ISRO's 'Next Workhorse Rocket' SSLV Takes Giant Leap For Itself, With Implications For Gaganyaan And Disaster Management Too

This morning (16 August), the Indian Space Research Organisation (ISRO) accomplished a space mission with implications for its newest rocket, its maiden human spaceflight mission, and disaster monitoring, which has become essential due to the devastating effects of extreme weather events occurring around the country.

ISRO successfully launched its smallest and youngest rocket, called the small satellite launch vehicle (SSLV), on its third and final developmental flight from the first launch pad of the Satish Dhawan Space Centre-Sriharikota Range (SDSC SHAR).

After accomplishing the various flight stages, the launch vehicle placed the primary satellite, the Earth Observation Satellite EOS-08, weighing 175.5 kilograms (kg), into a 475-kilometre (km) circular, low-earth orbit with an inclination of 37.4 degrees. The satellite separation occurred about 13 and a half minutes into the flight.

The separation of the 0.2 kg passenger satellite, SR-0 DEMOSAT, from Space Kidz India followed just under 2 minutes later.

In demonstrating the repeatable flight performance of the vehicle systems and successfully injecting the satellites into a 475-km orbit, ISRO’s SSLV accomplished its mission objectives.

“I find that there are no deviations in the injection conditions. The final orbit, of course, will be known after tracking. But the current indication is that everything is perfect,” ISRO Chairman S Somanath said in his address at SDSC.

“With this third developmental flight of SSLV, we can declare the development process of SSLV is completed,” he added.

And thus, in fulfilling its flight this morning, the SSLV completed a journey of its own, from the developmental phase to the operational phase.

SSLV, The ‘Next Workhorse’

The SSLV is a three-stage launch vehicle capable of launching mini, micro, and nano satellites, ranging in mass from 5 kg to 500 kg, into a 500 km planar orbit. It is 2 metres (m) in diameter and 34 m in height and capable of lifting off with 120 tonnes of mass.

The rocket’s three stages are all solid propulsion stages, with the liquid propulsion-based velocity trimming module serving as the terminal stage.

The need for the SSLV emerged from the fact that there is a growing demand for small satellite launches. Small satellites have the potential to take the benefits of space technology to even the remotest of places. The space industry is especially keen on launching constellations of earth observation and communication satellites at a low cost.

With its ability to launch multiple satellites into multiple orbits with minimal infrastructure requirements, the SSLV is set to be an appealing prospect for the global space industry, if not an outright game changer.

The SSLV comes at a low cost, has a low turnaround time, and can be launched on demand.

The first developmental flight of the SSLV took place in August 2022. The SSLV-D1/EOS-2 mission predictably went through the various flight stages, but due to an anomaly, the satellites were placed in an unstable, elliptical orbit.

ISRO got it all right in its second attempt. The second developmental flight, the SSLV-D2/EOS-07, held in February 2023, was textbook.

The completion of the third developmental flight, the SSLV-D3/EOS-08, on 16 August, 2024, propels the rocket into the operational phase for further launches.

“We are on the process of transfer of technology of SSLV to industries and for serial production and launches of SSLV in a commercial basis. So it is a great beginning for the rocket, the small satellite launch vehicle,” Somanath said.

“Now that the development phase of the SSLV is over, the next phase of ISRO’s next workhorse will commence soon. We are definite that there will be many more launches of SSLV soon,” Mission Director S S Vinod said.

Significance Of The Satellite Launched

The EOS-08 satellite will serve as a test platform to prove many novel technologies, including crucial payloads.

“EOS-08 is a very unique spacecraft where we have many new technologies, including flexible solar panels, integrated avionics, embedded multifunctional structural panels. These are to name a few. We have more than 20 new technologies which we are demonstrating through EOS-08,” Satellite Director Avinash M said at SDSC.

The microsatellite was built on ISRO’s standard Microsat/IMS-1 bus platform. The primary objectives of designing this satellite were to create payload instruments compatible with the microsatellite bus and to incorporate new satellite-related mainframe technologies required for future micro-operational satellites.

The EOS-08 is equipped with three payloads: the electro-optical infrared payload (EOIR), the global navigation satellite system system-reflectometry payload (GNSS-R), and the silicon carbide ultraviolet dosimeter (SiC-UV).

The data from the satellite will be used for disaster monitoring, fire detection, volcanic activity observation, industrial and power plant disaster monitoring, cryosphere studies over the Himalayan region, and flood detection.

The infrared payload EOIR, with its day-and-night imaging capability, will be useful in disaster management, while the GNSS-R will provide a new type of remote sensing for applications like soil moisture tracking, ocean winds monitoring, cryosphere applications over the Himalayan region, flood detection, and so on.

Notably, the SiC-UV has a Gaganyaan connection. The payload is designed to monitor the UV irradiance at the viewport of the crew module in the human spaceflight mission. It will also come in handy as a high-dose alarm sensor for UV radiation.

The UV dosimeter, said Avinash, “is to be flown on the Gaganyaan mission, but we are flying it here to get the on-orbit experience. These payloads will have applications which will not only change or influence the common man but will also help the astronauts on Gaganyaan.”

The mission life of the EOS-08 is expected to be one year.