February 16, 1996. Copyright, 1996, Graphic News. All rights reserved

SECOND TIME LUCKY FOR THE INDIAN ROPE TRICK IN SPACE
By Nicholas Booth, Science Editor

LONDON, February 16, Graphic News Ð Next week NASA will make another attempt at performing the Indian rope trick in space and officially describes the mission as Ôa scientific adventureÕ. Astronauts aboard Space Shuttle Columbia will unfurl a ball-shaped satellite on the end of a 20.7 kilometre-long tether which, if successful, may revolutionise the way power is generated in space. The first attempt to deploy the tethered satellite on a Shuttle mission in July 1992 ended in failure when the reel jammed around a bolt and the satellite could only extend 270 metres away.

The tethered satellite consists of a 1.6-metre diameter ÔballÕ out of which the reel is slowly unfurled. It was built and entirely paid for by the Italian Space Agency. This time the winching mechanism has been strengthened and an extra motor has been added to the satellite to ensure that it does not wobble once deployed. A serious worry is that the tether could mimic a skipping rope during deployment, so explosive bolts are carried to ensure that it could be jettisoned at any moment. The partial deployment in 1992 showed that the satellite was far more stable than had been predicted.

Tethered satellites will have many uses in space flight. They could be used to generate thrust to compensate for atmospheric drag on orbiting satellites as well as being deployed towards the Earth to allow experiments to be carried out in regions of our atmosphere which are hard to measure. They could be used to transmit very low frequency radio signals which could penetrate water and allow communications not possible with standard radio. But it is the possibility for new power sources in space that are exciting space scientists. 

The astronauts aboard Columbia will measure the electrical current induced by the reelÕs passage through the electrically-conducting influence of the EarthÕs magnetic field. If the current is as large as expected, scientists believe that larger tethers could generate sufficient electricity to power permanently manned space stations. Dr Paul Gough of Sussex University is involved with one aspect of the test, seeing how charged particles in space are attracted by the electrical current. There is a possibility that if the build-up is too great, electricity could be discharged, thereby reducing the effectiveness of a tether as a power source.
 
Columbia is scheduled for launch at 8.18pm British time on February 22, with a 13 day mission planned. The seven-man crew will attempt to release the tethered satellite on the third day of the mission, when it will be hoisted out of the ShuttleÕs cavernous payload bay by the ShuttleÕs robotic arm. This will be carried out by Claude Nicollier, a Swiss-born astronaut from the European Space Agency, who performed the task on the last mission. This will be the 75th flight of the Shuttle programme and the 19th by Columbia.

Source: NASA, Royal Astronomical Society

EditorÕs note: For further information about BritainÕs involvement in the mission, contact Dr Paul Gough of the University of Sussex on (01273) 678421.