CAPE CANAVERAL, Fla. -- A rain cloud chased the shuttle Discovery to a surprise pre-dawn landing in the California desert yesterday, scrapping what would have been the first night touchdown at the Kennedy Space Center.
Shuttles travel through space at six times the speed of sound, accelerating and decelerating sharply and sometimes performing feats of celestial acrobatics. But even a small rain cloud daunts the spacecraft, NASA spokesman Mitch Varnes said.
The shuttle is covered with thousands of individually fitted thermal tiles that absorb heat and keep the craft from burning up during its fiery re-entry into the Earth's atmosphere.
"Flying it through even a small rain cloud at the speed the shuttle is going when it gets here would tear the heat tiles to pieces," Mr. Varnes said.
In the mid-1980s, the National Aeronautics and Space Administration learned how susceptible the shuttle was to rain damage. "We accidentally went through a little bit of rain and tore the heck out of a bunch of the tiles," Mr. Varnes said.
He offered this analogy: Imagine sticking your head out of a car window in a rainstorm while driving 70 mph, and then imagine magnifying that experience by a hundred times or so.
So shuttle landing rules stipulate that there can be no rain or lightning within 30 miles of the touchdown site.
Although visibility was perfect for the shuttle's planned route to Kennedy Space Center and wind conditions were excellent, about 20 minutes before NASA had to make a decision on the site, a small rain cloud appeared nine miles south of the center. Still hoping to bring Discovery home to Florida, NASA managers postponed the landing for one more 90-minute orbit.
But, within an hour, the first cloud was joined by others, and the landing was diverted to Edwards Air Force Base. Discovery set down there shortly before 4 a.m. EDT. The shuttle's five-member crew had been up for five days.