NASA's Kepler space telescope could soon be shut down permanently
Washington: The Kepler space telescope - NASA's primary instrument for detecting planets beyond our solar system-had suffered a critical failure and could soon be shut down permanently, the agency's officials announced Wednesday.
Scott Hubbard, a consulting professor of aeronautics and astronautics at Stanford's School of Engineering, served as director of NASA Ames Research Center during much of the building phase of the Kepler space telescope. He also worked on the project alongside William Borucki, the Kepler science principal investigator at Ames and the driving force behind the effort, for the decades leading up to formal approval of the mission.
The Kepler spacecraft's photo-detector array registers more than 100,000 stars at a time, Hubbard said, and in order to detect exoplanets (planets orbiting stars outside our solar system), the telescope must remain extremely steady so that the stars do not wander across the optics.
A series of four gyroscope-like reaction wheels whir within the telescope to hold its gaze. At least three must be functioning to keep Kepler stable. One failed about a year ago and was shut off, and NASA scientists announced Wednesday, May 15, that a second wheel was no longer operating and that Kepler had paused operations.
In a conversation with Stanford News Service, Hubbard explained the possible ways that NASA could bring the spacecraft back online, and what planet hunters will do next if that's not possible.
When asked how big of a loss will it be if the Kepler space telescope can't be repaired, he said that it will be very sad if it can't go on any longer, but the taxpayers did get their money's worth.
He noted that Kepler has, so far, detected more than 2,700 candidate exoplanets orbiting distant stars, including many Earth-size planets that are within their star's habitable zone, where water could exist in liquid form.
Kepler has done what the program managers said it would do, and that is to give us an inventory of extrasolar planets. It completed its primary observation phase, and had entered its extended science phase.
He added that there's still a year and a half's worth of data in the pipeline that scientists will analyze to identify other candidate planets, and there will continue to be Kepler science discoveries for quite some time.
When asked how NASA engineers might go about getting Kepler functional again, he hinted that there are two possible ways to salvage the spacecraft.
One is that NASA engineers could try turning back on the reaction wheel that they shut off a year ago. It was putting metal on metal, and the friction was interfering with its operation, so they could see if the lubricant that is in there, having sat quietly, has redistributed itself, and maybe it will work, he explained.
The other scheme, and this has never been tried, involves using thrusters and the solar pressure exerted on the solar panels to try and act as a third reaction wheel and provide additional pointing stability, he added.
If neither of these options works, could Kepler be able to conduct other types of experiments.
To this he replied people have asked about using it to find near-Earth objects, or asteroids, but whether or not it could function as a detector for asteroids is something that would have to be studied, but since it wasn't built as a camera, he said, he's skeptical.
Hubbard admitted that Kepler has paved the way for additional missions, such as TESS-Transiting Exoplanet Survey Satellite-and TPF-Terrestrial Planet Finder-which will continue the search for Earth-like exoplanets in the near future.