Megha Tropiques Mission(MTM) - A Joint collaborative Effort of ISRO-CNES

The Megha-Tropiques Mission (MTM) is a planned mission to study the water cycle in the tropical atmosphere in the context of climate change. The MTM project is a collaborative project between Indian Space Research Organisation (ISRO) and French Centre National d’Etudes Spatiales (CNES), MTM was scrapped in 2003, but later revived in 2004 when India increased its contribution and costs were lowered.

Overview of Megha-Tropiques Mission:
The Megha-Tropiques mission resulted from the association of two major requirements for study of the tropical climate: ocean-atmosphere interactions and energy exchange with special emphasis on clouds and precipitation.

The climate in tropical regions is known to be very sensitive to internal and external changes in the ocean-atmosphere land coupled system. The characteristics of these events are large intra-seasonal, interseasonal and inter-annual variations and may lead to catastrophic manifestations like floods, cycle of monsoon onset, active and decay phase, and impact of changes in cloud-radiative forcing due to anthropogenic effects, etc. The consequences of these processes is also known to impact the global climate systems as well since the regions provide much of the energy required for sustaining the system. The study will, therefore, require enhancement of the existing information by more intensive and simultaneous radiometric measurements for:

• Atmospheric water cycle 
• Corresponding radiation budget  for cloud-radiative interaction properties 
• High temporal sampling in order to characterize the life-cycle of convective 
• systems 
• All-weather capability to provide a sustainable data base for characterization of 
• the processes in the atmosphere and ocean.

Generally all weather capability is best provided by microwave instruments, and therefore, the sensors selected for Megha-Tropiques mission are: 

• Microwave imager, MADRAS (Microwave Analysis and Detection of Rain and Atmospheric Structures), aimed at measurements for precipitation, cloud 
• micro-physics, ocean surface winds, total water vapour and liquid water content 
• of the atmosphere.  
• Millimeter wave sounder for vertical profile of humidity, SAPHIR(Sondeur Atmospherique du Profil d’Humidite Intertropicale par Radiometrie)
• And an optical-IR radiometer ScaRaB(a broadband radiation measurement instrument) for radiation budget measurements at the 
• top atmosphere. 

Central Scientific Objectives of Megha-Tropiques: 

1. Improving the understanding of processes related to large tropical convective systems and their life cycle, 
2. Improving the determination of atmospheric energy and water budget in the tropical area at various time & space scales, and 
3. Tropical climate impacts and their predictability: draught, monsoon variability, floods and tropical cyclones. 

To improve the time sampling of the tropical region, the satellite will be placed in a highly inclined orbit (around 20°) and will cover a latitudinal region of ±30° at most. The sampling will be at irregular times, but will be more frequent (3-6 visits per day in a given area). The scientific applications plan for Megha-Tropiques is based on synergistic analysis of data from Megha-Tropiques and the other satellites, with MT 

data providing higher temporal sampling.

Mission Specifications:

The satellite will have minimum lifetime of three years and the swath of around 2200 km in order to observe the inter-annual variability and El-Nino type event in tropics.  This Megha-Tropiques satellite will carry four payloads namely MADRAS, SAPHIR and SCARAB. Other Specifications are:

• Altitude - 867 km
• Orbit inclination - 20 deg
• Repetivity - 7 days (Approx)
• Orbit Type - Tropical Coverage (Inclined)
• No of Orbits Per day - 14 orbits (Approx)
• Life Time -  more than 3 years