The second demonstrator launch mission of the Small Satellite Launch Vehicle (SSLV) was undertaken by the Indian Space Research Organisation (ISRO) from Sriharikota on Friday.
The SSLV-D2 took off from the first launch pad at the Satish Dhawan Space Centre at 9:18 am. The space agency had annouced on Wednesday about the mission in a tweet: A tweet by the ISRO read: "SSLV-D2/EOS-07 Mission: launch is scheduled for Feb 10, 2023, at 09:18 hrs IST from Sriharikota. Intended to inject EOS-07, Janus-1 & AzaadiSAT-2 satellites into a 450 km circular orbit Vehicle ready at the launch pad undergoing final phase checks."
It will attempt to three satellites - ISRO's EOS-07, US-based firm Antaris' Janus-1, and Chennai-based space startup SpaceKidz's AzaadiSAT-2 - into a 450 km circular orbit during its 15-minute flight.
Interestingly, AzaadiSAT is a student satellite built by 750 girl students and supported by Space Kidz India. Of the 750, 150 students arrived at Sriharikota to witness the launch on Friday.
This is the second launch of the ISRO's smallest vehicle after the first attempt ended up in partial failure as the SSLV rocket failed to inject its satellite payload into its intended orbits.
Unlike ISRO's workhorse PSLV, the mini SSLV caters to the launch of up to 500 kg satellites to low earth orbits on a 'launch-on-demand' basis.
It provides low-cost access to space, offers low turn-around time and flexibility in accommodating multiple satellites, and demands minimal launch infrastructure. The highlight of the rocket, however, is that it can be assembled in a week.
According to ISRO chairman S Somanath, the assembly of SSLV can be done in two days. While the testing requires another two days and rehearsal and launch would only take another two days.
It is configured with three solid propulsion stages and a velocity terminal module. It is a 34 m tall, 2 m diameter vehicle having a lift-off mass of 120 tonnes.
Failed mission
A probe launched by the agency into the failed first mission revealed that the mission failed after the upper stage of the launch vehicle injected the satellite into a highly elliptical unstable orbit due to a shortfall in velocity.
It also revealed that there was a vibration disturbance for a short duration on the Equipment Bay (EB) deck during the second stage separation.
The vibration affected the Inertial Navigation System (INS), resulting in declaring the sensors faulty by the logic in the Fault Detection & Isolation (FDI) software.
The failure detection logic identified a degraded accelerometer and isolated it for improved mission performance.
During the second stage separation, all six accelerometers experienced measurement saturation due to high vibration levels for a short duration.
This malfunction initiated a salvage mode with the purpose of saving the mission, but it could not inject the satellite into a safe orbit.
(With inputs from PTI)
