It didn’t find little green men, but the Kepler space telescope has discovered 1,284 new planets outside our solar system — more than doubling the total number, NASA announced Tuesday.
Of the new trove of 1,284, almost 550 could be rocky planets like Earth, based on their size. And nine of those could have Earth-like conditions — which could make extraterrestrial life possible.
Nine of them orbit in their suns’ habitable zone, which is the distance from a star where orbiting planets can have surface temperatures allowing liquid water to pool, NASA said.
The additional nine bring the number of potentially habitable planets outside our solar system — so-called exoplanets — to 21.
“This gives us hope that somewhere out there, around a star much like ours, we can eventually discover another Earth,” said Ellen Stofan, chief scientist at NASA headquarters in Washington, AFP reported.
NASA scientists pointed out, however, that Kepler is a “statistical mission” that is not aimed at probing further into the conditions of certain planets in the habitable zone of their stars.
And even if life does exist on any of the exoplanets, the most advanced space telescopes now being built may still be incapable of shedding much more light on the planets because of their sheer distance — at least 11 light-years away.
The $600 million Kepler, which launched in 2009, has been scanning 155,000 stars for signs of orbiting celestial bodies, particularly those that might be able to support life.
It works by observing a dimming in the light of a star, known as a transit, each time an orbiting planet passes in front of it.
A perfect example of the technique was Monday’s “Mercury transit,” when the smallest planet in our solar system crossed the sun’s face from Earth’s perspective for the first time in a decade.
“Of the nearly 5,000 total planet candidates found to date, more than 3,200 now have been verified, and 2,325 of these were discovered by Kepler,” the US space agency said.
Before Kepler, astronomers did not know if exoplanets were rare or common in our Milky Way galaxy.
“Thanks to Kepler and the research community, we now know there could be more planets than stars,” said Paul Hertz, astrophysics division director at NASA headquarters. “This knowledge informs the future missions that are needed to take us ever closer to finding out whether we are alone in the universe.”
Last month, Kepler survived an emergency when a “transient event … triggered a barrage of false alarms that eventually overwhelmed the system,” NASA said.
It suffered another crisis in 2013 related to a problem with the reaction wheels that typically keep the spacecraft steady.
NASA saved it back then, and set the spacecraft on a new mission called K2, to study supernovas (massive explosions that occur at the end of a star’s life cycle), asteroids and other cosmic objects.
The latest failure, which NASA described as leaving the spacecraft in a “fuel-intensive coma,” was discovered on April 8.
Engineers on Earth were able to rescue the spacecraft and restored its ability to collect data on April 22.