NASA will make its second attempt to launch its “mega moon rocket” this Saturday (September 3), the space agency announced, just days after aborting the rocket’s first launch attempt following an engine problem.
The Artemis 1 rocket is made up of the six-seat Orion capsule atop the Space Launch System (SLS) – dubbed the “mega moon rocket” – and was originally scheduled to set off on its maiden voyage to the moon and back on Monday (August 29). But engineers failed to cool one of the rocket’s four RS-25 main stage engines to a safe temperature in time for launch. That problem, as well as poor weather conditions, forced NASA to cancel the launch just two minutes before the spacecraft’s two-hour launch window expired, NASA officials said at a news conference Tuesday (Aug. 30).
The rocket’s new window for a second attempt will be Sept. 3, one day later than the earliest possible window on Friday (Sept. 2), which NASA ruled out because of the high risk of adverse weather conditions.
“The launch time from the launch pad for Saturday’s attempt will be 2:17 p.m. EDT (9:17 p.m. EDT),” Mike Sarafin, NASA’s Artemis mission manager, announced at a news conference Tuesday. “That’s a two-hour window.” NASA officials add that if the rocket does not lift off Saturday, another launch could be scheduled as soon as 48 hours later.
NASA views this flight as the first of three missions that will be a vital test of the hardware, software and ground systems that are designed to one day transport the first humans to Mars and beyond.
The programme is named after the Greek goddess Artemis, who is the twin sister of the god Apollo (the Apollo mission is named after this Greek god of light and the arts). “Artemis 1 will be followed by Artemis 2 and Artemis 3 in 2024 and 2025/2026, respectively. Artemis 2 will make the same journey as Artemis 1, but with a crew of four, and Artemis 3 will bring the first person of colour and the first woman on the Moon as early as 2025 to the South Pole of the Moon.
Monday’s launch was scheduled for 3:33 p.m. Bulgarian time, but the attempt was beset by problems from the start. Initial refuelling attempts were delayed in the early hours of Monday morning when lightning, which had already struck the Artemis rocket pad two days earlier, threatened to hit the rocket again.
Then, shortly after 10 a.m., the launch team announced there were problems filling the rocket with supercooled liquid hydrogen fuel. These problems were reminiscent of those the team reported experiencing during the wet dress rehearsal in April, when a faulty helium valve and a liquid hydrogen leak prevented the rocket from being prepared by the time of ignition. Another setback to Monday’s failed launch occurred when engineers noticed a suspected crack in the rocket’s thermal insulation, although it was later judged to be superficial.
The problem that ultimately scuttled the launch came shortly after 1 p.m. EDT when the team announced that the liquid hydrogen fuel cooled only three of the rocket’s four engines to a sufficient temperature before ignition. The problem engine, dubbed engine three, turned out to be about 22 degrees Celsius warmer than the minus 250 degrees Celsius temperature needed for launch.
NASA will try to fix that problem for Saturday afternoon’s launch by performing the engine-cooling procedure a half-hour earlier – a trick that officials say was effective during the successful test conducted last year.
NASA scientists speculate that a faulty temperature sensor may have mistakenly reported that the engine temperature was much higher and much farther from flight readiness than it actually was.
“The way the sensor is behaving is not consistent with the physics of the situation,” noted John Hannicutt, program manager for NASA’s Artemis 1 mission, during the press conference.
The faulty sensor can’t be easily replaced, and replacing it would likely mean the rocket would have to be sent back to NASA’s Rocket Assembly Building for rigorous testing. Because that would likely mean delaying the launch for several months, Hannicutt says his team is exploring the possibility of a workaround plan that would allow onboard engineers to make an “informed decision” about whether the rocket can take off without taking sensor readings into account.
NASA is betting heavily on the successful Artemis 1 mission, which has come under scrutiny because of the cost, which has soared to dizzying levels. The program, which began in 2017, has already cost more than $40 billion to develop and is expected to cost U.S. taxpayers $93 billion by the end of 2025, according to NASA Inspector General Paul Martin’s office, the space agency’s internal auditor.
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