NASA engineers working to fix Hubble after gyroscope failure

Mindy Sparks
October 12, 2018

This is not the first time that Hubble's gyroscopes have failed, as they were always problematic and all six of them had to be replaced in 2009.

However, if we look back, we must say that since it launched into orbit in 1990, at 500 kilometres above the surface of the Earth, it has made nearly one and a half million observations and has located three quarters of the exoplanets we know today, amounting to about 4000.

But when ground controllers tried to bring the backup gyroscope online, it behaved erratically, sending garbled messages back to the ground, said Ken Sembach, director of the Space Telescope Science Institute in Baltimore, which operates the telescope.

The telescope orbits high up, around 350 miles up, but its path decays over time, due to the small particles from the Earth's upper atmosphere that bombard the spacecraft and drag it down towards our planet. The remaining three gyros available for use are technically enhanced and expected to have significantly longer operational lives. This essentially leaves Hubble with only two fully functional ones. In fact, one of the three enhanced gyroscopes was reported as nonfunctional after the instrument was tested to run on all three of them.

For normal operation, the telescope needs at least three gyroscopes.

The telescope went into safe mode after one of the three gyroscopes (gyros) being used to point and steady it failed last week. Like cataracts, he says, it's "a sign of aging, but there's a very good remedy."While we wait for news of how Hubble is faring, here's a look back at some of its previous hiccups and fix missions.1990: The blurry mirrorOn June 27, 1990, three months after the space telescope launched, astronomers discovered an aberration in Hubble's primary mirror". Right now, HST is in safe mode while we figure out what to do. "An Anomaly Review Board, including experts from the Hubble team and industry familiar with the design and performance of this type of gyro, is being formed to investigate this issue and develop the recovery plan". The test analysis results indicate that gyro is not usable then it will resume the science operations in the reduced gyro mode as it will be using one gyro for this. While the mode offers less sky coverage at any particular time, there is a relatively limited impact on overall scientific capabilities. In other words, it has been the most critical asset that helped scientists take a better look at the Universe that, thanks to Hubble, is a little less unknown today. The Hubble Space Telescope was designed with several redundancies in the instance of inevitable part failure.

The Hubble Space Telescope had to be placed into safe mode after it encountered a major issue on Friday, Oct. 5.

Amateur astronomers have also been given access to Hubble for research purposes.

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