NASA's planet-hunting Kepler spacecraft goes into 'emergency mode'

Artist's composite of the Kepler telescope Credit: NASA

NASA has declared a "spacecraft emergency" after its planet-hunting Kepler spacecraft unexpectedly went into "emergency mode".

Engineers made the discovery during a scheduled contact last Thursday, and are working to recover the £425 million probe from what is its lowest operational mode.

Kepler found more than 1,000 planets outside of our solar system during its original mission which finished in 2012, and since then has been used for the K2 mission, studying further planets and other astronomical objects such as stars and supernovae.

It was responsible for the discovery of a planet dubbed 'Earth 2.0' - the most Earth-planet discovered so far.

An artist's concept depicts one possible appearance of the planet Kepler-452b, or 'Earth 2.0' Credit: NASA

Solving the issue is problematic for engineers, as the spacecraft is nearly 75 million miles from Earth.

This means even at the speed of light, it takes 13 minutes for a signal to travel to the spacecraft and back.

NASA said the last regular contact with Kepler was on April 4, and the spacecraft was in good health and operating as expected.