Satellite injured in space wreck

A FRENCH spy satellite called Cerise has just become space’s first
confirmed victim of a hit-and-run accident. The satellite went tumbling head
over heels when the boom that stabilises it was vaporised in a collision with a
10-year-old chunk of an Ariane rocket. The debris was travelling at 50 000
kilometres per hour at the same height as Cerise, more than 700 kilometres above
the Earth.

Although the satellite is owned by the French military, it is operated from a
mission control centre at the University of Surrey in Guildford. It was built by
Surrey Satellite Technology, an offshoot of the University’s Centre for
Satellite Engineering Research.

At first the group had no idea why the satellite was spinning off course.
However, with the aid of NASA and the UK Space Track Network they narrowed it
down to a collision with this particular piece of orbiting junk.

The mission controllers are now feverishly trying to calculate whether the
debris and the satellite will collide again next time round. “We are trying to
work out whether we are likely to get another collision with the same chunk
coming back,” says Martin Sweeting, managing director of Surrey Satellite
Technology.

Sweeting points out that there are more than 20 000 known pieces of space
junk—so many that it is impossible to predict potential collisions. And
even if mission control had known that the collision was imminent, says
Sweeting, it could have done nothing to protect the satellite. “We cannot
manoeuvre it once it is in orbit. Had we known, there was nothing we could have
done but watch.”

The boom kept the satellite stable. Now, says Sweeting, Cerise is like a ship
without a rudder and has moved slightly out of its usual orbit. Because it
carries no fuel it will be difficult to stabilise the craft and bring it back
into position.

Mission control, however, hopes to use the satellite’s electromagnets to
regain control. By polarising the electromagnets so that they interact with the
Earth’s magnetic field, mission control hopes to stop the spinning and stabilise
the spacecraft. Sweeting estimates that it may take a month to rewrite the
software that controls the electromagnets, upload it to the onboard computer and
slowly make changes to the satellite’s position.

The satellite, which cost £11 million, was launched in July last year
and should have lasted two-and-a-half years. Its payload is classified, but it
was built so that the French defence ministry could eavesdrop on radio
transmissions at frequencies between 500 megahertz and 20 gigahertz.