Why ISRO’s maiden SSLV mission failed despite successful launch of new rocket

Despite successfully launching India’s brand new Rs 56 crore rocket on its maiden flight, ISRO’s Small Satellite Launch Vehicle (SSLV) mission ended up being unsuccessful. The reason for the mission being a failure is that the two satellites transported onboard the rocket were rendered unusable.

Let us know in-depth about what this means and what went wrong with the SSLV-D1 mission.

Timeline to failure

The 34-metre tall, 120 ton SSLV-D1 was launched from the launch pad in Sriharikota at around 9:18 am on Sunday. The progress of the rocket launch was smooth and successful as all the solid fuel powered engines performed normally.

The launch vehicle was supposed to deliver the two satellites on board into orbit a little over 12 minutes into its voyage, as per the flight plan. It first had to dispatch the EOS-2 satellite and then the AZAADISAT a few seconds after it. This is where the mission entered troubled waters.

ISRO announced separation of the two satellites as per time, but soon after the Mission Control Centre at the rocket port was engulfed in silence. It was announced the mission was completed with all stages of the rocket performing “as expected”. However, ISRO added that there is “some data loss in the terminal stage of the rocket”.

Couple of hours after the launch, ISRO said in a briefing that the satellites were unusable as “the orbit achieved was less than expected, which makes it unstable”. 

Why did the mission fail?

Despite successful lift off into space, the SSLV-D1 was unable to complete its mission. Satellites achieving a lower orbit meant that they would not hold up in space and would drop back to Earth.

This was explained by ISRO Chairman S. Somanath: “SSLV-D1 placed the satellites into 356 km x 76 km elliptical orbit instead of 356 km circular orbit - 76 km is the lowest point close to the surface of the earth.”

In such an orbit, the satellites would not stay for long and come back down, he added.

“The two satellites have already come down from that orbit and they are no longer usable,” informed the top scientist.

What went wrong?

The failure of the mission appears to have been the result of a faulty sensor. As per ISRO, “failure of logic to identify a sensor failure and go for salvage action caused the deviation.”

Nevertheless, the entire architecture of ISRO’s newest rocket performed well apart from the “anomaly” that led to the mission’s failure. Scientists are happy that all the stages of the rocket functioned as per the plan.

The space agency has said that a committee made up of experts will analyse the mission and identify what led to the satellites being delivered into an unacceptable orbit. The agency will be back with the second developmental flight of SSLV post these corrections and their revalidations, ISRO chief said.

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(With inputs from agencies)