NASA corrects hubble malfunction – BBC News

NASA thinks it has fixed a malfunction of the Hubble telescope, threatening to limit the performance of the observatory in orbit.

Earlier this month, one of Hubble's gyroscopes – which was to point the spacecraft – failed, forcing controllers to place the telescope in "safe mode" – operating only with essential functions.

This was necessary because a backup gyroscope also worked poorly when it was turned on.

But after a series of tests, the backup seems to work normally.

The telescope, launched in 1990, has been described as one of the most important scientific instruments ever created.

Hubble telescope hit by mechanical failure

A gyroscope is a device that measures the speed of rotation of the spacecraft. It is necessary to help Hubble rotate and lock on new targets. It consists of a wheel inside a sealed cylinder – called float – suspended in a thick fluid.

There were originally six gyros; the observatory had been operating for four years until about two weeks ago. At any time, Hubble needs three gyroscopes for optimal efficiency.

The failure of another gyroscope and the discovery that a backup was faulty left Hubble with only two fully functional gyroscopes.

This could have forced the controllers to use the telescope on one, in order to extend the life of both components as long as possible.

At the time, Rachel Osten, Hubble's Assistant Chef de Mission, said, "The plan has always been to switch to 1 gyroscope mode when there are only two players left. There is not much difference between 2 and 1, and that brings in a lot of observation time, which the astro community desperately wants. "

Hubble is prized by the astronomical community and the observation of time has to be handled with care because of the high demand.

Professor Nial Tanvir, astronomer, from the University of Leicester, told the BBC that Hubble could have continued to operate with a relatively small impact on a gyroscope.

But this mode would probably have limited the part of the sky that Hubble could observe at once. It would also have taken more time for the telescope to move from one target to another.

NASA stated that the failed emergency gyroscope – shut down for 7.5 years – displayed "extremely high rotational speeds".

In an attempt to solve the problem, the Hubble Operations team restarted the gyro on October 16th.

This procedure disabled the gyroscope for one second and then restarted it before the spinning wheel inside the gyroscope slows down.

However, the controllers have not seen any improvement.

Two days later, the operations team ordered the spacecraft to conduct a series of maneuvers. This has been designed to dislodge blockages in the gyro itself.

In a statement, NASA said that on 19 October, "the operations team asked Hubble to perform additional maneuvers and switch to gyro, which seems to have solved the problem."

Hubble then performed additional maneuvers to ensure that the gyroscope remained stable within operational limits as the spacecraft was changed.The team found no problem and continued to observe it throughout the weekend to ensure its stability. "

The James Webb Space Telescope (JWST) is the designated successor to Hubble, but has experienced a series of delays and will only be launched in 2021, at the earliest.

Astronomers have recently explained how to extend Hubble's life so that he can continue to serve the astronomy community.

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