The European Space Agency says it's preparing for the launch of a probe that will test technology for a future mission to measure gravitational waves.
The agency says the launch from French Guiana is scheduled for Thursday 0104 local time (0404 GMT).
Engineers had checked a technical problem that had been discovered in the Vega rocket and postponed the lift-off into orbit which was initially planned for Wednesday. ESA said in a statement the check had "provided satisfactory results."
Scientists hope the $450-million LISA Pathfinder mission will demonstrate it's possible to shield objects from external influences well enough to detect the minute effects of gravitational waves.
Explore further: Image: LISA Pathfinder launch sequence
Mission website: sci.esa.int/lisapf