Nasa will make repairs to its latest Moon rocket to prepare for a launch later this year.
The 101-metre Space Launch System, the most powerful yet built, underwent a crucial test on June 20, with results the US space agency is satisfied with.
It will be rolled back to the Vehicle Assembly Building from a launch pad in Florida’s Kennedy Space Centre on July 1 or July 2.
Engineers will spend six to eight weeks preparing the rocket and the Orion spacecraft for launch as part of the Artemis 1 mission, which involves an uncrewed test flight to the Moon.
But first, they have to fix a hydrogen leak.
During an online media briefing on Friday, Nasa officials said they were on track for a launch attempt in late August.
“We have completed the rehearsal phase, and everything we've learnt will help improve our ability to lift off during the target launch window,” said Tom Whitmeyer, deputy associate administrator for common exploration systems at Nasa headquarters.
“The team is now ready to take the next step and prepare for launch.”
During the test, the rocket was fuelled and a practice countdown was held in a process known as a wet dress rehearsal.
Most of the objectives were met, but 13 out of 128 commanded functions were not successfully accomplished and the countdown ended 20 seconds short.
This was the fourth test. Three previous in April also failed because of a hydrogen leak.
Before returning to the Vehicle Assembly Building, engineers will carry out one more test on the rocket’s hydraulic power unit on Friday night to provide additional data for the countdown schedule.
“Once inside the [building], teams will replace a seal on the quick disconnect of the tail service mast umbilical to address a liquid hydrogen leak detected during the rehearsal,” Nasa said on its website.
“Nasa plans to return SLS and Orion to the pad for launch in late August and will set a specific target launch date after replacing hardware associated with the leak.”
The space agency has set several prospective launch dates from late August until June 2023.
This is the first of many missions under the Artemis programme, which aims to build a sustainable human presence on the Moon.
The launch of Artemis 2 is planned for 2024 and includes a crewed mission that will orbit the Moon.
Artemis 3, the first human lunar landing mission under the programme, has been delayed until 2025.