When the $1 billion Solar and Heliospheric Observatory (SOHO) spun out of control and lost power last June, astronomers feared that extreme heat and cold would ruin its sensitive instruments. They imagined metal bands around lenses contracting until the glass cracked, and soldered wires melting in the sun's unrelenting glare. But after scientists miraculously recaptured the craft in September, they were amazed to find that the instruments had not only survived but that one sophisticated telescope is working better than before the accident.
The Extreme Ultraviolet Imaging Telescope, used to study the sun's corona, fiery plumes, and other features, has produced spectacular images since SOHO's launch in 1995. But it had been increasingly plagued by blurring contaminants such as frozen water vapor and hydrocarbon residues. When SOHO was disabled, however, the craft flipped on its side, placing its solar panels edge-on toward the sun. That bathed the telescope in constant sunlight, heating it to more than 30 degrees Celsius. It looks like the contaminants "got baked out of the instrument," says SOHO scientist Joe Gurman of NASA's Goddard Space Flight Center in Greenbelt, Maryland. This "curing," which he says "seems to be long-term," has improved the scope's sensitivity by 60% over its preaccident performance.
