ISRO has precisely launched 36 OneWeb satellites, many completing maiden missions

India’s heaviest launch vehicle – now referred to as Launch Vehicle Mark III (LVM3) instead of Geosynchronous Launch Vehicle Mark III (GLSV-MK III) – successfully injected 36 satellites of the OneWeb Broadband constellation into precise orbits in five phases early on Sunday.

At 01:42 am the space agency announced, “LVM3 M2/OneWeb India-1 mission completed successfully. All 36 satellites have been placed in the intended orbit,” after a tracking blackout in which 20 satellites were placed.

About 37 minutes after liftoff from the second launch pad at the country’s only spaceport in Sriharikota, ISRO Chairperson S Somanath said, “Sixteen (satellites) have separated very safely as we expected and the remaining 20 satellites will separate when. We are not able to see it from this place (the rocket will be on the other side of the world) and the data will come a little later.” The Chairperson, wishing everyone a Happy Diwali, said the space agency has started the celebrations a little earlier.

During this break, he announced that the same launch vehicle would carry 36 more OneWeb satellites on its next LVM-M3 launch.

A mission of many firsts

It was the first mission of many for the space agency.

This was the LVM3’s first foray – indeed, any launch vehicle other than ISRO’s workhorse PSLV – into the commercial space market. And, with this, India has also entered the heavy launch vehicle segment of the market. The mission, however, was not to position India itself to capture a larger share of the commercial space sector (currently India accounts for only 2% despite being one of the leading countries in the space industry).

This is the first time this launch vehicle has carried multiple satellites and launched them into low Earth orbit.

LVM3 – M2/OneWeb India-1 Mission: Launch scheduled at 0007 hrs. IST on October 23, 2022. Cryo stage, equipment bay (EB) assembly completed. The satellites are encapsulated and integrated into the vehicle. Final testing of the vehicle is underway. @NSIL_India @OneWeb pic.twitter.com/pPbqjDjFmS

— ISRO (@isro) October 14, 2022

This is also the first time an Indian rocket has carried a 6 tonne payload into space. The total weight of the 36 satellite payloads is about 5.8 tonnes, the heaviest payload ever carried by the space agency. The LVM3 rocket has a payload capacity of up to 8 tonnes into low earth orbit. PSLV is a much lighter vehicle and can carry a payload of 1.4 to 1.75 tonnes.

In fact, before LVM3 was launched – its first operational mission after two development flights – Chandrayaan 2 – several of the 2 to 5 ton GSAT satellites were launched by European launch provider Arianespace. Two GSAT missions have since been flown by Arianespace, most recently in June this year.

The mission assumes significance as it was LVM3’s first commercial mission and also NSIL’s first with the said launch vehicle. (Twitter/@ISRO)

It also proved LVM3 to be a reliable launch vehicle, with all four of its missions being successful. This is important as the vehicle is currently being manned and will carry our astronauts into space under the Gaganyaan mission. “LVM3 is being human-rated for the human spacecraft mission Gaganyaan. And further confidence-building tests of all propulsion systems are being successfully conducted as part of the human rating,” Vikram Sarabhai Space Center Director Dr S Unnikrishnan Nair said in a video address.

Challenging missions

Apart from what the mission proved about the space agency’s capabilities, the mission itself was challenging.

This was the LVM3’s first foray – indeed, any launch vehicle other than ISRO’s workhorse PSLV – into the commercial space market. Twitter/@ISRO

United Kingdom-based Network Access Associated Ltd – India’s Bharti is a major investor – plans to build a 588-satellite-strong constellation to provide high-speed, low-latency global connectivity.

These satellites will be deployed in 12 rings of 49 satellites, each satellite completing a complete trip around the Earth in 109 minutes. This was the fourteenth launch for OneWeb, increasing the fleet to 464 satellites to date. With the constellation likely to be completed by next year, ISRO will launch another batch of 36 satellites.

The current mission was also a long one, with a total time of more than 5,500 seconds or 91 minutes from liftoff to deployment of the last satellite. This is because, as per the company’s demands, ISRO not only has to ensure precise injection of the satellites into the 600 km orbit but also ensure that the satellites do not collide with each other during or after deployment.

Dr. Nair said, “The mission calls for separation of all 36 satellites in a 600 km orbit and the separation should be sequenced in such a way that a minimum distance of 137 meters is maintained between any pair of customer satellites. This is achieved by orienting and re-orienting the cryo stage (rocket’s third stage) using on-board thrusters.”

Dr D Sam Dayala Dev, director of ISRO Inertial Systems Unit, said, “Precise injection is required so that they do not collide during separation. They should not only collide but maintain separation for a long time. Some techniques for this, including pointing the launch vehicle and increasing the separation between the satellites. Velocity needs to be added. It needs to be done very precisely.”

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