The Hubble Space Telescope is back online and resumed scientific operations, as confirmed by NASA, even though every part of the old device is not working as it should. The telescope – which was put into orbit in 1990 and has since been instrumental in uncovering the secrets of distant stars and galaxies – switched to safe mode last weekend.
NASA said that this came after the discovery of a software bug inside the main computer of the spacecraft. It is a cautionary process, designed to stop any successive faults and lock the telescope into a stable configuration so that a problem can be identified and a fix developed.
In this case, it turned out that the latest software patch had an unexpected side effect when it was uploaded to Hubble. The aim of the new program was to compensate for fluctuations from one of the spacecraft’s gyroscopes, which are used to help it orient itself as it is locked to new targets. The correction was correct, but it turns out that the program itself does not have the correct permissions to write to a specific memory location. This resulted in a stalled bug, thus putting Hubble into Safe Mode.
Although it was unintended – and NASA quickly moved to rewrite the patch to avoid the same problem – the flaw actually helped identify another potentially more serious problem than the mission operations team at Goddard Space Flight Center was not aware of.
With entering safe mode on Sunday, the team discovered that the opening door at the top of the telescope failed to close automatically. NASA says. “This door is a protective device designed to keep harmful sunlight and heat away from the inside of the telescope, and to protect its sensitive instruments and their surroundings. It serves as a safety net if Hubble is accidentally pointing in the direction of the sun due to an error or hardware problem.”
It is unclear exactly when this mechanical problem arose. NASA reports that an opening door wasn’t actually required during the more than 30 years of Hubble’s operations. Although the primary engine doesn’t seem to be responding, the backup engine appears to be working, so the team has switched that into a primary engine while it works on other repairs. NASA confirmed that science operations resumed at 8 pm EST on Thursday, March 11th.
Meanwhile, another problem appeared with the Wide Field Camera 3. which remained pending, with the low voltage issue identified.
Hubble wasted no time once the majority of its systems were back online. The space telescope has already completed a new observation, using the Cosmic Origins Spectrophotometer to map gas flows in the galaxy’s energetic nuclei.
As Hubble continues to enable new scientific discoveries with the data it collects, operating the Space Telescope has become about pushing the boundaries of its ancient devices as much as it collects new insights about the universe. The service life of the spacecraft has been extended several times, and experts point out that it could last until 2030-2040, preventing unforeseen problems.
However, work on replacing the species has been underway for some time. The James Webb Space Telescope is expected to launch in October 2021 – although the project has seen its own share of delay before now – and will use a complex series of mirrors to make observations through long-wave visible light through mid-infrared. While this will partly overlap with Hubble’s observations, it extends considerably, allowing NASA to observe higher redshift objects that are much older and farther away than Hubble can see.