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Wednesday, August 5, 1998 Published at 10:33 GMT 11:33 UK


Soho wakes up

Soho is coming back to life as its solar batteries are being recharged

A European space probe has begun to revive after six weeks out of contact with mission control. Our science editor Dr David Whitehouse reports

Martin Redfern: "The hope is that Soho will recover sufficiently"
Last week radio telescopes on Earth detected the Soho spacecraft (Solar and Heliospheric Observatory), apparently rotating slowly near to its monitoring point in space.

Contact was lost with Soho on June 25 after a sequence of incorrect commands during what should have been a routine manoeuvre.

Science correspondent James Wilkinson on signs of life from Soho
All attempts to re-establish contact with the $400ml spacecraft failed and no one knew where Soho was for certain, for four weeks.


Last week, a powerful radar signal from Earth produced a faint echo from the spacecraft.

[ image: Storms, hot and cool spots and prominences on the Sun, as seen by Soho (Photo: Nasa)]
Storms, hot and cool spots and prominences on the Sun, as seen by Soho (Photo: Nasa)
Soho was still in the right place and angled in such a way that sunlight would begin to fall on its solar cells again during the next two months.

Now, sooner than scientists had expected, a faint radio signal has been received from the craft.

So far, it is only short bursts of a carrier signal, but it shows that the radio is warming up and power is slowly returning.

Engineers from the US Space agency, Nasa, and the European Space Agency, ESA, are continuing their efforts to re-establish radio data communication with the spacecraft, which seems to have suffered only minimal damage.

Long recovery

Next comes a long period of careful checks and repairs conducted with radio messages from Earth. The craft can be turned to the Sun, restoring the rest of the power.

The hope is that Soho will recover sufficiently to complete its mission, studying the flares and activity on the Sun and how they affect us here on Earth.

Spectacular success

Soho is a joint project of Nasa and ESA and was launched in December 1995.

[ image: Spectacular magnetic loops on the Sun]
Spectacular magnetic loops on the Sun
It has been monitoring the Sun with 11 different instruments from a vantage point 1,500,000km closer to the Sun than the Earth.

Until June, when Soho was lost, the mission had been a spectacular success, revealing new details of the motions of the Sun's surface and magnetic activity of its hot, thin atmosphere.

This success persuaded planners to extend its life - originally due to end last spring - until 2003. This would have allowed the spacecraft to observe the Sun as its 11-year cycle of activity peaks.

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