NASA: The Hubble Space Telescope, arguably history's most valuable tool of astronomy, will undergo a repair job today that amounts to a heart transplant. The operation was replete with all the risks and potential rewards of such major surgery, a NASA official said in Florida.
Astronauts from the space shuttle Columbia made the second of five ambitious space walks planned for their 11-day mission, finishing work on a new pair of wing-like solar-power arrays.
But early today, NASA will command Hubble to shut off its power for the first time since it was launched in 1990.
Then the space agency will learn whether astronauts in bulky pressure suits and thick gloves can replace a power control unit designed as a permanent feature of the telescope, with no thought that it would ever be replaced while passing 350 miles over Earth in the vacuum of space.
If Hubble turns back on, the astronauts will be ready to make upgrades that should boost the orbiting observatory's performance tenfold. If not, there is a very real chance Hubble might have to be abandoned.
"You could say that tomorrow Hubble gets a heart transplant," said Mr Dave Leckrone, the Hubble programme scientist for NASA. "Major surgery entails a certain degree of risk." The power unit, which sends electricity to all of Hubble's science instruments and flight systems, acts very much like a heart.
The unit has had a problem - a loose screw, in fact - that has caused some impediment in the flow of electricity since 1993. But the telescope has made almost all its textbook-shattering discoveries since then.
One official acknowledged that turning off Hubble seemed to violate a fundamental tenet of space flight. But NASA said that, based on numerous ground tests and simulations, it was confident the telescope could return to duty.