Indian space scientists are set to add another feather to their caps with the launch of the country’s first state-of-the-art agile Earth Observation Satellite (EOS) on August 12. Perched in an orbit high above the Earth, this “eye in the sky” will allow real-time monitoring of the entire subcontinent, helping with everything from agriculture to defence.
Developed by the Indian Space Research Organisation (ISRO), GISAT is an imaging satellite that will be launched via the indigenously made Geosynchronous Satellite Launch Vehicle-F10 (GSLV-F10) from the Satish Dhawan Space Centre at Sriharikota in Andhra Pradesh. The tentative take-off is at 5.43 am on August 12, 2021, weather permitting.
The satellite weighs more than 2 tonnes and ISRO will for the first time be using an Ogive-shaped fairing — basically, a classic bullet-shaped pointed curved surface casing — with the view to accommodating a larger payload.
The satellite will be placed by GSLV-F10 in a geosynchronous transfer orbit following which it will climb to its geostationary orbit at a height of about 36,000 km above the Earth’s surface using its onboard propulsion system.
Geostationary implies that the satellite will be located above the Equator and always appear to be fixed at one point in the sky. But such satellites aren’t motionless. All that happens is that the high orbit they are placed in “makes the satellite travel at the same rate as the Earth’s spin“. With its movement thus synchronised with the rotation of the Earth, GISAT-1 will be circling the Earth once every 24 hours.
How such satellites help on-ground receiving stations is that they can be pointed to a fixed location in the sky and don’t have to constantly readjust — which would be the case with low-Earth satellites, which need to be tracked across the sky.
ISRO says that India now “has one of the largest constellations of remote sensing satellites” for Earth observation with data from these satellites used for “several applications covering agriculture, water resources, urban planning, rural development, mineral prospecting, environment, forestry, ocean resources and disaster management”.
Reports say that the advanced imaging satellite has been described as a “game-changer” for India with its high-resolution cameras allowing constant, real-time monitoring of the Indian landmass and the oceans. Among the key areas where it can prove its utility is defence, enabling “special attention to the country’s borders for security reasons”.
Further, when it comes to natural disasters, monitoring by the satellite can ensure that precautions are taken well in advance to reduce their impact. Apart from disaster warning, ISRO said the satellite will also provide “spectral signatures for agriculture, forestry, mineralogy, cloud properties, snow and glaciers and oceanography” and will be carrying multispectral and hyperspectral cameras in different bands “with improved spatial and temporal resolution”.
However, the satellite needs cloud-free conditions to capture images. Union minister Jitendra Singh has told Rajya Sabha that the satellite can accomplish imaging of the whole country 4-5 times daily.
From technical glitches to the Covid-19 pandemic, the GISAT-1 launch has had to suffer multiple delays and will be only the second launch by ISRO so far in 2021 following the February launch of 18 small satellites.
It was originally slated for launch on 5 March 2020, but that was cancelled due to technical reasons. Right after following the pandemic and the lockdowns it brought along with it, which meant the GISAT-1 launch suffered a lengthy delay. Rescheduled for March 28 this year, “a minor issue” first led the launch to be put off till April and, then, as the second wave broke, to May.