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Solar mission freezes to death

ulysses-20080222-200.jpgAfter 17 year’s of service, solar mission Ulysses is at its end. The craft, which has been circling the Sun since 1992 tracing solar wind and studying the Sun’s poles, is about to run out of power and fall below a critical temperature of 2 degrees Celsius, at which point its hydrazine fuel will freeze.

Sadly a cleverly hatched plan to try and save power in the aging craft hasn’t worked out for NASA.

Mission scientists decided to temporarily turn off the craft’s transmitter, hoping to shunt this power over to the scientific instruments and the heater. They planned to turn the transmitter back on only when data was ready to be sent back to Earth. This would have made it possible to run Ulysses for up to another two years.

Unfortunately, this cunning plan proved to be a dud. A test revealed that the transmitter couldn’t be turned back on. And, to make matters worse, the fault seemed to lie with the power source of the transmitter, meaning there was no extra power to shunt over to the heater after all. “The decision to switch the transmitter off was not taken lightly. It was the only way to continue the science mission,” said Richard Marsden, ESA project scientist and mission manager (press release). Its life expectancy is now down to only a few months.

New Scientist points out the irony of a spacecraft orbiting the Sun freezing to death. Discovery News rings the death bell for the craft. Elsewhere the annoying habit of humanizing inanimate objects continues, as the lump of metal is tagged as ‘brave’ (AFP).

Last time we heard from the Ulysses team the craft was bagging some good data from the solar cycle switch by flying over the pole at an opportune time.


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