SpaceX has fired its powerful Starship engines in cold lunar-like conditions, to prepare for a human moon landing a few years from now.
SpaceX, which is tasked with bringing the Artemis 3 crew to the surface of the moon with Starship in 2025 or 2026, successfully wrapped up a "cold engine" start in August, NASA officials wrote in a blog post Thursday (Sept. 14). The test aimed to show that the company's Raptor engine can restart in space after leaving Earth, to safely carry astronauts to the moon's surface.
SpaceX also posted a video on X (formerly Twitter) showing a steaming-cold Raptor firing for about three seconds at NASA's Marshall Space Flight Center in Alabama.
Related: FAA closes investigation of SpaceX's Starship rocket launch mishap, 63 fixes needed
Starship is the next-generation system that SpaceX plans to use for deep-space missions. Starship has not made it to space yet. In April, SpaceX launched a fully stacked Starship —the biggest, most powerful rocket ever built — for the first time. But the system suffered several serious problems. Starship spun out of control, was remotely detonated and caused a debris shower in the surrounding area.
The U.S. Federal Aviation Administration (FAA) supervised a SpaceX-led investigation of the launch mishap. On Sept. 8, the agency announced the conclusion of that investigation, which identified 63 corrective actions for the Hawthorne, California-based company to take. Two days later, SpaceX founder and CEO Elon Musk said the company has finished all 57 corrections required for an upcoming second launch, with the remaining remedies only needed for future flights.
Musk has suggested that Starship could go up again very quickly, while recent comments by the FAA suggest that SpaceX could get a license for a new Starship launch attempt in October. Meanwhile, SpaceX and the FAA are seeking to dismiss a lawsuit by environmental groups filed after the Starship launch in April.
As for the Raptor engine test, NASA officials said its success gives the agency more confidence that SpaceX is progressing toward its Artemis 3 obligations. "These tests provide early and mission-like validation of the systems necessary for carrying astronauts to and from the lunar surface," agency officials wrote in the blog post. "Data reviews following these tests provide NASA with continually increasing confidence in U.S. industry's readiness for the mission."
SpaceX also finished a milestone effort for Raptor in November 2021, NASA wrote, showing that the engine can fire for 281 seconds (4.5 minutes), the duration needed for the long descent to the moon. Raptor also changed its power level during testing to meet agency requirements. SpaceX released footage of that test on Thursday as well.
While Starship's engine tests are progressing, NASA Associate Administrator Jim Free warned in August that the agency is prepared to launch Artemis 3 even if Starship is not ready for a moon landing in 2025 or 2026, which is the current target for the mission. (This followed comments Free made in June in which he expressed "concern" about Starship meeting a 2025 launch date.)
In the Aug. 8 press conference at NASA's Kennedy Space Center in Florida attended by Space.com, Free suggested the agency could leave off the moon landing for Artemis 3,if necessary, and fly an alternate mission with a crew. In that scenario, Starship would be used on a future mission (such as Artemis 4) for the first human lunar landing since Apollo 17 in 1972.
The agency is looking for multiple successful launches by Starship ahead of authorizing the landing with astronauts, among other milestones, Free said. (Indeed, NASA wrote in its blog post on Thursday that the agency will be watching the performance of Raptor engines during the second launch attempt by Starship.)
Artemis 3 will be the third mission of the NASA-led Artemis program. NASA and a set of international partners are working together on the missions under the Artemis Accords. (The accords are both a set of commitments for lunar exploration, and an agreement to perform peaceful exploration norms in space with NASA. Not all signatories have committed to working directly on Artemis.)
Related: SpaceX Starship problems likely to delay Artemis 3 moon mission to 2026, NASA says
The first mission of the series, Artemis 1, saw an uncrewed NASA Orion spacecraft orbit the moon in late 2022 after launching there aboard the agency's Space Launch System (SLS) rocket. Next will come Artemis 2, which will send three NASA astronauts and a Canadian around the moon no sooner than November 2024, also using SLS and Orion.
SpaceX isn't the only vendor tasked with bringing humans to the moon for NASA missions; in May 2023, a consortium led by Blue Origin also earned eligibility to bid for missions after Artemis 4, following a competitive process.
SpaceX was initially selected as the only company eligible for Artemis 3 and Artemis 4 under a Human Landing System (HLS) NASA award from April 2021, which was the winner among three bids. The decision was framed as a surprise by the competitors, who had expected the agency would choose at least two landing systems (to have a backup option, which is common agency practice).
The other two coalitions, led by Blue Origin and Dynetics, respectively, issued protests to the Government Accountability Office (GAO) that were later overturned. Blue Origin also filed a lawsuit. Amid the legal matters, the SpaceX contract did not proceed for several months.
While NASA was eventually cleared to go ahead with SpaceX's contract, in September 2021 the Senate Appropriations Committee directed NASA to choose a second company to build a crewed Artemis lander. That began the new HLS bidding process that Blue Origin won.
Senate officials also noted that NASA's HLS program was not underfunded, which the agency had cited as justification for proceeding with only SpaceX. NASA's $24.83 billion budget that fiscal year was a little more than the $24.8 billion that NASA requested, with most of the increase going to HLS.
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