An experimental spacecraft with an inflatable heat shield has disappeared during its return to Earth on the remote Kamchatka peninsula in eastern Russia. "Our landing zone is very big and the craft is very small," says Lionel Marraffa, lead European Space Agency engineer for the project. "The area is populated by only 100 bears and a few soldiers so it may take us days or even weeks to find it."
The experimental craft, which looks like a giant shuttlecock, is designed to massively reduce costs by cutting launch weight and size. Engineers also hope that the craft could form the basis for "lifeboats" on the International Space Station or even escape pods for burning skyscrapers.
Normal spacecraft use thick metal or ceramic heat shields to protect the vehicle during re-entry to the Earth's atmosphere and massive parachutes to slow it down. But these are heavy and bulky.
Instead, the new craft uses an inflatable heat shield made from ceramic fibres and a silicon-based rubber. This also acts as a parachute, slowing descent to a "landing" speed of 50 km/h.
A Russian submarine launched the Inflatable Re-entry and Descent Technology (IRDT) mission on 12 July. It successfully separated from the launch vehicle at an altitude of 200 km and should then have began its descent to Earth.
But just after separation, controllers from the European and Russian space agencies lost sight of the craft. It is not unusual to lose contact with a spacecraft at this stage as debris, heat and electromagnetic fields can obscure the returning vehicle.
Assuming the craft survived separation, the first stage of the heat shield should then have inflated. It is designed to withstand a re-entry speed of 7 km per second, which generates temperatures in excess of 1000 °C. The second stage should have deployed 30 seconds later to further reduce re-entry speed and - in theory - bring the craft to a gentle landing in the target zone.
But engineers fear that the shield may have failed, causing the craft to burn up during re-entry. The first IRDT test craft, launched in February 2000, returned to Earth intact, but at a lower re-entry speed.
"We still have a lot of data to analyse and homework to do," Marraffa told New Scientist . "We're still studying the data to see if we have actually lost contact with the craft. Its signals would be faint and difficult to detect anyway. The search is continuing."
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