Isro to launch heaviest commercial mission today

PSLV-C28 to place into orbit five British satellites at 9:58 pm today

Indian space agency Isro is all set to launch its heaviest commercial mission that would put five British satellites on board PSLV-C28 from the spaceport of Sriharikota near here today.

This is Isro's first commercial mission in 2015. 

Isro's workhorse would lift-off 44.4 metre tall PSLV-XL version from the Satish Dhawan Space Centre at Sriharikota at 9:58 pm and would put into orbit the five satellites.

The Mobile Service Tower (MST) withdrawal upto parking end, N2O4 propellant filling operation of second stage (PS2) and UH-25 propellant filling operation of second stage (PS2) have been completed by 09:40 am.

With the overall mass of five satellites is about 1,440 kg, this launch becomes the "heaviest commercial mission" ever undertaken by Isro.  

France's SPOT 7 satellite weighing 714 kg was the heaviest single foreign satellite carried by a PSLV rocket till now. It was launched on June 30, 2014. The total carrying capacity for such a mission is around 1,750 kg. 

Of the five British satellites on board, three are identical DMC3 optical earth observation satellites, weighing 447 kg. The CBNT-1 weighs 91 kg and is an optical earth observation technology demonstration microsatellite, while the De-OrbitSail weighs 7 kg. This is an experimental nano satellite for demonstration of large thin membrane sail and drag deorbiting.

After 17 minutes, the rocket will eject the DMC3 satellites one after another and they will be followed by De-OrbitSail and CNBT-1 satellites. The satellites were built by Surrey Satellite Technology while the De-OrbitSail is built by Surrey Space Centre. The whole process will take 19 minutes time.

According to Isro, the DMC3 constellation, comprising of three advanced mini-satellites DMC3-1, DMC3-2 and DMC3-3, are designed to address the need for simultaneous high spatial resolution and high temporal resolution optical earth observation.

Launched into a single low earth orbit plane and phased with a separation of 120° between them, these satellites can image any target on the earth’s surface every day. Major application areas include surveying the resources on earth and its environment, managing urban infrastructure and monitoring of disasters.

Isro officials earlier said that accommodating the three DMC3 satellites, with about three meters height each, within the existing payload of the PSLV was one of the major challenges. A circular L-adaptor and a triangular Multiple Satellite Adapter-Version 2 (MSA-V2) were designed and realised by Isro for this specific purpose.