At 9:18 am on Sunday, the Small Satellite Launch Vehicle (SSLV), a three-stage rocket newly developed by the Indian Space Research Organisation (Isro) roared through the cloudy morning on its way to Low Earth Orbit (LEO). The objective of the mission was to introduce a new class of launch vehicle that can deploy small, nano, and cube satellites in orbit around Earth at a lower cost compared to its competition and with a faster turnaround.

The flight, as Isro chief S Somnath puts it, was “majestic” as the first stage separated. It was in the minutes that followed when chaos struck and the mission launched with two satellites ended up at the bottom of the Pacific Ocean. The spacecraft, while managing to reach the intended altitude, failed to put the satellites into the desired orbit.

This was Isro’s second loss in just a year, which in the past has had a clean track record.

What happened with SSLV?

SSLV took off smoothly from the first launch pad at the Satish Dawan Space Centre at Sriharikota and the three stages separated on cue after completing their ignition phases. The spacecraft had achieved the desired altitude climbing nearly 350 kilometers above the planet, thanks to the new propulsion system.

The problem arose in the final stage with the Velocity Trimming Module, which is designed to inject the satellites into the selected orbits. While the VTM was programmed to fire for 30 seconds, it burned for just one second. Isro said that the anomaly was with a logic in identifying a sensor failure that forced it to go for salvage action causing the deviation in the orbit.

Isro chief S Somnath in a statement said, “The issue has been identified but we will go deeper into it. It is due to a logic that exists in the rocket to identify a sensor failure and go for a salvage option. The system has a deficiency which we need to look at very closely and correct it with regard to the sensor isolation principle.”

What happened to the two satellites?

The SSLV deployed the two satellites, AzadiSAT and Earth Observation Satellite (EOS-02) in an elliptical orbit of 356*76 kilometers, with the latter being the closest altitude to Earth, instead of a circular orbit. This made the satellites unstable.

An unstable orbit of a satellite is problematic since it could lead to a collision with other satellites in the orbit and create space debris. The other issue is the atmospheric drag that disintegrates the satellite completely and the two launched by Isro suffered a similar fate.

Johnathan McDowell, who tracks global space developments with the Center for Astrophysics, noted that the vehicle likely failed to complete even half an orbit and fell into the Pacific. Isro chief later confirmed that the satellites, due to atmospheric drag, came down.

What is the future of SSLV?

The center has allocated a budget of Rs 169 crore to the project which covers the cost of developing the rocket and conducting three experimental launches to verify the system and Isro had factored the contingencies ahead of the launch.

Somnath maintained that, even though the satellites were lost, the launch verified the SSLV system. “Every other new element in the rocket performed well, including propulsion, hardware aerodynamic designs, new gen low-cost electronic systems, control systems, separation systems, all have been proven,” the Isro chief said.

The Indian space agency has set up a committee which will look into the problems encountered by SSLVD1. Somnath added that the system has a deficiency that needs to be looked at very closely and corrected with regard to the sensor isolation principle. The agency is going to identify the specific option and why the isolation happened and why it went into the wrong orbit and do a deep evolution in days to come.

Isro cleared that it will go ahead with SSLV-D2 and SSLV-D3 missions in the coming months.


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