The September 26, 2016, launch of the Polar Satellite Launch Vehicle (PSLV)-C35 set two records: It was the longest satellite-launch mission yet, two hours, having completed its previous mission in just under 30 minutes on June 22, 2016 (another benchmark occasion with the launching of 20 satellites in one go); and the rocket released eight satellites — five foreign and three Indian — into two orbits, something ISRO has not done before.
No more than 38 per cent of satellites launched over the last 10 years have been Indian. Over this period, ISRO has had 34 launches, successfully sending up 121 satellites, 75 of them foreign: 18 (24 per cent) were from US, 11 (15 per cent) Canadian, 8 (11 per cent) each from Singapore and Germany and 6 (8 per cent ) from the UK.
However, in terms of weight, the Indian satellites that ISRO has launched were 10 times heavier, by kg, than foreign satellites carried aloft by PSLV and other launch vehicles over the last decade.
Although foreign satellites (one US, one Canadian, and three Algerian) outnumbered domestic launches on Monday, according to the ISRO list of foreign satellites launched, Indian spacecraft occupied most of the 1,750-kg capacity of the PSLV, which completed its 36th successive, successful launch.
Up to 16 per cent of the PSLV’s capacity was occupied by small satellites from foreign nations, who bought space on the Indian launcher. Deals are arranged by Antrix, the commercial arm of the Department of Space, and these are becoming more profitable by the year.
India earned 205 per cent greater revenue in financial year 2014-15 (Rs 415.4 crore/ $62.3 million) than the previous year (Rs 136 crore/$20.4 million) and 704 per cent more than in 2013 (Rs 51.3 crore/$7.7 million) for satellite-launch services.
On Monday’s launch, the combined weight of the five foreign craft was 279 kg, the heaviest being the ALSAT-2B (117 kg), which is an Earth observation satellite meant to help Algeria with the management of natural disasters and land planning, among other things.
The combined weight of the three Indian craft was 386 kg. The Indian SCATSCAT-1 alone weighs 371 kg. The SCATSCAT-1 is a government-owned craft intended to observe the earth, aiding weather forecasts among other things. It will operate for five years.
The other two weighed only 15 kg combined, and were from Indian Universities. The PRATHAM (10 kg) is from the Indian Institute of Technology (IIT) Bombay, and the PISAT (5 kg) is from PES University in Bengaluru. They are both conducting scientific experiments of their own.
If a satellite is heavier, assuming it is efficiently built, it is because of multiple payloads, indicating a greater amount of equipment to measure things more accurately or to measure different things. Consider the seven IRNSS spacecraft (1A-1G), all of which featured a separate payload for navigation and ranging. Each IRNSS weighed 1,425 kg, or 84 per cent of the PSLV’s capacity.
The heaviest foreign satellite ever launched by ISRO was 400 kg, an Earth observation satellite from Singapore on December 16, 2015. Only 20% of Indian Earth observation crafts weighed less than that, and most weigh well over 1,000 kg.
India will benefit from the scientific experience of launching heavier craft, but it has also been suggested — by the BBC here — that foreign investors want Indian PSLV craft to take their heavy payloads instead, and that the commercial future of India’s space project could lie in that direction.
By Charlie Moloney