Return to sender

A joint European Union and Russian space project suffered a setback when a novel inflatable space vehicle was lost after launch, it was revealed this week.

The missing Demonstrator-2 module was a prototype of the Inflatable Re-entry and Descent Technology (IRDT) device designed by Russia’s Babakin space centre and space technology company Astrium in Germany.

The IRDT is an engine-less, unmanned vessel in which astronauts aboard the International Space Station could send samples or materials back to Earth without the need for expensive Space Shuttle missions and station capsule launches.The spherical vehicle, initially designed to be 800mm in diameter, would be ejected from the space station and drawn back to Earth by gravity.

The ‘space postbag’ relies on a system of parachutes or conical sails, which are inflated at different stages of its descent to protect it and break its fall to Earth.The first sail is deployed to reduce its speed and shield it from the heat generated by re-entry into Earth’s atmosphere. The sail extends from the sphere as a cone and is held in shape by an inflated ring at its large end.

Once it has completed this stage, the second sail is inflated. This extends beyond the first cone and is held rigid by a similar inflated ring. The second sail produces a large amount of drag and further slows the craft’s final drop to Earth.

The technology is also designed so that it could be used to land ‘moon buggies’ on planets, or conduct atmospheric tests. The IRDT was originally designed to enter the less severe atmosphere of Mars at the slower speed of 5.5km per second as opposed to 7km/s.

The parachute descent was due to be tested last week when the prototype was fired into the upper atmosphere aboard a converted 1970s Russian Volnya ballistic missile. The missile was launched from a Russian nuclear submarine on 12 July in the Barents Sea, but the trial failed in the latter stages of the missile’s flight.

Astrium spokesman Dr Mathias Spude said that information on the experiment was still sketchy. It appeared that the mission went to plan until the sphere was due to separate from the missile.

This did not happen and the sphere fell straight to Earth without the sails inflating. ‘Detailed mission analysis’ is still underway and teams are still searching for the module itself in Russia’s Kamchatka peninsula.

Spude said that the Volnya missile was chosen due to its ‘more reasonable price’. The first IRDT test in January 2000 used a different missile launched by a Soyuz rocket already in orbit. In this test the sails failed to work properly. Another test last year also went wrong.

Worth about £1.2m, Demonstrator-2 also carried more sensors than before and at about 125kg was 25 per cent heavier. Lionel Marraffa, an engineer with the European Space Agency, which is contributing to the project, said the payload included an extra video camera to study the inflation mechanism, and sensors to study contamination and influx measurements. The thermal protection was also thicker.

Despite the loss, Marraffa said that any future tests would depend upon conclusions reached from this one. The team has to rely on scheduled Russian missile firings during the summer when recovery is not restricted by weather.

The IRDT is funded by the ESA and the International Science and Technology Centre in Moscow, a body that aids western co-operation with Russia.