Earth Observation Mission: When ISRO’s Trusted Workhorse PSLV Suffered A Rare Setback

Sriharikota (Andhra Pradesh), May 18: ISRO’s most trusted and versatile launch vehicle, PSLV on Sunday suffered a rare setback when it failed to inject an earth observation satellite into the desired orbit.
Boasting of an excellent strike rate–a mere three failures in 63 launches so far, PSLV was expected to deliver yet again with ease on Sunday and it seemed to be cruising towards its mission before things went the other way.
On Sunday the mission involving the earth observation satellite EOS-09 onboard the PSLV-C61 rocket could not be accomplished following a pressure issue in the third stage of the launch vehicle, the Bengaluru-headquartered space agency said.
Known for its versatility, the Polar Satellite Launch Vehicle has been deployed by ISRO for launching three types of payloads– Earth Observation, Geo-stationary and Navigation.
With the latest mission being unaccomplished, it is only the third time the 44 metre tall rocket has failed to deliver, the previous setbacks coming in September 1993 and August 2017.
The first development flight, PSLV-D1, was unsuccessful as it failed to put the remote sensing satellite (IRS-1E) into orbit.
Again in August 2017, PSLV C39 carrying the eighth satellite of the Indian Regional Navigation Satellite System (IRNSS) suffered a technical glitch and did not meet the mission objective.
The four stage PSLV rocket, measuring 44.5 metre tall and 2.8 metre in diameter, can carry payloads of up to 1,750 kg to Sun Synchronous Polar Orbit of 600 km altitude.
According to the Indian Space Research Oragnisation (ISRO), PSLV earned its title ‘workhorse of ISRO’ for its consistency in placing various satellites in Low Earth Orbits (LEO).
Because of its ‘unmatched reliability’, ISRO said PSLV was also used to launch various satellites into the Geosynchronous and Geostationary orbits like those from the IRNSS constellation.
The third stage of PSLV is a solid rocket motor that provides the upper stages high thrust after the atmospheric phase of the launch. It is where PSLV-C61 also faced a technical glitch on Sunday.
“Today we targeted the 101st launch from Sriharikota, the PSLV-C61 EOS-09 mission. The PSLV is a four-stage vehicle and up to the second stage, the performance was normal. The third stage motor started perfectly but during the functioning of the third stage we are seeing afn observation and the mission could not be accomplished,” Indian Space Research Organisation Chairman V Narayanan said.
He said there was a fall in the chamber pressure of the motor case and the mission could not be accomplished.
Some of the significant successful missions where PSLV was used were Chandrayaan-1 in 2008, Mars Orbiter Spacecraft in 2013, Aditya L1 Mission in September 2023, among others.
The PSLV is capable of placing multiple payloads into orbit; thus multi-payload adaptors are used in the payload fairing. The payload performance of the vehicle and mission flexibility is evident from the challenging missions where multi-orbit and satellite missions are accomplished.
The long string of consecutive successes and multi-satellite launch capability has reinforced the status of PSLV as a reliable, versatile and affordable launcher in the global market.
PSLV uses 6,4,2 solid rocket strap-on motors to augment the thrust provided by the first stage. It has XL,QL, DL variants respectively. Strap-ons are not used in the core alone version–PSLV-CA, ISRO said. (Agencies)

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