NASA Has Finally Identified the Cause of Hubble's Crash

And it's about to try a 'risky' switchover.
Brad Bergan
Hubble and a Space Shuttle arm, from long ago.NASA Hubble Space Telescope / Flickr

We've waited more than a month, and we're finally getting answers.

NASA engineers have identified the cause of the computer glitch that caused the Hubble Space Telescope to halt all scientific operations, while the world prepared to lose one of the greatest devices ever constructed, according to a NASA blog post.

It turns out, the space telescope's Power Control Unit (PCU) was on the fritz, disrupting the steady supply of electricity. But now, NASA is going to attempt a "risky" switchover to the backup computer.

NASA's now-defunct Space Shuttle program used to repair Hubble

The payload computer is housed in the Science Instrument Command and Data Handling (SI C&DH) unit, according to the NASA update, and it has a vital role: controlling, monitoring, and coordinating all scientific instruments aboard Hubble. When the payload computer stopped, Hubble's science instruments went immediately into safe mode on June 13. The following weeks saw agency engineers work around the clock to isolate and identify the problem. Specifically, the voltage levels fell below the 5-V line, which led to a secondary protection circuit instructing the payload computer to cease all operations. "The team's analysis suggests that either the voltage level from the regulator is outside of acceptable levels (thereby tripping the secondary protection circuit), or the secondary protection circuit has degraded over time and is stuck in this inhibit state," said the update from NASA.

Lucky for Hubble, the agency's engineering team can execute a switchover of the space telescope to a backup payload computer, which is also equipped with its own PCU. The team at NASA aims to kick-off the repair procedure tomorrow, which will continue for days. This isn't overwhelmingly different from another problem that happened with Hubble's Command Unit, which was fixed during a 2009 service mission, courtesy of the now-defunct Space Shuttle.

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Hubble's status in history is impervious to failure

Obviously, we don't do that anymore. Since the Space Shuttle program was shuttered in the early twenty-teens, NASA has lacked a launch system capable of putting engineers where they need to be to do complex repairs on the telescope. SpaceX's Crew Dragon is great for lifting humans to the International Space Station, but it doesn't have a giant arm and cargo bay, like the Shuttles did (or do, depending on your level of nostalgia).

The Hubble Space Telescope was launched in 1990, and has since served as a world-historical force of expanding our grasp of the universe.  More than 1.5 million observations of the cosmos have been made by the telescope, serving as a boon for more than 18,000 published scientific papers based on its data. The space observatory had a crucial role in revealing the expansive acceleration of the cosmos, in addition to the ongoing evolution of galaxies through the history of the unimaginably ancient universe. And, in more modern times, Hubble played a part in executing the first atmospheric studies of planets beyond our solar system. While we can't guarantee that NASA's forthcoming switchover attempts will be successful, an imminent demise would do nothing to tarnish the already solidified status of this legendary piece of scientific hardware.

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