Kepler, which has discovered 132 exoplanets and thousands of other candidate worlds, could still be used to seek out planets using a gravitational magnifying glass, Keith Horne of the University of St Andrews said.
Kepler has found exoplanets by observing stars and looking for tiny variations in starlight when a planet transits, or crosses in front of, its host star. So-called reaction wheels that allow Kepler to lock in on a star from long periods have failed, ending its ability to detect such transits.
Horne, working with Andrew Gould at Ohio State University, suggests Hubble could still use its instruments in an alternative way known as microlensing to spot planets.
When two distant stars align, the gravity field of the closer star bends and magnifies the light of the more distant star, and if the nearer star has orbiting planets, their gravity provides added magnification.
"The signals from planets are quite large in this case, sometimes even 100 percent change of brightness of the star, so it's relatively easy to see these things," Horne told NewScientist.com.
Horne and Gould said they estimate Kepler, though not specifically designed for microlensing, could find a few dozen exoplanets a year using the technique.