At the last second, Elon Musk’s SpaceX scrubbed plans to launch a Falcon 9 rocket on Sunday, again delaying an attempt to put an satellite into orbit and then land the vehicle’s first stage intact on a sea platform, a step that may eventually slash costs.

The 23-story rocket, carrying a communications satellite for Luxembourg-based SES SA, was less than two minutes from blast-off at 6:47 p.m. (1147 GMT) when the launch team aborted the countdown, SpaceX said during a webcast. It was the third time that the company postponed the launch of the satellite. Musk, founder and chief executive of SpaceX, said that Air Force safety officers stopped the countdown after a boat strayed into a restricted zone east of SpaceX’s Cape Canaveral Air Force Station launch site.

‘Scrambling (helicopter) to get them to move,’ Musk posted on Twitter. SpaceX resumed the countdown a few minutes later, aiming for a 7:21 p.m. (0121 GMT) launch, but a technical issue automatically stopped the liftoff again, just a second before the planned launch. ‘Launch aborted on low thrust alarm. Rising oxygen temps due to hold for boat and helium bubble triggered alarm,’ Musk posted on Twitter after the countdown stopped the second time. He said the launch team was reviewing data and would provide an update afterwards. SpaceX, based in Hawthorne, California, did not immediately say when it would make its next attempt to launch the rocket. It would be no earlier than Tuesday, the Air Force said in a statement.