SAOCOM (SAR Observation & Communications Satellite)
The SAOCOM (SAtélite Argentino de Observación COn Microondas) satellite series represents Argentina's approved polarimetric L-band SAR (Synthetic Aperture Radar) constellation of two spacecraft, a program defined, managed and operated by CONAE (Comisión Nacional de Actividades Espaciales), Argentina's Space Agency, Buenos Aires. The SAOCOM-1 mission is composed of two satellites (SAOCOM-1A and -1B) to be launched consecutively. The overall objective of is to provide an effective Earth observation and disaster monitoring capability. 1) 2) 3) 4)
The SAOCOM requirements call for a capability to provide timely information in support of natural and anthropogenic disaster management (such as regional flooding, volcanic eruptions, Earth quakes, land slides, forest fires, etc.), and to conduct monitoring services for agriculture, mining and ocean applications - including monitoring surveys of Antarctica (study of continental glacier evolution, global change indicators, etc.). The goal is to obtain data with high-quality radiometric and geometric accuracy (eg. natural resources identification, interferometry, glaciology), and to provide also high revisit frequencies (daily) in support of specific operational requirements.
International participation in the SAOCOM mission:
• As of 2000, SAOCOM is a joint project of CONAE and ASI (Agenzia Spaziale Italiana), the Space Agency of Italy. To this effect, an agreement called SIASGE (Sistema Italo Argentino de Satélites para la Gestión de Emergencias - Italian/Argentinian satellite system for emergency management) has been signed under which the satellites in the Argentine SAOCOM system will operate jointly with the Italian COSMO-SkyMed constellation in X-band to provide frequent information relevant for emergency management. This approach of a two SAOCOM and a four COSMO-SkyMed spacecraft configuration offers an effective means of a twice-daily coverage capability. By joining forces, both agencies will be able to generate SAR products in X-band and in L-band for their customers.
• Belgium takes also part in the SAOCOM project of CONAE by the joint development of a processor, a simulator and the necessary tools for processing the data from the polarimetric SAR instrument. 5)
Figure 1: Illustration of the SAOCOM spacecraft (image credit: CONAE)
INVAP (Rio Negro, Argentina) is the prime contractor for the design and construction of the SAOCOM-1 spacecraft and its SAR payload. The spacecraft platform is of SAC-C heritage. 6)
Each SAOCOM-1 spacecraft (SAOCOM-1A and SAOCOM-1B) has an estimated wet mass of ~1600 kg. The mission design life is 5 years.
- h = 4.468 m, Ø=2.965 m stowed envelope
- 10 m x 3.5 m (35m2) SAR ActivePhase Array antenna
- 15 m2 foldable solar array wing.
RF communications: S-band for TT&C communications and X-band for SAR payload data download at a rate of 310 Mbit/s. An onboard mass memory of 256 Gbit is provided.
A spacecraft description will be provided when available.
• August 1, 2018: SAOCOM 1A – the Argentinian Earth observation satellite – has shipped to Vandenberg Air Force Base ahead of launch aboard a SpaceX Falcon 9. The mission will be the first on the west coast to see a Falcon 9 first stage perform an RTLS (Return to Launch Site) recovery. 7)
Figure 2: Photo of the SAOCOM-1A spacecraft at VAFB (image credit: CONAE)
• July 29, 2018: Argentina is preparing for the launch of their first of four satellites to help monitor geological conditions and manage disasters, according to that nation's CONAE (National Space Activities Commission). 8)
- Argentina's SAOCOM-1A SAR satellite will be shipped later this month to Vandenberg Air Force Base in California for a launch that is scheduled for September. The satellite, designed and built by INVAP, will contribute to a number of tasks according to CONAE spokesperson Josefina Peres.
- With an expected operational life of 5.5 years, the satellite will orbit some 620 km above the Earth's surface and will collect data that is useful for agriculture, fishing, mining, geology, urban development and disaster management. And, according to Peres, the SAOCOM will be capable of capturing 500 images as it orbits 15 times a day. The satellite's mission, Peres said, will focus on two aspects: measuring soil humidity in the Argentine Pampas, or lowlands, as well as detecting and helping to manage natural and human disasters, such as floods, landslides, oil spills, fires, earthquakes and volcanic eruptions.
Figure 3: Artist's rendition of the deployed SAOCOM-1A satellite (image credit: CONAE)
- Once on orbit, the satellite will mark CONAE's fifth space mission as it joins the country's two prior orbiting satellites — Arsat-1 and Arsat-2 — which were built by Argentine satellite maker ArSat and launched in 2014 and 2015, respectively.
- SAOCOM -1A features six computers that work in synchronicity; the spacecraft has a mass of 3,000 kg. Its antenna, designed in central Cordoba province, is composed of 140 smaller antennas. As many as 600 Argentine professionals have been working on the $500 million-satellite since 2011.
- SAOCOM 1-B is expected to be launched in 2019, followed by another two satellites as part of the SAOCOM 2 series, which will have the experiences collected from the first mission built in. Both INVAP and CONAE have ample experience in designing satellites and in space missions, as they developed the SAC-B, SAC-A, SAC-C and SAC-D Aquarius satellites.
• January 2, 2018: Professionals from CONAE (National Space Activities Commission), CNEA (National Commission of Atomic Energy), and the companies VENG, INVAP and CEATSA/Arsat concluded in Bariloche (Argentina) the electrical verifications and the mechanical assembly of the SAOCOM-1A, the new Argentine observation satellite developed by the CONAE together with other national organizations and companies. 9)
- The "body" of the satellite (the service platform) and its "eyes" (the radar antenna), with which it will observe the earth, are in communication. All the interfaces are correctly connected, in good condition and safe.
- After the electrical integration was completed and the communication of the platform with each of the seven panels of the radar antenna was verified, the mechanical assembly of the SAOCOM-1A satellite was concluded. This week, the deployment of the SAR antenna will be tested for the first time, entering the final testing stage of the satellite.
Figure 4: Photo of the SAOCOM-1A sapcecraft along with members of the integration teams (image credit: CONAE)
Figure 5: SAOCOM-1A in the clean room of INVAP in October 2017 (image credit: Casa Rosada)
Launch: The SAOCOM-1A satellite was launched on 8 October 2018 (02.21 UTC) on a SpaceX Falcon-9 vehicle from VAFB, CA. Following stage separation, Falcon-9's first stage returned to land at SpaceX's Landing Zone 4 (LZ-4) at Vandenberg Air Force Base. This was SpaceX's first land landing on the West Coast. 10)
The launch of SAOCOM-1B is scheduled for 2019. — In April 2009, CONAE signed a contract with the launch service provider SpaceX (Space Exploration Technologies Corp.) of Hawthorne, CA, USA, the launch site is VAFB, SLC-4E (use of Falcon-9 1.2 launch vehicle). 11)
Figure 6: In the early hours of Monday morning (8 October), as Argentina's CONAE space agency launched the SAOCOM-1A satellite into space, photographer William T. Reid captured this dramatic image of Earth's newest admirer catching a lift on the back of a SpaceX Falcon 9 rocket (image credit: William T. Reid) 12)
- An Earth observation satellite, SAOCOM-1A will provide welcome new data on our planet, stimulating projects to monitor the planet's forests, map soil moisture and measure surface deformation and motion from space, in the context of natural and anthropogenic disasters.
- With teams of experts at its ESOC operations center in Darmstadt, Germany, ESA is proud to be supporting CONAE with this important new endeavor.
- Moments after launch, ESA's flight dynamics specialists provided critical information to ground stations so they could track SAOCOM-1A, and soon after made their first 'orbit determination' — a vital step toward being able to communicate with the satellite. The flight dynamics team will continue calculating the satellite's orbit in the following weeks (Ref. 12).
Orbit: Sun-synchronous near-circular orbit (frozen dawn/dusk orbit), altitude = 619.6 km, inclination = 97.86º, period = 97.1 minutes, repeat cycle of 16 days (8 days for the constellation), LTAN (Local Time on Ascending Node) at 6:00 hours.
Figure 7: SIASGE integrated constellation of 2 SAOCOM and 4 COSMO-SkyMed spacecraft (image credit: CONAE)
The same repeat cycles (16 days) of the COSMO-SkyMed and the SAOCOM constellations allows both projects to establish a common planning cycle and fixed operational chronologies for both constellations, to define meaningful programming requests, schedule image acquisitions, receive the download data from the satellites, and then process and correlate the relevant SAR imagery. 13)
The nominal SAR looking direction is to the right and the full SAR access range covers ten swaths in quad-pol (QP) mode and nine swaths in dual-pol mode. The SAR will be able to operate in stripmap imaging mode (the baseline for bistatic operations described later), with a swath width larger than of 40 km, as well as in TOPSAR (Terrain Observation with Progressive Scans SAR) mode. The SAR antenna radiating area approximate dimensions are 10 m by 3.5 m. The total mass of the SAOCOM-1 satellites is approximately 3 tons.
• October 8, 2018: After the separation of the launcher, the initial sequence of activities of the new Argentine satellite SAOCOM-1A began. This involved deploying the solar panels and making the release of the radar antenna, whose wings were attached to the main body of the satellite to give rigidity to the whole, avoiding the impact of strong vibrations due to takeoff. 14)
- The first contact of SAOCOM-1A on a portable earth station in Tahiti allowed verifying that these automatic activities had been executed successfully, as planned. The following passes through the different stations of the terrestrial network were used to carry out the necessary measurements for the determination of the orbit by two methods, on the one hand the measurements with GPS (even without validation) and on the other hand through the use of "ranging" signals (this is measurement of the transit time of the S-band signal) and its subsequent processing by the flight dynamics service of the ESA.
- On October 8, from early morning until 6:00 pm, the two wings of the radar antenna were deployed, first the wing + X and then the wing -X as they are called. Each panel was deployed one by one as the spacecraft passed over a station, until completing the three panels of each wing. This very delicate deployment operation began to be carried out from the Mission Control Center through the Cordoba Earth Station and ended 12 hours later from the Tierra del Fuego Earth Station, all commanded from the Mission Control Center in Cordoba.
- On October 9, the satellite was maneuvered so that its orientation was fixed as it will remain throughout its useful life and will be maintained by the attitude control system.
- The SAOCOM 1A already has its solar panels working, producing the energy that is stored in the battery of the satellite platform, and the radar antenna of 35 m2 is fully deployed and pointing into the right direction of the flight path. Each system enabled so far operates within the expected performance or better.
Sensor complement: (SAOCOM-SAR)
SAOCOM-SAR (SAOCOM-Synthetic Aperture Radar)
• To provide all weather, day/night polarimetric L-band SAR observations
• To satisfy most of the applications considered in the Argentinean National Space Program, involving studies on agriculture, fishery, forestry, weather, hydrology, oceanography, emergencies, natural resources of land and sea, urban areas, cartography, geology, mining, soil exploitation, archeology and health. Emergencies, such as floods, droughts, desertification, landslides, oil slicks in land and ocean, fires, seismology, earthquake activity and volcanism, are mainly considered.
• To develop soil moisture map products for giving support to agricultural, hydrological and health applications, and emergencies in general
• To develop SAR interferometric techniques for collaborating with the development of different applications.
Table 1: Summary of SAOCOM-SAR parameters
Figure 8: SAOCOM-SAR central electronics (image credit: CONAE)
Legend to Table 2: SP = Single Polarization; DP = Dual Polarization; QP = Quad Polarization
The ground segment, includes all the activities from spacecraft monitoring/control to data product generation and distribution.
• The spacecraft operation is being done by the CONAE Control Center at Cordoba, Argentina (also location of the Cordoba ground station). All data processing, archiving and distribution is being provided by the MOC (Mission Operations Center) facility at Cordoba.
• The Matera ground station of ASI, Italy will be available for L-band SAR imagery downlinks.
1) Laura Frulla, Jorge Milovich, Gladys Rodriguez Ortega, Marc Thibeault, "CONAE's SAR Missions Overview," International GEO Workshop on Synthetic Aperture Radar (SAR) to Support Agricultural Monitoring, Nov. 2-4, 2009, Kananaskis, Alberta, Canada
2) A. E. Giraldez, "SAOCOM-1 Argentina L-band SAR Mission Overview," Proceedings of the 2nd Workshop on Coastal and Marine Applications of SAR (CMASAR), Sept. 8-12, 2003, Svalbard, Norway, URL: http://earth.esa.int/workshops/cmasar_2003/papers/E27gira.pdf
3) L. Frulla, "L-band SAR SAOCOM Mission and SIASGE System. Some applications," Proceedings of POLinSAR 2003, ESA/ESRIN, Frascati, Italy, Jan. 14-16, 2003
5) C. Barbier, "Argentina - Belgium Cooperation on the SAOCOM Mission
6) Laura Frulla, J. Medina, J. Milovich, G. R. Ortega, Marc Thibeault, "SAOCOM Mission Overview," 2011 CEOS SAR Calibration and Validation Workshop Fairbanks, Alaska, USA, Nov. 7-9, 2011, URL: http://media.asf.alaska.edu/asfmainsite/documents/2011-ceos-workshop/SAOCOM-mission%20overview,%20J.Medina.pdf
7) Michael Baylor, "SAOCOM 1A ships to Vandenberg as Falcon 9 prepares for the first west coast RTLS," NASA Spaceflight.com, 1 August 2018, URL: https://www.nasaspaceflight.com/2018/08/saocom-1a-ships-vandenberg-falcon-9-first-west-coast-rtls/
8) "Argentina's SAOCOM 1-A Satellite Continues Launch Preparations," Satnews Daily, 29 July 2018, URL: http://www.satnews.com/story.php?number=1716361527&menu=1
9) "The assemblage of the SAOCOM 1A satellite was concluded," INVAP, 2 January 2018, URL: http://www.invap.com.ar/en/invap-2/newsroom/news-invap/1580-the-assemblage-of-the-saocom-1a-satellite-was-concluded.html
10) "SpaceX's NightLight Launches SAOCOM 1A Satellite and a Successful Return of Falcon 9," Satnews Daily, 8 October 2018, URL: http://www.satnews.com/story.php?number=1392175371
11) "SpaceX signs Argentina's Space Agency for two Falcon 9 Launches," 16 April , 2009, URL: https://www.spacex.com/press/2012/12/19/spacex-signs-argentinas-space-agency-two-falcon-9-launches
12) "Argentina ascends," ESA, Operations image of the week, 10 October 2018, URL: http://m.esa.int/spaceinimages/Images/2018/10/Argentina_ascends
13) Giuseppe Francesco De Luca, Giovanni Rum, Francesco Caltagirone, Pasquale Maurizio De Carlo, Graziano Marano, Giuseppe Angino, Matteo Piemontese, "COSMO-SkyMed Interoperability, Expandability and Multi-Sensor Capabilities: The Keys for Full Multi-Mission Spectrum Operations," Proceedings of NATO Research and Technology Organization RTO-MP-SCI-150, Paper 3., 2005, Neuilly-sur-Seine, France URL: http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA469910&Location=U2&doc=GetTRDoc.pdf
14) "Successful launch of the SAOCOM 1A Satellite — The first steps of SAOCOM 1A in Space," CONAE, 10 October 2018, URL: https://www.argentina.gob.ar/noticias/exitoso-lanzamiento-del-satelite-saocom-1a
15) D. Dadamia, M. Thibeault, "Towards obtaining operative soil moisture products using SAR data from the SAOCOM mission," URL: http://smap.jpl.nasa.gov/files/smap2/apps_p2_Dadamia.pdf
16) Davide Giudici, Andrea Monti Guarnieri, Juan Pablo Cuesta Gonzalez, "Pre-Flight SAOCOM-1A SAR Performance Assessment by Outdoor Campaign," Remote Sensing, 2017, Vol.9, No 7, URL of abstract, https://doi.org/10.3390/rs9070729 URL: http://www.mdpi.com/2072-4292/9/7/729/htm
17) Laura Frulla, J. Medina, J. Milovich, G. R. Ortega, Marc Thibeault, "SAOCom Misson Overview," 2011 CEOS SAR Calibration and Validation Workshop Fairbanks, Alaska, USA, 7-9 November 2011, URL: http://sarcv.ceos.org/site_media/media/documents/SAOCOM-mission_overview_J.Medina_1.pdf
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).