NASA revives a Hubble gyroscope after seven years of hibernation

After NASA's Hubble Space Telescope went into "secure" mode about two weeks ago, its operations team set out to put an inaccurate gyroscope online. Now, the space agency says that she thinks she has solved the problem.

"The Hubble Operations team plans to conduct a series of tests to evaluate gyroscope performance under conditions similar to those encountered during routine scientific observations, including moving to targets, locking a target and achieving a precision score, "said NASA. A press release. "Once these engineering tests are completed, Hubble should soon resume normal scientific activities."

Ground operators put the telescope in a stable configuration earlier this month after one of three active gyroscopes that point the telescope down. According to NASA, the gyroscope that failed last week had end-of-life behavior for about a year and its failure was not surprising.

Hubble has three pairs of two gyroscopes, each consisting of a primary gyroscope and a backup gyroscope. In addition, in each pair, one of the gyroscopes is of an "old" design, while the other is an "improved" (or newer) design intended to last longer.

After this month's failure, the three "old" design gyroscopes have stopped working. This left NASA with two improved gyroscopes that were working normally and one that was running more than seven years ago before being decommissioned at that time. The Hubble Telescope can only operate on one gyroscope, but three of them are optimal for normal operations.

Back to science, soon

Over the last two weeks, operators have tried to put back on line this third gyro, which was previously chaotic. And they are now reporting some success.

Inside the gyroscope, a wheel rotates rapidly in a sealed cylinder, and some obstruction of the fluid around this cylinder appears to cause erroneous rotational speeds. A series of maneuvers, including turns in opposite directions, seem to have eliminated any blockage.

"After the October 18 maneuvers, the team found a significant reduction in high rates, allowing rates to be measured in low mode for brief periods," NASA reported. "On Oct. 19, the operations team asked Hubble to perform additional maneuvers and gyroscopic mode switches, which seems to have solved the problem." The gyro rates now look normal in high and low. low."

At present, the space agency plans to test the gyroscope under conditions similar to those of routine scientific activities. Once these tests are complete, the telescope should resume its normal scientific observations.

The Hubble Space Telescope has been operational since its launch in 1990.