Isro.Us | Space Exploration

The Megha-Tropiques Mission (MTM) is a planned mission to study the water cycle in the tropical atmosphere in the context of climate change. A collaborative effort between French Centre National d’Etudes Spatiales (CNES) and Indian Space Research Organisation (ISRO), MTM was scrapped in 2003, but later revived in 2004 when India increased its contribution and costs were lowered. With the progress made by GEWEX (Global Energy and Water Cycle Experiment), MTM currently is being designed to understand tropical meteorological and climatic processes, by obtaining reliable statistics on the water and energy budget of the tropical atmosphere. MTM will complement other data in the current regional monsoon projects such as MAHASRI and the completed GAME project. MTM also seeks to describe the evolution of major tropical weather systems. The focus will be the repetitive measurement of the tropics.

Design

Primarily MTM provides instruments that allow simultaneously observation of 3 interrelated components of the atmospheric engine: water vapor, condensed water (clouds and precipitations), and radiative fluxes. Secondarily is to facilitate the repetitive sampling of the inter-tropical zone over long periods of time. Finally a microwave radiometer, Multi-frequency Microwave Scanning Radiometer (MADRAS), would compliment other research of the Global Precipitation Measurement mission.

Payload

Instruments fulfill a complementary role to other on geostationary satellites. In this, microwave instruments are essential.

• MADRAS is a microwave imager, with conical scanning (incidence angle 56°), close from the SSM/I and TMI concepts. The main aim of the mission being the study of cloud systems, a frequency has been added (150 Ghz) in order to study the high level ice clouds associated with the convective systems, and to serve as a window channel relative to the sounding instrument at 183 GHz.
• SAPHIR is a sounding instrument with 6 channels near the absorption band of water vapor at 183 Ghz. These channels provide relatively narrow weighting functions from the surface to about 10 km, allowing retrieving water vapor profiles in the cloud free troposphere. The scanning is cross-track, up to an incidence angle of 50°. The resolution at nadir is of 10 km.
• ScaRaB is a scanning radiative budget instrument, which has already been launched twice on Russian satellites. The basic measurements of ScaRaB are the radiances in two wide channels, a solar channel (0.2 - 4 µm), and a total channel (0.2 - 200 µm), allowing to derive longwave radiances. The resolution at nadir will be 40 km from an orbit at 870 km. The procedures of calibration and processing of the data in order to derive fluxes from the original radiances have been set up and tested by CNES and LMD.

For more information, please visit Megha-Tropiques Official Site.