The Kepler Space Telescope, an instrument that altered our sense of our place in the universe by revealing that Earth-sized planets orbited other stars, has suffered a malfunction with a mechanism that helps point the telescope.
NASA officials were not ready Wednesday to say Kepler’s mission was done, but said in a conference call with reporters that the spacecraft went into “safe mode” on Sunday because of an error in its position. They are still working to see if it is possible to restore the telescope’s ability to precisely point in particular directions.
“Unfortunately, Kepler is not in a place where I can go up and rescue it or any other astronaut,” said John Grunsfeld, associate administrator of NASA’s Science Mission Directorate. “We’re looking at the data carefully. We’re not ready to call it mission over.”
Kepler detects planets in other solar systems by searching for the slight dimming that occurs as a planet crosses between its star and the telescope, and much of the data analysis for the mission was done by two dozen astronomers at the Harvard-Smithsonian Center for Astrophysics in Cambridge.
NASA and Harvard-Smithsonian scientists said that regardless of what occurs over the coming days, the $600 million mission has already been a clear scientific success: it has outlasted its initial four-year mission and discovered 130 planets and 2,700 planet candidates in other solar systems. It has also laid the foundation for the search for habitable worlds, allowing astronomers to estimate that one in six stars in the Milky Way has an Earth-sized planet circling it.
“I’m actually quite upbeat,” said David Latham, a co-investigator for Kepler from the Harvard-Smithsonian Center for Astrophysics. “I would’ve loved to see this mission continue. ... We certainly would’ve gotten even more great results. But in fact we already have an incredible data set to work on.”
The mission had been approved for an additional two years in 2012, and scientists had proposed new research projects. David Charbonneau, a Harvard-Smithsonian astronomer and Kepler scientist, said a student of his had been approved to look for exoplanets around small red dwarf stars and that she would now have to begin looking for alternative thesis projects.
“Of course many of us are upset to hear this news and certainly there are many new investigations we were looking forward to,” Charbonneau said.
Latham, who said that he proudly wears his Kepler lapel pin everywhere he goes, said that the failure was not entirely unexpected.
“We had warnings there was a problem with reaction wheel four,” Latham said. The spacecraft has four wheels, which are used to point the spacecraft. One wheel had already failed, but the telescope could manage beautifully with three wheels. Last week at a science working group meeting, however, Latham said they saw signs one of the wheels was in trouble.
“I said to myself, ‘This could happen at any date,’” Latham said.
The Harvard-Smithsonian scientists said that there is plenty of data to be analyzed until the scheduled launch in 2017 of a next-generation spacecraft, led by MIT scientists.
That mission, called TESS, will be able to look for planets circling half a million stars.
Scientists were unfazed by the possible end of the mission.
“Any of us who have been involved in building and working with machines are sort of unemotional about this,” Charbonneau said. “It’s a machine, and you demand certain things of it and if it breaks, it’s nothing personal.”
When astronomers began organizing a conference at the Harvard-Smithsonian Center a year ago, they were thinking beyond Kepler, about the future of the search for planets orbiting other stars. The meeting, convened in part to honor Latham, who began working at Harvard in 1961, is set to kick off Monday.
They did not anticipate at the time how accidentally accurate the title of the meeting would be: “Exoplanets in the post-Kepler Era.”
“We meant it to be a look ahead,” Charbonneau said. “But now the title is all too fitting.”