GISAT-1: India’s ‘Eye in the Sky’

  • The Indian Space Research Organisation (ISRO) is working towards launching India’s GISAT-1, an Earth Observation satellite, in August 2021, Dr K Sivan, Chairman ISRO, said in a statement.
  • This will be the state-run space agency’s second launch of 2021, after Brazilian Amazonia-1 was injected into orbit by a PSLV rocket in February, on a commercial basis. GISAT-1 will be launched by India’s medium-lift capability rocket, the GSLV Mk2.
  • According to ISRO, GISAT-1 is meant to provide near-realtime imaging of large regions of interest at frequent intervals, quick monitoring of natural disasters, episodic events, and also obtain spectral signatures for agriculture, forestry, mineralogy, disaster warning, cloud properties, snow & glaciers, and oceanography.
  • Conventionally, such earth-observation satellites are placed in low-earth orbit (between 500 and 2000kms), to ensure high resolution imagery and better capabilities.
  • However, it is pertinent to note that ISRO’s latest agile earth-observation satellite is to be placed 36,000kms away from the earth’s surface, Geostationary Orbit (GEO).
  • GEO orbit is generally meant for communication satellites that are required to relay signals across a vast landmass. Being placed in a 36,000km circular orbit would also mean that the 2268kg GISAT-1 is beyond the range of anti-satellite missiles.
  • ISRO had earlier said that, despite GISAT’s placement in a far-away 36,000km orbit, it can use different types of imaging technologies to provide constant monitoring of a region of interest/calamity/weather pattern.
  • This is unlike low earth orbit satellites, which can make a pass only once every 110 minutes or so to click pictures and collect data.
  • If a cyclone or similar rapidly-changing weather pattern is being continually monitored by GISAT-1, then the satellites in low earth orbit can also be tasked with getting higher resolution imagery from a relatively closer range. GISAT was originally meant to be launched in March 2020, but the launch was called off for technical reasons.