Thursday, September 17, 1998 Published at 14:52 GMT 15:52 UK
Soho pointing at the Sun again
Struggle to take control of Soho
After weeks of effort the Soho solar observation satellite is once again pointing at the Sun. Our science editor Dr David Whitehouse reports:
It has been a landmark day for solar scientists. At last the troubled Soho spacecraft has obeyed commands to turn its face fully towards the sun.
For the first time since 25 June, when Soho spun out of control and communication was lost, it points the right way.
Now its solar panels will be able to recharge its onboard batteries and bring the spacecraft fully back to life.
'It is a big step forward in our recovery plan for Soho," said Francis Vandenbussche, head of the Soho recovery team at Nasa's Goddard spaceflight centre.
'We were never quite sure that we would manage to make the spacecraft point back towards the sun, which is essential for its proper operation.'
Next comes a comprehensive check of all the spacecraft's systems and scientific instruments.
In some cases the instruments have been through an ordeal of heat or cold, with temperatures approaching plus or minus 100 degrees C (212 F).
Soho, the Solar and Heliospheric Observatory, operates at a special vantage point 1.5 million km (about one million miles) out in space, on the sunward side of the Earth. It is a joint project of the European Space Agency and Nasa.
Since its launch on 2 December 1995, Soho has brought about a revolution in solar science. Apart from amazing discoveries about flows of gas inside the sun, giant 'tornadoes' of hot, electrically charged gas, and clashing magnetic field-lines.
Soho also proved its worth as the chief watchdog for the sun, giving early warning of eruptions that could affect the Earth.
In April 1998, Soho's scientists celebrated two years of successful operations, and the decision of ESA and Nasa to extend the mission to 2003.
The extension will enable Soho to observe intense solar activity, expected when the count of sunspots rises to a maximum around the year 2000.