| A helicopter carries the mock space capsule and (right) the recovered capsule at the shallow lake in Sriharikota last year
New Delhi, Aug. 27: From a helicopter, hovering 5 km above the Bay of Bengal, a cone-shaped capsule, resembling a giant brown flowerpot, dropped towards the sea. Seconds later, parachutes ballooned open to slow its descent before it hit the water.
The impact triggered a flotation system, and electronic beacons drew engineers who hoisted the capsule onto a boat, completing the simulation of the terrestrial part of an experiment that Indian space scientists hope to conduct next year.
The helicopter drop test, conducted 25 km east of the Sriharikota spaceport on June 9 this year, was part of preparations for India’s first-ever attempt to recover an orbiting space capsule, scheduled to take place in early 2006.
In the space capsule recovery experiment (SRE), a capsule will piggyback on a satellite aboard a Polar Satellite Launch Vehicle, orbit Earth for two weeks from a distance of about 600 km, and then be guided back for a splashdown in the Bay of Bengal.
Indian Space Research Organisation (Isro) sources said the experiment will test an array of technologies with applications in future space goals: reusable launch vehicles, remote-operated science experiments in space, and manned space missions.
“The helicopter drop test off Sriharikota demonstrated that the flotation and tracking systems worked well,” a source said.
Last year, Isro had tested the parachutes in helicopter drop exercises over land and a shallow lake in Sriharikota.
The 510-kg space capsule will carry payloads for two science experiments. One, designed by National Metallurgical Laboratory, Jamshedpur, will observe how microgravity (the very low gravity obtaining in space) influences biological processes.
The other, also a microgravity experiment, has been put together by the Indian Institute of Science, Bangalore, and the Vikram Sarabhai Space Centre, Thiruvananthapuram.
The most challenging part of the capsule recovery mission will be its re-entry into Earth’s atmosphere at speeds of about 25,000 km an hour during which it will encounter searing 1,800-degree Celsius temperatures, Isro scientists said. A blanket of silica tiles and composite materials will protect the returning capsule from the heat.
Only the US, Russia and China possess spacecraft re-entry technology, which is crucial for the development of reusable launch vehicles that are expected to emerge as alternatives to the US space shuttle.
Except for the space shuttle, no commercial launch vehicle today can be reused after liftoff.
Isro had earlier signalled its intentions to join the international race to build cheap reusable launch vehicles. “The SRE experience would help us toward that goal,” an Isro source said.
While Isro sources said there are no approved plans yet for indigenous manned space missions, they acknowledged that the heat-protection blankets and de-orbiting and return manoeuvres in the experiment are all prerequisites for manned missions.
Isro has already decided to build an extra-powerful launch vehicle called the GSLV (Geosynchronous Satellite Launch Vehicle) MkIII, configured to carry a 10-tonne payload into low Earth orbit (at a distance of about 300 km), which is large enough to support manned missions.
The sources, however, said Isro has no expertise whatsoever in the development of life support systems on spacecraft, vital for the safe return of astronauts.
While Indian satellites have carried myriad payloads into space in the past, the SRE will mark the first time that a scientific payload will return so that the micro-gravity experiments can be analysed on the ground.