SMOS is another Earth Explorer Mission within ESA's Living Planet Program. SMOS was launched together with PROBA-2 in November 2009 using the Rockot launch vehicle from Plesetsk Cosmodrome in Northern Russia. The satellite was attached to Rockot via an adapter system which also hosted PROBA-2, a technology demonstrator, operated by ESA.
Mission Objectives of SMOS and PROBA-2
The principal objective of SMOS (Soil Moisture and Ocean Salinity) is the provision of global maps of high resolution and sensitivity showing soil moisture and ocean salinity and their variations based on the continuous exchange of water between the oceans, atmosphere and land. These data are the basis of a deeper comprehension of the global water cycle and, thus, allow an improved forecasting of climate, weather and meteorological extremes. It will also monitor global vegetation water content and allow observations of snow and ice regions. SMOS is the first-ever space-borne mission that will provide such maps for a period of at least 3 years.
SMOS comprises a French-built Proteus spacecraft platform supplied by the French CNES space agency and a Spanish-designed instrument. The MIRAS instrument (Microwave Imaging Radiometer using Aperture Synthesis), a 2-D interferometric radiometer, that operates between 1400 and 1427 MHz (L-band), was supplied by EADS-CASA Espacio.
The satellite weights around 680 kg and was attached to the Rockot launch vehicle via an interface ring. Rockot injects SMOS into a sun-synchronous orbit of 756 km altitude. The satellite flies in a dawn-dusk-orbit required to obtain the optimum scientific measurements.
PROBA-2 (Project for On-Board Autonomy) was launched as a secondary payload together with the SMOS mission into the same orbital plane but into a lower orbit altitude. This was achieved by an orbit change maneuver of the re-ignitable Breeze-KM upper stage.
PROBA-2 is a technology demonstrator weighing 130 kg. Its objectives are in-orbit demonstration and evaluation of new hard- and software for spacecraft technologies and for on-board operational autonomy as well as in-orbit trial and demonstration of sun observation and space environment instruments. PROBA-2 is an evolution of PROBA-1 which has been working successfully since 2001. PROBA-2 offers increased miniaturisation and integration of avionics, improved spacecraft performance, addition of propulsion and more resources allocated to payloads. PROBA-2 as well was deployed into a sun-synchronous orbit at approx. 700 km.