NASA’s Kepler telescope will no longer scan the universe for Earth-like planets, the space agency said on Thursday, after attempts to fix a critical piece of equipment failed.
Scientists stressed however that much was left to be discovered from the data already gathered by Kepler.
“At the beginning of the mission, no one knew if Earth-size planets were abundant or rare in our galaxy,” chief Kepler scientist William Borucki told reporters. “Now at the completion of the Kepler observations we know that our galaxy is filled to the brim with planets.” He said it is likely most stars have planets and many host Earth-like planets. Just a few of those planets however are close enough to their stars to potentially host life.
“We expect hundreds, maybe thousands of new planet discoveries, including the long awaited Earth-like planet orbiting a star like our Sun,” from already collected data, he said.
In the next few years scientists should be able to answer the question that inspired the mission: “Are Earths common or rare?” Borucki added.
The US space agency said earlier this year that two of four gyroscopes that helped the craft maintain its position in space had failed, leaving it unable to focus on a narrow swath of stars.
Three years after its launch in 2009, a first gyroscope failed in July 2012 and the second malfunctioned in May. Three gyroscopes were needed to the steer the telescope.
NASA was weighing other ways of using the telescope.
Kepler has identified 135 confirmed planets and more than 3,500 potential planets, including a handful that look similar to Earth.
Its primary mission ended last year, but scientists had hoped to extend it to 2016 to identify planets in the so-called habitable zones that like Earth could harbour life.
The Kepler space telescope is finely tuned enough to detect Earth-sized planets orbiting distant stars. The $590 million telescope programme scanned a large swath of the Milky Way galaxy, which contains about 4.5 million stars.
The most advanced cameras ever used in space focussed on 100,000 to 150,000 stars deemed most likely to have orbiting planets. Data from the cameras is being examined for distortions in the light emitted, which often indicates an orbiting planet is crossing in front of the star.