Precession
The irony is thick out there in low-earth orbit these days. Mere days after finally launching
Gravity Probe B, equipped with the most precise gyroscopes ever built, NASA has
lost one of the gyroscopes on the International Space Station. This leaves them with two functioning gyros (out of four), the minimum number necessary to keep the ISS from tumbling (which wouldn't be a disaster, but would require the expenditure of fuel to keep it the station in alignment. Yes, I know that the gyros on the ISS are completely different from those on GPB; we can't blame the failure on conservation of angular momentum.
Bob Park in the
What's New newsletter from the American Physical Society put it this way:
SPACE TURKEY: GYROSCOPES ARE NOT COVERED BY DEALER'S WARRANTY. Two of the four gyroscopes on the International Space Station have now failed. The ISS can maintain orientation with only two gyroscopes, but what if there's another failure? We called the customer-service desk to ask how long repairs would take. They connected us to Hi Rodomontade, who sets NASA schedules. "You're in luck," Hi said, "we have one in stock. We'll send it up on the next shuttle." We asked when that would be. "Well, that's a problem, the shuttle fleet is being fixed. We use the Russian Soyuz to get to the ISS." But the Soyuz just traveled to the ISS on Wednesday for a crew change, "Did it deliver a new gyro," we wondered? "Unfortunately, the gyroscope is too large for the Soyuz. You'll just have to wait for the shuttle." When will that be? "It's scheduled for May," there was a pause, "May 2005."