The launch of Nasa’s Tess planet-hunter has been postponed and it will not now lift off until Wednesday at the earliest.
The telescope was due to go up from Cape Canaveral in Florida at 18:32 local time on a SpaceX Falcon 9 rocket.
But the flight was stood down some three hours before lift-off.
SpaceX said it wanted some additional time to understand an issue related to the guidance, navigation and control of its vehicle.
It added that its teams were now working towards an 18 April launch at 18:51 EDT (2351 BST)
The mission is expected to find thousands of new worlds orbiting the nearest and brightest stars.
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