Soil Moisture and Ocean Salinity

SMOS is the abbreviation of Soil Moisture and Ocean Salinity and refers to a earth observation satellite of the European Space Agency ESA. SMOS is the second satellite (as Opportunity mission, as opposed to the larger core mission ) was the Earth Explorer Missions, in a long-term framework program of ESA's Earth observation started. The first satellite of this series was CryoSat. SMOS was launched on 2 November 2009 at 1:50 UTC clock together with the probe Proba -2 from the northern Russian launch site Plesetsk with a Rockot rocket into space.

Structure and Mission

The SMOS satellite based on the Proteus satellite bus has as main instrument working at L-band 1.4 - GHz microwave radiometer called MIRAS (Microwave Imaging Radiometer using Aperture Synthesis). It receives radiation in the frequency range of 1400-1427 MHz was allocated by the International Telecommunications Union world for the reception of radiation for research purposes and in which must not be sent. However, the scientists realized that was sent but in some areas of the world there, and so the data for these areas were not available. The ESA turned the competent authorities of the respective States to eliminate radio interference. Development and construction of the innovative two-dimensional microwave radiometer were made by Astrium España. The instrument consists of 69 antennas in diameter and 19 mm height of 165 mm on each of three four-meter long booms. From the received radiation in this frequency range statements about the soil moisture and salt content can make in the oceans. Both soil moisture and salinity are important factors for the improvement of global climate models and has never been previously measured from a satellite. The instrument makes every 1.2 seconds a hexagonal receiving a 1000 km ² territory.

The measurement of the near-surface salinity of the oceans with an L -band radiometer was first tested on the space station Skylab in 1973/74 with the S- 194 instrument. Besides SMOS measures the Argentine SAC -D mission since 2011 soil moisture and the global salinity of the oceans. Similar tasks should carry out the planned for launch in October 2014 Satellite SMAP.

The power supply of the satellite take two solar boom with silicon solar cells and a combined peak output of 1065 watts, buffered by lithium-ion batteries with a total capacity of 78 Ah.

The 3-axis stabilization and track control is provided by star and sun sensors, gyro instruments, magnetometers and GPS as well as reaction wheels, Magnettorquer and four 1 -N thrusters.

For data storage there is a 2x20 Gb Solid State Drive, for data transfer, an X - band downlink at 16.8 Mbit / s and for telemetry an S- band transmission with 4 kbit / s uplink and 722 kbit / sDownlink available.