Isro to launch final batch of OneWeb satellites on Sunday

Tirupati: The Indian Space Research Organization (Isro) is gearing up for launch of LVM3 (Launch Vehicle Mark-3)-M3/OneWeb India-2 mission from the Satish Dhawan Space Centre in Sriharikota on Sunday.

This is the second mission for the private entity Network Access Associates Ltd, UK, a part of the OneWeb Group) under a commercial agreement with Isro's commercial arm - M/s. NewSpace India Ltd (NSIL). The agreement is to launch 72 satellites to Low-Earth Orbits.

While the first batch of 36 satellites were successfully launched by the Isro on October 23, 2022, the second and final batch of OneWeb's 36 more satellites under the LVM3-M3/OneWeb India-2 mission will be launched from the SDSC-SHAR at 9 am on Sunday.

Isro's NSIL released the LVM3-M3 OneWeb India-2 mission brochure on Thursday. It said the integration-related activities were under way at the second launchpad at SDSC-SHAR. In this mission, the LVM3 would place 36 OneWeb Gen-1 satellites totalling about 5,805 kg into a 450 km circular orbit with an inclination of 87.4 degrees.

This is the sixth flight of LVM3, the heavy lift launch vehicle of Isro, for achieving a 4000kg spacecraft launch capability to GTO (geosynchronous transfer orbit) in a cost-effective manner. The heavy lift Isro launcher has a track record of five successive launches, including the Chandrayaan-2 mission.

LVM3 is a three-stage launch vehicle consisting of two solid propellant S200 (solid) straps-on and core stages consisting of L110 liquid stage, C25 cryogenic stage, equipment bay and encapsulated assembly (EA).

EA comprises spacecraft, payload adaptor and payload fairing. With a lift-off mass of 643 tonnes, this 43.5metre-tall three-stage launch vehicle gives the ISRO full self-reliance in launching heavier communication satellites that weigh up to 4000kg in GTO. The vehicle takes off with the simultaneous ignition of the two S200 boosters.

The core stage (L110) is ignited at about 111 seconds through the flight, during the firing of the S200 stages. Both S200 motors burn for about 134 seconds and the separation occurs at 138.20 seconds. The payload fairing is separated at an altitude of 115.76km and at about 187.16seconds during L110 firing.

The L110 separation, C25 ignition and C25 shut-off occur at 308.48 seconds, 310.88 seconds and 942.70 seconds respectively. The satellite separation event-I occurs at 455.538km and at about 1,182.70 seconds.

Isro said the UK-based OneWeb is a global communication network powered from space, enabling connectivity for governments, businesses, and communities. It is implementing a constellation of 648 low earth orbit satellites. Its Gen-1 satellites utilize a bent-pipe technology approach to offer communication in Ku-band and Ku-bands.