Spacecraft, which has detected almost 5,000 planets, remains in lowest operational mode to conserve fuel while Nasa assess issue that began last week

This article is more than 4 years old

This article is more than 4 years old

Nasa was on Sunday trying to save its Kepler spacecraft, the ageing planet hunter that has survived several crises and has once again slipped into a state of emergency, nearly 75 million miles away from Earth.

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The spacecraft, which has detected nearly 5,000 planets outside our solar system, was found to be in its emergency mode sometime last week. Scientists last made regular contact with it on 4 April, when there were no signs of distress.

In a weekend update from the Ames Research Center in Mountain View, California, Nasa reported that Kepler remained in its “lowest operational mode”, which is “fuel intensive”.

“Even at the speed of light, it takes 13 minutes for a signal to travel to the spacecraft and back,” mission manager Charlie Sobeck said in a statement. Recovering from this emergency condition “is the team’s priority at this time”, Sobeck said.

Ground controllers discovered the problem on Thursday, not long before they were due to point Kepler towards the center of the Milky Way as part of a new planetary survey.

Nasa had planned for Kepler to join ground observatories searching millions of stars in our galaxy for stray planets wandering between stars; Earth-like planets that orbit at middling range from their sun; and outer planets that swirl at a distance from the center of their solar systems.

Kepler has survived several crises. Launched in 2009, it completed its original mission in 2012, finding more than 1,000 confirmed planets – including the first confirmation of a rocky planet outside our solar system and the first discovery of a planet in the habitable zone of a star.

Despite repeated breakdowns, the spacecraft then began a mission called K2, aiming to not only scan for planets but to collect data on supernovas, the formation of stars and asteroids and comets.

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Last year alone, Kepler discovered what Nasa’s scientists called the Earth’s “closest twin” outside the solar system; a rocky world in the habitable zone of another star; a bizarre dimming pattern from a faraway star; and the first supernova shockwave ever seen with visible light.

Kepler accomplished all this two years after Nasa thought it was beyond all repair, when its guiding wheels broke down. Engineers saved the spacecraft by using the light of the sun as force to push Kepler’s solar panels, then using the surviving wheels to push against that force and point the telescope again.

The enormous distance between the Earth and Kepler, now in deep space, makes it more difficult to fix.

The craft is named after Johannes Kepler, the German astronomer who helped revolutionize science alongside Galileo despite the political and religious upheaval of the 17th century.