Minimize ISS: SpaceX CRS-6

ISS Utilization: SpaceX CRS-6 (Commercial Resupply Services-6) mission

Overview     Launch   Mission Status    Recovery Attempt   References

Dragon is packed with a total of 2015 kg of scientific experiments, technology demonstrations, crew supplies, spare parts, food, water, clothing and assorted research gear for the six person Expedition 43 and 44 crews serving aboard the ISS. The science payloads (844 kg) will study new ways to possibly counteract the microgravity-induced cell damage seen during spaceflight, the effects of microgravity on the most common cells in bones, gather new insight that could lead to treatments for osteoporosis and muscle wasting conditions, continue studies into astronaut vision changes and test a new material that could one day be used as a synthetic muscle for robotics explorers of the future. 1) 2)

Also making the trip will be a new espresso machine (ISSpresso) for space station crews. Lavazza and Argotec, in cooperation with ASI (Italian Space Agency), have developed a coffee machine. — After five weeks at the space station, the spacecraft will return with about 1370 kg of cargo, including crew supplies, hardware and computer resources, science experiments, space station hardware, and trash.

Launch: The CRS-6 mission was launched on April 14, 2015 (20:10:41 UTC) from Cape Canaveral SLC-40 (Space Launch Complex-40) on a Falcon-9 v1.1 vehicle. 3) 4)

Orbit: Near-circular orbit of the ISS, altitude of ~400 km, inclination = 51.6o.

Secondary payloads:

• AggieSat-4, a technology demonstration microsatellite (50 kg) of Texas A&M University.

• Bevo-2, a 1U CubeSat of the University of Texas, Austin. The goal is to perform to rendezvous with AggieSat-4 and to perform docking and undocking maneuvers.

• Arkyd-3A, a 3U CubeSat of Planetary Resources Inc. of Bellevue, WA (4 kg). Arkyd-3A is a reflight of Arkyd-3, which was lost in the Cygnus CRS Orb-3 flight accident in October 2014.

• Flock-1e x 14, an imaging constellation of 14 3U CubeSats of Planet Labs Inc., each with a mass of ~5 kg.

All secondary payloads will be deployed from an ISS airlock at a later date.

Approach to Station: As Dragon chases the station, the spacecraft will establish UHF communication using its COTS Ultra-high-frequency Communication Unit (CUCU). Also, using the crew command panel (CCP) on board the station, the space station crew will interact with Dragon to monitor the approach. This ability for the crew to send commands to Dragon will be important during the rendezvous and departure phases of the mission (Ref. 2).

During final approach to the station, a go/no-go is performed by Mission Control in Houston and the SpaceX team in Hawthorne to allow Dragon to perform another engine burn that will bring it 250 m from the station. At this distance, Dragon will begin using its close-range guidance systems, composed of LIDAR (light radar) and thermal imagers. These systems will confirm that Dragon's position and velocity are accurate by comparing the LIDAR image that Dragon receives against Dragon's thermal imagers. Using the Crew Command Panel, the ISS crew, monitored by the Dragon flight control team in Hawthorne and the NASA flight control team at the Johnson Space Center's International Space Station Flight Control Room, will command the spacecraft to approach the station from its hold position.

After another go/no-go is performed by the Houston and Hawthorne teams, Dragon is permitted to enter the Keep-Out Sphere (KOS), an imaginary sphere drawn 200 m around the station within which the Dragon approach is monitored very carefully to minimize the risk of collision. Dragon will proceed to a position 30 m from the station and will automatically hold. Another go/no-go is completed. Then Dragon will proceed to the 10 m position—the capture point. A final go/no-go is performed, and the Mission Control Houston team will notify the crew they are go to capture Dragon.


Figure 1: Schematic view of the Dragon approach sequence (image credit: NASA)

Capture and Berthing: At that point, Expedition 43 Flight Engineer Samantha Cristoforetti of ESA, with assistance from Commander and NASA Astronaut Terry Virts, will use the station's 17.6 m robotic arm (Canadarm2) to reach out and capture the Dragon spacecraft as they operate from the station's cupola. Ground commands will be sent from Houston for the station's arm to rotate Dragon around and install it on the bottom side of the station's Harmony module, enabling it to be bolted in place for its stay at the International Space Station.



Status of the CRS-6 mission:

• On May 21, SpaceX's Dragon cargo CRS-6 spacecraft splashed down into the Pacific Ocean at 16:42 UTC, about 300 km southwest of Long Beach, California, with 1400 kg of NASA cargo from the International Space Station, including research samples pertaining to a host of experiments on how spaceflight and microgravity affect the aging process and bone health. 5)

- Equipment and data from the Special Purpose Inexpensive Satellite (SpinSat) investigation also made the trip back to Earth. The SpinSat study tested how a spherical satellite, measuring 56 cm in diameter, moves and positions itself in space using new thruster technology. Researchers can use high-resolution atmospheric data captured by SpinSat to determine the density of the thermosphere, one of the uppermost layers of the atmosphere. With better knowledge of the thermosphere, engineers and scientists can refine satellite and telecommunications technology.

- Following the complete success of the SpaceX Dragon CRS-6 mission, NASA just announced that the next SpaceX Dragon is currently slated to launch on June 26, 2015.

• April 22, 2015: The Dragon spacecraft has brought fresh supplies and experiments to the weightless research laboratory. Samantha has been performing experiments as diverse as studying fruit flies, investigating small particles in liquids, looking at microscopic worms and growing plants. 6)

- Fruit flies are a model organism for scientists and are studied extensively – they live for around a week and share many genes with humans. This experiment will chart gene changes over generations of fruit flies in space in relation to diseases.

- Samantha has been looking at colloids – small particles suspended in liquids, found in milk and paint for example – for a NASA experiment to understand how they behave without gravity's interference. This research ties in with ESA's colloid experiments.

- Another common traveller on the Station and an often-studied animal for biologists is the Caenorhabditis elegans worm. Previous research has shown that the worm adapts and even thrives in weightlessness, implying that muscles might age less in space.

- The latest Dragon spacecraft delivered the second part of ESA's Triplelux experiment that is investigating the immune system of organisms on a cellular level. Samantha kicked off the Triplelux-B experiment earlier this year by recording how immune cells from the common blue mussel react to an infection. Samantha will continue the experiment now that a second set of samples from a rat's immune system has arrived.


Figure 2: ESA astronaut Samantha Cristoforetti is working with ESA's Biolab facility in the Columbus laboratory on the Station for the Triplelux experiment (image credit: ESA, NASA)

• April 18, 2015: Following the flawless blastoff of the SpaceX Falcon-9 booster and Dragon cargo ship on April 14, the resupply vessel arrived at the International Space Station on April 17, and was successfully captured by the Expedition 43 Flight Engineer Samantha Cristoforetti of ESA. Cristoforetti grappled the SpaceX Dragon freighter with the station's Canadarm2 robotic arm at 02:55 GMT, with the able assistance of fellow crewmate and Expedition 43 Commander Terry Virts of NASA. Dragon is berthed to the Harmony module. 7)

By the next day, crew will pressurize the vestibule between the station and Dragon and will open the hatch that leads to the forward bulkhead of Dragon. The crew will work over the next four weeks to unload Dragon's payload and reload it with cargo that Dragon will bring back to Earth.


Figure 3: Astronaut Terry Virts tweeted this picture of the SpaceX Dragon supply ship approaching the ISS (image credit: NASA, AstroTerry)



First stage recovery attempt:

The mission will also feature the next daring attempt by SpaceX to recover the Falcon 9 booster rocket through a precision guided soft landing onto an ocean-going barge. The Falcon 9 first stage is outfitted with four landing legs and grid fins to enable the landing attempt, which is a secondary objective of SpaceX. Cargo delivery to the station is the overriding primary objective and the entire reason for the mission. 8)

After a 24 hour delay due to threatening clouds, a SpaceX Falcon-9 rocket soared spectacularly to orbit from the Florida Space coast. SpaceX's bold attempt to land and recover the 14 story tall first stage of the Falcon-9 rocket successfully reached a tiny ocean floating barge in the Atlantic Ocean, but tilted over somewhat over in the final moments of the approach, and tipped over after landing and broke apart. - SpaceX will continue with attempt to soft land and recover the rocket on upcoming launches, which was a secondary goal of the company. 9)


Figure 4: View of the CRS-6 Falcon 9 first stage landing burn and touchdown on the landing barge (image credit: SpaceX) 10)

The dramatic high-resolution landing video was released by SpaceX CEO Elon Musk. It clearly reveals the deployment of the four landing legs at the base of the booster as planned in the final moments of the landing attempt, aimed at recovering the first stage booster.

At about three minutes after launch, the spent fourteen story tall first stage had separated from the second stage and reached an altitude of some 125 km following a northeastwards trajectory along the U.S. east coast.

SpaceX engineers relit a first stage Merlin 1D engine some 320 km distant from the Cape Canaveral launch pad to start the process of a precision guided descent towards the barge, known as the ADCS (Autonomous Spaceport Drone Ship). It had been pre-positioned offshore of the Carolina coast in the Atlantic Ocean.

The Falcon-9 first stage successfully reached the tiny ocean floating barge in the Atlantic Ocean, but tilted over somewhat over in the final moments of the approach, and tipped over after landing and exploded in a fireball.

The next landing attempt is set for the SpaceX CRS-7 launch, currently slated for mid- June, said Hans Koenigsmann, SpaceX Director of Mission assurance, at a media briefing at KSC.

1) "SpaceX CRS-6 Mission Overview," NASA, April 7, 2015, URL:

2) SpaceX CRS-6 Mission Cargo Resupply Services Mission," NASA Press Kit, Pril 2015, URL:

3) Stephanie Schierholz, Dan Huot, "Research for One-Year Space Station Mission Among NASA Cargo Launched Aboard SpaceX Resupply Flight," NASA, April 14, 2015, Release 15-062, URL:

4) "Liftoff: Falcon 9 and Dragon begin CRS-6 mission to resupply the Space Station," SpaceX, April 14, 2015, URL:

5) Kathryn Hambleton, Dan Huot, "Critical NASA Research Returns to Earth Aboard U.S. SpaceX Dragon Spacecraft," NASA, May 21, 2015, Release 15-103, URL:

6) "Second Dragon, fruit flies and fresh coffee for Samatha," ESA, April 22.2015, URL:

7) Ken Kremer, "Dragon Snared by Stations ‘Star Trek' Crewmate, Delivers Science for 1 Year Mission," Universe Today, April 17, 2015, URL:

8) Ken Kremer, "SpaceX Resets CRS-6 Space Station Launch to April 13 with Booster Landing Attempt," Universe Today, April 4, 2015, URL:

9) Ken Kremer, "SpaceX Dragon Launches on Science Supply Run to Station, Booster Hard Lands on Barge," Universe Today, April 14, 2015, URL:

10) Ken Kremer, "High Resolution Video Reveals Dramatic SpaceX Falcon Rocket Barge Landing and Launch," Universe Today, April 17, 2015, URL:

The information compiled and edited in this article was provided by Herbert J. Kramer from his documentation of: "Observation of the Earth and Its Environment: Survey of Missions and Sensors" (Springer Verlag) as well as many other sources after the publication of the 4th edition in 2002. - Comments and corrections to this article are always welcome for further updates (

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