The launch of Polar Satellite Launch Vehicle (PSLV-C16) from the Satish Dhawan Centre, Sriharikota went off smoothly on April 20.
The lift-off was bang on schedule. In 18 minutes, the target altitude of 822 km was reached and three satellites were placed in orbit. The big payload was the 1206 kg Resourcesat-2, along with the 92 kg Youthsat and the 106 kg X-SAT.
That routine launch was a relief for the Indian Space Research Organisation (ISRO). The four-stage, 45-metre, 290-tonne PSLV, which went into service in 1993, is very reliable. This was the 18th consecutive successful launch. It was also successfully adapted for the 2008 Chandrayaan Mission.
But two failed Geosynchronous SLV (GSLV) launches in 2010 had everyone on tenterhooks. ISRO has also faced much flak due to the now-cancelled deal between its marketing arm, Antrix and Devas Multimedia where transponder spectrum in an upcoming GSAT6 launch was leased for a song to Devas. Although the Rs 230 crore PSLV-C16 has no direct relevance to the Devas deal (GSAT also uses PSLV platforms), failure would have damaged ISRO’s image and hit Antrix’s revenues.
Control of satellites is maintained from ISRO’s Telemetry Tracking and Command Network Centre (ISTRAC) in Bangalore, which is connected to a network of ground stations at Lucknow, Mauritius, Biak (Indonesia), Svalbard (North Pole) and Troll (South Pole).
Resourcesat 2 will replace Resourcesat 1, which is still operational, three years after its design life-span ended in 2008. Resourcesat2’s LISS-4 camera sweeps 70 km at one go. Resourcesat 2 also carries a Canadian automatic identification system (AIS) for ship surveillance — this is part of global anti-piracy plans.
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Overall, Resourcesat-2 carries three cameras of different resolutions and two solar panels for power. The images are used in mapping natural resource in applications like crop health surveys, ground water mapping, deforestation tracking, monitoring water-levels in reservoirs and lakes, snow-melt in the Himalayas and so on.
A typical application is Forecasting Agricultural output using Space, Agrometeorology and Land-based observations (FASAL) that provides accurate crop forecasting. There are also apps in town-planning, airport and road-building design.
YouthSat is an Indo-Russian construct, with one payload from Russia and two from ISRO. It’s focussed on upper atmosphere studies between 50 km and 1,000 km altitude. X-Sat is Singapore’s first indigenous satellite and the 26th foreign satellite launched by PSLV — an index of ISRO’s commitment to commercial launches.
On April 28, the first high-res images came through from Resourcesat2, which is in a polar sun-synchronous orbit. Sun-synchronous orbits ensure that given parts of the Earth are surveyed at the same local time, for consistent lighting. The first images covered 3,000 kms from Joshimath (Uttarakhand) to Kannur (Kerala).
Before April 20, there were already nine Indian remote-sensing (IRS) satellites in orbit, including Resourcesat-1. IRS images are sold commercially and Antrix generates over 20 per cent of its annual revenues (Rs 900 crore in 2009-10) from IRS.
PSLV is a “mixed”, solid-liquid propellant, four-stage design, adapted mainly from French specs. It has at least five variants. Each stage has its own control systems. An inertial guidance system navigates, guides and offers attitude control and flight sequencing.
PSLV are workhorses with respectable payloads of about 1600 kg. In 2011, PSLVs will launch GSAT-12, the Megha-Tropiques satellite, GSAT-6 and Radar Imaging Satellite (RISAT-1), all from Sriharikota. Another GSAT would also be launched from Kourou, French Guiana, by an Ariane rocket from Arianespace in June 2011.
The next-generation triple-stage GSLV costs Rs 350 crore and is designed to carry a massive 4,500 kg. But the design is not yet stable. GSLV-FO6 had to be aborted and blown up within 50 seconds of launch on Christmas Day, 2010. An earlier GSLV launch in April 2010 also failed.
Until GSLV is “pucca”, India will rely on Ariane to launch heavier satellites. The key third-stage of GSLV is a Russian cryogenic engine, developed by GlavKosmos. The first and second stage are Vikas engines, based on Ariane’s Viking. In April 2010, GSLV used an Indian cryogenic engine. All stages use Indian avionics. In December, there was a problem with a fuel booster pump; in April, ground-to-air communications failed.
While remote-sensing has huge utility – including locating aircraft wreckage as in the recent Arunachal Pradesh tragedy – a Comptroller and Auditor General of India ( CAG) report suggests the image-processing techniques are inefficient.
The CAG cites delays in image processing at the National Remote Sensing Centre (Hyderabad) and claims around 90 per cent of images are not utilised. An ISRO wasteland-mapping project has also been delayed for 14 years. ISRO chairman, K Radhakrishnan accepts, “The CAG findings are hundred per cent correct,” which implies an overhaul in IRS processing systems is overdue.
For years, ISRO maintained a pristine image. It delivered a string of glittering successes. It created the satellite network, which is the cornerstone of India’s electronic media and telecom revolution. Recent events have rubbed off some of the sheen. This launch should lift morale, and put the ambitious space exploration programme back on track.