The news was announced by the American space agency Nasa, which is looking to see what can be salvaged from the Kepler space telescope.
Kepler, which cost £395 million, was launched in March 2009 with the chief aim of searching for Earth-sized planets that might support life. It has proved one of Nasa's most successful missions, delivering a mass of data on planets orbiting distant stars.
From the observations analysed so far scientists have confirmed the existence of 135 new exoplanets and identified more than 3500 candidates. Several of these worlds are "super-Earths" with up to 10 times the Earth's mass situated in orbits where conditions may be suitable for life.
In November last year, Kepler completed its primary mission and began a four-year extended mission.
But now two of the four spinning gyroscope-like wheels used to position the telescope with the incredible level of precision required have failed. Efforts to get at least one of them working again have also failed.
The Nasa team is now investigating whether Kepler can conduct a more limited science programme using its remaining reaction wheels and thrusters.
John Grunsfeld, associate administrator at Nasa's Science Mission Directorate in Washington DC, said:"I am confident that more amazing discoveries are on the horizon."