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Why ISRO's maiden SSLV mission failed

Minor hiccups were expected, say experts

ISRO's Small Satellite Launch Vehicle during its launch from the Sathish Dhawan Space Centre, in Sriharikota | PTI ISRO's Small Satellite Launch Vehicle during its launch from the Sathish Dhawan Space Centre, in Sriharikota | PTI

It was challenging day for the Indian Space Research Organisation (ISRO) with its maiden SSLV mission running into rough weather. The mission was carrying an earth observation satellite and a student satellite. After a few hours of the launch from Sriharikota, the newly developed small satellite launch vehicle suffered certain data loss in the final stage of the flight. The space agency announced that the satellites were no longer usable due to the SSLV D1 placing them into 356 km x 76 km elliptical orbit instead of 356 km circular orbit. 

The new rocket was equipped with an earth observation satellite EOS-02 weighing 145 kg along with the AzaadiSat, weighing approx 8 kg, developed by 750 school girls in order to celebrate the 75 years of Independence under Space Kidz India. “It is a traumatic day for all of us space lovers. I think ISRO will get back to their drawing board and come back strong,” Srimathy Kesan, the founder and CEO of SpaceKidz India told THE WEEK. 

SSLV, which reportedly makes use of three solid fuel-based stages and a liquid fuel-based velocity trimming module (VTM) for placing the satellite into orbit, was designed keeping in mind the quick turnaround time needed for commercial launch. It weighs a little over 120 tonnes and stands 34 metres tall. 

“The problem appeared to be the SSLV’s terminal stage, called the velocity trimming module (VTM). According to the launch profile, the VTM was supposed to have burnt for 20 seconds at 653 seconds after launch. However, it burnt for only 0.1 seconds, denying the rocket of the requisite altitude boost. Two satellites onboard the rocket – the primary EOS-2 Earth-observing satellite and the secondary AzaadiSAT student satellite – separated from the vehicle after the VTM burnt. This means they are likely to have missed their intended orbital trajectories as well, and entered an elliptical orbit instead. This is not the first time for the space agency to witness a setback on its maiden launch missions. PSLV that was dubbed as one of the trusted workhorses for the space agency, was not successful in its first flight way back on September 20, 1993,” said space expert Girish Linganna. 

Space experts say that since this was SSLVs first flight, minor hiccups were expected. “It wasn’t a major trouble. As far as the first flights go, it was almost perfect with a minor hiccup at the end. Next launch should go much more smoothly. We at Pixxel look forward to using the SSLV as well very soon for some satellites in our constellation,” said Awais Ahmed, Founder and CEO, Pixxel. He says that it was a failure of a sensor and the software logic that is supposed to figure out that the sensor failed. “Due to this the fourth burn for the fourth stage couldn’t happen properly and the satellites were deployed in a 356x76 km orbit rather than a 356x356 circular orbit. Since 76 km is very low the atmospheric friction would have burnt up the satellites deployed making them unusable,” added Ahmed. 

As per ISRO, a committee would analyse the issue and following its recommendations it will come back with SSLV-D2 soon. 


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