For over two decades, it has impeccably accomplished the tasks allotted. This morning, with 37 consecutive successes behind it, the Polar Satellite Launch Vehicle (PSLV) will lift-off from Sriharikota with 104 satellites on board, almost thrice the number that a Russian rocket, which currently holds the record, carried three years ago.

It is not that there is no other rocket in the world that can haul so many spacecraft. Indeed, there are several with much higher payload capacities than the PSLV. Rather, today’s flight is a testament to the meticulous mission planning and flawless execution capabilities that Isro’s launch vehicle teams are capable of.

Since its first successful flight in 1994, this Indian rocket has placed 122 satellites in orbit, 43 of them Indian (including the Chandrayaan-1 lunar probe and the Mars Orbiter Mission) as well as 79 foreign ones from 21 other countries. It has carried multiple satellites on 18 occasions. Last June saw the PSLV lift 20 satellites (21 if a tiny satellite snuggled inside another spacecraft and ejected only a few months later is also included), its previous best that helped prepare for today’s all-time record.

The higher the number of satellites being taken on a single rocket, the greater the attention that must go into every small detail to make sure nothing goes wrong and jeopardises the whole mission. It is far easier—and much less nerve-racking—to launch one or two satellites instead of a whole swarm of them.

AS Kiran Kumar, who heads the Indian space agency, points out that today’s launch was not undertaken in order to achieve a new record. The principal payload for the mission included Isro’s own earth imaging spacecraft, a Cartosat-2 series satellite, and two Indian nano satellites, INS-1A and -1B, each weighing around 9kg. After these were accommodated, the rocket still had some capacity to spare. Carrying another 101 satellites from abroad earned money that almost halved the cost of launching the Indian satellites.

In recent years, there has been an explosion in the number of small satellites weighing between 1kg to 50kg being built and planned. The low cost of these satellites makes space accessible to universities as well as governments of non-spacefaring nations. Companies, too, are looking at constellations of such satellites for applications such as rapid earth imaging and global tracking of ships. As a result, small launchers are meeting the growing demand from this market segment.

The PSLV has emerged as a cost-effective and reliable launcher for such satellites. Today’s launch, if successful, should further consolidate that position. Cramming as many satellites as possible on the rocket might for Isro also be a way of remaining competitive, perhaps allowing it to avoid the development of a new Small Satellite Launch Vehicle (SSLV) of its own.

AUTHOR

Gopal Raj

Gopal is a science journalist based in Thiruvananthapuram who has written extensively about the Indian space programme for over two decades and published a book, ‘Reach for the Stars: The Evolution of India’s Rocket Programme’. Follow him on Twitter @GopalRajN

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