Kepler uses 42 CCDs (rectangles), paired into square-shaped modules, to search for dips in starlight due to alien planets (Image: NASA/Ames/JPL-Caltech)

OUR best eye on alien worlds has developed a blind spot. NASA’s planet-hunting telescope Kepler has developed a fault that means it sees the equivalent of static in some parts of its view.

Kepler launched in 2009 to hunt for planets orbiting other stars. Many giant planets on tight orbits have already been found, but the telescope’s main aim is to find Earth-sized planets orbiting their stars at distances that can support the presence of liquid water and potentially life.

A total of 42 light-detecting chips called CCDs are used to look for periodic dips in starlight when planets pass in front of their host stars. But one of the 21 modules – containing two CCDs – is now malfunctioning, rendering the stars in its view invisible.

Since the craft rotates its field of view by 90 degrees every three months, the fault means that four regions of the sky are only observable 75 per cent of the time. The good news is that the problem is not expected to spread, and it might be possible to repair it.