Capella X-SAR (Synthetic Aperture Radar) Constellation
The Palo Alto California-based commercial startup company Capella Space, founded in 2016 by Payam Banazadeh and William Woods, is in the process of developing a constellation of X-SAR microsatellites to provide global coverage. The Capella constellation will consist of 36 microsatellites, each one will operate at an altitude of around 500 km in an approximately 90-minute polar orbit, providing average imaging revisit times of less than one hour. The radars will be single-polarization X-band systems, capable of operating over a 500 MHz bandwidth in stripmap and spotlight imaging modes. 1)
This year, Capella Space will launch two sub-50 kg satellites as the prelude to a constellation of 36 that will provide hourly revisit time. This constellation will enable delivery of products to meet specific user demands anywhere in the world.
The constellation will be launched in 2019 with the initial deployment of 6 satellites in two orbital planes. The average imaging revisit time will be between 3 and 6 hours, and the maximum revisit time will be 6 hours. Hourly maximum revisit times will be achieved when the full constellation of 36 satellites is deployed in 2021 (Figure 1).
Each Capella satellite has a three-year design life. By launching 12 satellites per year, the constellation will maintain its imaging capability indefinitely. With the ability to continually update and refresh the satellite technology, Capella will be able implement improvements to the constellation and radar performance quarterly. The system specifications for the first satellites are listed in Table 2.
Table 1: Capella constellation timeline and capability
Sensor complement (X-SAR)
Capella SAR satellites will operate at X-band with a bandwidth of up to 500 MHz. Ground resolution and swath width vary with look angle (Figure 2), but users will be able to select a combination of transmit bandwidth and PRF to meet their imaging requirements. The first Capella radars will operate with a single polarization. Improvement in radar system performance, such as polarimetric measurements, are planned for future generations of Capella satellites.
Figure 2: Ground range resolution plotted as a function of transmit bandwidth and look angle (image credit: Capella Space)
Radar Imaging Modes
The Capella satellites will be capable of imaging in several modes, including staring and sliding spotlight, traditional stripmap, and multi-swath stripmap. These modes are described below. Note that for most modes, the user can select the image size, and is able to trade resolution for imaging quality.
Spotlight: Capella satellites will be capable of staring-spotlight imaging, in which the beam is focused on a single point on the Earth throughout the acquisition. In this mode, azimuth resolution is limited by the duration of antenna beam on the target. US regulations control the resolution at which Capella can sell imagery. As a result, Capella can only offer single-look complex spotlight data for resolutions greater than 0.5 m, but is able to offer amplitude-only multi-looked spotlight images for resolutions between 0.3 m and 0.5 m. These multi-looked images will be acquired using a dwell time that results in a finer azimuth resolution than 0.3 m. The raw SAR data will be processed to full resolution, and then pixels in the amplitude-only image will be averaged (multi-looked) to produce high-resolution, speckle-free imagery that Capella is legally permitted to sell.
Multi-looking reduces speckle and increases detectability of objects in a SAR image. However, with many SAR systems, multi-looking comes at the cost of coarser azimuth resolution. Because Capella spacecraft can stare at a point on the ground for tens of seconds, Capella can provide multi-looked images constructed from tens of looks at very high final resolution, e.g., 0.3 m.
An example of the improvement in image quality achieved through multi-looked staring-spotlight has been simulated using airborne circular data. Simulated Capella multi-looked staring spotlight images are shown in Figure 3 (rows 2 through 5). Simulated single-look staring-spotlight acquisition images are shown in Figure 3 (row 1). The scene contains a road, cars in a parking lot, and several corner reflectors. NESZ values of typical large SAR systems such as TerraSAR-X are chosen to simulate the non-Capella radar simulated images. The simulations highlight contrast recovered in a SAR image by multi-looked staring-spotlight data processing, even when the NESZ is relatively poor (right-most column, rows 3, 4, and 5 in Figure 3. For example, the road emerges clearly in the 10-, 20-, and 30-look Capella images, but is hard to distinguish in the non-Capella radar single-look image despite that system having a lower NESZ. Note that in each column, multi-looking does not degrade resolution.
Capella satellites will also be able to acquire multiple staring spotlight images adjacent to each other. Each acquisition will have a shorter dwell time than the maximum dwell time possible with a single-spot staring spotlight acquisition, so either the resolution of each spot will be degraded as the number of spots increases, or the number of looks available for multi-looking will decrease as the number of spots increases. This mode is useful for extending the width (swath) of an area being imaged. For imaging a larger area in the along-track direction, i.e., increasing the length of a spotlight acquisition, sliding spotlight (see below) is more efficient. Maximum image sizes for 0.3 m and 1 m azimuth resolutions and associated number of looks for staring spotlight and multi-spot spotlight are shown in Table 3.
Sliding Spotlight: Sliding spotlight is a combination of stripmap and spotlight imaging modes. The beam slew rate is set so that it does not track a single point on the earth surface as in spotlight mode, but dwells on points for longer than that in stripmap mode. This mode is an approach to achieving a higher resolution pseudo-stripmap mode. Sliding spotlight scene sizes and best possible azimuth resolutions are shown in Table 4. For azimuth resolutions less than 0.3 m, pixels will be multi-looked and imagery provided as amplitude only data. For a sliding spot acquisition that results in an azimuth resolution of greater than 0.5 m, single-look complex data will be available (as with staring spotlight).
Figure 3: Simulated results for a typical large SAR (row 1) and Capella SAR (rows 2 through 5) showing the tradeoff between multi-looking, ground-range resolution, and NESZ for a spotlight image acquisition. Multi-looked staring spotlight acquisitions with Capella SAR recover contrast in the image without degrading resolution (image credit: Capella Space)
Stripmap and Multi-swath Stripmap: This mode is a standard synthetic aperture radar stripmap imaging mode. The swath is limited by a combination of the look angle, the radar beamwidth, and the PRF (Pulse Repetition Frequency) selected for the acquisition. The PRF is selected to either provide maximum swath with reduced azimuth ambiguity sidelobe ratio performance, or reduced swath with better azimuth ambiguity sidelobe ratio performance. The minimum slant range resolution is 0.3 m.
Capella satellites will capture a single wide-swath SAR image in a single horizon-to-horizon pass by collecting multiple sequential stripmap swaths adjacent in the range direction. The number of sequential stripmap swaths is limited by the length of the final wide-swath image and spacecraft slewing times. Stripmap and multi-swath stripmap image sizes are listed in Table 5.
With six satellites in two planes, repeat-pass (repeat-track) interferometric measurements are possible according to timeseries 0 in Table 6 (i.e., collections at hours 0, 54, 120, 174, ...). In addition, a different timeseries of repeat-pass interferometric collections made at a different look angle, but of the same area on the ground, is possible 12 hours later, i.e., at timeseries 1 in Table 6 (hours 12, 66, 132, 186, ...). Notice that the timeseries sequence repeats after 10 time-series, or 120 hours (5 days), i.e., time-series 10 in Table 6 is timeseries 0 at 120 hours. A single timeseries is suitable for observing processes that change over time scales of five or more days.
Capella Space is preparing for its first launch on a SpaceX rocket this fall, an important milestone in the company’s plan to build a constellation of the world’s smallest commercial radar satellites. The Capella microsatellites have a mass of < 40 kg, which means four will fit on a single Rocket Lab Electron rocket, said Payam Banazadeh, Capella co-founder and chief executive. 2) 3)
In orbit, Capella plans to unfurl antennas made of a flexible material the company declined to specify. Once deployed, the antennas will span 8 m2, Banazadeh said during a recent tour of the firm’s San Francisco headquarters.
Figure 4: Capella graphic showing the size of its SAR satellites (image credit: Capella Space)
• January 21, 2020: Capella Space, an information services company providing Earth observation data on demand, today unveiled its evolved satellite design to enable on-demand observations of anywhere on Earth. Informed by extensive customer feedback and findings from the launch of Denali, Capella's testbed satellite, the re-engineered design features a suite of technological innovations to deliver timely, flexible and frequent sub-0.5 meter very high quality images to the market. The enhanced technology package will deliver the most advanced offering for small satellite SAR imagery on the market. 4)
"Our customers have spoken: today's industry standard of waiting eight hours to receive data is woefully outdated. They want access to imagery that is reliable, timely and, most importantly, high-quality," said Christian Lenz, vice president of engineering at Capella Space. "The innovations packed into our small satellite make Capella the first and only SAR provider to provide real-time tasking and capture of sub-0.5 m very high-quality imagery anywhere on Earth at any time. This is a game-changer for a variety of industries — from monitoring military threats to assessing crop yields in agriculture to coordinating disaster response."
Figure 5: Artist impression of Capella SAR satellite (background image courtesy NASA), image credit: Capella)
The satellite evolution is a direct result of customer feedback, extensive on-orbit testing with Capella's first testbed satellite Denali, as well as ground-based testing. Enhancements include:
- Advanced design delivering high contrast, low-noise, sub-0.5 meter imagery: A 3.5 meter deployed mesh-based reflector antenna combined with a high power RADAR enable key performance improvements including quality advances.
- Extended duty cycle: A deployed 400 W solar array increases on-orbit duty cycle to 10 minutes per orbit.
- Continuous imaging over long distance: Advanced thermal management systems allow continuous imaging of up to 4000 km long strip images.
- Highly agile platform: Enabled by large reaction wheels, the new satellite quickly adjusts pointing to collect images from diverse targets.
- Staring spotlight image mode: New mode further enhances image quality with the ability to collect the highest commercially available multi-look data.
- Enhanced data downlink rate: A high average data rate downlink of 1.2 Gbit/s supports the massive image collection rate and extended duty cycle, providing more data per orbit than any other commercial SAR system in its class.
- Real-time tasking: A highly secure encrypted two-way link with Inmarsat through an exclusive partnership with Addvalue provides real time tasking capability for the entire Capella constellation.
The new satellite design cemented major deals with multiple divisions of the U.S. government, including a contract with the United States Air Force and National Reconnaissance Office (NRO). The technological enhancements will be embedded in Capella's next six commercial satellites, named the "Whitney" constellation, starting with the launch of Sequoia slated for March of 2020. The Sequoia satellite is currently completing system level tests and will arrive at the launch site in early March.
Capella is also licensed by NOAA (National Oceanic and Atmospheric Administration) for its 36 small satellite constellation, along with approval to sell the highest resolution legally allowed SAR commercial imagery to customers globally.
• December 16, 2019: Space-based radar imagery provider Capella Space will launch seven satellites and start commercial operations in 2020, the company announced Dec. 16. 5)
- The San Francisco-based startup deployed one small synthetic aperture radar (SAR) satellite in December 2018 to test the service. The next seven it plans to launch in 2020 are a new design, Payam Banazadeh, CEO and founder of Capella Space, told SpaceNews.
- The first satellite, to be named Sequoia, will launch from Cape Canaveral in March into a polar sun-synchronous orbit on a SpaceX rocket. The next three satellites are booked on an Indian PSLV (Polar Satellite Launch Vehicle) flight scheduled for June to a polar sun-synchronous orbit. These would be the first batch of a constellation to be named Whitney.
- The next batch of three are being booked to go up late 2020. “We hope to finalize booking in the next few months,” said Banazadeh.
- Sequoia and Whitney are identical satellites but get different names because they are built in separate production cycles, he said. “We plan to launch between six and 12 satellites per year.” The goal is to have 36 satellites on orbit by 2023.
- Banazadeh said details of the new satellite design will be unveiled in January. Based on market research and tests with the prototype satellite, the company decided it needed larger spacecraft to accommodate a bigger sensor aperture that can provide high-resolution sub-0.5 meter imagery.
- Higher resolution imagery is especially important to government and military customers the company is pursuing in addition to commercial business. Capella has contracts with the U.S. Air Force and recently won a study contract from the National Reconnaissance Office.
- The new microsatellite design, at under 100 kg, is larger than the original 40 kg design. “It is still small but deploys to something really big in space,” said Banazadeh. “Over the last 12 months looking at the competition and talking to customers we realized we really want to dominate the very high resolution market. To meet that demand, we need a large aperture so we changed the size.”
- During the past year the company built the ground infrastructure and developed a process from when a customer puts in an imagery request to when the data gets downlinked into an Amazon Web Services (AWS) ground station and cloud service. “That process is fully automated,” said Banazadeh.
- The advantage of radar is that it can see through clouds. Customers want to see how patterns are changing but the higher resolution is important as well, he said. “We will be able to detect any object bigger than a half meter, and identify any object larger than 1.5 meters in any dimension.”
- A half-meter SAR image resolution of an airport, for example, would be able to discriminate the types of aircraft on the ground. A picture of a combat zone would show vehicles and identify if they are military or civilian.
- “That’s where the sub half-meter becomes very useful,” said Banazadeh. “Customers want to understand change and what is changing.”
- Capella expects to have an edge over competitors because it designed the new satellites to consume less power so they can image for 10 minutes per orbit, he noted.
- Radar in general even for bigger satellites consumes a lot of power. While optical imagery satellites are always imaging, radar satellites are only sent to take pictures of a specific area because they have limited power on board. “You have to know where you want to look at,” said Banazadeh. Capella predicts that 10 minutes of imaging per orbit will give it a competitive advantage over other small satellite services that can only image for two minutes per orbit, he said. “That limits how many locations they can look at and how they manage orders.”
- The company is promising customers that once it begins commercial operations it will be able to deliver SAR data in less than 30 minutes from the time of collection, a much faster turnaround than the industry average of eight to 12 hours, according to Banazadeh.
- To help shorten the cycle, Capella signed an agreement with Inmarsat to provide a communications terminal to go on every satellite. “We can access our satellites through the Inmarsat network in real time all the time,” he said. When a request comes in, it is immediately uploaded to a specific satellite. The time it takes for the satellite to reach the target will come down as more satellites are deployed, said Banazadeh.
- The 30 minute turnaround begins once the data is collected and beamed to the Amazon Ground Station. “The data gets into the cloud in 25 minutes, and we make it accessible to customers,” he said.
- Banazadeh said this is important to customers that use radar imagery precisely because they’re in a hurry and can’t wait for the clouds to go away. “Having to wait eight to 12 hours defeats the purpose.”
- Capella says it has funding to complete a seven satellite constellation launch in 2020, with backing from investors DCVC (Data Collective) and Spark Capital.
• September 26, 2018: Capella Space, an aerospace and information services company providing on-demand Earth observation data via advanced space radar,announced $19 million Series B funding led by Spark Capital and DCVC (Data Collective) and joined by Mark VC and Harmony Partners among other investors. This will finance the first operational launches of the company's cloud-penetrating, radar-powered small satellites, designed to deliver high-quality imaging anywhere and under any condition, day or night. In an unprecedented engineering feat, Capella's satellite, the size of a backpack on launch, combines an origami-like antenna that unfolds to almost 100 square feet with radically efficient electronics that together deliver effectively the same image quality as radar satellites the size of a school bus. The first Capella test satellite launch is scheduled for November 2018 ahead of next year's first operational launches of a planned 36-satellite constellation that will deliver reliable images from anywhere on the planet in under an hour. 6)
- "Major industries and governments are starved for timely satellite data, and even more so for data with the unique signal and intelligence advantage Capella's synthetic aperture radar tech can provide. Commodity trading, urban development, critical infrastructure, shipping and security: businesses across the board realize that milliseconds matter in today's global economy, and a steady stream of reliable, easily accessible Earth information just does not exist," said Matt Ocko of DCVC. "Capella is solving that problem for a broad range of customers, from typical players like the Department of Defense, and also for blue-chip companies and NGOs that need to understand risks to our collective future."
• In March 2018, NOAA awarded Capella a license to send two X-band SAR satellites into polar orbits between 450 to 600 km with an inclination of ~97.5º.
• Since it was founded in 2016, Capella has raised more than $15 million in private investment, including $12 million raised in 2017 through its Series A investment round led by Nabeel Hyatt of Spark Capital. Capella is currently raising Series B funding.
Figure 6: Artist's rendition of the deployed Capella microsatellite. The spacecraft is using an origami-like antenna that unfolds to 8 m2 (image credit: Capella Space) 7)
Launch: The Capella-1 demonstration spacecraft, a microsatellite of 37 kg, was launched on the SSO-A rideshare mission on 3 December 2018 (18:34:05 GMT) on a SpaceX Falcon-9 Block 5 vehicle from VAFB (Vandenberg Air Force Base) in California. 8) 9) 10)
Orbit: Sun-synchronous circular orbit with an altitude of 575 km, inclination of ~98º, LTDN (Local Time of Descending Node) of 10:30 hours.
• SpaceX statement: On Monday, December 3rd at 10:34 a.m. PST (18:34 GMT), SpaceX successfully launched Spaceflight SSO-A: SmallSat Express to a low Earth orbit from Space Launch Complex 4E (SLC-4E) at Vandenberg Air Force Base, California. Carrying 64 payloads, this mission represented the largest single rideshare mission from a U.S.-based launch vehicle to date. A series of six deployments occurred approximately 13 to 43 minutes after liftoff, after which Spaceflight began to command its own deployment sequences. Spaceflight’s deployments are expected to occur over a period of six hours. 11)
- This mission also served as the first time SpaceX launched the same booster a third time. Falcon 9’s first stage for the Spaceflight SSO-A: SmallSat Express mission previously supported the Bangabandhu Satellite-1 mission in May 2018 and the Merah Putih mission in August 2018. Following stage separation, SpaceX landed Falcon 9’s first stage on the “Just Read the Instructions” droneship, which was stationed in the Pacific Ocean.
• Capella Space information on 3 December 2018: Capella Space, an aerospace and information services company providing Earth observation data on demand, today announced the launch of its first small synthetic aperture radar (SAR) satellite. The satellite, named "Denali" after the tallest mountain in the U.S., will allow Capella to fine-tune their technology and operations as they progress toward reliably delivering hourly information and imagery in any condition anywhere on Earth. This launch marks a pivotal moment for American innovation, as Capella is the first and only U.S. company to develop and launch a radar satellite for commercial markets. 12)
List of payloads on the Spaceflight SSO-A rideshare mission
The layout of the list follows the alphabetical order of missions as presented on the Wikipedia page ”2018 in spaceflight” https://en.wikipedia.org/wiki/2018_in_spaceflight#November — as well as with the help of Gunter Krebs's short descriptions at https://space.skyrocket.de/doc_sdat/skysat-3.htm
This mission enabled 34 organizations from 17 different countries to place spacecraft on orbit. It’s also special because it was completely dedicated to smallsats. Spaceflight launched 15 microsatellite and 49 CubeSats from government and commercial entities including universities, startups, and even a middle school. The payloads vary from technology demonstrations and imaging satellites to educational research endeavors.
• AISTechSat-2, a 6U CubeSat for Earth observation of AISTech (Access to Intelligent Space Technologies), Barcelona, Spain.
• Al Farabi-2, a 3U CubeSat technology demonstration mission of the Al-Farabi Kazakh National University, Kazakhstan.
• Astrocast-0.1, a 3U CubeSat technology demonstration mission of Astrocast, Switzerland, dedicated to the Internet of Things (IoT)
• Audacy-0, a 3U CubeSat technology demonstration mission of Audacy, Mountain View, CA, built by Clyde Space.
• BlackSky-2, a microsatellite (55 kg) of BlackSky Global (Seattle, WA) which will provide 1 m resolution imagery with improved geolocation accuracy.
• BRIO, a 3U CubeSat of SpaceQuest Ltd. of Fairfax, VA to test a novel communications protocol that uses SDR (Software Defined Radio).
• Capella-1, a microsatellite (37 kg) of Capella Space, San Francisco, CA featuring a X-band SAR (Synthetic Aperture) payload.
• Centauri-1, a 3U CubeSat of Fleet Space Technologies, Adelaide, South Australia. Demonstration of IoT technologies.
• CSIM-FD (Compact Spectral Irradiance Monitor-Flight Demonstration), a 6U CubeSat of LASP (Laboratory for Atmospheric and Space Physics) at the University of Boulder, CO, USA. The goal is to measure solar spectral irradiance to understand how solar variability impacts the Earth’s climate and to validate climate model sensitivity to spectrally varying solar forcing.
• Eaglet-1, the first 3U CubeSat (5 kg) of OHB Italia SpA for Earth Observation.
• Elysium Star-2, a 1U CubeSat of Elysium Space providing space burial services.
• ESEO (European Student Earth Orbiter) sponsored by ESA, a microsatellite of ~40 kg with 6 instruments aboard.
• Eu:CROPIS (Euglena and Combined Regenerative Organic-Food Production in Space), a minisatellite (230 kg) of DLR, Germany. The objective is to study food production in space in support of future long-duration manned space missions (life sciences). The main payloads are two greenhouses, each maintained as a pressurized closed loop system, simulating the environmental conditions of the Moon or of Mars.
• eXCITe (eXperiment for Cellular Integration Technology), a DARPA (Defense Advanced Research Projects Agency) mission to demonstrate the 'satlets' technology. Satlets are a new low-cost, modular satellite architecture that can scale almost infinitely. Satlets are small modules that incorporate multiple essential satellite functions and share data, power and thermal management capabilities. Satlets physically aggregate in different combinations that would provide capabilities to accomplish diverse missions.Built by NovaWurks, eXCITE has a mass of 155 kg. eXCITE also carries the See Me (Space Enabled Effects for Military Engagements), a prototype microsatellite (~22 kg) built by Raytheon for DARPA to obtain on-demand satellite imagery in a timely and persistent manner for pre-mission planning.
• ExseedSat-1, a 1U CubeSat mission by the Indian company Exseed Space. The goal is to provide a multifunction UHF/VHF NBFM (Narrow Band Frequency Modulation) amateur communication satellite.
• FalconSat-6, a minisatellite (181 kg) of the USAFA (U.S. Air Force Academy) and sponsored by AFRL. FalconSat-6 hosts a suite of five payloads to address key AFSPC (Air Force Space Command) needs: SSA (Space Situational Awareness) and the need to mature pervasive technologies such as propulsion, solar arrays, and low power communications.
• Flock-3, three 3U CubeSats (5 kg each) of Planet Labs to provide Earth observation.
• Fox-1C, a radio amateur and technology research 1U CubeSat developed by AMSAT and hosting several university developed payloads.
• HawkEye, a formation-flying cluster of three microsatellites (13.4 kg each) of HawkEye 360, Herndon, VA, USA. The goal is to demonstrate high-precision RFI (Radio Frequency Interference) geolocation technology monitoring.
• Hiber-1 and-2, these are 6U CubeSats, a pathfinder mission of Hiber Global, Noordwijk, The Netherlands, for Hiber Global's planned (IoT) communications CubeSat constellation.
• ICE-Cap (Integrated Communications Extension Capability), a 3U CubeSat of the US Navy. The objectives are to demonstrate a cross-link from LEO (Low Earth Orbit) to MUOS (Mobile User Objective System) WCDMA (Wideband Code Division Multiple Access) in GEO (Geosynchronous Orbit). The objective is to send to users on secure networks.
• ICEYE-X2, a X-band SAR (Synthetic Aperture Radar) microsatellite (~ 80 kg) of Iceye Ltd, a commercial satellite startup company of Espoo, Finland.
• Irvine 02, a 1U CubeSat educational mission by the Irvine Public School Foundation, Irvine, CA. The Irvine CubeSat STEM Program (ICSP) is a multi-year endeavor that directly impacts over a hundred students from six high schools and two school districts.
• ITASAT-1 (Instituto Tecnológico de Aeronáutica Satellite), a Brazilian 6U Cubesat (~8kg) built by the Instituto Tecnológico de Aeronáutica (ITA). A former rescoped microsatellite mission.
• JY1-Sat, a 1U CubeSat of Jordan developed by students of various universities. The satellite will carry a UHF/VHF amateur radio.
• KazSTSAT (Kazakh Science and Technology Satellite), a microsatellite (<100 kg) of Ghalam LLP, Astana, Kazakhstan. Developed by SSTL on a SSTL-50 platform including an SSTL EarthMapper payload designed for global commercial wide-area imaging with a resolution of 17.5 m on a swath of 250 km.
• KNACKSAT (KMUTNB Academic Challenge of Knowledge SATellite) of Thailand, a 1U technology demonstration CubeSat, the first entirely Thai-built satellite, developed by students of King Mongkut’s University of Technology North Bangkok (KMUTNB). Use of an amateur radio for communication.
• Landmapper-BC (Corvus BC 4), a 6U CubeSat (11 kg) of Astro Digital (formerly Aquila Space), Santa Clara, CA, USA. The satellite features a broad coverage multispectral (Red, Green, NIR) imaging system with a resolution of 22 m.
• MinXSS-2 (Miniature X-ray Solar Spectrometer-2), a 3U CubeSat(4 kg) of LASP (Laboratory for Atmospheric and Space Physics) at the University of Colorado at Boulder,CO, USA. The objective is to study the energy distribution of solar flare SXR (Soft X-ray) emissions and its impact on the Earth’s ITM (Ionosphere, Thermosphere, and Mesosphere) layers.MinXSS-2 is a copy of the MinXSS-1 but with some improvements. — MinXSS-1 was launched on 06 December 2015 onboard of Cygnus CRS-4 to the ISS, were it was deployed into orbit on 16 May 2016. It reentered Earth's atmosphere on 6 May 2017.
• NEXTSat-1, a multi-purpose microsatellite (~100 kg) of Korea designed and developed at SaTReC (Satellite Technology Research Center) of KAIST (Korea Advanced Institute of Science and Technology). The goal is to conduct scientific missions such as star formation and space storm measurements and also technology demonstration in space. Instruments: ISSS (Instrument for the Study of Space Storms) developed at KAIST to detect plasma densities and particle fluxes of 10 MeV energy range near the Earth. NISS (NIR Imaging Spectrometer for Star formation history), developed at KASI (Korean Astronomy and Space Science Institute).
• Orbital Reflector, a 3U CubeSat project (4 kg) of the Nevada Museum of Art and artist Trevor Paylon. The Orbital Reflector is a 30 m sculpture constructed of a lightweight material similar to Mylar. On deployment, the sculpture self-inflates like a balloon. Sunlight reflects onto the sculpture making it visible from Earth with the naked eye — like a slowly moving artificial star as bright as a star in the Big Dipper.
• ORS-7 (Operationally Responsive Space 7), two 6U CubeSats (-7A and -7B) of the USCG (US Coast Guard) in cooperation with DHS (Department of Homeland Security), the ORS (Operationally Responsive Space Office) of DoD, and NOAA. The objective is to detect transmissions from EPIRBs (Emergency Position Indicating Radio Beacons), which are carried on board vessels to broadcast their position if in distress.
• PW-Sat 2 (Politechnika Warszawska Satellite 2), a 2U CubeSat of the Institute of Radioelectronics at the Warsaw University of Technology, Warsaw, Poland. The objective is to demonstrate a deorbitation system - a drag parachute opened behind the satellite - which allows faster removal of satellites from their orbit after it completes its mission.
• RAAF-M1 (Royal Australian Air Force-M1), an Australian 3U CubeSat (~4 kg) designed and built by UNSW (University of New South Wales) for the Australian Defence Force Academy, Royal Australian Air Force. RAAF-M1 is a technology demonstration featuring an AIS receiver, and ADS-B receiver, an SDR (Software Defined Radio).
• RANGE-A and -B (Ranging And Nanosatellite Guidance Experiment), two 1.5 CubeSats of Georgia Tech (Georgia Institute of Technology), Atlanta, GA, USA, flying in a leader-follower formation with the goal of improving the relative and absolute positioning capabilities of nanosatellites.
• ROSE-1, a 6U CubeSat of Phase Four Inc., El Segundo, CA, USA. ROSE-1 is an experimental spacecraft designed to provide an orbital test-bed for the Phase Four RFT (Radio Frequency Thruster), the first plasma propulsion system to fly on a nanosatellite.
• SeaHawk-1, a 3U CubeSats of UNCW (University of North Carolina, Wilmington), NC. The goal is to measure the ocean color in project SOCON (Sustained Ocean Observation from Nanosatellites). SeaHawk is considered a prototype for a larger constellation. The SOCON project is a collaboration between Clyde Space Ltd (spacecraft bus), the University of North Carolina Wilmington, Cloudland Instruments, and NASA/GSFC (Goddard Space Flight Center).
• See Me (Space Enabled Effects for Military Engagements), a prototype microsatellite (~22 kg) built by Raytheon for DARPA to obtain on-demand satellite imagery in a timely and persistent manner for pre-mission planning.
• SkySat-14 and -15. Planet Labs of San Francisco has 13 SkySats in orbit. The commercial EO satellites were built by Terra Bella of Mountain View, CA, which Planet Labs acquired from Google last year. At the time of the purchase, there were 7 SkySats in orbit. On 31 October 2017, Planet launched an additional six on a Minotaur-C rocket. The 100 kg SkySats are capable of sub-meter resolution – making them the most powerful in the constellation. Customers can request to have these high-resolution satellites target their locations of interest.
• SNUGLITE, a 2U CubeSat designed by the SNU (Seoul National University) for technology demonstrations and amateur radio communication.
• SpaceBEE, four picosatellites of Swarm Technologies (a US start-up), built to the 0.25U form factor to make up a 1U CubeSat.
• STPSat-5 is a science technology minisatellite of the US DoD STP (Space Test Program), managed by the SMC of the USAF. STPSat-5 will carry a total of five technological or scientific payloads to LEO (Low Earth Orbit) in order to further the DoD’s understanding of the space environment. The satellite was built by SNC (Sierra Nevada Corporation) on the modular SN-50 bus with a payload capacity of 50-100 kg and compatible with ESPA-class secondary launch adaptors.
• THEA, a 3U CubeSat built by SpaceQuest, Ltd. of Fairfax, VA to demonstrate a spectrum survey payload developed by Aurora Insight, Washington DC. The objective is to qualify Aurora’s payload, consisting of a proprietary spectrometer and components, and demonstrate the generation of relevant measurements of the spectral environment (UHF, VHF, S-band). The results of the experiment will inform future development of advanced instrumentation by Aurora and component development by SpaceQuest.
• VESTA is a 3U CubeSat developed at SSTL in Guildford, UK. VESTA is a technology demonstration mission that will test a new two-way VHF Data Exchange System (VDES) payload for the exactEarth advanced maritime satellite constellation. Honeywell Aerospace is providing the payload. VESTA is a flagship project of the National Space Technology Program, funded by the UK Space Agency and managed by the Center for EO Instrumentation and Space Technology (CEOI-ST).
• VisionCube-1, a 2U CubeSat designed by the Korea Aerospace University (KAU) to perform research on Transient Luminous Events in the upper atmosphere. The image processing payload consists of a multi-anode photon multiplier tube(MaPMT), a camera, and a real-time image processing engine built by using SoC (System-on-Chip) FPGA technologies.
Spaceflight has contracted with 64 spacecraft from 34 different organizations for the mission to a Sun-Synchronous Low Earth Orbit. It includes 15 microsatellites and 49 CubeSats from both commercial and government entities, of which more than 25 are from international organizations from 17 countries, including United States, Australia, Italy, Netherlands, Finland, South Korea, Spain, Switzerland, UK, Germany, Jordan, Kazakhstan, Thailand, Poland, Canada, Brazil, and India. 13)
Figure 7: This infographic released by Spaceflight illustrates the types of payloads booked on the SSO-A mission (image crdit: Spaceflight)
Statement from the Mission Manager of Spaceflight
Most will never know all that is necessary to plan a launch, and then add to that the challenge of managing and being responsible for the launch of 64 satellites, a record breaking event to be sure, but that's exactly what Spaceflight did. 14)
Spaceflight, the leading rideshare and mission management provider, today announced the success of its SSO-A: SmallSat Express mission, the largest single rideshare mission from a U.S.-based launch vehicle to date. The company successfully launched 64 spacecraft to sun-synchronous low Earth orbit via a SpaceX Falcon 9 that launched today from Vandenberg Air Force Base.
“This was an incredibly complex mission, and I’m extremely proud of what our talented team at Spaceflight has achieved,” said Curt Blake, president of Spaceflight. “SSO-A is a major milestone for Spaceflight and the industry. We’ve always been committed to making space more accessible through rideshare. This mission enabled 34 organizations from 17 different countries to place spacecraft on orbit. It’s also special because it was completely dedicated to smallsats.”
Figure 8: Photo of the happy Spaceflight team after the launch of the SSO-A mission (image credit: Spaceflight)
Spaceflight launched 15 MicroSats and 49 CubeSats from government and commercial entities including universities, startups, and even a middle school. The payloads vary from technology demonstrations and imaging satellites to educational research endeavors.
One research payload includes the University of North Carolina Wilmington’s CubeSat, SeaHawk-1 carrying the HawkEye Ocean Color Imager. UNCW has been funded by the Gordon and Betty Moore Foundation, and NASA serves in an advisory capacity to ensure the maximum scientific utility of the science data. NASA’s Science Mission Directorate and UNCW have created a partnership to expand accessibility to the data.
“We are thrilled to have SeaHawk-1 on orbit and to be part of such a historic launch superbly executed by Spaceflight,” said Professor John Morrison, SeaHawk’s co-project manager and lead principal investigator. “SeaHawk will make ocean observations at significantly higher spatial resolution and at much lower costs than standard satellite systems. Since the data collected will be publicly available, our hope is that it will benefit not only researchers, but policymakers and others to make informed decisions when addressing issues related to the environment.”
To accommodate the large number of payloads, Spaceflight built an integrated payload stack that was nearly 20 feet tall. Once the launch vehicle reached orbit, the upper and lower free flyers separated from the vehicle. The free flyers then successfully deployed all spacecraft, dispensing one payload every five minutes over five hours.
“This launch was an impressive undertaking and an important milestone for the smallsat industry as well as for many of the organizations involved,” said Payam Banazadeh, founder and CEO of Capella Space Corporation. “Capella’s first satellite is now on orbit and we are one step closer to our goal of providing timely, reliable, and frequent information using Synthetic Aperture Radar technology.”
With the success of SSO-A, Spaceflight has now launched more than 210 satellites since its founding in 2011. In addition, the company is contracted to launch nearly 100 satellites in 2019. Among the upcoming launches is Spaceflight’s next dedicated rideshare mission, which will occur in 2019 on a Rocket Lab Electron.
• September 3, 2019: Capella Space is partnering with SpaceNet®, a nonprofit organization dedicated to accelerating open source, artificial intelligence (AI) applied research for geospatial applications. 15)
- Capella joins the collaborative SpaceNet partnership alongside In-Q-Tel’s (IQT) CosmiQ Works, Maxar Technologies, Intel AI and Amazon Web Services (AWS). Capella’s addition to the partnership presents an exciting opportunity to expand SpaceNet’s existing geospatial open source research to a new data type, Synthetic Aperture Radar (SAR). Opening access to this data will help broaden the use of high-quality SAR in a variety of geospatial analytic applications.
- There is tremendous potential in applying machine learning to SAR data for a range of applications, from natural disaster response to monitoring global supply chain activity, but the industry still faces significant barriers to adoption. Developers and data scientists lack open data and software tools. Capella seeks to help overcome these obstacles through its partnership with SpaceNet and the development of a new SAR user community.
- The Capella User Community will broaden the adoption of high-resolution SAR data to solve a range of global issues. Data scientists and software engineers will have access to free and open Capella data along with tools and techniques to work more easily with SAR data. The company invites academics, non-government organizations (NGOs), governments, and companies to join Capella’s User Community — access this direct link for additional information...
- Ryan Lewis, the SVP at IQT and General Manager of SpaceNet, said that SAR promises substantial value for a wide variety of geospatial applications because, unlike satellite imagery, it is not limited by weather or lighting conditions. Furthermore, SAR phase data can offer additional insights into a particular location such as land subsidence. Capella’s contribution of an open-source, high-resolution SAR data set is an important next step for SpaceNet and the company is excited to see how participants use this data for machine learning models in an upcoming challenge.
• August 5, 2019: Capella Space, an information services company that provides Earth observation data on demand, today entered into an agreement with Addvalue, a one-stop digital, wireless and broadband communications technology products innovator, for use of its Inter-Satellite Data Relay System (IDRS™) via Inmarsat’s global L-band satellite communications network. The Inmarsat network provides satellite uplink and downlink services, which enable Capella to task any satellite in its constellation in any location in the world in real-time. Through its agreement with Addvalue, Capella will have a significant market lead as the only SAR (Synthetic Aperture Radar) provider with real-time tasking capability. This unique partnership will position Capella as the only SAR operator capable of real-time responsiveness.
• June 3, 2019: San Francisco-based Capella launched the first small U.S. radar satellite in December 2018. Capella has not published any imagery from that satellite, a technology demonstration called Denali. 16)
- Instead, the company has focused on developing the infrastructure it will need to operate a constellation, including automated satellite tasking, image processing and delivery, billing and customer service. Capella also is establishing its ground infrastructure to allow customers to downlink data directly or to rely on Amazon Web Services to delivery data through the Amazon cloud.
- “We are getting ready for primetime,” said Capella CEO Payam Banazadeh.
- Capella has raised more than $50 million to date. That money will carry the startup into 2020, when it plans to begin building its constellation of 36 synthetic aperture radar satellites to obtain imagery with a resolution of 50 cm and to revisit sites within the hour. Unlike electro optical satellites which require light, radar satellites capture imagery during the day, at night and through clouds.
- By the end of this year, Capella plans to launch Sequoia, its first operational satellite. “I want to wow people with Sequoia data,” Banazadeh said. “I want them to say, ‘I can’t believe that image came from a small satellite.’”
- Capella has been expanding its staff of about 60 full-time employees and 15 contractors. In April Joerg Hermann joined Capella. Hermann led efforts to create a commercial market for satellite radar data in Germany where he led Infoterra Ltd., a geospatial data supplier.
- Capella has been ordering components in bulk for its operational constellation. Capella has ordered 12 attitude control systems from Blue Canyon Technologies. Capella also is buying Maxwell radio frequency thrusters for in-space propulsion from Phase Four.
1) Gordon Farquharson, William Woods, Craig Stringham, Navneet Sankarambadi, Lucas Riggi, ”The Capella Synthetic Aperture Radar Constellation,” Proceedings of IGARSS (International Geoscience and Remote Sensing Symposium), Valencia, Spain, July 23-27, 2018
2) Debra Werner, ”Capella’s first satellite launching this fall,” Space News, 8 August 2018, URL: https://spacenews.com/capellas-first-satellite-launching-this-fall/
3) CraigStringham,GordonFarquharson,DavideCastelletti,EricQuist,LucasRiggi,DuncanEddy,andScottSoenen, ”The Capella X-band SAR constellation for rapid imaging,” Proceedings of the 39th annual IGARSS (International Geoscience and Remote Sensing Symposium) 2019, Yokohama, Japan, 28 July - 2August 2019
”Capella Space Unveils Advanced Satellite Design to Deliver High
Resolution On-Demand Earth Observation Data,” PR Newswire, 21
January 2020, URL: https://www.prnewswire.com/news-releases
Sandra Erwin, ”Capella Space to launch seven radar satellites in
2020 as it prepares for commercial operations,” Space News, 16
December 2019, URL: https://spacenews.com/capella-space-to-launch-
”Capella Space closes $19M Series B to deliver reliable Earth
observation data on demand,” PR Newswire, 26 September 2018, URL:
8) Stephen Clark, ”Spaceflight’s 64-satellite rideshare mission set to last five hours,” Spaceflight Now, 3 December 2018, URL: https://spaceflightnow.com/2018/12/03/spaceflights-64-satellite-rideshare-mission-set-to-last-five-hours/
Stephen Clark, ”Spaceflight preps for first launch of unique
orbiting satellite deployers,” Spaceflight Now, 23 August 2018,
10) Jeff Foust, ”Spaceflight gears up for dedicated Falcon 9 launch,” Space News, 6 August 2018, URL: https://spacenews.com/spaceflight-gears-up-for-dedicated-falcon-9-launch/t).
11) ”Spaceflight SSO-A: SmallSat Express Mission,” SpaceX, 3 December 2018, URL: https://www.spacex.com/news/2018/12/03/spaceflight-sso-smallsat-express-mission
”Capella Space Is First American Company to Send Advanced
Commercial Radar Satellite to Space,” PR Newswire Press Release,
3 December 2018, URL:
14) ”Statement from Spaceflight, the Mission Manager, Launches 64 Satellites on First Dedicated Rideshare Mission,” Satnews Daily, 4 December 2018, URL: http://www.satnews.com/story.php?number=270036615
15) ”Capella Space Partners with SpaceNet and Others for Collaborative AI-Based Geospatial Research,” Satnews, 3 September 2019, URL: http://www.satnews.com/story.php?number=2116101381
16) Debra Werner, ”Capella Space gets ready for primetime as constellation operator,” SpaceNews 3 June 2019, URL: https://spacenews.com/capella-space-gets-ready-for-primetime-as-constellation-operator/
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)