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Two of NASA's first space telescopes, Hubble and Kepler, are currently out of commission – sad, if not surprising surprising, news for astronomers who depend on NASA's aging fleet.
The 28-year-old Hubble went into temporary safe mode on Friday.
Meanwhile Kepler, the powerhouse planet hunter has detected 4,000 new planets since it launched in 2009, has been in sleep mode since Sept. 26 to preserve dwindling fuel before its next data dump.
Both telescopes are nearing the ends of storied careers in space.
NASA stopped servicing Hubble in 2009, shortly before ending the shuttle program. Two of the six gyroscopes installed during the 2009 repair mission have already broken down, and the one that has recently been exposed exhibiting what NASA called "end of life behavior" for about a year. It was no surprise when the slumping device stopped working.
But then the backup gyro did not kick into action, creating a "very stressful weekend" for staff at NASA 's Goddard Space Flight Center and the Space Telescope Science Institute, Rachel Osten said on Twitter. All astronomy is trying to figure out what is wrong.
If they are not able to get rid of the problem, then they will be able to reduce their mode, using only one of its two remaining gyroscopes at a time. This mode would limit where Hubble can point to extend the overall mission.
"It buys lots of extra observing time," Osten said, "which the astro community desperately wants."
NASA had hoped that Hubble would stay in the sky long enough to observe the James Webb Space Telescope, a gold-plated Goliath that will be able to capture the oldest light in the universe. But repeated budget snafus and human failures have delayed the Webb telescope's launch by more than a decade.
; it's not expected to launch until at least 2021. NASA's current operations contract for Hubble ends that year, though optimists say the spacecraft could last into the 2030s.
Many of NASA's top space telescopes are more than 10 years old. The Chandra X-ray Observatory, Spitzer Space Telescope, Swift Observatory, and Fermi Gamma-ray Space Telescope have all exceeded the duration of their original missions by at least five years.
The end for Kepler is even nearer. The spacecraft has already operated for the first time in its original form. but zero gravity makes it hard to measure how much fuel is left in the spacecraft's tank.
"It's like trying to decide when to gas up your car. Do you stop now? Or try to make it to the next station? "Kepler system engineer Charlie Sobeck wrote in a blog post this year. "In our case, there is no next station, so we want to stop collecting data while we're still comfortable that we can love the spacecraft to bring back to Earth."
Kepler can make contact with the Deep Space Network, the global system of antennae through which spacecraft communicates with Earth. When Kepler's Allotted DSN Time Begins Oct. 10, it will switch on and beam back data on more than 30,000 stars and galaxies in the constellation Aquarius collected during its most recent 27-day observing campaign.
There is no guarantee that the spacecraft will be able to transmit the science data.
"The fact that we managed to collect data in light of Kepler 's low fuel pressure is yet another achievement by our engineers," the mission' s guest observes office tweeted last week. "If successful, it would be an unexpected bonus."
Once NASA decides to close the mission, the engineers will command the spacecraft to turn off its transmitters – preventing "pollution" of the airwaves. Then the spacecraft will be allowed to drift, alone in the dark.
Its wide, Earth-trailing orbit around the sun means that it will fall behind the planet until Earth actually "laps" it, giving the spacecraft a gravity boost that slows it down until it nearly catches up with Earth from behind. This graceful gravitational dance may continue indefinitely, with the moon continuing to expand, and until the sun expands into a giant and engulfs the inner solar system or some other cosmic phenomenon.
In the meantime, Kepler's demise does not signal the end of humanity's planet hunting. The spacecraft's successor, the Transiting Exoplanet Satellite Survey (TESS), was launched into orbit around Earth in April and has already sent back its first science images and detected two potential planets.
Like Kepler, TESS is designed to scan the sky in the visible part of the light spectrum, but its specialty is finding planets around bright, nearby stars. Researchers anticipate that it may discover 10,000 worlds during its mission.
"Kepler broke open the field in a rather dramatic way," TESS principal investigator George Ricker said before the launch in April. "Purpose TESS is opening an entirely new window on the universe."
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