The fuel tanks onboard the Solar and Heliospheric Observatory (SOHO) have been successfully thawed out and the spacecraft will be moved back into position next week. Contact with the spacecraft was lost in June when a computer fault caused it to spin out of control and lose power. Contact was re-established four weeks ago and space scientists hope that SOHO will be able to observe the Sun during the period of maximum solar activity in 1999.
Luckily, SOHO drifted back into sunlight long enough to recharge its solar cells for communications with Earth, and in the past month the fuel has been heated from -100 C to 10 C. Engineers had to be careful not to rupture the tanks while heating the fuel. The tanks have survived so far and the next step is to fire thruster rockets to manoeuvre SOHO so that it faces the Sun again. This procedure will be carried out early next week.
“This is one of the most dramatic deep-space rescues ever attempted, and I’m delighted to say it looks to be going exactly to plan, ” says Richard Harrison of the Rutherford Appleton Laboratory near in Oxford. “For six weeks we had no idea if SOHO would ever get back in touch. This was a race against time, because without power and without direction from Earth it wouldn’t be long before SOHO’s orbit decayed. That would be a great shame – even though SOHO had already completed its main mission we were hopeful for more information.”
In related news the joint NASA-ESA Investigation Board has concluded that the original mistake was a direct result of operational errors, including a failure to adequately monitor spacecraft status by the Goddard Space Flight Center.
