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The Hubble Space Telescope, April 25, 1990. (NASA via AP)
Two of NASA's top space telescopes, Hubble and Kepler, are currently out of order – a sad, if not altogether surprising, news for astronomers who rely on data from NASA's aging fleet.
Hubble, 28, went into temporary security mode Friday after detecting a mechanical failure with one of his gyroscopes, namely rotating instruments that keep the telescope constantly pointed at its targets.
Meanwhile, Kepler, the powerful planet hunter who has detected some 4,000 new planets since its launch in 2009, has been in sleep mode since September 26 to reduce fuel consumption before its next data dump.
The two telescopes are approaching the ends of legendary quarries in space.
NASA stopped serving Hubble in 2009, shortly before the end of the shuttle program. Two of the six gyroscopes installed during the 2009 repair mission have already broken down, and the one that just shut down was showing what NASA had called "end-of-life behavior" for about a year. It was not surprising that the fall arrest device stopped working a few days ago.
But the emergency gyroscope did not come into action, creating a "very stressful weekend" for staff at NASA's Goddard Space Flight Center and the Space Telescope Science Institute, said Rachel's assistant head of mission Osten, on Twitter. All astronomy work is on hold while researchers are trying to figure out what's wrong.
If they fail to restart the "problematic" device, Hubble will revert to reduced gyro mode, using only one of the two remaining gyroscopes at a time. This mode would limit the points Hubble can point to, but extend the overall mission.
"It saves us a lot of observation time," Osten said.[nomy] the community desperately wants. "
At one point, NASA had hoped that Hubble would stay in the sky long enough to be able to watch it in concert The James Webb Space Telescope, a gold-plated Goliath that will be able to capture the oldest light in the universe. However, repeated budget difficulties and human failures have delayed the launch of the Webb telescope by more than 10 years; its current operating contract for Hubble ends this year, but optimists say the satellite could last until 2030.
Most of NASA's space telescopes are over 10 years old. The Chandra X-ray observatory, the Spitzer Space Telescope, the Swift Observatory and the Fermi Gamma Ray Space Telescope have all exceeded the expected duration of their original missions by at least five years.
The end for Kepler is even closer. The spacecraft has already run more than twice its original 3.5-year mission – even after the loss of the second of four four-wheelers that keep it focused in 2013. It has long been expected to that it lacks propeller this year, but zero gravity makes it difficult to measure the amount of fuel remaining in the tank of the spacecraft.
"It's like trying to decide when to refuel your car. Stop now? Or try to get to the next station? Charlie Sobeck, a systems engineer at Kepler, wrote in a blog article this year. "In our case, there is no next station, so we want to stop collecting data, but we are quite convinced that we can target the probe to bring it back to Earth."
The recent decision to put the telescope on standby aims to preserve the remaining fuel until Kepler can get in touch with the Deep Space Network, the global system of antennas through which spacecraft communicate with each other. with the Earth. When Kepler's DSN deadline begins Oct. 10, it will re-ignite and transmit data from more than 30,000 stars and galaxies in the constellation Aquarius collected during its last 27-day observation campaign.
There is no guarantee that the spacecraft will be able to transmit scientific data.
"The fact that we were able to collect data in light of Kepler's low fuel pressure is another incredible feat of our engineers," said the mission's guest observer office. tweeted last week. "If successful, it would be an unexpected bonus."
Once NASA has decided to end the mission, the engineers will order the spacecraft to turn off its transmitters, thus avoiding the "pollution" of the airwaves. Then, the spacecraft will be allowed to drift, alone in the dark.
Its wide earth orbit around the sun means that it will fall further behind our planet until the Earth bypasses it, which will give the spacecraft an acceleration of gravity that will direct it towards the planet. Until it almost catches up with Earth from behind. This graceful gravitational dance can continue indefinitely, Kepler never approaches closer than the moon, until the sun turns into a red giant and engulfs the inner solar system or another one. cosmic phenomenon intervenes.
In the meantime, the disappearance of Kepler does not mark the end of the hunt for the planet. Its successor, the Transiting Exoplanet Survey Satellite (TSS), was launched in orbit around the Earth in April and has already sent back its first scientific images and detected two potential planets.
Like Kepler, TESS is designed to sweep the sky in the visible part of the spectrum of light, but his specialty is finding planets around bright, near stars. The researchers predict that he could discover 10,000 worlds during his mission.
"Kepler has opened the field quite dramatically," said TESS senior investigator George Ricker before the launch in April. "But TESS opens a whole new window on the universe."
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