THIRUVANANTHAPURAM: Countdown is under way for the launch of the Polar Satellite Launch Vehicle (PSLV-C7) from the Satish Dhawan Space Centre (SDSC) at Sriharikota in Andhra Pradesh on January 10. It will be a multi-mission launch, as it will put in orbit four satellites. What is significant is that one of these will be a recoverable satellite called Space Capsule Recovery Experiment (SRE). This is the first time that the Indian Space Research Organisation (ISRO) will be attempting to recover a satellite.

SDSC Director M. Annamalai and PSLV-C7 Mission Director N. Narayana Murthy told a team of presspersons, who visited the SDSC on Wednesday, that if the countdown held, the vehicle would lift off at 9.23 a.m. on January 10. "Everything is perfectly in place and a Mission Readiness Review meeting will be held on Saturday," they said.

The four satellites that the PSLV-C7 will launch are SRE, Cartosat-II, LAPAN-Tubsat and Pehuensat-I. ISRO has built both the SRE and the Cartosat-II. The other two are from abroad.

The SRE will be a technological forerunner to re-entry technology and ISRO's plans to build reusable launch vehicles.

After the SRE stays in orbit anywhere between 13 and 30 days, it will be de-orbited and it will splash down in the Bay of Bengal, 140 km east of the Sriharikota island. A flotation system will keep the satellite afloat and the Coast Guard will recover it.

During its stay in orbit, the 615-kg SRE will demonstrate the technology of using an orbiting platform for conducting experiments in micro-gravity conditions. The satellite has an indigenously developed thermal protection system. Silica tiles have been used for reducing the impact of heat during the SRE's descent through the atmosphere.

The durability of the tiles will be known after the satellite is de-orbited and brought back to the earth.

According to Mr. Annamalai and Mr. Narayana Murthy, "the thermal protection system is a milestone in our experiments. With this experimental module (SRE), we are taking a step forward that will lead us to reusable launch vehicles." The SRE will provide ISRO with valuable experience in navigation, guidance and control systems during the satellite's re-entry phase.

To enable the PSLV-C7 to launch four satellites in four different orbits, a Dual Launch Adopter is being used for the first time.

The 44-metre tall PSLV-C7 has a lift-off mass of 295 tonnes. C-7 stands for continuation flight 7. The vehicle looked majestic as it stood encased in the 75-metre-tall Mobile Service Tower. All the four satellites have been mated with the launcher. The heat-shield is closed. The launch will take place from the first launch pad. The PSLV was originally designed to put remote-sensing satellites weighing 1,000 kg in orbit.

Its payload capacity was enhanced with each successive mission. In its flight in May 2006, the PSLV-C6 orbited two payloads — a 1,560-kg Cartosat-I and a 42-kg amateur radio satellite called HAMSAT.

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