.

One challenge will be getting a complete look at Mars using only one location. Most seismology on Earth takes measurements from multiple stations. InSight will have the planet's only seismometer, requiring scientists to parse the data in creative ways. "We have to get clever," Banerdt said. "We can measure how various waves from the same quake bounce off things and hit the station at different times."

Moonquakes and Marsquakes: InSight won't be the first NASA mission to do seismology. The Apollo missions included four seismometers for the Moon. Astronauts exploded mortar rounds to create vibrations, offering a peek about 100 meters under the surface. They crashed the upper stages of rockets into the Moon, producing waves that enabled them to probe its crust. They also detected thousands of genuine moonquakes and meteorite impacts.

The Viking landers attempted to conduct seismology on Mars in the late 1970s. But those seismometers were located on top of the landers, which swayed in the wind on legs equipped with shock absorbers. "It was a handicapped experiment," Banerdt said. "I joke that we didn't do seismology on Mars — we did it three feet above Mars."

InSight will measure more than seismology. The Doppler shift from a radio signal on the lander can reveal whether the planet's core is still molten; a self-burrowing probe is designed to measure heat from the interior. Wind, pressure and temperature sensors will allow scientists to subtract vibrational "noise" caused by weather. Combining all this data will give us the most complete picture of Mars yet.

JPL, a division of Caltech in Pasadena, manages the InSight Project for NASA's Science Mission Directorate, Washington. Lockheed Martin Space in Denver, Colorado, built and tested the spacecraft. InSight is part of NASA's Discovery Program, which is managed by NASA's Marshall Space Flight Center in Huntsville, Alabama.




InSight Lander

NASA's InSight lander opens a window into the "inner space" of Mars. Its instruments peer deeper than ever into the Martian subsurface, seeking the signatures of the processes that shaped the rocky planets of the inner Solar System, more than four billion years ago. InSight's findings are expected to shed light on the formation of Mars, Earth, and even rocky exoplanets.

The lander builds on the proven design of NASA's Mars Phoenix lander. InSight's over 2.4-meter-long robotic arm lifts a seismometer and heat-flow probe from the deck and places them on the surface. The camera on the arm will provide color 3D views of the landing site, instrument placement, and activities. Sensors measure weather and magnetic field variations.

The state-of-the art robotic arm was built by SSL Robotics in Pasadena, CA, previously known as MDA US Systems and now part of Maxar Technologies. The robotic arm will use its five nimble fingers to remotely grasp the lander’s instruments and carefully place each piece of hardware onto the Martian surface.

Length

6 meters with solar panels deployed ("wingspan")

Width

1.56 meters (lander deck diameter)

Deck height

83 to 108 cm

Length of Robotic Arm

2.4 m

Electrical power

Two solar panels, about 2.2 m each in diameter

Science instruments

3 (a seismometer, heat probe and a radio science experiment)

Table 1: Specifications of the InSight Lander

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Figure 2: An artist's rendition of the InSight lander operating on the surface of Mars (image credit: NASA/JPL-Caltech)


InSight Spacecraft

The spacecraft is the protective "spaceship" that protects the lander during its travel between Earth and Mars. The spacecraft is separate from the launch vehicle that carries the spacecraft and the lander outside of Earth's atmosphere and gravitational pull. The spacecraft includes the mechanical units that safely maneuver the lander through the Martian atmosphere to a landing on Mars.

The three major parts that make-up the InSight spacecraft are:

Cruise Stage: The Cruise Stage encapsulates the lander and its landing system for travel between Earth and Mars. It includes an aeroshell, which consists of a backshell and a heat shield that protects the lander from harsh forces encountered during launch and landing.

EDL (Entry, Descent, and Landing) System: The EDL system includes the aeroshell, parachute, and descent vehicle that lower the lander to the Martian surface. The final touchdown is enabled by shock-absorbing legs.

Lander: InSight’s stationary lander is constructed to deploy sensitive instruments on the surface of Mars from where they can directly sense the planets "vital signs."

Lockheed Martin is the InSight prime contractor and is responsible for the complete spacecraft system – cruise stage, aeroshell and the lander itself. Based on a proven spacecraft design from the successful 2007 Phoenix mission, InSight will incorporate the latest avionics technology as well as advanced science instruments. 7) 8)

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Figure 3: NASA's InSight Mars lander spacecraft in a Lockheed Martin clean room in Littleton, CO (image credit: NASA/JPL-Caltech/Lockheed Martin)

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Figure 4: Illustration of spacecraft and lander components (image credit: NASA/JPL)




Insight Development status

• May 4, 2018: ESA's deep space ground stations in Australia and South America will track the InSight spacecraft on NASA’s behalf as it begins its cruise to the Red Planet. 9)

- Set to be launched from Vandenberg Air Force Base in California on an Atlas V at 1105 UTC on 5 May, InSight will bring a lander to Mars to study its interior, with equipment to measure internal heat and detect ‘marsquakes’. InSight’s 485 million km journey to Mars will take about six months, beginning soon after it separates from its launcher in Earth orbit.

- Five hours after launch, ESA’s deep space ground station at New Norcia in Western Australia, will pick up the signal from InSight. It will maintain contact as a ‘hot backup’ at the same time as NASA’s own Deep Space Network ground station at Canberra, over on the easterly side of the continent.

- Once Canberra loses contact, the 35 m dish antenna at New Norcia will maintain contact with the mission until it vanishes under the horizon. ESA’s second southern-hemisphere deep space ground station at Malargüe in Argentina will pick up the contact two and a half hours after that.

• April 6, 2018: In the early morning hours of May 5, millions of Californians will have an opportunity to witness a sight they have never seen before - the historic first interplanetary launch from America's West Coast. On board the 57.3 m United Launch Alliance Atlas V rocket will be NASA's InSight spacecraft, destined for the Elysium Planitia region located in Mars' northern hemisphere. 10)

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Figure 5: NASA's InSight to Mars undergoes final preparations at Vandenberg AFB, CA, ahead of its May 5 launch date Image credit: NASA/JPL-Caltech)

• March 23, 2018: Scientists in Germany are working hard to ensure NASA's next Mars mission, the Insight mission, gets the most accurate data possible. Researchers are currently testing a replica of the probe's SEIS (Seismic Experiment for Interior Structure) instrument package, a combination of six seismometers that will be used to study geologic structures deep beneath the Martian surface. The testing will help scientists back in the United States properly calibrate the real SEIS instrument package. 11) 12)

- The testing is being carried out at the Joint Geoscientific Observatory, or BFO (Black Forest Observatory), in Schiltach, by a team of researchers from KIT (Karlsruhe Institute of Technology) and Stuttgart University. The combination of three short-period seismometers and three broadband seismometers allows the instrument package to target a wide range of frequencies.

- "Ground movement in vertical and two horizontal directions can be measured," BFO researcher Rudolf Widmer-Schnidrig said in a news release.

- The instruments were developed by engineers in France and the United States, and have previously been tested at BFO. Earlier tests focused on a pair of short-period seismometers, while a single broadband seismometer is the focus of the latest round of testing. All the tests will offer a baseline under optimal conditions against which scientists can compare the data returned by the real instrument package.

- "At the BFO, we have excellent measurement conditions. Seismic noise is low. The seismometers supply data with the lowest noise worldwide," Widmer-Schnidrig said.

- Scientists are testing the instruments inside measurement chambers installed in the tunnel system of a former ore mine in the Black Forest. At 150 m beneath Earth's surface, the testing chambers protect instruments from air pressure and temperature fluctuation, as well as interference from communication systems.

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Figure 6: Researchers at Germany's BFO (Black Forest Observatory) are calibrating a replica of the SEIS instrument package on NASA's InSight probe(image credit: KIT)

• February 28, 2018: NASA's InSight spacecraft has arrived at VAFB (Vandenberg Air Force Base) in central California to begin final preparations for a launch this May. The spacecraft was shipped from Lockheed Martin Space, Denver, today and arrived at VAFB. InSight will be the first mission to look deep beneath the Martian surface, studying the planet's interior by listening for marsquakes and measuring the planet's heat output. It will also be the first planetary spacecraft to launch from the West Coast. 13)

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Figure 7: Personnel supporting NASA's InSight mission to Mars load the crated InSight spacecraft into a C-17 cargo aircraft at Buckley Air Force Base, Denver, for shipment to Vandenberg Air Force Base, California (image credit: NASA/JPL)

• February 22, 2018: NASA's Mars InSight lander team is preparing to ship the spacecraft from Lockheed Martin Space in Denver, where it was built and tested, to Vandenberg Air Force Base in California, where it will become the first interplanetary mission to launch from the West Coast. The project is led by NASA's Jet Propulsion Laboratory in Pasadena, California. 14)

- InSight is the first mission to study the deep interior of Mars. InSight will take the "vital signs" of Mars: its pulse (seismology), temperature (heat flow), and its reflexes (radio science). It will be the first thorough check-up since the planet formed 4.5 billion years ago.

- InSight will teach us about planets like our own. InSight's team hopes that by studying the deep interior of Mars, we can learn how other rocky planets form. Earth and Mars were molded from the same primordial stuff more than 4 billion years ago, but then became quite different. Why didn't they share the same fate?

- InSight will try to detect marsquakes for the first time. One key way InSight will peer into the Martian interior is by studying motion underground — what we know as marsquakes. NASA has not attempted to do this kind of science since the Viking mission. Both Viking landers had their seismometers on top of the spacecraft, where they produced noisy data. InSight's seismometer will be placed directly on the Martian surface, which will provide much cleaner data.

• January 23, 2018: NASA's next mission to Mars passed a key test, extending the solar arrays that will power the InSight spacecraft once it lands on the Red Planet this November. 15)

- The fan-like solar panels are specially designed for Mars' weak sunlight, caused by the planet's distance from the Sun and its dusty, thin atmosphere. The panels will power InSight for at least one Martian year (two Earth years) for the first mission dedicated to studying Mars' deep interior.

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Figure 8: This photo shows the completion of one solar panels during the InSight deployment test (image credit: NASA, Lockheed Martin)

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Figure 9: The test took place at Lockheed Martin Space just outside of Denver, where InSight was built and has been undergoing testing ahead of its launch (image credit: NASA, Lockheed Martin)

• November 3, 2017: Last month, NASA invited members of the public to send their names to Mars. And the public responded loud and clear. More than 1.6 million people signed up to have their names etched on a microchip that will be carried on NASA's upcoming InSight mission, which launches in May of 2018. 16)

- NASA's Jet Propulsion Laboratory in Pasadena, California, reopened the opportunity after it proved successful in 2015. During that open call, nearly 827,000 names were collected for a microchip that now sits on top of the robotic InSight lander.

- The grand total once a second microchip is added in early 2018 will be 2,429,807 names. Space enthusiasts who signed up this last round shared their downloadable "boarding passes" on social media, complete with the total number of flight miles they've collected by participating in engagement initiatives for other Mars missions.

• September 13, 2017: NASA scientists have found evidence that Mars’ crust is not as dense as previously thought, a clue that could help researchers better understand the Red Planet’s interior structure and evolution. A lower density likely means that at least part of Mars’ crust is relatively porous. At this point, however, the team cannot rule out the possibility of a different mineral composition or perhaps a thinner crust. 17)

- The researchers mapped the density of the Martian crust, estimating the average density is 2,582 kg/m3. That’s comparable to the average density of the lunar crust. Typically, Mars’ crust has been considered at least as dense as Earth’s oceanic crust, which is about 2,900 kg/m3.

- The new value is derived from Mars’ gravity field, a global model that can be extracted from satellite tracking data using sophisticated mathematical tools. The gravity field for Earth is extremely detailed, because the data sets have very high resolution. Recent studies of the Moon by NASA’s GRAIL (Gravity Recovery and Interior Laboratory) mission also yielded a precise gravity map.

- The data sets for Mars don’t have as much resolution, so it’s more difficult to pin down the density of the crust from current gravity maps. As a result, previous estimates relied more heavily on studies of the composition of Mars’ soil and rocks.

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Figure 10: A new map of the thickness of Mars’ crust shows less variation between thicker regions (red) and thinner regions (blue), compared to earlier mapping. This view is centered on Valles Marineris, with the Tharsis Montes near the terminator to its west. The map is based on modeling of the Red Planet’s gravity field by scientists at NASA/GSFC in Greenbelt, Maryland. The team found that globally Mars’ crust is less dense, on average, than previously thought, which implies smaller variations in crustal thickness (image credit: NASA/Goddard/UMBC/MIT/E. Mazarico)

• August 26, 2017: Preparation of NASA's next spacecraft to Mars, InSight, has ramped up this summer, on course for launch next May from Vandenberg Air Force Base in central California — the first interplanetary launch in history from America's West Coast. 18)

- Lockheed Martin Space Systems is assembling and testing the InSight spacecraft in a clean room facility near Denver. "Our team resumed system-level integration and test activities last month," said Stu Spath, spacecraft program manager at Lockheed Martin. "The lander is completed and instruments have been integrated onto it so that we can complete the final spacecraft testing including acoustics, instrument deployments and thermal balance tests." InSight is the first mission to focus on examining the deep interior of Mars. Information gathered will boost understanding of how all rocky planets formed, including Earth.

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Figure 11: The Mars lander portion of NASA's InSight spacecraft is lifted from the base of a storage container in preparation for testing, in this photo taken June 20, 2017, in a Lockheed Martin clean room facility in Littleton, Colorado (image credit: NASA/JPL-Caltech, Lockheed Martin)

• September 2, 2016: NASA is moving forward with a spring 2018 launch of its InSight mission to study the deep interior of Mars, following final approval this week by the agency’s Science Mission Directorate. 19)

- The InSight mission was originally scheduled to launch in March of this year, but NASA suspended launch preparations in December due to a vacuum leak in its prime science instrument, the Seismic Experiment for Interior Structure (SEIS).

- The new launch period for the mission begins May 5, 2018, with a Mars landing scheduled for Nov. 26, 2018. The next launch opportunity is driven by orbital dynamics, so 2018 is the soonest the lander can be on its way.


Launch: The InSight mission was launched on 5 May 2018 (11:05 UTC), on an Atlas V-401 vehicle of ULA from VAFB, CA. This is the 12th mission of NASA's Discovery Program, managed by the agency's Marshall Space Flight Center in Huntsville, Alabama. InSight is on a 483 million km trip to Mars to study for the first time what lies deep beneath the surface of the Red Planet. 20) 21)

Secondary payloads:

MarCO (Mars Cube One): The InSight flight will include two experimental 6U CubeSats (MarCO-A and MarCO-B) of NASA/JPL. This will be the first time CubeSats have flown in deep space. If this flyby demonstration is successful, the technology will provide NASA the ability to quickly transmit status information about the main spacecraft after it lands on Mars.

- The two CubeSats will separate from the Atlas V booster after launch and travel along their own trajectories to the Red Planet. After release from the launch vehicle, MarCO's first challenges are to deploy two radio antennas and two solar panels. The high-gain, X-band antenna is a flat panel engineered to direct radio waves the way a parabolic dish antenna does. MarCO will be navigated to Mars independently of the InSight spacecraft, with its own course adjustments on the way.

- NASA's two MarCO CubeSats will be flying past Mars in November 2018 just as NASA's next Mars lander, InSight, is descending through the Martian atmosphere and landing on the surface. MarCO will provide an experimental communications relay to inform Earth quickly about the landing.

- The MarCO mission is described in a separate file on the eoPortal.

From liftoff to landing, Aerojet Rocketdyne propulsion systems are playing a critical role in the NASA InSight Mars lander mission, slated for launch May 5 from Vandenberg, Air Force Base, California, aboard a United Launch Alliance Atlas V rocket. NASA’s latest visitor to the red planet will rely on Aerojet Rocketdyne propulsion systems during the launch, cruise, entry and landing phases of its journey. All of these systems must execute flawlessly and in sequence for the mission to succeed.

“Mars missions, especially those that deliver a lander to the planet’s surface, are notoriously challenging, but our team of experienced propulsion engineers is up to the task,” Aerojet Rocketdyne CEO and President Eileen Drake said. “Aerojet Rocketdyne engines have flown aboard every NASA Mars mission, including orbiters and landers, since 1975.”

InSight, designed to gather data on Martian seismology, will be NASA’s first interplanetary mission to launch from Vandenberg; previous missions have lifted off from Cape Canaveral Air Force Station, Florida, where lower latitude translates into added boost for the launch vehicle courtesy of the Earth’s rotation. The Atlas V, whose Centaur upper stage is powered by a single Aerojet Rocketdyne RL10C-1 engine, is powerful enough to launch planetary probes from either U.S. coast, depending on their mission mass.

During its six-month transit to Mars, InSight will be guided by eight Aerojet Rocketdyne cruise engines, which will make precise burns—some preplanned, others as necessary—to ensure an accurate orbital arrival to the red planet. These engines are contained in four Rocket Engine Modules, each consisting of one MR-111C and one MR-106E, generating one and five pounds of thrust, respectively.

InSight will rely on six pairs of Aerojet Rocketdyne MR-107N engines, each engine generating 50 pounds of pulsed thrust, to bring it to the Martian surface in a controlled manner. Before touchdown, the engines will have to steer InSight clear of the parachute, lest it come down on top of the lander. Once that is accomplished, the thrusters will slow InSight to a speed of about 10 kilometers per hour, enabling a soft touchdown.

Table 2: Aerojet Rocketdyne propulsion throughout the Insight mission 22)

The InSight cruise phase begins soon after separation from the launch vehicle when the spacecraft completes the launch phase. Cruise ends when the spacecraft is about 60 days from entry into the Martian atmosphere, beginning with approach. 23)

During cruise, the InSight lander is tucked inside its protective aeroshell, with the aeroshell attached to the cruise stage. The spacecraft makes several corrections to its trajectory by firing the cruise stage engines, with the first one just 10 days after launch. The purpose of these is to fine-tune the flight path so it hits just the right entry point at the top of the Martian atmosphere on landing day.

Orbit of InSight (Ref. 3):

• Very fast, type-1 trajectory: 6.5-month cruise to Mars

• Landing: November 26, 2018 on the landing site Elysium Planitia, Mars.

• Two-month deployment phase

• Two years (one Mars year) science operations on the surface; repetitive operations

• Nominal end-of-mission: November 24, 2020

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Figure 12: Illustration of InSight trajectory to Mars (image credit: NASA/JPL)

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Figure 13: Illustration of the InSight spacecraft with deployed solar panels during the cruise phase (image credit: NASA)

Some of the key activities during the cruise phase include:

- Health checks and maintenance of the spacecraft in its cruise configuration.

- Monitoring and calibration of the spacecraft and subsystems.

- Attitude correction turns (adjusts) to maintain the antenna pointing toward Earth for communications and to keep the solar panels pointed toward the Sun for power).

- Navigation activities, including trajectory correction maneuvers, to keep track of InSight’s position and precisely control it prior to approach.

- Preparation for entry, descent, and landing and surface operations, including communication tests used during entry, descent, and landing.


EDL (Entry, Descent, and Landing): EDL begins when the spacecraft reaches the Martian atmosphere, about 128 km above the surface, and ends with the lander safe and sound on the surface of Mars six minutes later. 24)

For InSight, this phase includes a combination of technologies inherited from past NASA Mars missions such as NASA’s Phoenix Mars Lander. This landing system weighs less than the airbags used for the twin rovers or the skycrane used by the Mars Science Laboratory. The lean landing hardware helps InSight place a higher ratio of science instruments to total launch mass on the surface of Mars.

Compared with Phoenix, though, InSight's landing presents four added challenges:

• InSight enters the atmosphere at higher velocity 6.3 km/s vs. 5.6 km/s.

• InSight has more mass entering the atmosphere — about 608 kg vs. 573 kg.

• InSight lands at an elevation of about 1.5 km higher than Phoenix did, so it has less atmosphere to use for deceleration.

• InSight lands during northern hemisphere autumn on Mars, when dust storms are known to have grown to global proportions in some prior years.

InSight will use a combination of parachutes and onboard engines to gently lower itself down to the Martian surface. The entire landing will last just seven minutes, and if it’s successful, the spacecraft will spend the next two years studying Mars and its interior.

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Figure 14: Elysium Planitia, a flat-smooth plain just north of the equator makes for the perfect location from which to study the deep Martian interior (image credit: NASA) 25)

The InSight mission will place a stationary lander near Mars' equator (Figures 14 and 15). With two solar panels that unfold like paper fans, the lander spans about 6 meters. Within weeks after the landing — always a dramatic challenge on Mars — InSight will use a robotic arm to place its two main instruments directly and permanently onto the Martian ground, an unprecedented set of activities on Mars.

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Figure 15: Illustration of the deployed InSight Lander on Mars showing the main components of the lander and the two maon experiments (image credit: (image credit: NASA/JPL-Caltech)

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Figure 16: Mars Lander Deck of NASA's InSight Mission: This view looks upward toward the InSight Mars lander suspended upside down. It shows the top of the lander's science deck with the mission's two main science instruments SEIS and HP3 plus the robotic arm and other subsystems installed. The photo was taken on 9 Aug. 2017, in a Lockheed Martin clean room facility in Littleton, Colorado (image credit: NASA/JPL-Caltech, Lockheed Martin) 26)

Figure 17: NASA Mars InSight Overview (video credit: NASA/JPL)




Mission status

• June 21, 2022: The mission’s team has chosen to operate its seismometer longer than previously planned, although the lander will run out of power sooner as a result. 27)

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Figure 18: NASA’s InSight Mars lander took this final selfie on April 24, 2022, the 1,211th Martian day, or sol, of the mission. The lander is covered with far more dust than it was in its first selfie, taken in December 2018, not long after landing - or in its second selfie, composed of images taken in March and April 2019 (image credit: NASA/JPL-Caltech)

- As the power available to NASA’s InSight Mars lander diminishes by the day, the spacecraft’s team has revised the mission’s timeline in order to maximize the science they can conduct. The lander was projected to automatically shut down the seismometer – InSight’s last operational science instrument – by the end of June in order to conserve energy, surviving on what power its dust-laden solar panels can generate until around December.

- Instead, the team now plans to program the lander so that the seismometer can operate longer, perhaps until the end of August or into early September. Doing so will discharge the lander’s batteries sooner and cause the spacecraft to run out of power at that time as well, but it might enable the seismometer to detect additional marsquakes.

- “InSight hasn’t finished teaching us about Mars yet,” said Lori Glaze, director of NASA’s Planetary Science Division in Washington. “We’re going to get every last bit of science we can before the lander concludes operations.”

- InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) is in an extended mission after achieving its science goals. The lander has detected more than 1,300 marsquakes since touching down on Mars in 2018, providing information that has allowed scientists to measure the depth and composition of Mars’ crust, mantle, and core. With its other instruments, InSight has recorded invaluable weather data, investigated the soil beneath the lander, and studied remnants of Mars’ ancient magnetic field.

- All instruments but the seismometer have already been powered down. Like other Mars spacecraft, InSight has a fault protection system that automatically triggers “safe mode” in threatening situations and shuts down all but its most essential functions, allowing engineers to assess the situation. Low power and temperatures that drift outside predetermined limits can both trigger safe mode.

- To enable the seismometer to continue to run for as long as possible, the mission team is turning off InSight’s fault protection system. While this will enable the instrument to operate longer, it leaves the lander unprotected from sudden, unexpected events that ground controllers wouldn’t have time to respond to.

- “The goal is to get scientific data all the way to the point where InSight can’t operate at all, rather than conserve energy and operate the lander with no science benefit,” said Chuck Scott, InSight’s project manager at NASA’s Jet Propulsion Laboratory in Southern California.

• May 9, 2022: NASA’s InSight Mars lander has detected the largest quake ever observed on another planet: an estimated magnitude 5 temblor that occurred on May 4, 2022, the 1,222nd Martian day, or sol, of the mission. This adds to the catalog of more than 1,313 quakes InSight has detected since landing on Mars in November 2018. The largest previously recorded quake was an estimated magnitude 4.2 detected Aug. 25, 2021. 28)

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Figure 19: This spectrogram shows the largest quake ever detected on another planet. Estimated to be magnitude 5, the quake is the biggest ever detected on another planet (image credit: NASA/JPL-Caltech/EHT Zürich)

- InSight was sent to Mars with a highly sensitive seismometer, provided by France’s Centre National d’Études Spatiales (CNES), to study the deep interior of the interior of the planet. As seismic waves pass through or reflect off material in Mars’ crust, mantle, and core, they change in ways that seismologists can study to determine the depth and composition of these layers. What scientists learn about the structure of Mars can help them better understand the formation of all rocky worlds, including Earth and its Moon.

- A magnitude 5 quake is a medium-size quake compared to those felt on Earth, but it’s close to the upper limit of what scientists hoped to see on Mars during InSight’s mission. The science team will need to study this new quake further before being able to provide details such as its location, the nature of its source, and what it might tell us about the interior of Mars.

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Figure 20: This image shows InSight’s domed Wind and Thermal Shield, which covers its seismometer, called Seismic Experiment for Interior Structure (SEIS), image credit: NASA/JPL-Caltech

- “Since we set our seismometer down in December 2018, we’ve been waiting for ‘the big one,’” said Bruce Banerdt, InSight’s principal investigator at NASA’s Jet Propulsion Laboratory in Southern California, which leads the mission. “This quake is sure to provide a view into the planet like no other. Scientists will be analyzing this data to learn new things about Mars for years to come.”

- The large quake comes as InSight is facing new challenges with its solar panels, which power the mission. As InSight’s location on Mars enters winter, there’s more dust in the air, reducing available sunlight. On May 7, 2022, the lander’s available energy fell just below the limit that triggers safe mode, where the spacecraft suspends all but the most essential functions. This reaction is designed to protect the lander and may occur again as available power slowly decreases.

- After the lander completed its prime mission at the end of 2020, meeting its original science goals, NASA extended the mission through December 2022.

• February 5, 2022: NASA’s InSight Mars lander has recovered from a safe mode caused by a dust storm in January, but the project’s leader says the mission is still likely to end within a year because of declining power levels. 29)

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Figure 21: Increasing amouts of dust on solar panels (left) on the InSight Mars lander have drastically reduced available power and could force the mission to end in 2022 (image credit: NASA/JPL-Caltech)

- In a presentation at a meeting of the Mars Exploration Program Analysis Group (MEPAG) Feb. 3, Bruce Banerdt, principal investigator for the InSight mission, said he expected the lander to resume normal operations Feb. 5 after going into a safe mode Jan. 7.

- The safe mode was triggered by a regional dust storm that blocked sunlight for the solar-powered lander. That storm “expanded very rapidly,” he said, based on data from other spacecraft. “We did not really get any early warning on this.”

- Dust storms are measured by a factor called the optical depth, or tau, with a higher value meaning less sunlight reaching the ground. For this storm, Banerdt said the storm never got higher than about two. “It’s still pretty dusty, but not so dusty that it really threatened the spacecraft,” he said. InSight could have handed dust storms with a tau of about four before the lack of sunlight available for power caused major concerns. By comparison, the Opportunity rover, whose mission ended after a dust storm in 2018, measured a tau of 10.8 before going offline.

- The safe mode ended Jan. 18 and controllers have been gradually restoring the lander to normal operations, he said, with no sign of any lasting effects from the dust storm.

- The mission, though, has been grappling with a gradual decline in the spacecraft’s power because of dust accumulating on its solar arrays. Unlike the Spirit and Opportunity rovers, whose arrays were regularly cleaned by atmospheric activity, dust has continued to accumulate on InSight’s arrays. At a meeting of MEPAG in June 2021, Banerdt projected that power levels would drop below that needed to keep the spacecraft alive in the spring of 2022.

- That date has been pushed out slightly, but he said the long-term outlook for the lander still does not look promising. “Our current projections indicate that the energy will drop below that required to operate the payload in the May/June time frame and probably below survivability some time near the end of the year,” he said.

- The mission is still working on ways to clean the arrays, including procedures where the lander’s robotic arm scoops up dirt and drops it just upwind of the arrays, so that grains bounce off the array and jar loose accumulated dust through a process called saltation. “It sounds like a crazy thing to do, but it actually works,” Banerdt said. The project has done it several times, and in each case it raised the output of the arrays by 1-3%.

- Those efforts, though, may only delay the inevitable. “We don’t have a crystal ball, but our best estimate is that we probably won’t be getting very much science data past the summer,” he said. “The spacecraft is probably not going to last more than about a year.”

- The decline in power has matched expectations, he noted, with more than enough power for InSight to get through its primary mission of one Martian year after its November 2018 landing. The mission also met its top-level science goals despite the declining power and the failure of a heat flow probe to burrow into the Martian surface.

- InSight’s operations are funded through this year. Banerdt said that the mission has submitted a proposal as part of NASA’s ongoing senior review of planetary science missions for an extension in the event there’s a “cleaning event” that removes dust from the arrays and boosts the lander’s power. Such an event, though, is unlikely, he acknowledged. “We’re not betting our mortgage on it.”

• January 11, 2022: The lander has taken measures to conserve energy; engineers aim to return to normal operations next week. — NASA’s InSight lander is stable and sending health data from Mars to Earth after going into safe mode Friday, Jan. 7, following a large, regional dust storm that reduced the sunlight reaching its solar panels. In safe mode, a spacecraft suspends all but its essential functions. 30)

- The mission’s team reestablished contact with InSight on 10 January, finding that its power was holding steady and, while low, was unlikely to be draining the lander’s batteries. Drained batteries are believed to have caused the end of NASA’s Opportunity rover during an epic series of dust storms that blanketed the Red Planet in 2018.

- Even before this recent dust storm, dust had been accumulating on InSight’s solar panels, reducing the lander’s power supply. Using a scoop on the lander’s robotic arm, InSight’s team came up with an innovative way to reduce the dust on one panel, and gained several boosts of energy during 2021, but these activities become increasingly difficult as available energy decreases.

- Dust storms can affect solar panels in two ways: Dust reduces sunlight filtering through the atmosphere, and it can also accumulate on the panels. Whether this storm will leave an additional layer of dust on the solar panels remains to be determined.

- The current dust storm was first detected by the Mars Color Imager (MARCI) camera aboard NASA’s Mars Reconnaissance Orbiter, which creates daily color maps of the entire planet. Those maps allow scientists to monitor dust storms and can serve as an early warning system for spacecraft on the Martian surface. InSight’s team received data indicating the regional storm is waning.

- The whirlwinds and gusts of dust storms have helped to clear solar panels over time, as with the Spirit and Opportunity Mars rover missions. While InSight’s weather sensors have detected many passing whirlwinds, none have cleared any dust.

- InSight’s engineers are hopeful they will be able to command the lander to exit safe mode next week. This will allow more flexibility in operating the lander, as communication, which requires a relatively large amount of energy, is limited in safe mode to conserve battery charge.

- InSight landed on Mars on Nov. 26, 2018, to study the inner structure of the planet, including its crust, mantle and core. The spacecraft achieved its science objectives before its prime mission ended a year ago. NASA then extended the mission for up to two years, to December 2022, based on the recommendation of an independent review panel composed of experts with backgrounds in science, operations and mission management.

More About the Mission

- JPL manages InSight for NASA’s Science Mission Directorate. InSight is part of NASA’s Discovery Program, managed by the agency's Marshall Space Flight Center in Huntsville, Alabama. Lockheed Martin Space in Denver built the InSight spacecraft, including its cruise stage and lander, and supports spacecraft operations for the mission.

- A number of European partners, including France’s Centre National d’Études Spatiales (CNES) and the German Aerospace Center (DLR), are supporting the InSight mission. CNES provided the Seismic Experiment for Interior Structure (SEIS) instrument to NASA, with the principal investigator at IPGP (Institut de Physique du Globe de Paris). Significant contributions for SEIS came from IPGP; the Max Planck Institute for Solar System Research (MPS) in Germany; the Swiss Federal Institute of Technology (ETH Zurich) in Switzerland; Imperial College London and Oxford University in the United Kingdom; and JPL. DLR provided the Heat Flow and Physical Properties Package (HP3) instrument, with significant contributions from the Space Research Center (CBK) of the Polish Academy of Sciences and Astronika in Poland. Spain’s Centro de Astrobiología (CAB) supplied the temperature and wind sensors.

• September 22, 2021: On Sept. 18, NASA’s InSight lander celebrated its 1,000th Martian day, or sol, by measuring one of the biggest, longest-lasting marsquakes the mission has ever detected. The temblor is estimated to be about a magnitude 4.2 and shook for nearly an hour-and-a-half. 31)

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Figure 22: This selfie of NASA’s InSight lander is a mosaic made up of 14 images taken on March 15 and April 11 – the 106th and 133rd Martian days, or sols, of the mission – by the spacecraft Instrument Deployment Camera located on its robotic arm (image credit: NASA/JPL-Caltech)

- The lander cleared enough dust from one solar panel to keep its seismometer on through the summer, allowing scientists to study the three biggest quakes they’ve seen on Mars.

- This is the third major quake InSight has detected in a month: On Aug. 25, the mission’s seismometer detected two quakes of magnitudes 4.2 and 4.1. For comparison, a magnitude 4.2 quake has five times the energy of the mission’s previous record holder, a magnitude 3.7 quake detected in 2019.

- The mission studies seismic waves to learn more about Mars’ interior. The waves change as they travel through a planet’s crust, mantle, and core, providing scientists a way to peer deep below the surface. What they learn can shed light on how all rocky worlds form, including Earth and its Moon.

- The quakes might not have been detected at all had the mission not taken action earlier in the year, as Mars’ highly elliptical orbit took it farther from the Sun. Lower temperatures required the spacecraft to rely more on its heaters to keep warm; that, plus dust buildup on InSight’s solar panels, has reduced the lander’s power levels, requiring the mission to conserve energy by temporarily turning off certain instruments.

- The team managed to keep the seismometer on by taking a counterintuitive approach: They used InSight’s robotic arm to trickle sand near one solar panel in the hopes that, as wind gusts carried it across the panel, the granules would sweep off some of the dust. The plan worked, and over several dust-clearing activities, the team saw power levels remain fairly steady. Now that Mars is approaching the Sun once again, power is starting to inch back up.

- "Even after more than two years, Mars seems to have given us something new with these two quakes."

- “If we hadn’t acted quickly earlier this year, we might have missed out on some great science,” said InSight’s principal investigator, Bruce Banerdt of NASA’s Jet Propulsion Laboratory in Southern California, which leads the mission. “Even after more than two years, Mars seems to have given us something new with these two quakes, which have unique characteristics.”

Temblor Insights

- While the Sept. 18 quake is still being studied, scientists already know more about the Aug. 25 quakes: The magnitude 4.2 event occurred about 5,280 miles (8,500 km) from InSight – the most distant temblor the lander has detected so far.

- Scientists are working to pinpoint the source and which direction the seismic waves traveled, but they know the shaking occurred too far to have originated where InSight has detected almost all of its previous large quakes: Cerberus Fossae, a region roughly 1,000 miles (1,609 kilometers) away where lava may have flowed within the last few million years. One especially intriguing possibility is Valles Marineris, the epically long canyon system that scars the Martian equator. The approximate center of that canyon system is 6,027 miles (9,700 km) from InSight.

- To the surprise of scientists, the Aug. 25 quakes were two different types, as well. The magnitude 4.2 quake was dominated by slow, low-frequency vibrations, while fast, high-frequency vibrations characterized the magnitude 4.1 quake. The magnitude 4.1 quake was also much closer to the lander – only about 575 miles (925 km) away.

- That’s good news for seismologists: Recording different quakes from a range of distances and with different kinds of seismic waves provides more information about a planet’s inner structure. This summer, the mission’s scientists used previous marsquake data to detail the depth and thickness of the planet’s crust and mantle, plus the size of its molten core.

- Despite their differences, the two August quakes do have something in common other than being big: Both occurred during the day, the windiest – and, to a seismometer, noisiest – time on Mars. InSight’s seismometer usually finds marsquakes at night, when the planet cools off and winds are low. But the signals from these quakes were large enough to rise above any noise caused by wind.

- Looking ahead, the mission’s team is considering whether to perform more dust cleanings after Mars solar conjunction, when Earth and Mars are on opposite sides of the Sun. Because the Sun’s radiation can affect radio signals, interfering with communications, the team will stop issuing commands to the lander on Sept. 29, though the seismometer will continue to listen for quakes throughout conjunction.

• July 22, 2021: Mars has had its first CT scan, thanks to analyses of seismic waves picked up by NASA’s InSight lander. Diagnosis: The Red Planet’s core is at least partially liquid, as some previous studies had suggested, and is somewhat larger than expected. 32)

- InSight reached Mars in late 2018 and soon afterward detected the first known marsquake (SN: 11/26/18; SN: 4/23/19). Since then, the lander’s instruments have picked up more than a thousand temblors, most of them minor rumbles. Many of those quakes originated at a seismically active region more than 1,000 kilometers away from the lander. A small fraction of the quakes had magnitudes ranging from 3.0 to 4.0, and the resulting vibrations have enabled scientists to probe Mars and reveal new clues about its inner structure.

- Simon Stähler, a seismologist at ETH Zurich, and colleagues analyzed seismic waves from 11 marsquakes, looking for two types of waves: pressure and shear. Unlike pressure waves, shear waves can’t pass through a liquid, and they move more slowly, traveling side to side through solid materials, rather than in a push-and-pull motion in the same direction a wave is traveling like pressure waves do.

- Of those 11 events, six sets of vibrations included shear waves strong enough to stand out from background noise. The strength of those shear waves suggests that they reflected off of the outer surface of a liquid core, rather than entering a solid core and being partially absorbed, Stähler says. And the difference in arrival times at InSight for the pressure waves and shear waves for each quake suggest that Mars’ core is about 3,660 kilometers in diameter, he and colleagues report in the July 23 Science. 33)

- That’s a little more than half of the diameter of the entire planet, larger than most previous estimates. The Red Planet’s core is so big, in fact, that it blocks InSight from receiving certain types of seismic waves from a large part of the planet. That, in turn, suggests that Mars may be more seismically active than the lander’s sensors can detect. Indeed, one of the regions in the lander’s seismic blind spot is the Tharsis region, home to some of Mars’ largest volcanoes. Volcanic activity there, as well as the motion of molten rock within the crust in that region, could trigger quakes or seismic waves.

- While the newly analyzed data confirm the planet’s outer core is liquid, it’s not clear yet whether Mars has a solid inner core like Earth, says study coauthor Amir Khan, a geophysicist also at ETH Zurich. “The signal should be there in the seismic data,” he says. “We just need to locate it.”

- In a separate analysis also published in Science, Khan and colleagues suggest that InSight’s seismic blind spot may also stem, in part, from the way that seismic waves slow down and bend as they travel deep within the planet. Changes in seismic wave speed and direction can result from gradual variations in rock temperature or density, for example. 34)

- Mars’ seismic waves also hint at the thickness of the planet’s crust. As they bounce back and forth within the planet, the waves bounce off interfaces between different layers and types of rocks, says Brigitte Knapmeyer-Endrun, a seismologist at the University of Cologne in Bergisch Gladbach, Germany. In a separate study in Science, she and her team analyzed seismic signals that reflected off several such interfaces near Mars’ surface, making it difficult to determine the depth at which the planet’s crust ends and the underlying mantle begins, she says. The researchers concluded, however, that the average thickness of the crust likely lies between 24 and 72 kilometers. For comparison, Earth’s oceanic crust is about 6 to 7 kilometers thick, while the planet’s continental crust averages from 35 to 40 kilometers thick. 35)

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Figure 23: Seismic waves (red lines in this illustration) traveling through Mars from a quake’s source (example, red dot) to the InSight lander (white dot) reveal the Red Planet’s internal structure, including a massive core (yellow-white) more than half the diameter of the planet (image credit: Chris Bickel/Science)

- Together, these seismic analyses are the first to investigate the innards of a rocky planet other than Earth, Stähler says. As such, they provide “ground truth” for measurements made by spacecraft orbiting Mars, and could help scientists better interpret data gathered from orbit around other planets, such as Mercury and Venus.

- The findings could also provide insights that would help planetary scientists better understand how Mars formed and evolved over the life of the solar system, and how the Red Planet ended up so unalike Earth, says Sanne Cottaar, a geophysicist at the University of Cambridge. Cottaar wrote a commentary, also published in Science, on the new research. “Mars was put together with similar building blocks” as Earth, she says, “but had a different result.” 36)

• July 22, 2021: Before NASA’s InSight spacecraft touched down on Mars in 2018, the rovers and orbiters studying the Red Planet concentrated on its surface. The stationary lander’s seismometer has changed that, revealing details about the planet’s deep interior for the first time. 37)

- Three papers based on the seismometer’s data were published today in Science, providing details on the depth and composition of Mars’ crust, mantle, and core, including confirmation that the planet’s center is molten. Earth’s outer core is molten, while its inner core is solid; scientists will continue to use InSight’s data to determine whether the same holds true for Mars.

- “When we first started putting together the concept of the mission more than a decade ago, the information in these papers is what we hoped to get at the end,” said InSight’s principal investigator Bruce Banerdt of NASA’s Jet Propulsion Laboratory in Southern California, which leads the mission. “This represents the culmination of all the work and worry over the past decade.”

- InSight’s seismometer, called the Seismic Experiment for Interior Structure (SEIS), has recorded 733 distinct marsquakes. About 35 of those – all between magnitudes 3.0 and 4.0 – provided the data for the three papers. The ultrasensitive seismometer enables scientists to “hear” seismic events from hundreds to thousands of miles away.

Figure 24: Clouds drift over the dome-covered seismometer, known as SEIS, belonging to NASA's InSight lander, on Mars (image credit: NASA/JPL-Caltech)

Peering Into Mars

- Seismic waves vary in speed and shape when traveling through different materials inside a planet. Those variations on Mars have given seismologists a way to study the planet’s inner structure. In turn, what the scientists learn about Mars can help improve the understanding of how all rocky planets – including Earth – formed.

- Like Earth, Mars heated up as it formed from the dust and larger clumps of meteoritic material orbiting the Sun that helped to shape our early solar system. Over the first tens of millions of years, the planet separated into three distinct layers – the crust, mantle, and core – in a process called differentiation. Part of InSight’s mission was to measure the depth, size, and structure of these three layers.

- Each of the papers in Science focuses on a different layer. The scientists found the crust was thinner than expected and may have two or even three sub-layers. It goes as deep as 12 miles (20 km) if there are two sub-layers, or 23 miles (37 km) if there are three.

- Beneath that is the mantle, which extends 969 miles (1,560 km) below the surface.

- At the heart of Mars is the core, which has a radius of 1,137 miles (1,830 km). Confirming the size of the molten core was especially exciting for the team. “This study is a once-in-a-lifetime chance,” said Simon Stähler of the Swiss research university ETH Zurich, lead author of the core paper. “It took scientists hundreds of years to measure Earth’s core; after the Apollo missions, it took them 40 years to measure the Moon’s core. InSight took just two years to measure Mars’ core.”

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Figure 25: NASA’s InSight lander detected a marsquake, represented here as a seismogram, on July 25, 2019, the 235th Martian day, or sol, of its mission. Seismologists study the wiggles in seismograms in order to confirm whether they’re really seeing a quake or noise caused by wind (image credit: NASA/JPL-Caltech)

Hunting for Wiggles

- The earthquakes most people feel come from faults caused by tectonic plates shifting. Unlike Earth, Mars has no tectonic plates; its crust is instead like one giant plate. But faults, or rock fractures, still form in the Martian crust due to stresses caused by the slight shrinking of the planet as it continues to cool.

- InSight scientists spend much of their time searching for bursts of vibration in seismograms, where the tiniest wiggle on a line can represent a quake or, for that matter, noise created by wind. If seismogram wiggles follow certain known patterns (and if the wind is not gusting at the same time), there’s a chance they could be a quake.

- The initial wiggles are primary, or P, waves, which are followed by secondary, or S, waves. These waves can also show up again later in the seismogram after reflecting off layers inside the planet.

- “What we’re looking for is an echo,” said Amir Khan of ETH Zurich, lead author of the paper on the mantle. “We’re detecting a direct sound – the quake – and then listening for an echo off a reflector deep underground.”

- These echoes can even help scientists find changes within a single layer, like the sub-layers within the crust.

- “Layering within the crust is something we see all the time on Earth,” said Brigitte Knapmeyer-Endrun of the University of Cologne, lead author on the paper about the crust. “A seismogram’s wiggles can reveal properties like a change in porosity or a more fractured layer.”

- One surprise is that all of InSight’s most significant quakes appear to have come from one area, Cerberus Fossae, a region volcanically active enough that lava may have flowed there within the last few million years. Orbiting spacecraft have spotted the tracks of boulders that may have rolled down steep slopes after being shaken loose by marsquakes.

- Curiously, no quakes have been detected from more prominent volcanic regions, like Tharsis, home to three of the biggest volcanoes on Mars. But it’s possible many quakes – including larger ones – are occurring that InSight can’t detect. That’s because of shadow zones caused by the core refracting seismic waves away from certain areas, preventing a quake’s echo from reaching InSight.

Waiting for the Big One

- These results are only the beginning. Scientists now have hard data to refine their models of Mars and its formation, and SEIS detects new marsquakes every day. While InSight’s energy level is being managed, its seismometer is still listening and scientists are hopeful they’ll detect a quake bigger than 4.0.

- “We’d still love to see the big one,” said JPL’s Mark Panning, co-lead author of the paper on the crust. “We have to do lots of careful processing to pull the things we want from this data. Having a bigger event would make all of this easier.”

- Panning and other InSight scientists will share their findings at 9 a.m. PDT (12 p.m. EDT) on July 23 in a livestreamed discussion on NASA Television, the NASA app, the agency’s website, and multiple agency social media platforms, including the JPL YouTube and Facebook channels.

• June 22, 2021: Dust accumulation on the solar panels of NASA’s InSight Mars lander is reducing the power to the spacecraft and could force the mission to end within a year. 38)

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Figure 26: Increasing amounts of dust on solar panels (left) on the InSight Mars lander have drastically reduced available power and could force the mission to end in 2022 (image credit: NASA/JPL-Caltech)

- At a June 21 meeting of NASA’s Mars Exploration Program Analysis Group, Bruce Banerdt, principal investigator for the InSight mission at NASA’s Jet Propulsion Laboratory, said dust accumulating on the lander’s two solar panels has drastically reduced the amount of power they produce, requiring some instruments to be turned off at least temporarily.

- “The dust accumulation on the solar arrays has been considerable. We have about 80% obscuration of the arrays,” he said. The amount of energy available to the lander per Martian day, or sol, has dropped from nearly 5,000 watt-hours shortly after its November 2018 landing to less than 700 watt-hours now, according to data Banerdt presented at the meeting.

- The decline in energy was expected, and the mission was designed to have enough power for its prime mission, which lasted one Martian year or 687 days. The continued decline in power, though, is becoming an issue as InSight operates in an extended mission funded through the end of 2022 to collect additional seismic data.

- Banerdt said the mission had hoped for “cleaning events” where winds remove some of the dust, allowing the panels to generate more power. Such cleaning events allowed the solar-powered Mars Exploration Rovers, Spirit and Opportunity, to operate for years, far longer than expected.

- Those cleaning events have not taken place for InSight, though, and other attempts to remove the dust, such as shaking the panels, have failed. More recently, the mission tried a novel approach for cleaning the panels: using the lander’s robotic arm to scoop up regolith and then release it near the panels. Winds allowed some particles to bounce off the panels, in the process removing dust, a process known as saltation.

- “We had some success with that,” he said. The first attempt at saltation increased energy output by 25 to 30 watt-hours, he said. A second attempt, though, provided only a temporary increase in energy, and a third attempt last weekend offered “a little bit of an increase.”

- “This has bought us a little bit of headroom that we didn’t have before,” he said. Energy levels are dropping because of both the increased dust accumulation as well as Mars nearing aphelion, or the farthest point in its orbit from the sun. Mars will reach aphelion in about two months, after which sunlight, and thus power levels, should increase slightly.

- Banerdt said the mission is closely monitoring power levels to determine what systems may need to be turned off as aphelion approaches. “It’s going to be extremely challenging to operate through that, especially with the instruments,” he said.

- Some sensors, such as for collecting weather and magnetic field data, have already been turned off, or used only sporadically. “We hope to get some of these instruments up to at least do periodic measurements after aphelion,” he said.

- InSight’s main instrument, a seismometer, has remained in operation. Banerdt, though, did not rule out having to turn it off near aphelion. “We may have to power off the entire payload for some period around aphelion,” he said. “There may be a month or two of time where we might have to turn off the seismometer, but we’re trying to tighten our belts and sharpen our pencils to see whether we can operate straight through.”

- InSight will get a respite after aphelion as sunlight levels increase, but Banerdt warned it will be temporary. By April 2022, energy levels will decrease further, which he said was due to increased dust accumulation on the panels, more dust in the atmosphere and changes in orbital geometry. In a chart he showed, those power levels fell to the “survival energy” line below which the lander cannot operate.

- “Unless we get a fairly significant increase in our solar array output, we’re likely to end our mission sometime around that time next year,” he said.

• June 3, 2021: The InSight spacecraft successfully cleared some dust off its solar panels, helping to raise its energy and delay when it will need to switch off its science instruments. 39)

- The team behind NASA’s InSight Mars lander has come up with an innovative way to boost the spacecraft’s energy at a time when its power levels have been falling. The lander’s robotic arm trickled sand near one solar panel, helping the wind to carry off some of the panel’s dust. The result was a gain of about 30 watt-hours of energy per sol, or Martian day.

Figure 27: To clean a bit of dust from one of its solar panels, NASA’s InSight lander trickled sand above the panel. The wind-borne sand grains then picked up some dust on the panel, enabling the lander to gain about 30 watt-hours of energy per sol on May 22, 2021, the 884th Martian day of the mission (video credit: NASA/JPL-Caltech)

- Mars is approaching aphelion, its farthest point from the Sun. That means less sunlight reaches the spacecraft’s dust-covered solar panels, reducing their energy output. The team had planned for this before InSight’s two-year mission extension. They’ve designed the mission to operate without science instruments for the next few months before resuming science operations later this year. During this period, InSight will reserve power for its heaters, computer, and other key components.

- The power boost should delay the instruments being switched off by a few weeks, gaining precious time to collect additional science data. The team will try to clear a bit more dust from the same solar panel this Saturday, June 5, 2021.

Dust in the Wind

- InSight’s team has been thinking up ways to try to clear dust from its solar panels for almost a year. For example, they tried pulsing the solar panel deployment motors (last used when InSight opened its solar panels after landing) to shake the dust off but didn’t succeed.

- More recently, several members of the science team started pursuing the counterintuitive technique of trickling sand near – but not directly on top of – the panels. Matt Golombek, a member of the InSight science team at NASA’s Jet Propulsion Laboratory in Southern California, which manages the mission, noted that it might be possible to strike dust on the panels with sand grains that would “saltate,” or hop off the solar panel surface and skip through the air in the wind. The larger grains might then carry off the smaller dust particles in the wind.

- To try the technique, the team used the scoop on InSight’s robotic arm to trickle sand next to InSight’s solar panels on May 22, 2021, the 884th sol of the mission, at around noon Mars time – the windiest time of day. It was easiest for InSight’s arm to be positioned over the lander’s deck, high enough for the winds to blow sand over the panels. Sure enough, with winds blowing northwest at a maximum of 20 feet (6 meters) per second, the trickling of sand coincided with an instantaneous bump in the spacecraft’s overall power.

- “We weren’t sure this would work, but we’re delighted that it did,” Golombek said.

- While it’s no guarantee that the spacecraft has all the power it needs, the recent cleaning will add some helpful margin to InSight’s power reserves.

Surviving on Mars

- InSight’s panels have outlasted the two-year prime mission they were designed for and are now powering the spacecraft through the two-year extension. Relying on solar panels for power enables such missions to be as light as possible for launch and requires fewer moving parts – thus, fewer potential failure points – than other systems. Equipping the spacecraft with brushes or fans to clear off dust would add weight and failure points. (Some members of the public have suggested using the Ingenuity Mars Helicopter’s whirring blades to clear off InSight’s panels, but that’s not an option, either: The operation would be too risky, and the helicopter is roughly 2,145 miles (3,452 km away.)

- However, as the Spirit and Opportunity Mars rovers showed, gusts and whirlwinds can clear solar panels over time. In the case of InSight, the spacecraft’s weather sensors have detected many passing whirlwinds, but none have cleared any dust.

- By August, as Mars moves in its orbit closer to the Sun, InSight’s solar panels should be able to gather more energy, allowing the team to turn the science instruments back on. Depending on the available power, they might begin by turning some on for short periods at key times during the day, as they’ve been doing to save energy.

- Whether the instruments are on or off, InSight operations will pause again around Oct. 7, when Mars and the Earth will be on opposite sides of the Sun. Known as Mars Solar Conjunction, this period happens every two years. Because plasma from the Sun can interrupt radio signals sent to spacecraft at that time, all of NASA’s Mars missions will become more passive, continuing to record data and send updates to engineers on Earth, though no new commands will be sent back to them. The moratorium on Mars commands will last several weeks until late October.

• April 01, 2021: NASA’s InSight lander has detected two strong, clear quakes originating in a location of Mars called Cerberus Fossae – the same place where two strong quakes were seen earlier in the mission. The new quakes have magnitudes of 3.3 and 3.1; the previous quakes were magnitude 3.6 and 3.5. InSight has recorded over 500 quakes to date, but because of their clear signals, these are four of the best quake records for probing the interior of the planet. 40)

- Studying marsquakes is one way the InSight science team seeks to develop a better understanding of Mars’ mantle and core. The planet doesn’t have tectonic plates like Earth, but it does have volcanically active regions that can cause rumbles. The March 7 and March 18 quakes add weight to the idea that Cerberus Fossae is a center of seismic activity.

- “Over the course of the mission, we’ve seen two different types of marsquakes: one that is more ‘Moon-like’ and the other, more ‘Earth-like,’” said Taichi Kawamura of France’s Institut de Physique du Globe de Paris, which helped provide InSight’s seismometer and distributes its data along with the Swiss research university ETH Zürich. Earthquake waves travel more directly through the planet, while those of moonquakes tend to be very scattered; marsquakes fall somewhere in between. “Interestingly,” Kawamura continued, “all four of these larger quakes, which come from Cerberus Fossae, are ‘Earth-like.’”

- The new quakes have something else in common with InSight’s previous top seismic events, which occurred almost a full Martian year (two Earth years) ago: They occurred in the Martian northern summer. Scientists had predicted this would again be an ideal time to listen for quakes because winds would become calmer. The seismometer, called the Seismic Experiment for Interior Structure (SEIS), is sensitive enough that, even while it is covered by a dome-shaped shield to block it from wind and keep it from getting too cold, wind still causes enough vibration to obscure some marsquakes. During the past northern winter season, InSight couldn’t detect any quakes at all.

- “It’s wonderful to once again observe marsquakes after a long period of recording wind noise,” said John Clinton, a seismologist who leads InSight’s Marsquake Service at ETH Zürich. “One Martian year on, we are now much faster at characterizing seismic activity on the Red Planet.”

Better Detection

- The winds may have quieted down, but scientists are still hoping to improve their “listening” capability even more. Temperatures near the InSight lander may swing from almost minus 148 degrees Fahrenheit (minus 100 degrees Celsius) at night to 32 degrees Fahrenheit (0 degrees Celsius) during the day. These extreme temperature variations may be causing the cable connecting the seismometer to the lander to expand and contract, resulting in popping sounds and spikes in the data.

- So the mission team has begun trying to partially insulate the cable from the weather. They’ve started by using the scoop on the end of InSight’s robotic arm to drop soil on top of the domed Wind and Thermal Shield, allowing it to trickle down onto the cable. That allows the soil to get as close to the shield as possible without interfering with the shield’s seal with the ground. Burying the seismic tether is in fact one of the goals of the next phase of the mission, which NASA recently extended by two years, to December 2022.

- Despite the winds that have been shaking the seismometer, InSight’s solar panels remain covered with dust, and power is running lower as Mars moves away from the Sun. Energy levels are expected to improve after July, when the planet begins to approach the Sun again. Until then, the mission will successively turn off the lander’s instruments so that InSight can hibernate, waking periodically to check its health and communicate with Earth. The team hopes to keep the seismometer on for another month or two before it has to be temporarily turned off.

• February 12, 2021: As dust collects on the solar panels and winter comes to Elysium Planitia, the team is following a plan to reduce science operations in order to keep the lander safe. 41)

- NASA’s InSight lander recently received a mission extension for another two years, giving it time to detect more quakes, dust devils, and other phenomena on the surface of Mars. While the mission team plans to continue collecting data well into 2022, the increasing dustiness of the spacecraft’s solar panels and the onset of the Martian winter led to a decision to conserve power and temporarily limit the operation of its instruments.

- InSight was designed to be long-lasting: The stationary lander is equipped with solar panels, each spanning 7 feet (2 meters) across. InSight’s design was informed by that of the solar-powered Spirit and Opportunity rovers, with the expectation that the panels would gradually reduce their power output as dust settled on them but would have ample output to last through the two-year prime mission (completed in November 2020).

- Additionally, InSight’s team chose a landing site in Elysium Planitia, a windswept plain on the Red Planet’s equator that receives lots of sunlight. It was hoped that passing dust devils might clean off the panels, which happened many times with Spirit and Opportunity, allowing them to last years past their design lifetime.

- But despite InSight detecting hundreds of passing dust devils, none has been close enough to clean off those dinner-table-size panels since they unfurled on Mars in November 2018. Today, InSight’s solar arrays are producing just 27% of their dust-free capacity. That power has to be shared between science instruments, a robotic arm, the spacecraft’s radio, and a variety of heaters that keep everything in working order despite subfreezing temperatures. Since the windiest season of the Martian year has just ended, the team isn’t counting on a cleaning event in the coming months.

- Mars is currently moving toward what’s called aphelion, the point in its orbit when it’s farthest away from the Sun. That means the already-weak sunlight on the Martian surface is growing even fainter, reducing power when InSight most needs its heaters to stay warm. Mars will start approaching the Sun again in July 2021, after which the team will begin to resume full science operations.

- “The amount of power available over the next few months will really be driven by the weather,” said InSight’s project manager, Chuck Scott of NASA’s Jet Propulsion Laboratory in Southern California. “As part of our extended-mission planning, we developed an operations strategy to keep InSight safe through the winter so that we can resume science operations as solar intensity increases.” JPL leads the InSight mission, though the spacecraft and its solar panels were built by Lockheed Martin Space of Denver, Colorado.

- Over the coming weeks and months, InSight scientists will be carefully selecting which instruments need to be switched off each day to preserve power for heaters and energy-intensive activities like radio communication. InSight’s weather sensors are likely to remain off much of the time (resulting in infrequent updates to the mission’s weather page), and all the instruments will have to be powered off for some period around aphelion.

- Currently, power levels look strong enough to take the lander through the winter. But solar power generation on Mars is always a little uncertain. The Opportunity rover was forced to shut down after a series of dust storms darkened the Martian sky in 2019, and Spirit did not survive the Martian winter in 2010. If InSight were to run out of power due to a sudden dust storm, it is designed to be able to reboot itself when the sunlight returns if its electronics survived the extreme cold.

- Later this week, InSight will be commanded to extend its robotic arm over the panels so a camera can take close-up images of the dust coating. Then the team will pulse the motors that unfurled each panel after landing to try to can disturb the dust and see if the wind blows it away. The team considers this to be a long shot but worth the effort.

- “The InSight team has put together a strong plan to safely navigate through winter and emerge on the other side ready to complete our extended science mission through 2022,” said Bruce Banerdt of JPL, InSight’s principal investigator. “We’ve got a great vehicle and a top-notch team; I’m looking forward to many more new discoveries from InSight in the future.”

• January 14, 2021: The heat probe hasn’t been able to gain the friction it needs to dig, but the mission has been granted an extension to carry on with its other science. 42)

- The heat probe developed and built by the German Aerospace Center (DLR) and deployed on Mars by NASA’s InSight lander has ended its portion of the mission. Since Feb. 28, 2019, the probe, called the “mole,” has been attempting to burrow into the Martian surface to take the planet’s internal temperature, providing details about the interior heat engine that drives the Mars’ evolution and geology. But the soil’s unexpected tendency to clump deprived the spike-like mole of the friction it needs to hammer itself to a sufficient depth.

- After getting the top of the mole about 2 or 3 centimeters under the surface, the team tried one last time to use a scoop on InSight’s robotic arm to scrape soil onto the probe and tamp it down to provide added friction. After the probe conducted 500 additional hammer strokes on Saturday, Jan. 9, with no progress, the team called an end to their efforts.

- Part of an instrument called the Heat Flow and Physical Properties Package (HP3), the mole is a 16-inch-long (40-centimeter-long) pile driver connected to the lander by a tether with embedded temperature sensors. These sensors are designed to measure heat flowing from the planet once the mole has dug at least 10 feet (3 meters) deep.

- “We’ve given it everything we’ve got, but Mars and our heroic mole remain incompatible,” said HP3’s principal investigator, Tilman Spohn of DLR (Figure 28). “Fortunately, we’ve learned a lot that will benefit future missions that attempt to dig into the subsurface.”

- While NASA’s Phoenix lander scraped the top layer of the Martian surface, no mission before InSight has tried to burrow into the soil. Doing so is important for a variety of reasons: Future astronauts may need to dig through soil to access water ice, while scientists want to study the subsurface’s potential to support microbial life.

- “We are so proud of our team who worked hard to get InSight’s mole deeper into the planet. It was amazing to see them troubleshoot from millions of miles away,” said Thomas Zurbuchen, associate administrator for science at the agency’s headquarters in Washington. “This is why we take risks at NASA – we have to push the limits of technology to learn what works and what doesn’t. In that sense, we’ve been successful: We’ve learned a lot that will benefit future missions to Mars and elsewhere, and we thank our German partners from DLR for providing this instrument and for their collaboration.”

Hard-Earned Wisdom

- The unexpected properties of the soil near the surface next to InSight will be puzzled over by scientists for years to come. The mole’s design was based on soil seen by previous Mars missions – soil that proved very different from what the mole encountered. For two years, the team worked to adapt the unique and innovative instrument to these new circumstances.

- “The mole is a device with no heritage. What we attempted to do – to dig so deep with a device so small – is unprecedented,” said Troy Hudson, a scientist and engineer at NASA’s Jet Propulsion Laboratory in Southern California who has led efforts to get the mole deeper into the Martian crust. “Having had the opportunity to take this all the way to the end is the greatest reward.”

- Besides learning about the soil at this location, engineers have gained invaluable experience operating the robotic arm. In fact, they used the arm and scoop in ways they never intended to at the outset of the mission, including pressing against and down on the mole. Planning the moves and getting them just right with the commands they were sending up to InSight pushed the team to grow.

- They’ll put their hard-earned wisdom to use in the future. The mission intends to employ the robotic arm in burying the tether that conveys data and power between the lander and InSight’s seismometer, which has recorded more than 480 marsquakes. Burying it will help reduce temperature changes that have created cracking and popping sounds in seismic data.

- There’s much more science to come from InSight, short for Interior Exploration using Seismic Investigations, Geodesy, and Heat Transport. NASA recently extended the mission for two more years, to Dec. 2022. Along with hunting for quakes, the lander hosts a radio experiment that is collecting data to reveal whether the planet’s core is liquid or solid. And InSight’s weather sensors are capable of providing some of the most detailed meteorological data ever collected on Mars. Together with weather instruments aboard NASA's Curiosity rover and its new Perseverance rover, which lands on Feb. 18, the three spacecraft will create the first meteorological network on another planet.

• October 16, 2020: NASA's InSight lander continues working to get its "mole" - a 16-inch-long (40 cm long) pile driver and heat probe - deep below the surface of Mars. A camera on InSight's arm recently took images of the now partially filled-in "mole hole," showing only the device's science tether protruding from the ground. 43)

Figure 28: NASA's InSight retracted its robotic arm on Oct. 3, 2020, revealing where the spike-like "mole" is trying to burrow into Mars. The copper-colored ribbon attached to the mole has sensors to measure the planet's heat flow. In the coming months, the arm will scrape and tamp down soil on top of the mole to help it dig (image credit: NASA/JPL-Caltech)

- Sensors embedded in the tether are designed to measure heat flowing from the planet once the mole has dug at least 10 feet (3 m) deep. The mission team has been working to help the mole burrow to at least that depth so that it can take Mars' temperature.

- The mole was designed so that loose soil would flow around it, providing friction against its outer hull so that it can dig deeper; without this friction, the mole just bounces in place as it hammers into the ground. But the soil where InSight landed is different than what previous missions have encountered: During hammering, the soil sticks together, forming a small pit around the device instead of collapsing around it and providing the necessary friction.

- After the mole unexpectedly backed out of the pit while hammering last year, the team placed the small scoop at the end of the lander's robotic arm on top of it to keep it in the ground. Now that the mole is fully embedded in the soil, they will use the scoop to scrape additional soil on top of it, tamping down this soil to help provide more friction. Because it will take months to pack down enough soil, the mole isn't expected to resume hammering until early 2021.

- "I'm very glad we were able to recover from the unexpected 'pop-out' event we experienced and get the mole deeper than it's ever been," said Troy Hudson, the scientist and engineer at NASA's Jet Propulsion Laboratory who led the work to get the mole digging. "But we're not quite done. We want to make sure there's enough soil on top of the mole to enable it to dig on its own without any assistance from the arm."

- The mole is formally called the Heat Flow and Physical Properties Package, or HP3, and was built and provided to NASA by the German Space Agency (DLR). JPL in Southern California leads the InSight mission. Read more about the mole's recent progress at this DLR blog.

• August 24, 2020: An electronics issue is suspected to be preventing the sensors from sharing their data about Mars weather with the spacecraft. 44)

- Weather sensors aboard NASA's InSight Mars lander stopped providing data on Sunday, Aug. 16, 2020, a result of an issue affecting the sensor suite's electronics. Engineers at NASA's Jet Propulsion Laboratory in Southern California are working to understand the cause of the issue.

- Called the Auxiliary Payload Sensor Suite (APSS), the sensors collect data on wind speed and direction, air temperature and pressure, and magnetic fields. Throughout each Martian day, or sol, InSight's main computer retrieves data stored in APSS' control computer for later transmission to orbiting spacecraft, which relay the data to Earth.

- APSS is in safe mode and unlikely to be reset before the end of the month while mission team members work toward a diagnosis. JPL engineers are optimistic that resetting the control computer may address the issue but need to investigate the situation further before returning the sensors to normal.

• August 5, 2020: Using data from NASA’s InSight Lander on Mars, Rice University seismologists of Houston, Texas, have made the first direct measurements of three subsurface boundaries from the crust to the core of the red planet. 45)

- “Ultimately it may help us understand planetary formation,” said Alan Levander, co-author of a study available online this week in Geophysical Research Letters. While the thickness of Mars’ crust and the depth of its core have been calculated with a number of models, Levander said the InSight data allowed for the first direct measurements, which can be used to check models and ultimately to improve them. 46)

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Figure 29: An artist’s impression of Mars’ inner structure. The topmost layer is the crust, and beneath it is the mantle, which rests on a solid inner core (image courtesy of NASA/JPL-Caltech)

- “In the absence of plate tectonics on Mars, its early history is mostly preserved compared with Earth,” said study co-author Sizhuang Deng, a Rice graduate student. “The depth estimates of Martian seismic boundaries can provide indications to better understand its past as well as the formation and evolution of terrestrial planets in general.”

- Finding clues about Mars’ interior and the processes that formed it are key goals for InSight, a robotic lander that touched down in November 2018. The probe’s dome-shaped seismometer allows scientists to listen to faint rumblings inside the planet, in much the way that a doctor might listen to a patient’s heartbeat with a stethoscope.

- Seismometers measure vibrations from seismic waves. Like circular ripples that mark the spot where a pebble disturbed the surface of a pond, seismic waves flow through planets, marking the location and size of disturbances like meteor strikes or earthquakes, which are aptly called marsquakes on the red planet. InSight’s seismometer recorded more than 170 of these from February to September 2019.

- Seismic waves are also subtly altered as they pass through different kinds of rock. Seismologists have studied the patterns in seismographic recordings on Earth for more than a century and can use them to map the location of oil and gas deposits and much deeper strata.

- “The traditional way to investigate structures beneath Earth is to analyze earthquake signals using dense networks of seismic stations,” said Deng. “Mars is much less tectonically active, which means it will have far fewer marsquake events compared with Earth. Moreover, with only one seismic station on Mars, we cannot employ methods that rely on seismic networks.”

- Levander, Rice’s Carey Croneis Professor of Earth, Environmental and Planetary Sciences, and Deng analyzed InSight’s 2019 seismology data using a technique called ambient noise autocorrelation. “It uses continuous noise data recorded by the single seismic station on Mars to extract pronounced reflection signals from seismic boundaries,” Deng said.

- The first boundary Deng and Levander measured is the divide between Mars’ crust and mantle almost 35 kilometers beneath the lander.

- The second is a transition zone within the mantle where magnesium iron silicates undergo a geochemical change. Above the zone, the elements form a mineral called olivine, and beneath it, heat and pressure compress them into a new mineral called wadsleyite. Known as the olivine-wadsleyite transition, this zone was found 1,110 - 1,170 km beneath InSight.

- “The temperature at the olivine-wadsleyite transition is an important key to building thermal models of Mars,” Deng said. “From the depth of the transition, we can easily calculate the pressure, and with that, we can derive the temperature.”

- The third boundary he and Levander measured is the border between Mars’ mantle and its iron-rich core, which they found about 1,520 - 1,600 km beneath the lander. Better understanding this boundary “can provide information about the planet’s development from both a chemical and thermal point of view,” Deng said.

- The research was supported by Rice’s Department of Earth, Environmental and Planetary Sciences.

• July 7, 2020: NASA's InSight lander has been using its robotic arm to help the heat probe known as the "mole" burrow into Mars. The mission is providing the first look at the Red Planet's deep interior to reveal details about the formation of Mars and, ultimately, all rocky planets, including Earth. 47)

Figure 30: The movement of sand grains in the scoop on the end of NASA InSight's robotic arm suggests that the spacecraft's self-hammering "mole," which is in the soil beneath the scoop, had begun tapping the bottom of the scoop while hammering on June 20, 2020 (image credit: NASA/JPL-Caltech)

- Akin to a 16-inch-long (40-centimeter-long) pile driver, the self-hammering mole has experienced difficulty getting into the Martian soil since February 2019. It's mostly buried now, thanks to recent efforts to push down on the mole with the scoop on the end of the robotic arm. But whether it will be able to dig deep enough - at least 10 feet (3 meters) - to get an accurate temperature reading of the planet remains to be seen. Images taken by InSight during a Saturday, June 20, hammering session show bits of soil jostling within the scoop - possible evidence that the mole had begun bouncing in place, knocking the bottom of the scoop.

- While the campaign to save the mole continues, the arm will be used to help carry out other science and engineering work. Here's what you can expect in the months ahead from the mission, which is led by NASA's Jet Propulsion Laboratory in Southern California.

What's next for the mole?

- The mole is part of an instrument called the Heat Flow and Physical Properties Package, or HP3, that the German Aerospace Center (DLR) provided NASA. While the scoop on the end of InSight's arm has blocked the mole from backing out of its pit again, it also blocks the arm's camera from seeing the mole and the pit that has formed around it. Over the next few weeks, the team will move the arm out of the way to better assess how the soil and mole are interacting.

- The mole needs friction from soil in order to burrow. Ironically, loose soil provides that friction as it collapses around the mole. But the soil beneath InSight has proven to be cement-like duricrust, with dirt granules that stick together. As a result, recoil from the mole's self-hammering action causes it to bounce in place. So the team's next moves may be to provide that friction by scraping or chopping nearby soil to move it into the pit it's in.

- More thoughts about the mole's recent progress can be found on a blog written by HP3's principal investigator, Tilman Spohn of DLR.

What's next for InSight's arm?

- InSight landed on Mars on Nov. 26, 2018. Its robotic arm subsequently set HP3, a seismometer and the seismometer's Wind and Thermal Shield on to the planet's surface. While the arm has been key to helping the mole, scientists and engineers are eager to use the arm's camera to pan over InSight's solar panels, something they haven't done since July 17, 2019.

- It's the dusty season on Mars, and the panels are likely coated with a fine layer of reddish-brown particles. Estimating how much dust is on the solar panels will let engineers better understand InSight's daily power supply.

- Scientists also want to resume using the arm to spot meteors streaking across the night sky, as they did earlier in the mission. Doing so could help them predict how often meteors strike this part of the planet. They could also cross-check to see whether data from InSight's seismometer reveals a meteor impact on Mars shortly afterward.

What's next for the seismometer?

- InSight's seismometer, called the Seismic Experiment for Interior Structure (SEIS), detected its first marsquake nearly three months after starting its measurements in January 2019. By the fall of 2019, it was detecting a potential quake or two per day. While SEIS has detected more than 480 seismic signals overall, the rate has dropped to less than one per week.

- This rate change is tied to seasonal variations of atmospheric turbulence, which creates noise that covers up the tiny quake signals. Despite the protective Wind and Thermal Shield, SEIS is sensitive enough that shaking from the wind hitting the shield can make quakes harder to isolate.

More About InSight

- JPL manages InSight for NASA's Science Mission Directorate. InSight is part of NASA's Discovery Program, managed by the agency's Marshall Space Flight Center in Huntsville, Alabama. Lockheed Martin Space in Denver built the InSight spacecraft, including its cruise stage and lander, and supports spacecraft operations for the mission.

- A number of European partners, including France's Centre National d'Études Spatiales (CNES) and the German Aerospace Center (DLR), are supporting the InSight mission. CNES provided the Seismic Experiment for Interior Structure (SEIS) instrument to NASA, with the principal investigator at IPGP (Institut de Physique du Globe de Paris). Significant contributions for SEIS came from IPGP; the Max Planck Institute for Solar System Research (MPS) in Germany; the Swiss Federal Institute of Technology (ETH Zurich) in Switzerland; Imperial College London and Oxford University in the United Kingdom; and JPL. DLR provided the Heat Flow and Physical Properties Package (HP3) instrument, with significant contributions from the Space Research Center (CBK) of the Polish Academy of Sciences and Astronika in Poland. Spain's Centro de Astrobiología (CAB) supplied the temperature and wind sensors.

• February 24, 2020: A new understanding of Mars is beginning to emerge, thanks to the first year of NASA's InSight lander mission. Findings described in a set of six papers published today reveal a planet alive with quakes, dust devils and strange magnetic pulses. 48)

- Five of the papers were published in Nature. An additional paper in Nature Geoscience details the InSight spacecraft's landing site, a shallow crater nicknamed "Homestead hollow" in a region called Elysium Planitia.

- InSight is the first mission dedicated to looking deep beneath the Martian surface. Among its science tools are a seismometer for detecting quakes, sensors for gauging wind and air pressure, a magnetometer, and a heat flow probe designed to take the planet's temperature.

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Figure 31: A cutaway view of Mars showing the InSight lander studying seismic activity ( image credit: J. T. Keane/Nature Geoscience)

- While the team continues to work on getting the probe into the Martian surface as intended, the ultra-sensitive seismometer, called the Seismic Experiment for Interior Structure (SEIS), has enabled scientists to "hear" multiple trembling events from hundreds to thousands of miles away.

- Seismic waves are affected by the materials they move through, giving scientists a way to study the composition of the planet's inner structure. Mars can help the team better understand how all rocky planets, including Earth, first formed.

Underground

- Mars trembles more often - but also more mildly - than expected. SEIS has found more than 450 seismic signals to date, the vast majority of which are probably quakes (as opposed to data noise created by environmental factors, like wind). The largest quake was about magnitude 4.0 in size - not quite large enough to travel down below the crust into the planet's lower mantle and core. Those are "the juiciest parts of the apple" when it comes to studying the planet's inner structure, said Bruce Banerdt, InSight principal investigator at JPL.

- Scientists are ready for more: It took months after InSight's landing in November 2018 before they recorded the first seismic event. By the end of 2019, SEIS was detecting about two seismic signals a day, suggesting that InSight just happened to touch down at a particularly quiet time. Scientists still have their fingers crossed for "the Big One."

- Mars doesn't have tectonic plates like Earth, but it does have volcanically active regions that can cause rumbles. A pair of quakes was strongly linked to one such region, Cerberus Fossae, where scientists see boulders that may have been shaken down cliffsides. Ancient floods there carved channels nearly 800 miles (1,300 km) long. Lava flows then seeped into those channels within the past 10 million years - the blink of an eye in geologic time.

- Some of these young lava flows show signs of having been fractured by quakes less than 2 million years ago. "It's just about the youngest tectonic feature on the planet," said planetary geologist Matt Golombek of JPL. "The fact that we're seeing evidence of shaking in this region isn't a surprise, but it's very cool."

At the Surface

- Billions of years ago, Mars had a magnetic field. It is no longer present, but it left ghosts behind, magnetizing ancient rocks that are now between 200 feet (61 meters) to several miles below ground. InSight is equipped with a magnetometer - the first on the surface of Mars to detect magnetic signals.

- The magnetometer has found that the signals at Homestead hollow are 10 times stronger than what was predicted based on data from orbiting spacecraft that study the area. The measurements of these orbiters are averaged over a couple of hundred miles, whereas InSight's measurements are more local.

- Because most surface rocks at InSight's location are too young to have been magnetized by the planet's former field, "this magnetism must be coming from ancient rocks underground," said Catherine Johnson, a planetary scientist at the University of British Columbia and the Planetary Science Institute. "We're combining these data with what we know from seismology and geology to understand the magnetized layers below InSight. How strong or deep would they have to be for us to detect this field?"

- In addition, scientists are intrigued by how these signals change over time. The measurements vary by day and night; they also tend to pulse around midnight. Theories are still being formed as to what causes such changes, but one possibility is that they're related to the solar wind interacting with the Martian atmosphere.

In the Wind

- InSight measures wind speed, direction and air pressure nearly continuously, offering more data than previous landed missions. The spacecraft's weather sensors have detected thousands of passing whirlwinds, which are called dust devils when they pick up grit and become visible. "This site has more whirlwinds than any other place we've landed on Mars while carrying weather sensors," said Aymeric Spiga, an atmospheric scientist at Sorbonne University in Paris.

- Despite all that activity and frequent imaging, InSight's cameras have yet to see dust devils. But SEIS can feel these whirlwinds pulling on the surface like a giant vacuum cleaner. "Whirlwinds are perfect for subsurface seismic exploration," said Philippe Lognonné of Institut de Physique du Globe de Paris (IPGP), principal investigator of SEIS.

Still to come: The Core

- InSight has two radios: one for regularly sending and receiving data, and a more powerful radio designed to measure the "wobble" of Mars as it spins. This X-band radio, also known as the Rotation and Interior Structure Experiment (RISE), can eventually reveal whether the planet's core is solid or liquid. A solid core would cause Mars to wobble less than a liquid one would.

- This first year of data is just a start. Watching over a full Martian year (two Earth years) will give scientists a much better idea of the size and speed of the planet's wobble.

• October 17, 2019: NASA's InSight spacecraft has used its robotic arm to help its heat probe, known as "the mole," dig nearly 2 cm over the past week. While modest, the movement is significant: Designed to dig as much as 5 meters underground to gauge the heat escaping from the planet's interior, the mole has only managed to partially bury itself since it started hammering in February 2019. 49)

- The recent movement is the result of a new strategy, arrived at after extensive testing on Earth, which found that unexpectedly strong soil is holding up the mole's progress. The mole needs friction from surrounding soil in order to move: Without it, recoil from its self-hammering action will cause it to simply bounce in place. Pressing the scoop on InSight's robotic arm against the mole, a new technique called "pinning," appears to provide the probe with the friction it needs to continue digging.

- Since Oct. 8, 2019, the mole has hammered 220 times over three separate occasions. Images sent down from the spacecraft's cameras have shown the mole gradually progressing into the ground. It will take more time - and hammering - for the team to see how far the mole can go.

- The mole is part of an instrument called the HP3 (Heat Flow and Physical Properties Package), which was provided by the German Aerospace Center (DLR).

- "Seeing the mole's progress seems to indicate that there's no rock blocking our path," said HP3 Principal Investigator Tilman Spohn of DLR. "That's great news! We're rooting for our mole to keep going."

• October 3, 2019: NASA's InSight lander, which is on a mission to explore the deep interior of Mars, positioned its robotic arm this past weekend to assist the spacecraft's self-hammering heat probe. Known as "the mole," the probe has been unable to dig more than about 35 cm since it began burying itself into the ground on Feb. 28, 2019. 50)

- The maneuver is in preparation for a tactic, to be tried over several weeks, called "pinning."

Figure 32: NASA InSight's robotic arm will use its scoop to pin the spacecraft's heat probe, or "mole," against the wall of its hole. The mole is part of an instrument formally called the HP3 (Heat Flow and Physical Properties Package), provided by DLR (image credit: NASA/JPL-Caltech)

- "We're going to try pressing the side of the scoop against the mole, pinning it to the wall of its hole," said InSight Deputy Principal Investigator Sue Smrekar of NASA's Jet Propulsion Laboratory in Pasadena, California. "This might increase friction enough to keep it moving forward when mole hammering resumes."

Figure 33: NASA’s InSight lander on Mars is trying to use its robotic arm to get the mission’s heat flow probe, or mole, digging again. InSight team engineer Ashitey Trebbi-Ollennu, based at NASA’s Jet Propulsion Laboratory in Pasadena, California, explains what has been attempted and the game plan for the coming weeks. The next tactic they'll try will be "pinning" the mole against the hole it's in (video credit: NASA/JPL)

- Whether the extra pressure on the mole will compensate for the unique soil remains an unknown.

- Designed to burrow as much as 5 meters underground to record the amount of heat escaping from the planet's interior, the mole needs friction from surrounding soil in order to dig: Without it, recoil from the self-hammering action causes it to simply bounce in place, which is what the mission team suspects is happening now.

- While JPL manages the InSight mission for NASA, the German Aerospace Center (DLR) provided the heat probe, which is part of an instrument called the Heat Flow and Physical Properties Package (HP3). Back in June, the team devised a plan to help the heat probe. The mole wasn't designed to be picked up and relocated once it begins digging. Instead, the robotic arm removed a support structure intended to hold the mole steady as it digs into the Martian surface.

- Removing the structure allowed the InSight team to get a better look at the hole that formed around the mole as it hammered. It's possible that the mole has hit a rock, but testing by DLR suggested the issue was soil that clumps together rather than falling around the mole as it hammers. Sure enough, the arm's camera discovered that below the surface appears to be 5 to 10 cm of duricrust, a kind of cemented soil thicker than anything encountered on other Mars missions and different from the soil the mole was designed for.

- "All we know about the soil is what we can see in images InSight sends us," said Tilman Spohn, HP3's principal investigator at DLR. "Since we can't bring the soil to the mole, maybe we can bring the mole to the soil by pinning it in the hole."

- Using a scoop on the robotic arm, the team poked and pushed the soil seven times over the summer in an effort to collapse the hole. No such luck. It shouldn't take much force to collapse the hole, but the arm isn't pushing at full strength. The team placed HP3 as far from the lander as possible so that the spacecraft's shadow wouldn't influence the heat probe's temperature readings. As a result, the arm, which wasn't intended to be used this way, has to stretch out and press at an angle, exerting much less force than if the mole were closer.

- "We're asking the arm to punch above its weight," said Ashitey Trebi-Ollennu, the lead arm engineer at JPL. "The arm can't push the soil the way a person can. This would be easier if it could, but that's just not the arm we have."

- Interplanetary rescue operations aren't new to NASA. The Mars Exploration Rover team helped save Spirit and Opportunity on more than one occasion. Coming up with workable solutions requires an extraordinary amount of patience and planning. JPL has a working replica of InSight to practice arm movements, and it has a working model of the heat probe as well.

- Besides pinning, the team is also testing a technique to use the scoop in the way it was originally intended to work: scraping soil into the hole rather than trying to compress it. Both techniques might be visible to the public in raw images that come down from InSight in the near future.

• October 1, 2019: Put an ear to the ground on Mars and you'll be rewarded with a symphony of sounds. Granted, you'll need superhuman hearing, but NASA's InSight lander comes equipped with a very special "ear." 51)

Figure 34: NASA's InSight used its Instrument Context Camera (ICC) beneath the lander's deck to image these drifting clouds at sunset. This series of images was taken on April 25, 2019, the 145th Martian day, or sol, of the mission, starting at around 6:30 p.m. Mars local time (image credit: NASA/JPL-Caltech)

- The spacecraft's exquisitely sensitive seismometer, called the Seismic Experiment for Interior Structure (SEIS), can pick up vibrations as subtle as a breeze. The instrument was provided by the French space agency, Centre National d'Études Spatiales (CNES), and its partners.

- SEIS was designed to listen for marsquakes. Scientists want to study how the seismic waves of these quakes move through the planet's interior, revealing the deep inner structure of Mars for the first time.

- But after the seismometer was set down by InSight's robotic arm, Mars seemed shy. It didn't produce its first rumbling until this past April, and this first quake turned out to be an odd duck. It had a surprisingly high-frequency seismic signal compared to what the science team has heard since then. Out of more than 100 events detected to date, about 21 are strongly considered to be quakes. The remainder could be quakes as well, but the science team hasn't ruled out other causes.

Quakes

- Put on headphones to listen to two of the more representative quakes SEIS has detected. These occurred on May 22, 2019 (the 173rd Martian day, or sol, of the mission) and July 25, 2019 (Sol 235). Far below the human range of hearing, these sonifications from SEIS had to be speeded up and slightly processed to be audible through headphones. Both were recorded by the "very broad band sensors" on SEIS, which are more sensitive at lower frequencies than its short period sensors.

- The Sol 173 quake is about a magnitude 3.7; the Sol 235 quake is about a magnitude 3.3.

Figure 35: A recording of a magnitude 3.7 marsquake from InSight's seismometer, called SEIS. This quake was recorded on May 22, 2019 (the 173rd Martian day, or sol, of the mission). Far below the human range of hearing, this sonification from SEIS had to be sped up and slightly processed to be audible through headphones (image credit: NASA/JPL-Caltech)

Figure 36: A recording of a magnitude 3.3 marsquake from InSight's seismometer, called SEIS. This quake was recorded on July 25, 2019 (Sol 235). Far below the human range of hearing, this sonification from SEIS had to be sped up and slightly processed to be audible through headphones (image credit: NASA/JPL-Caltech)

- Each quake is a subtle rumble. The Sol 235 quake becomes particularly bass-heavy toward the end of the event. Both suggest that the Martian crust is like a mix of the Earth's crust and the Moon's. Cracks in Earth's crust seal over time as water fills them with new minerals. This enables sound waves to continue uninterrupted as they pass through old fractures. Drier crusts like the Moon's remain fractured after impacts, scattering sound waves for tens of minutes rather than allowing them to travel in a straight line. Mars, with its cratered surface, is slightly more Moon-like, with seismic waves ringing for a minute or so, whereas quakes on Earth can come and go in seconds.

Mechanical Sounds and Wind Gusts

- SEIS has no trouble identifying quiet quakes, but its sensitive ear means scientists have lots of other noises to filter out. Over time, the team has learned to recognize the different sounds. And while some are trickier than others to spot, they all have made InSight's presence on Mars feel more real to those working with the spacecraft.

- "It's been exciting, especially in the beginning, hearing the first vibrations from the lander," said Constantinos Charalambous, an InSight science team member at Imperial College London who works with the SP sensors. "You're imagining what's really happening on Mars as InSight sits on the open landscape."

- Charalambous and Nobuaki Fuji of Institut de Physique du Globe de Parisprovided the audio samples for this story, including the one below, which is also best heard with headphones and captures the array of sounds they're hearing.

Figure 37: Listen to NASA's InSight at Work on Mars. NASA's InSight lander placed a seismometer on the Martian surface to study marsquakes. While it's found many, it has also detected other kinds of seismic signals, including some produced by the spacecraft itself. That includes wind gusts, InSight's robotic arm moving around and "dinks and donks," friction caused by parts inside the seismometer moving against each other as the temperature changes (video credit: NASA/JPL)

• August 23, 2019: The daily chatter between antennas here on Earth and those on NASA spacecraft at Mars is about to get much quieter for a few weeks. 52)

Figure 38: This animation illustrates Mars solar conjunction, a period when Mars is on the opposite side of the Sun from Earth. During this time, the Sun can interrupt radio transmissions to spacecraft on and around the Red Planet (image credit: NASA/JPL-Caltech)

- That's because Mars and Earth will be on opposite sides of the Sun, a period known as Mars solar conjunction. The Sun expels hot, ionized gas from its corona, which extends far into space. During solar conjunction, this gas can interfere with radio signals when engineers try to communicate with spacecraft at Mars, corrupting commands and resulting in unexpected behavior from our deep space explorers.

- To be safe, engineers hold off on sending commands when Mars disappears far enough behind the Sun's corona that there's increased risk of radio interference.

- "It's that time again," said Roy Gladden, manager of the Mars Relay Network at NASA's Jet Propulsion Laboratory in Pasadena, California. "Our engineers have been preparing our spacecraft for conjunction for months. They'll still be collecting science data at Mars, and some will attempt to send that data home. But we won't be commanding the spacecraft out of concern that they could act on a corrupted command."

When is this taking place?

- Solar conjunction occurs every two years. This time, the hold on issuing commands - called a "command moratorium" - will run from Aug. 28 to Sept. 7, 2019. Some missions will have stopped commanding their spacecraft earlier in preparation for the moratorium.

What happens to the spacecraft?

- Although some instruments aboard spacecraft - especially cameras that generate large amounts of data - will be inactive, all of NASA's Mars spacecraft will continue their science; they'll just have much simpler "to-do" lists than they normally would carry out.

- On the surface of Mars, the Curiosity rover will stop driving, while the InSight lander won't move its robotic arm. Above Mars, both the Odyssey orbiter and the Mars Reconnaissance Orbiter will continue collecting data from Curiosity and InSight for return to Earth. However, only Odyssey will attempt to relay that data to Earth before conjunction ends. Meantime, another orbiter, MAVEN, will continue to collect its own science data but won't support any relay operations during this time.

- All of this means that there will be a temporary pause in the stream of raw images available from Curiosity, InSight and the other Mars missions. Mars solar conjunction impacts operations of all spacecraft currently at Mars, not just NASA's.

What happens when solar conjunction ends?

- Once conjunction is over, the spacecraft will beam the data they've collected to NASA's Deep Space Network, a system of massive Earth-based radio antennas managed by JPL. Engineers will spend about a week downloading the information before normal spacecraft operations resume.

- If the teams monitoring these missions determine any of the collected science data are corrupted, they can usually have that data retransmitted after the moratorium ends on Sept. 7.

• July 22, 2019: Southern California got all shook up after a set of recent quakes. But Earth isn't the only place that experiences quakes: Both the Moon and Mars have them as well. NASA sent the first seismometer to the Moon 50 years ago, during the Apollo 11 mission; the agency's InSight lander brought the first seismometer to Mars in late 2018, and it's called the Seismic Experiment for Interior Structure (SEIS). 53)

- Provided by the French space agency, Centre National d'Études Spatiales (CNES), the seismometer detected its first marsquake on April 6, 2019. The InSight mission's Marsquake Service, which monitors the data from SEIS, is led by Swiss research university ETH Zurich.

Figure 39: This artist's concept is a simulation of what seismic waves from a marsquake might look like as they move through different layers of the Martian interior (image credit: NASA/JPL-Caltech/ETH Zurich/ Van Driel)

- Quakes look and feel different depending on the material their seismic waves pass through. In a new video, scientists at ETH demonstrate this by using data from the Apollo-era seismometers on the Moon, two of the first quakes detected on Mars by SEIS and quakes recorded here on Earth.

- By running data from these worlds through a quake simulator, or "shake room," scientists can experience for themselves how different the earthquakes can be. Researchers had to amplify the marsquake signals by a factor of 10 million in order to make the quiet and distant tremors perceptible in comparison to the similarly amplified moonquakes and unamplified earthquakes.

Figure 40: Fifty years after Apollo 11 astronauts deployed the first seismometer on the surface of the Moon, NASA InSight's seismic experiment transmits data giving researchers the opportunity to compare marsquakes to moon and earthquakes. The Marsquake Service (MQS) center at ETH Zurich in Switzerland monitors daily seismic activity on Mars (video credit: ETH Zürich, Published on Jul 19, 2019)