Space telescope failure may endanger planet-hunting mission

This file artist's rendering shows the Kepler space telescope, which has found more than 100 planets.
This file artist's rendering shows the Kepler space telescope, which has found more than 100 planets.

The Kepler Space Telescope, an instrument that altered our sense of our place in the universe by revealing that Earth-size planets orbited other stars, has suffered a malfunction with a wheel mechanism that helps point the telescope, endangering the mission.

Since its launch in 2009, Kepler has found more than 100 planets, with much of the data analysis done by two dozen astronomers at the Harvard-Smithsonian Center for Astrophysics in Cambridge.

NASA officials were not ready Wednesday to declare Kepler’s demise. They said in a conference call with reporters that the spacecraft went into “safe mode” on Sunday because of an error in its position and they are working to see whether 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,” said John Grunsfeld, associate administrator of NASA’s Science Mission Directorate. “We’re looking at the ­data carefully. We’re not ready to call the mission over.”

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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.

Harvard-Smithsonian and NASA scientists said that regardless of what occurs over the coming days, the $600 million mission has already been a scientific success: It has outlasted its initial four-year mission and discovered 132 planets and more than 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-size planet circling it.

“I’m actually quite upbeat,” David Latham, a co-investigator for Kepler, said from the Harvard-Smithsonian Center. “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 Kepler. Though wheel two had already failed, the telescope could manage beautifully with three wheels, Latham said. But last week at a science working group meeting, Latham said they learned that one of the wheels was in trouble.

“I said to myself, ‘This could happen at any date,’ ” Latham said.

The Harvard-Smithsonian scientists said there is plenty of data to be analyzed until the scheduled launch in 2017 of a next-generation spacecraft being developed by a team led by MIT scientists.


That mission, called TESS, will be able to look for planets circling a half-million stars.

Scientists were unfazed by the possible end of Kepler’s 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 a year ago to organize a conference about the future of the search for planets orbiting other stars, they did not anticipate how accidentally accurate the title of the meeting would be. But on Monday, the conference, called “Exoplanets in the post-Kepler Era,” will kick off.

“We meant it to be a look ahead,” Charbonneau said. “But now the title is all too fitting.”

Carolyn Y. Johnson can be reached at cjohnson@
. Follow her on Twitter @carolynyjohnson.