After nine and a half years of combing the galaxy for planets that might support life, the Kepler space telescope's mission is over.

NASA says the probe has run out of fuel.

Mission engineers will turn off its radio transmitters and the craft, now orbiting the Sun 94 million miles from earth, will be retired and left to drift under its own momentum.

Since it's launch in March of 2009, Kepler has discovered more than 2,600 of the nearly 4,000 planets found outside our solar system in the last 20 years.

It has found about 50 that may be about the same size and temperature as Earth, including one named Kepler 22B, located more than 600 light years from Earth.

Scientists believe the planet could be covered with oceans with a water-based atmosphere that could theoretically support life.

Kepler has been succeeded by another satelite called TESS, but the probe's now-retired chief investigator William Borucki told reporters Tuesday that Kepler's importance cannot be understated.

He said "Basically, Kepler opened the gate for mankind's exploration of the cosmos."