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ISRO’s heaviest rocket successfully places 36 broadband satellites in low earth orbit

India’s heaviest rocket injected 36 broadband satellites of a UK-based customer into precise orbits early Sunday, successfully completing a complex mission of many firsts that bolsters ISRO’s reputation as a serious player in the commercial satellite market.

The Launch Vehicle Mark III (LVM3) took off after midnight from the second launchpad of the country’s only spaceport in Sriharikota. Around 37 minutes later, Indian Space Research Organisation (ISRO) chairperson S Somanath said: “Sixteen (satellites) have been separated very safely as we expected and the remaining 20 satellites will be separating when we are not able to see it from this place (the rocket will be on the other side of the earth) and the data will come a little later.”

After the tracking blackout during the deployment of 20 satellites, the space agency announced at 01:42 am: “LVM3 M2/OneWeb India-1 mission is completed successfully. All the 36 satellites have been placed into intended orbits.” The satellite placement took place in five phases.

Somanath announced that the same vehicle will carry 36 more OneWeb satellites in its next launch.

This was the first foray of any Indian launch vehicle, other than ISRO’s workhorse PSLV, into the commercial space market. With this, India also entered the heavier launch vehicle segment of the market.

The mission, however, was not just about India positioning itself to capture a larger chunk of the commercial space sector (currently, India accounts only for 2 per cent of the market despite being one of the foremost space-faring countries). This was the first time that this launch vehicle carried multiple satellites and launched them into low earth orbit.

The LVM3 rocket (earlier called the Geosynchronous Launch Vehicle Mark III or GSLV-MK3) can carry up to 8 tonnes into low earth orbit. The PSLV is much lighter and can carry between 1.4 and 1.75-tonne payloads.

Before the LVM3 was operationalised — its first operational mission after two development flights was Chandrayaan 2 — several of the 2 to 5-tonne GSAT satellites were launched by European launch provider Arianespace. Two GSAT missions were flown by Arianespace even after that, the latest being in June this year.

The launch has bolstered LVM3’s credentials as a dependable vehicle, with all four of its missions being successful. This is crucial as the vehicle is currently being human-rated and will carry Indian astronauts to space under the Gaganyaan mission. “As part of human-rating, more confidence-building tests of all propulsion systems are being conducted successfully,” said Vikram Sarabhai Space Centre director Dr S Unnikrishnan Nair in a video address.

Other than what the mission proved about the capabilities of the space agency, the mission itself was challenging.

UK-based Network Access Associated Ltd — India’s Bharti Group is a major investor — plans to create a 588 satellite-strong constellation to provide high speed, low latency global connectivity. These satellites will be placed in 12 rings of 49 satellites each, with every satellite completing a full trip around the Earth in 109 minutes.

This was the fourteenth launch for OneWeb, taking the fleet strength to 464 satellites so far. The constellation will likely be completed by next year, with ISRO’s 36-satellite launch being among the last ones.

The current mission was also a long one, totalling more than 5,500 seconds, or 91 minutes, from the lift-off to the deployment of the last satellite. This was because, as per the company’s demand, ISRO had to ensure not only precise injection of the satellites into a 600-km orbit but also ensure that the satellites did not collide with each other during deployment or later on.

Dr Nair said: “The mission demands the separation of all 36 satellites into the 600-km orbit and the separation has to be sequenced in such a way that the customer requirement of minimum 137-metre distance between any pair of satellites is maintained. This is achieved by orienting and reorienting the cryo stage (third stage of the rocket) using the on-board thrusters.”

(With the inputs of Indian Express).

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