Soil Moisture and Ocean Salinity

Soil Moisture and Ocean Salinity (SMOS) is a satellite which forms part of ESA's Living Planet Programme. It is intended to provide new insights into Earth's water cycle and climate. In addition, it is intended to provide improved weather forecasting and monitoring of snow and ice accumulation.[3][4][5][6]

This article is about the satellite. For the hydrologic concepts, see Soil moisture and Ocean salinity.
SMOS
Artist's view of SMOS
Mission typeEarth observation
OperatorESA
COSPAR ID2009-059A
SATCAT no.36036
Websitewww.esa.int/Our_Activities/Observing_the_Earth/SMOS
Mission durationPlanned: 3 years
Elapsed: 11 years, 2 months, 11 days
Spacecraft properties
BusProteus
ManufacturerThales Alenia Space
CNES
Launch mass658 kilograms (1,451 lb)
Dry mass630 kilograms (1,390 lb)
Dimensions2.4 by 2.3 metres (7.9 ft × 7.5 ft) (diameter)
Powerup to 1065 watts
Start of mission
Launch date2 November 2009, 14:21:00 (2009-11-02UTC14:21Z) UTC[1]
RocketRokot/Briz-KM
Launch sitePlesetsk 133/3
ContractorEurockot
Orbital parameters
Reference systemGeocentric
RegimeSun-synchronous
Perigee altitude765 kilometres (475 mi)[2]
Apogee altitude766 kilometres (476 mi)[2]
Inclination98.44 degrees[2]
Period100.02 minutes[2]
Repeat interval23 days
Epoch25 January 2015, 00:45:13 UTC[2]
Transponders
BandS Band (TT&C support)
X Band (science data acquisition)
Bandwidthup to 722kbit/s download (S Band)
up to 18.4Mbit/s download (X Band)
up to 4kbit /s upload (S Band)
Instruments
MIRAS: Microwave Imaging Radiometer using Aperture Synthesis
 

History

The project was proposed in November 1998; in 2004 the project passed ESA-phase "C/D" and,[7] after several delays, it was launched on 2 November 2009 from Plesetsk Cosmodrome on a Rockot rocket.[8] The first data from the MIRAS (Microwave Imaging Radiometer using Aperture Synthesis) instrument was received on 20 November 2009.[9] The SMOS programme cost is about €315 million ($465 million; £280 million). It is led by ESA but with significant input from French and Spanish interests.[8]

The satellite is part of ESA's Earth Explorer programme – eight spacecraft that will do innovative science in obtaining data on issues of pressing environmental concern. The first is already in orbit – a mission called GOCE, which is mapping variations in the pull of gravity across the Earth's surface. SMOS is the second Explorer to launch; and a third spacecraft, known as CryoSat-2 (the first CryoSat failed on launch), was launched on 8 April 2010. CryoSat will assess the state of the world's ice cover.

Launcher

The satellite was launched on 2 November 2009 (04:50 (01:50 GMT)) to a nearly circular orbit of 763 km aboard a Rokot, a modified Russian Intercontinental Ballistic Missile (ICBM) SS-19 launched from a decommissioned SS-19 launcher from Northern Russia's Plesetsk Cosmodrome.[4][10] The SMOS satellite was launched together with the Proba-2, a technology demonstration satellite.[11][12]

Science

The goal of the SMOS mission is to monitor surface soil moisture with an accuracy of 4% (at 35–50 km spatial resolution).[7] This aspect is managed by the HYDROS project. Project Aquarius will attempt to monitor sea surface salinity with an accuracy of 0.1 psu (10- to 30-day average and a spatial resolution of 200 km x 200 km).[7][13]

The first global map of oceanic surface salinity, produced by the SMOS satellite. The salinity varies from 32‰ (deep purple) to 38‰ (bright red).

Soil moisture is an important aspect of climate, and therefore forecasting. Plants transpire water from depths lower than 1 meter in many places and satellites like SMOS can only provide moisture content down to a few centimeters, but using repeated measurements in a day, the satellite can extrapolate soil moisture.[4][5] The SMOS team of ESA hope to work with farmers around the world, including the United States Department of Agriculture to use as ground-based calibration for models determining soil moisture, as it may help to better understand crop yields over wide regions.[14]

Ocean salinity is crucial to the understanding of the role of the ocean in climate through the global water cycle.[15] Salinity in combination with temperature determine ocean circulation by defining its density and hence thermohaline circulation.[16] Additionally, ocean salinity is one of the variables that regulate CO2 uptake and release and therefore has an effect on the oceanic carbon cycle.[17]

Information from SMOS is expected to help improve short and medium-term weather forecasts, and also have practical applications in areas such as agriculture and water resource management. In addition, climate models should benefit from having a more precise picture of the scale and speed of movement of water in the different components of the hydrological cycle.[8]

SMOS has been used to improve hurricane forecasting by collecting hurricane surface-level wind speed data using its novel microwave imaging radiometer, which can penetrate the thick clouds surrounding a cyclone. Hurricanes that have been studied by SMOS include Hurricane Florence, Typhoon Mangkhut, and Typhoon Jebi.[18]

Instrumentation

The SMOS satellite carries a new type of instrument called Microwave Imaging Radiometer with Aperture Synthesis (MIRAS). Some eight metres across, it has the look of helicopter rotor blades; the instrument creates images of radiation emitted in the microwave L-band (1.4 GHz). MIRAS will measure changes in the wetness of the land and in the salinity of seawater by observing variations in the natural microwave emission coming up off the surface of the planet.[6][8][13]

Operations and ground segment

The CNES Satellite Operations Ground Segment will operate the spacecraft with telecommunications from ESA's S-band facility located in Kiruna, Sweden. The Data Processing Ground Segment (CDTI, Villafranca, Spain) will process SMOS data through the X-band. Higher level processing of information will be done by scientists globally.[4]

Further information: Global Energy and Water Cycle Experiment

See also

References
  1. "Two new ESA satellites successfully lofted into orbit". ESA. 2009-11-01. Retrieved 2013-10-18.
  2. "SMOS Satellite details 2009-059A NORAD 36036". N2YO. 25 January 2015. Retrieved 25 January 2015.
  3. ESA's water mission SMOS European Space Agency
  4. SMOS Project Team, The Soil Moisture and Ocean Salinity (SMOS) Mission Archived 2006-05-06 at the Wayback Machine European Space Agency
  5. SMOS Special Issue of ESA Bulletin ESA Bulletin Special Issue 137, February 2009
  6. SMOS: The Challenging Sea Surface Salinity Measurement from Space, J. Font, A. Camps, A. Borges, M. Martin-Neira, J. Boutin, N. Reul, Y. Kerr, A. Hahne and S. Mecklenburg, Proceedings of the IEEE, vol. 98, no. 5, May 2010, pp. 649-665
  7. The Living Planet Program Soil Moisture and Ocean Salinity (MIRAS on RAMSES) Mission SMOS at Centre d'Etudes Spatailes de la BIOsphere (CESBIO)
  8. Jonathan Amos (2 November 2009). "European water mission lifts off". BBC News. Retrieved 2009-11-02.
  9. "First SMOS data received". ESA. 20 November 2009. Retrieved 26 January 2010.
  10. Jonathan Amos (3 November 2009). "Smos satellite unfurls instrument". BBC News. Retrieved 2009-11-06.
  11. Successful launch qualification test for PROBA2 Archived 2009-03-02 at the Wayback Machine
  12. ESA's SMOS Mission to be launched in July 2009 from Plesetsk Archived 2009-01-26 at the Wayback Machine The Rockot Missions. Eurolaunch Launch Service Provider
  13. Mecklenburg S, Kerr Y, Font J and Hahne A. The Soil Moisture and Ocean Salinity (SMOS) Mission - An overview. Geophysical Research Abstracts, Vol. 10, 2008,
  14. How Dry We Are: European Space Agency To Test Earth's Soil Moisture Via Satellite-Science News, Science Daily
  15. "The water cycle and Global Warming". WHOI. Retrieved 6 December 2011.
  16. "High-latitude salinity effects and interhemispheric thermohaline circulations" (PDF). Retrieved 6 December 2011.
  17. "Carbon Cycle - NASA Science".
  18. "SMOS offers new perspectives on hurricanes". ESA. 25 September 2018. Retrieved 12 March 2019.

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