A spacecraft that spun out of control earlier this year should soon be back
in action.
The Solar and Heliospheric Observatory (SOHO) lost power after NASA and the
European Space Agency (ESA) lost contact with it in June. Its hydrazine fuel
froze and its instruments were exposed to the harsh temperatures of space. But
early last month, controllers on the ground re-established contact.
Giving a progress report in Washington DC last week, Francis Vandenbussche,
who heads the ESA team trying to recover SOHO, said that one of three pipes
containing hydrazine has now thawed: 鈥淎bsolutely, we will have recovered before
the end of October.鈥� Once all the pipes are thawed, mission controllers should
be able to start SOHO鈥檚 propulsion system, orient the craft鈥檚 solar panels
towards the Sun, and fix its decaying orbit.
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The bad news is that some of the instruments may have been damaged by the
extreme cold and heat of space鈥攁nd some important data have already been
lost for good. According to Joe Gurman, a SOHO project scientist with NASA, the
loss of a continuous stream of data on the Sun鈥檚 seismology has ruined plans to
get a clear understanding of the very low-frequency rumbles that rock the solar
interior. 鈥淵ou need continuity for long-baseline modes of vibration,鈥� he says.
鈥淲e鈥檙e losing that and you can鈥檛 really replace it with anything.鈥�