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The Hubble Space Telescope, as planned after the deployment of part of its solar panels and antennas in April 1990. The telescope was shelved this month due to gyro failures. (NASA / AP)
Amy B Wang
Generalist journalist covering national and last-minute news
This is not the best month for the Hubble Space Telescope.
During the first week of October, one of the three gyroscopes of the spacecraft failed. The giant telescope needs devices allowing it to measure rotational speeds and focus on objects observed and photographed in space.
In a statement, NASA assured the public that the failure was expected, saying that the gyroscope "exhibited end-of-life behavior for about a year" and that, in any case, "two other gyroscopes of the same type had already failed . "
To replace it, NASA engineers have started a standby gyro since the beginning of 2011. They were comforted at first. The gyroscope started spinning despite it was not used for 7 and a half years. However, it returned readings significantly too high.
The difference was "similar to a speedometer on your car constantly showing that your speed is 100 miles faster than it actually is," NASA said. "It indicates when your car is accelerating or slowing down and how much, but the actual speed is imprecise."
The engineers concluded that the problem should be a kind of mechanical obstruction. After making a vow to fix the problem, NASA kept the telescope in "safe mode", thus limiting its operations in the same way that a computer in this mode works with basic settings.
Keeping the telescope in safe mode also meant "we were not doing science," said Patrick Crouse, project manager for Hubble Operations, Washington Post.
Days passed.
[As NASA’s prized telescopes falter, astronomers fear losing their eyes in space]
NASA crews conducted tests, examined the flight software, and examined ways they could take action to remedy the problem by minimizing the damage to their valuable telescope (and cost). (Although the Hubble can operate with fewer gyroscopes, it normally uses three for maximum efficiency.)
On October 16, the Hubble team even attempted a "reboot in progress," turning off the problematic gyroscope for a second, then turning it on again. Unfortunately, the "did you try to turn it off and turn it on?" Approach – long favored for a long time by tech support personnel on Earth – did not work in space. If that were so easy, said Crouse.
Instead, what seemed to work was to repeatedly turn the entire Hubble spacecraft to see if it would "dislodge" anything that was blocking the gyroscope in question.
NASA explained the fix in more technical terms in an article published Monday on his blog:
On October 18th, the Hubble Operations team ordered a series of maneuvers or turns in opposite directions to remove any blockage that could decenter the float and produce extremely high speeds. During each maneuver, the gyroscope was toggled from high mode to low mode to eliminate any blockage that may have accumulated around the float.
Following the maneuvers of October 18, the team found a significant reduction in high rates, allowing rates to be measured in low mode for short periods. On Oct. 19, the operations team commissioned Hubble to perform additional maneuvers and gyro mode switches, which seems to have solved the problem. The gyro rates now look normal in high and low mode.
Hubble then performed additional maneuvers to ensure that the gyro remained stable within operational limits as the spacecraft moved. The team saw no problem and continued to watch the gyroscope throughout the weekend to ensure stability.
Repetitive maneuvering seemed to be working, as the gyroscope's rotation rate returned to normal, relieving Hubble engineers, said Crouse.
"We always believed, or very early, that the gyroscope seemed to be useful and we just had to make sure to restore it to a useful state," he said.
Crouse paused when asked to explain what had happened in simple terms.
"At a high level, if people want to talk about jolting, I guess they can," he said. "But we were trying to do very specific activities that we thought would solve the problem. It certainly was not as easy as turning it off and on again.
Nevertheless, this did not prevent many media reports that NASA had repaired its telescope "in the same way that you repair your router."
"NASA corrects the Hubble gyro by turning it off and on again," Engadget said Wednesday.
"Which NASA Hubble Space Telescope is fixed? Someone turned on and off a switch, "followed USA Today.
Crouse said these headlines were "an oversimplification", although he could understand the confusion caused by extremely technical issues.
"It's hard to keep everyone informed about the process," he said. "I can understand that some people may have chosen the easy way. But to reflect where we are [with Hubble]we are very optimistic. We are not yet at the end of our sentences, but we are very optimistic that we can start doing science again. "
The Hubble Space Telescope was launched in orbit in 1990, and since its first photo – a disappointing image of the grainy and black-and-white grain of some stars, thanks to a fault in a main mirror – it has delivered real images of l & # 39; space. Time magazine lists Hubble's 50 best photos, although they are all extraordinary in their own way, depending on how interested they are in a corner of the universe.
NASA has developed a new telescope, the $ 8 billion James Webb Space Telescope, which will be able to go back in time, almost to the beginning of the universe. The Webb will be able to capture seven times more light than the Hubble and observe the universe in infrared wavelengths, which the Hubble can not, announced the Washington Post's Joel Achenbach in February. Finally, the Webb telescope should replace the Hubble, which "still works fabulously, but it is already long in the tooth," wrote Achenbach.
Read more:
As NASA's valuable telescopes falter, astronomers fear losing their eyes in space
This is the last close-up photo of Jupiter's Hubble telescope
NASA's next large space telescope remains stuck on Earth after nasty mistakes
NASA astronaut films its release in space – and a breathtaking view of the Earth
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