The Indian Space Research Organisation (ISRO)’s highly-anticipated launch of Earth observation satellite -3 or GISAT-1 failed after the rocket entered the lower reaches of space (an altitude of 139kms), after a flight of nearly 340 seconds (5mins 40 seconds). The first two stages of the rocket (that give initial thrust for lift-off and later carry the 52-meter tall vehicle to space) performed as expected. However, shortly after the rocket switched over to its final stage – the Cryogenic engine (that burns liquid hydrogen and oxygen), there was a marked deviation in its planned flight path. A typical rocket consists of two or more stages, each of which would have its own engines (either single or grouped in a cluster). Simply put, a rocket is a combination of multiple engines(stages) that are vertically stacked.
The rocket blasted off from the second launch pad at the Satish Dhawan Space Center in Sriharikota at 5:43 am, as scheduled. It was after 350 seconds of flight when the payload fairing (the nose cone or protective shield that houses the satellite) had separated that the rocket’s path deviated from the planned one.
Several minutes of anxiety and stunned silence followed at ISRO’s Mission Control in Sriharikota and the Live commentary on the National broadcaster Doordarshan’s telecast had been stopped. Top ISRO officials and scientists at the mission control were also seen discussing urgently, while several others had already gotten off their seats(something that is done usually after the mission is accomplished successfully).
While this indicated something amiss, Dr K Sivan, Chairman, ISRO later confirmed the news at the end of the Doordarshan broadcast – “Mission could not be accomplished fully because there was a technical anomaly observed in the cryogenic stage”.
GSLV-F10 LAUNCH TOOK PLACE TODAY AT 0543 HRS IST AS SCHEDULED. PERFORMANCE OF FIRST AND SECOND STAGES WAS NORMAL. HOWEVER, CRYOGENIC UPPER STAGE IGNITION DID NOT HAPPEN DUE TO TECHNICAL ANOMALY. THE MISSION COULDN’T BE ACCOMPLISHED AS INTENDED.
— ISRO (@ISRO) AUGUST 12, 2021
This means that the cryogenic engine (the stage that failed) was supposed to perform from 4 minutes and 56seconds until 18minutes and 29seconds(in space), following which the satellite was supposed to be ejected into orbit at 18 minutes and 39 seconds. But that process was hit by a glitch sometime around 5 minutes and 40 seconds.
This is the second failure of the GSLV variant of ISRO (which can lift about 2.5 tons to space). The earlier failure was in 2010 when the vehicle had exploded nearly 45 seconds after lift-off. This was the second launch for ISRO in the calendar year 2021, the earlier one being a PSLV launch in late February. ISRO’s missions and crucial work had been affected during the second wave of the COVID-19 pandemic that struck the country between March and June. However, it is also notable that this was the third launch attempt of this satellite – the first two attempts in March 2020 and March 2021 were called off.
According to ISRO, GISAT-1 or EOS-3 was meant to provide near-real-time imaging of a large region 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.
EOS-3, an agile earth observation satellite was meant to be placed in Geostationary orbit (36,000kms from earth’s equator). This orbit is typically meant for communication satellites that have to cover a large swathe of land. A satellite in geostationary orbit would be in sync with the rotation cycle of the earth(24hrs) and it would appear to be stationary when seen from the earth, thus giving it the name. It is said that three aptly positioned Geostationary satellites can cover pretty much all of Earth’s surface.
Conventionally, such earth-observation satellites are placed in Low-Earth orbit (between 500 and 2000kms), to ensure high-resolution imagery, 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. Being placed in the 36,000km circular orbit would also mean that the 2268kg GISAT-1 is beyond the range of Anti-satellite missiles.