Cesium Mission 1
|Launch date||September 27, 2021|
|End of life date||September, 2023|
CM1 (Cesium Mission 1)
May 25, 2021: CesiumAstro Inc. with HQs in Austin, Texas, is preparing to launch two CubeSats in September 2021 to demonstrate the firm's active phased array technology and to provide customers with an on-orbit testbed. 1)
Through the Cesium Mission 1 announced May 25, Cesium plans to demonstrate proprietary hardware and software in addition to testing intersatellite links and Ka-band communications.
"We have flight-qualified our products in-house, but the ultimate test is to get them in orbit," Shey Sabripour, Cesium founder and CEO, told SpaceNews.
Sabripour founded Cesium in 2017 to provide plug-and-play phased array communication payloads for space and airborne applications. After years of operating in stealth mode during the firm's initial research and development campaign, Cesium is now ramping up in-house manufacturing, testing components and shipping flight hardware to government and commercial customers.
Customers include the U.S. Navy, NASA and the U.S. Missile Defense Agency, which have awarded Cesium Small Business Innovation Research contracts. In addition, Cesium has backing from the Pentagon's Defense Innovation Unit (DIU).
DIU is helping to fund Cesium Mission 1. As part of that mission, two six-unit CubeSats are scheduled to travel to low Earth orbit in September as secondary payloads on the United Launch Alliance Atlas 5 rocket transporting the NASA-U.S. Geological Survey Landsat-9 Earth-observation satellite.
Once the CubeSats are in orbit, Cesium plans to demonstrate the performance of its Ka-band active phased array, SDR (Software-Defined Radio) and single-board computer, a device about the size of a credit card. In addition, the firm plans to conduct on-orbit experiments.
Cesium is offering customers the ability to purchase time on the five-year Cesium Mission 1 to experiment with active phased array and intersatellite links. Customers have expressed interest, for example, in testing waveform switching, edge processing and communications link optimization, Sabripour said.
Austin, Texas-based Cesium established a spacecraft design facility in 2020 in Broomfield, Colorado to offer the type of "end-to-end system analysis and design" the firm plans to demonstrate in orbit, Sabripour said.
After Cesium Mission 1, Cesium's roadmap calls for annual missions to demonstrate technologies like the Link 16 active phased array for military communications that the company developed and tested under a Navy SBIR (Small Business Innovation Research) contract. Link 16 is an encrypted radio frequency favored by the United States and NATO Allies for sharing information in military theaters.
Cesium also is working with the NASA Ames Research Center to test a compact intersatellite link communication system designed for satellites operating in swarms.
In addition, CesiumAstro is delivering a communications system this week to the NASA Glenn Research Center as part of the SmallSat Ka-band Operations User Terminal (SKOUT) project. SKOUT is a Ka-band communications system for a NASA mission that is designed to connect government and commercial relay satellite constellations as well as direct-to-ground communications networks.
Cesium Mission 1 (CM1) is CesiumAstro's first mission to launch and operate its own hardware in space. CM1 provides an on-orbit platform that consists of two 6U CubeSats, CM1 and CM2, for customer experiments that push the boundaries of small satellite communication (Figure 1). In addition, it gives Cesium the capability to demonstrate advanced features of our technology such as dynamic waveform switching and dynamic link optimization. With the launch of Mission 1, Cesium will have a complete commercial phased array communication system as well as an intersatellite link in LEO.
The spacecrafts have a high-accuracy attitude system with a star tracker and a state-of-the-art electric propulsion system. The satellites will perform several orbital maneuvres using thei electric propulsion system. At the end of the mission, they will also actively deorbit with their propulsion system.
The CM1 ground segment includes Cesium ground stations and the GlobalStar network for persistent command and telemetry. Cesium is developing ground stations at office locations in Texas and Colorado. These ground stations can communicate with the spacecraft over both payload and telemetry links. Additionally, the ground stations are remote-operable on the Cesium network across Cesium locations.
• September 17, 2021: CesiumAstro expects to be building satellites mostly by itself in two years to house the active phased arrays it has been developing, aiming to shift the paradigm for electronically steered antennas with commercial-like industrialization processes that lower costs and speed up production. 2)
- Austin, Texas-based CesiumAstro bought parts from small satellite manufacturers for the first two satellites featuring its antenna technology, which are currently slated to fly Sept. 27 as secondary payloads when a United Launch Alliance Atlas 5 Rocket launches Landsat-9 into near-polar orbit.
- However, the startup seeks more direct access to the end customers that have expressed interest in its active phased array antennas.
- "Our end customers fly communications and ISR (Intelligence Surveillance and Reconnaissance) payloads as a core mission, and so if you have the core technology for the core mission, why not use a commodity bus or build our own satellite bus," CesiumAstro founder and CEO Shey Sabripour told SpaceNews.
- The venture has been investing in a second division in Broomfield, Colorado, to build satellite platforms, although it will stop short of building the more complex parts of a satellite's architecture.
- "We're not going to build our own electric propulsion, maybe the star tracker, but pretty much everything else we have in-house capability," he said.
- Sabripour added: "We are keeping it a little bit under wraps, but we do have plans to have two vertically integrated Cesium satellites: One in 2023 and one in 2024."
• September 14, 2021: CesiumAstro, Inc., today announced it has secured AS9100 quality certification—a key milestone as the company readies to launch its first satellites into orbit this Fall. 3)
- Cesium has passed all quality audit requirements and received its AS9100D certification, widely recognized as the most adopted standard for quality management by the aerospace industry encompassing the requirements of the ISO 9001:2015 quality standard and additional requirements for quality and safety critical to aerospace applications.
- This certification comes after the successful completion of an extensive multi-site audit at both the company's Austin and Denver facilities and affirms Cesium's commitment to meeting and exceeding the demanding quality standards required by its customers.
- "Cesium's AS9100 certification is an important step in our company's development roadmap," said Shey Sabripour, Founder and CEO of CesiumAstro. "This certification formally recognizes our focus on quality which we have been building into our culture from day one."
- Preparing for an AS9100 certification audit is no small feat. Cesium's Quality Manual and processes were developed from the ground-up with the full commitment of leadership with an emphasis on applying aerospace best practices to new space and airborne applications.
- "Given CesiumAstro's growth trajectory and our commitment to mission critical applications, quality is a core value of our company," said Vera Chuang, Manager of Quality at CesiumAstro. "Every employee recognizes that they play a critical role in supporting and improving CesiumAstro's quality management system as well as ensuring we deliver the best products to our customers."
- Receiving this certification displays the commitment of CesiumAstro in developing a management system that aligns with the wider business strategy, making the organization accountable in all business processes, while improving communications and driving continuous improvements.
• August 31, 2021: CesiumAstro Inc., a leading manufacturer of active phased array communications payloads for space and airborne platforms has selected Keysight Technologies' design and validation solutions to help accelerate the design, manufacturing, and test of CesiumAstro's high-performance phased array communications payloads. 4)
- CesiumAstro's approach to phased array design dramatically reduces the cost to build, time to manufacture, and power to operate active phased array technologies making them ideal for a wide range of space and airborne platforms. However, test and calibration of large multi-element arrays can present both technical and resource challenges. Cesium's Nightingale 1 active phased array, launching on Cesium Mission 1 satellites in September, features 186 elements each with 64 phase states and 32 gain states behind each element requiring nearly 400,000 discrete measurements for a single run. Characterizing performance for transmit and receive across just a few different temperatures and operational scenarios increases the number of measurements exponentially. Utilizing the advanced triggering and memory features on the latest Keysight Technologies PNA-X network analyzer, CesiumAstro was able to reduce array characterization time from hours to minutes representing nearly 100x improvement in test times.
- "We would typically start a test around lunch time and collect our results late the next day," said Erik Luther, Director of Product at CesiumAstro. "Now we can collect a full set of measurements in just a few minutes."
- Rapid testing is a critical aspect of phased array design that extends beyond convenience. Environmental variables such as temperature changes over the time the array is operated introduces temperature gradients that adds to RF measurement uncertainty and makes the results difficult to correlate. Taking fast measurements minimizes temperature variation and other environmental phenomena ensuring that the phase and gain states are the only variables impacting performance. Faster measurements also allow the engineering team to calibrate and test the array under a wider range of scenarios, which ultimately gives the customer a more refined product.
- "The support of Keysight has been a critical aspect of our success," said Shey Sabripour, CEO and founder of CesiumAstro. "We utilize Keysight test equipment across sites to enable all of our teams to collaborate with a common set of state-of-the-art tools."
- "Keysight establishes close working relationships with our customers to accelerate their innovations," said Dan Dunn, Vice President of Keysight's Aerospace Defense Government Solutions. "Our collaboration with CesiumAstro has enabled the company to develop new high speed antenna test approaches which will benefit the entire space industry."
- CesiumAstro's cutting edge RF labs include high performance test equipment, multiple RF chambers, antenna ranges, and environmental test stands for parametric characterization, calibration, and over-the-air testing of its space and airborne communication products. To learn more about CesiumAstro's active phased array technology and see the hardware in-person visit the CesiumAstro booth at 'Satellite 2021' in National Harbor, MD the week of September 5, 2021.
• August 26, 2021: CesiumAstro Inc. today announces a key milestone in its collaboration with the U.S. Department of Defense's Defense Innovation Unit; CesiumAstro's first two spacecraft have been successfully integrated as secondary payloads onto the Atlas V rocket which will deliver NASA's Landsat-9 to orbit next month. 5)
- "This collaboration allows CesiumAstro to showcase the benefits of its scalable software-defined AESA (Active Electronically Steerable Array) technology in support of future DoD missions."
- The two-satellite on-orbit testbed allows both commercial and defense customers to run experiments using its AESA communications and crosslink communications payloads. Consisting of two 6U CubeSats, this mission will enable Low Earth Orbit (LEO) experimentation from September 2021 through 2026. CM1 is the first of several planned technology demonstration missions showcasing CesiumAstro's leading-edge communications payloads.
- CesiumAstro is partnering with the Defense Innovation Unit (DIU) to demonstrate a reduced-latency direct downlink to tactical ground terminals as one of several planned commercial and defense experiments. DIU, a US Department of Defense (DoD) organization, partners with leading commercial enterprises across the country to adopt and scale technologies that help solve critically important challenges. DIU selected CesiumAstro as one of the latest additions to its distinguished cohort of companies demonstrating excellence and creating rich, inventive solutions in a variety of critical areas from autonomy and AI to human systems, cyber, space, and connectivity.
- Multiple experiments are planned on CM1 with partners across both commercial and government sectors. The communications payloads featured on CM1 are available for sale as standard and customizable products for both satellite and airborne missions.
• July 14, 2021: CesiumAstro announced today the release of the flight-ready SDR-1001 credit-card-sized modular software-defined radio (SDR) for commercial, government and defense applications, tested to NASA GEVS (General Environmental Verification Standard) and available in volume. Featuring 4 TX and 4 RX channels tunable from 300 MHz to 6 GHz, the SDR-1001 ships with a default BPSK/QPSK modem and optional FPGA Developer Toolkit enabling custom waveform development. 6)
- SDR-1001 Highlights:
a) High-reliability flight-ready solution for Low Earth Orbit (LEO) and airborne missions
b) Credit-card-sized stand-alone module weighing 100 grams
c) 4 TX / 4 RX Channels tunable from 300 MHz to 6 GHz with 100 MHz RF bandwidth per channel
d) Custom waveform support with 70% FPGA resources available for custom designs
e) Ships with a default CSMA mesh networking modem with SpaceWire and Ethernet connectivity.
- Designed to meet the demanding requirements for launch, as well as the extreme conditions of space and airborne environments, the SDR-1001 integrates a flexible RF front-end with high-performance FPGA to support a 5-to-7-year mission duration. Mil-Spec connectors provide access to RF signals and enable both SpaceWire and Ethernet connectivity. Integrated redundancy and failover logic provide resiliency from radiation events with onboard telemetry delivering system health and power management information.
- The pre-loaded reference modem functionality provides a CSMA (Carrier Sense Multiple Access) based multi-point mesh networking capability out of the box. When two SDRs establish a connection, data packets from Ethernet, SpaceWire, or serial port are routed across the link. Cesium is also developing turnkey waveform support for DVB-S2, DVB-S2X and CCSDS with TX data rates up to 500 Mb/s.
- Cesium's FPGA Development Kit allows communications engineers to build and deploy custom waveforms on the SDR-1001's open and reconfigurable FPGA. The underlying BSP (Board Support Package) firmware provides a simplified API for controlling the RF front end and data management while enabling full access to baseband IQ data for custom waveform and modem development. Support and training are provided with the FPGA Development Kit to accelerate user success. - "SDR-1001 is a key component of Cesium's product portfolio of modular payload solutions," said Shey Sabripour, founder and CEO of CesiumAstro. "We're focused on providing high-reliability solutions at scale to meet the growing needs of New Space and airborne markets using the latest technology advancements."
- The SDR-1001 is offered as a stand-alone module, but also forms the backbone of other Cesium products, including fully integrated L-band, S-band, X-band, Ku-band, and Ka-band connectivity and phased array solutions. Producing low-SWaP, plug-and-play hardware with high-volume manufacturing techniques, Cesium is uniquely suited to support volume orders for LEO space and airborne applications.
• June 15, 2021: Opportunity Austin, the Greater Austin Chamber's five-county prosperity initiative, today announced plans for space communications company CesiumAstro to expand its presence in the Austin region. CesiumAstro designs and manufactures high-throughput, plug-and-play APA (Active Phased Array) communication payloads and satellites for space and airborne platforms. Their software-defined, modular APA communication systems are used within a multitude of diversified markets spanning across space, air, ground and sea. The company recently announced the launch of their first mission to space – Cesium Mission 1, which will take place this September. 7)
- "Innovative companies like CesiumAstro demonstrate how diverse the Austin region's business community is," Charisse Bodisch, Austin Chamber senior vice president, economic development, said. "We're thrilled to have someone in the space industry call Austin home, and excited to see their rapid expansion in the coming months."
- CesiumAstro, one of BuiltIn Austin's 21 companies to watch in 2021, is currently operating out of a 10,000 square foot space in the Hill Country Galleria and will soon turn that location into a state-of-the-art New Product Introduction facility as they move their Engineering and Corporate functions down the road to a new 29,000 square foot space at 13215 Bee Cave Parkway. CesiumAstro, with an employee growth rate exceeding 250% since early 2020, plans to continue expanding its headcount both in its Austin Headquarters and Broomfield, Colorado office. The company is currently hiring for hardware and software engineering positions as well as a variety of business administration professionals, including IT, HR, Finance, and more.
- "Our team rapidly expanded throughout the pandemic in part due to the incredible talent looking to make Austin their home," Shey Sabripour, founder and chief executive officer of CesiumAstro, said. "Austin is known as a technology and innovation hub, allowing companies such as CesiumAstro to attract the very best engineers and business professionals on the market. We appreciate the Austin Chamber's vision and support as we grow within the region."
• May 25, 2021: CesiumAstro, Inc. announces the upcoming launch of Cesium Mission 1, an on-orbit testbed allowing customers to run experiments on electronically steerable, multibeam APA (Active Phased Array) technology. Spearheaded by Founder and CEO Shey Sabripour, an industry pioneer who spent over two decades at Lockheed Martin Space Systems, CesiumAstro is a full-scale manufacturer advancing airborne and next-generation aerospace platforms. 8)
- "At CesiumAstro, we are modernizing global connectivity. Through this new mission, CesiumAstro's customers will directly benefit from the rich range of opportunities APA communication and sensing systems with a fully software-defined digital backend can provide," notes Sabripour. "As our team supplies critical defense and commercial sector customers, the breadth of our expanding product offerings is now on full display with our most recent shipments of flight-qualified hardware."
- CesiumAstro has rapidly matured both hardware and software solutions, with key support from major government programs, since its inception:
a) Granted the U.S. Navy's Rapidly Integrated Tactical Communications Payload Award, CesiumAstro developed a multi-beam active phased array antenna, enriched by software-defined radio, digital backend, and capable of connecting disparate networks and providing stand-in resilience in contested environments;
b) Honored with NASA's Transformational Communications Technology Development Award, CesiumAstro completed a conceptual design for a next-generation payload to be used for commercial-scale arrays in lunar exploration;
c) In collaboration with the Missile Defense Agency, CesiumAstro has been developing a high-speed missile-to-missile communication system; and
d) Coordinating with the Defense Innovation Unit (DIU), CesiumAstro is launching its first two satellites in September 2021 on a rideshare with Landsat-9.
- In recent months, CesiumAstro has also manufactured and shipped flight hardware for several NASA programs:
1) CesiumAstro completed shipment of a compact intersatellite link communication system, gearing up to test mobile networking technologies within swarm missions, through a contract with NASA's Ames Research Center in Silicon Valley;
2) In support of NASA's Glenn Research Center and its SmallSat Ka-band Operations User Terminal (SKOUT) project, CesiumAstro delivered a space communication system designed to provide direct-to-earth communication between NASA mission spacecraft operating with NASA and commercial relay satellite constellations in GEO, as well as direct-to-ground (DTG) networks;
3) CesiumAstro manufactured and shipped a communications system to NASA's Glenn Research Center for use in cognitive communications research, aiding NASA in the development of techniques supporting autonomy for swarm missions and future lunar architecture deployment.
• December 17, 2020: Shey Sabripour was first exposed to active phased array antennas while designing satellites at Lockheed Martin in the early 1990s. 9)
- At the time, engineers spent three to five years building a geostationary communications satellite that cost hundreds of millions of dollars to perform a specific job. If that job was broadcasting television programming to the United States, the satellite's fixed beams offered coverage in the shape of the U.S. map.
- High-end military satellites with active phased arrays were far more flexible. Operators could steer beams electronically, modify power levels to address changing demand and even move a satellite to a different orbit to fulfill a new mission.
- "I thought, ‘Why aren't we building all communication satellites around active phased arrays,'" Sabripour told SpaceNews. "We should be able to have lots of beams we can put where the customers are. When the business plan changes, just go ahead and change the beams."
- For the next 25 years, Sabripour watched as the cost of phased array technology dropped and the entrepreneurial space sector blossomed. "I just couldn't get it out of my mind," he said.
- Dramatic improvements in semiconductor technology produced inexpensive, radiation tolerant chips, meaning the cost of active phased arrays, which require considerable numbers of amplifiers and beamformers, was falling as well.
- Sabripour was tempted to form his own company in the late 1990s, just before the dot-com bubble burst and low Earth orbit telecommunications constellations like Iridium, Globalstar and Teledesic struggled.
- "I stayed at Lockheed Martin," Sabripour said.
- Finally in 2017, after spending three years as chief technology officer for launch vehicle developer of Firefly Space Systems, predecessor to Firefly Aerospace, Sabripour founded CesiumAstro in Austin, Texas, with the goal of making phased arrays as ubiquitous as he envisioned decades earlier.
- "If there was ever a time for this technology, it's now," Sabripour said. "There's more demand on spectrum and low Earth orbit constellation require phased array technologies."
- In late November, CesiumAstro raised $15 million in an investment round led by Airbus Ventures and Kleiner Perkins.
- CesiumAstro has raised $29.2 million to date to establish its business of selling phased array communications and radio frequency sensing payloads for government and commercial customers including the Aerospace Corp., Airbus, Defense Advanced Research Projects Agency, Defense Innovation Unit, Honeywell, NASA, Northrop Grumman, the U.S. Missile Defense Agency and the U.S. Navy.
- "One of the pillars of the company is providing the full stack a payload requires," Sabripour said. "We want it to work right out of a box, where all you should need is a high-speed data cable to steer your beams."
- CesiumAstro plans to offer Lego-like building blocks for full-stack phased arrays in frequencies from L-band to V-band. The company has built, qualified and begun shipping its first-generation S-band products with the Ka-band products scheduled to ship in the spring of 2021.
- With the latest funding, CesiumAstro plans to launch two CubeSats to prove its technology in space and to expand the number of frequencies it offers customers.
- In addition, CesiumAstro plans to expand its workforce from the current level of about 60 employees to 100 people by late 2021. CesiumAstro also plans to establish a new facility.
- The company established a second office in Broomfield, Colorado, in May to build end-to-end CubeSat missions for customers. CesiumAstro also is preparing to open a design center for radio frequency payloads in El Segundo, California, in early 2021.
The CM1 mission of CesiumAstro with two 6U CubeSats (CM1 and CM2) was launched as a secondary payload on a United Launch Alliance Atlas-5 vehicle AV-092) from Vandenberg Space Force Base (SLC3E), California on 27 September 2021 at 18:12 UTC. The primary payload on this mission was Landsat-9 of NASA/USGS. 10)
Orbit of Landsat-9: Sun-synchronous near-circular orbit, altitude = 705 km, inclination = 98.2º, period = 99 minutes, repeat coverage = 16 days. The Landsat-9 satellite will be in coplanar orbit with Landsat-8, 180º apart. This reduces the repeat coverage to 8 days.
Four CubeSats for NASA's 37th Educational Launch of Nanosatellites (ELaNa 37) mission and the Mission Manifest Office at the U.S. Space Force Space Systems Command will begin separating from Centaur at approximately T+plus 2 hours, 14 minutes. The CubeSats are carried on the Evolved Expendable Launch Vehicle Secondary Payload Adapter (ESPA) Flight System, or EFS. It is a ring positioned below the Landsat-9 and above the top of Centaur carrying the four science and national security CubeSats. 11)
ULA's four-meter-diameter metallic payload fairing, built at the company's facility in Harlingen, Tex., protects Landsat-9 and the CubeSats during ascent through Earth's atmosphere. The longest of available Atlas V four-meter fairings will be used, known as the Extra Extended Payload Fairing (XEPF).
• CUTE (Colorado Ultraviolet Transit Experiment), a 6U CubeSat astronomy mission of the University of Colorado at Boulder, Boulder, Colorado.
• CuPID (Cusp Plasma Imaging Detector), a 6U CubeSat space weather science mission of Boston University, Boston Massachusets.
• CM1 (Cesium Mission 1) of CesiumAstro with two 6U CubeSats (CM1 and CM2), a technology demonstration mission.
Orbit of the secondary payloads: After deployment of Landsat-9, the Centaur stage will reignite its engine two times to maneuver into a different orbit for separation of four small CubeSat rideshare payloads. The CubeSats will be delivered into a near-circular sun-synchronous orbit of 550 km altitude with an inclination of 97.6º.
2) Jason Rainbow, "CesiumAstro plots in-house satellite production ramp-up after debut launch," SpaceNews, 17 September 2021, URL: https://spacenews.com/cesiumastro-plots-in-house-satellite-production-ramp-up-after-debut-launch/
3) "CesiumAstro Achieves AS9100 Quality Certification," CesiumAstro, 14 September 2021 Press Release, URL: https://www.cesiumastro.com/press-releases/cesiumastro-achieves-as9100-quality-certification
4) CesiumAstro selects Keysight Technologies for state-of-th- art phased array calibration," CesiumAstro Press Release, 31 August 2021: URL: https://www.cesiumastro.com/press-release/cesiumastro-selects-keysight-technologies-for-state-of-the-art-phased-array-calibration
5) "CesiumAstro, Inc. Partners With the U.S. Department of Defense to Launch On-Orbit Active Phased Array Satellite Testbed for Global Users," Businesswire news, 26 Aug. 2021, https://www.businesswire.com/news/home/20210826005009/en/CesiumAstro-Inc.-Partners-With-the-U.S.-Department-of-Defense-to-Launch-On-Orbit-Active-Phased-Array-Satellite-Testbed-for-Global-Users
6) "CesiumAstro Releases Space Qualified Software-Defined Radio with Open Reconfigurable FPGA," CesiumAstro Press Release, 14 July 2021, URL: https://www.cesiumastro.com/press-release/cesiumastro-releases-space-qualified-software-defined-radio-with-open-reconfigurable-fpga
7) "Opportunity Austin announces CesiumAstro expansion in Austin," AustinChamber Press Release, 15 June 2021, URL: https://www.austinchamber.com/press-releases/austin-chambers-opportunity-austin-announces-cesiumastro-expansion-in-austin
8) "Airborne and In-Orbit Communications Leader CesiumAstro, Inc. Readies for First Mission to Launch; Company Wins Swath of Commercial Milestones," Businesswire, 25 May 2021, https://www.businesswire.com/news/home/20210525005653/en/Airborne-and-In-Orbit-Communications-Leader-CesiumAstro-Inc.-Readies-for-First-Mission-to-Launch-Company-Wins-Swath-of-Commercial-Milestones
9) Debra Werner, "CesiumAstro founder closes in on decades-old dream," Space News, 17 December 2020, URL: https://spacenews.com/cesiumastro-founder-closes-in-on-decades-old-dream/
10) "NASA Launches New Mission to Monitor Earth's Landscapes," NASA Press Release 21-126, 27 September 2021, URL: https://www.nasa.gov/press-release/nasa-launches-new-mission-to-monitor-earth-s-landscapes
11) "Landsat 9: Payloads stacked atop Atlas V for launch," ULA, 16 September 2021, URL: https://blog.ulalaunch.com/blog/landsat-9-payloads-stacked-atop-atlas-v-for-launch
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 (firstname.lastname@example.org).