Nasa to finish Moon rocket fuel test after technical issues forced delay

Space agency will try again after Axiom-1 launch later this week

After technical issues forced Nasa to halt an important test of its massive Moon rocket, the space agency will try again following the Axiom-1 mission scheduled to launch from Cape Canaveral at the end of the week.

Although the “wet dress rehearsal” suffered pauses on both Sunday and Monday, testing of Nasa’s Space Launch System rocket and Orion spacecraft are still going according to plan, space agency officials said in a press call.

“The rocket is fine. The spacecraft is fine,” Michael Serafin, Nasa’s Artemis mission manager, said during the call. Artemis is the name of the Nasa program that aims to use the SLS rocket and Orion to return humans to the Moon in 2025.

“Most of the stuff we’re picking up is small or procedural in nature,” Mr Serafin said. “We’re learning features and systems that we characterise in subscale testing. But when you put it all together, you learn where some of your uncertainties are and we’re working our way through that.”

A wet dress rehearsal for launch is “wet” because it involves pumping the rocket full of liquid oxygen and liquid hydrogen fuel in addition to a simulated countdown and other tests of how the rocket, launch tower, and other ground systems interact.

Nasa first rolled the SLS to launchpad 39B at Kennedy Space Center from the cavernous Vehicle Assembly Building on 17 March, and the plan was to begin the wet dress rehearsal 1 April, but severe weather put a hold on the test.

Nasa tried again on Sunday, but two fans used to create positive pressure around the rocket to prevent the leakage of hazardous gasses were not functioning properly, so Nasa delayed until Monday morning.

The space agency’s ground team began loading liquid oxygen into the SLS rocket, but issues with a pressure control valve forced the team to halt the test again in the late morning after loading about 50 per cent of the liquid oxygen into the rocket.

They then drained and recovered the liquid oxygen from the SLS main booster,  “which is something that we also wanted to demonstrate how we would work through,” said Artemis launch director Charlie Blackwell-Thompson.

The wet dress rehearsal is designed to draw out the kinds of problems that presented themselves Monday, according to Ms Blackwell-Thompson and Mr Serafin, and they reiterated that the testing was going well.

“The purpose of the test is to fully understand our systems in a day of launch configuration,” Ms Blackwell-Thompson said, “and this was the first test in this configuration at the pad with cryogenic [liquid oxygen], so it was a pretty big day for us.”

Nevertheless, Nasa will wait until after the Friday launch of Axiom-1, the first all private mission to the International Space Station, before resuming testing of the SLS and Orion.

The successful completion of the wet dress rehearsal, and the resolution of any problems it reveals with SLS and Orion, are necessary before Nasa can schedule Artemis I, the first mission of the Artemis moon program and first uncrewed test flight of the rocket and spacecraft. The space agency is considering launch windows in May, June, and early July.

Assuming Artemis I sees Orion successfully fly around the Moon and back to Earth, Artemis II will send the first human crew around the Moon in an Orion spacecraft in May 2024. Artemis III, which will land the first woman on the Moon, is targeted for sometime in 2025, after which Nasa hopes to send human crews to the Moon about once a year beginning in 2027.