ISRO's cryogenic leap

Cryogenic technology powers India into an exclusive club

The Indian Space Research Organisation (ISRO) must be complimented for the successful launch of the Geosynchronous Satellite Launch Vehicle (GSLV-FO5) last week. The GSLV-FO5 launched the INSAT-3DR satellite, one of the three Indian satellites exclusively dedicated to weather research. This satellite, which tips the scales at 2.2 tonnes, will gather meteorological data apart from helping out in search and rescue services. The satellite uses an imaging instrument called the atmospheric infrared sounder (AIRS), which generates vertical 3D profiles of temperature and moisture data. It can also provide very high-resolution images, both visible and infrared, as well as night images. INSAT-3DR can also make accurate estimations of sea and river temperatures. But beyond the merits of the satellite, the GSLV’s latest launch underscores that ISRO now has a reliable grasp of the cryogenic engine (CE) technology. This is the fourth time an indigenous CE has been deployed successfully, and it puts India into an exclusive club of six nations.

CEs are essentially high-tech steam engines, burning liquid hydrogen and liquid oxygen. These two elements are liquefied and stored separately at very low temperatures of minus 250 degree C. They combine explosively to produce steam. The technology is tricky: Very cold fuel tanks are placed in close proximity to very hot combustion chambers. But CEs’ key merit is that they provide higher thrust-to-weight ratios and are generally used at the latter stages of a multistage rocket.

India has had a rather chequered history when it comes to developing the CE technology. The CE programme started in the early 1990s with the help of the Russians. But since CEs fall under the “dual use” technology category, ie, technologies that can be used for both civilian and military applications, the US imposed sanctions on India in 1992. The Russians were pressured to stop assisting India in research and development. However, they did give six CEs to India. The ensuing development went through many ups and downs with two launch failures in 2010. However, in January 2014, with the launch of GSLV-D5, ISRO successfully used the CE-7.5 engine. But all the flights till now were developmental. The latest one is the first operational deployment. For ISRO, the next stage involves two key challenges: Developing larger CE engines and achieving a greater level of indigenisation. The GSLV and the key components of India's CEs have only about 60 per cent indigenous content, much lower than the 92 per cent in the older and smaller PSLVs (Polar Satellite Launch Vehicles).

But ISRO has a long way to go. The country is still launching vehicles that launch satellites weighing about 2 tonnes, but the bulk of the international market is for launching satellites in the 4-tonne range. Besides, there are about 200 satellite launches annually; India does an average of just three. In that sense, India is still a very small player, as countries like the US, Russia, China and the European space agencies do 15-20 and more each year. Also, ISRO's advantage is supposed to be its low cost. However, with the advent of private players like Spacex, costs have come down by 25-30 per cent, and will drop further, even as satellite sizes increase. So, ISRO needs to be doing much more if it is to be more than a bit player in the game.