International Space Agencies – Missions and Discoveries



From UPSC perspective, the following things are important :

Prelims level : SnowEx

Mains level : Snowfall and its significance

For a better understanding of how much water is contained in each winter’s snowfall and how much will be available when it melts in the spring, NASA has launched a seasonal campaign — part of a five-year programme called SnowEx.


  • SnowEx was initiated in 2016-17.
  • The overall target is optimal strategies for mapping global snow water equivalent (SWE) with remote sensing and models leading to a Decadal Survey “Earth System Explorer” mission.
  • Within its geographic range, SnowEx assesses where snow has fallen, how much there is and how its characteristics change as it melts.

How does it work?

  • It uses airborne measurements, ground measurements and computer modelling.
  • The airborne campaign will fly radar and lidar to measure snow depth, microwave radar and radiometers to measure SWE, optical cameras to photograph the surface, infrared radiometers to measure surface temperature, and hyperspectral imagers for snow cover and composition.
  • Ground teams will measure snow depth, density, accumulation layers, temperature, wetness and snow grain size — the size of a typical particle.

Why such campaign?

  • Around 1.2 billion people, or nearly one-sixth of the world, depend on seasonal snow and glaciers for their water supply.
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