Artemis 1 Cleaned Up Launch Raises Concerns Over Unfinished Rehearsals

SLS on the Kennedy Space Center launch pad in Florida.

SLS on the Kennedy Space Center launch pad in Florida.
Photo: Nasa

NASA failed in its first attempt to launch the Artemis 1 uncrewed mission on Monday, with engineers difficulty in solving an engine cooling problem. This is quite a surprising result, given that NASA was unable to complete a single wet dress rehearsal, four of which were attempted earlier in the year. The space agency appears to be piloting it, with the botched launch attempt effectively serving as a wet fifth dress rehearsal, which is a disturbing sign.

NASA’s Space Launch System (SLS) was supposed to take off on Monday morning, but instead we wonder about the state of the program as a whole. NASA will provide more updates on the rocket later tonight, including whether a Friday or Monday launch might be possible, or whether the 322-foot-tall (98-meter) rocket will need to make its now familiar 4-mile ( 6.4 kilometres) back to the vehicle assembly building for repairs.

The unstolen SLS mega rocket is essential for NASA’s Artemis program, which aims for a permanent and sustainable return to the Moon. For the Mission Artemis 1, an uncrewed Orion rocket will be sent on a multi-week mission to the Moon and back. A successful integrated test of SLS and Orion would set the stage for a crewed Artemis 2 mission in about two years, and a crewed mission to land on the lunar surface later this decade.

A Friday launch seems unlikely, and not just because of poor weather forecasts. from NASA Monday launch attempt was far from successful, the countdown not exceeding T-40 minutes. An “engine purge” problem stop one of the rocket’s four RS-25 engines from reaching the ultra-cold temperature required for liftoff, resulting in gumming.

Thousands of spectators gathered near the launch site, as did hundreds of journalists. Vice President Kamala Harris was also present at the Kennedy Space Center in Florida. Everyone left disappointed, but it doesn’t take a rocket scientist to admit that a Monday launch would still be unlikely. With ground crews failing to complete a single full wetsuit rehearsal, it seemed a stretch to believe that NASA would somehow succeed in the Artemis mission’s first launch attempt. 1.

Indeed, the problems began almost immediately early Monday morning, with the threat of lightning delaying refueling operations by almost an hour. Working on an accelerated schedule, ground crews proceeded with the six-hour refueling process. A problem arose when the team switched from a slow tank to a fast tank, with a leaking 8-inch intake valve causing high hydrogen readings. The leak was resolved by reverting to slow fill and restarting the process, allowing the center stage hydrogen tank to be completely filled.

When using the thruster to cool the four RS-25 engines, however, the team found that one of the engines – engine number three – refused to cool to the ultra-low temperatures required. Engineers worked their way through previously established troubleshooting guidelines in an effort to get more liquid hydrogen into the engine. They tried to increase the pressure in the tank, but this led to the detection of another problem: an apparently leaking vent valve placed between the liquid hydrogen and liquid oxygen tanks.

Speaking to reporters yesterday, Mike Sarafin, NASA’s Artemis mission manager, said engineers “wanted to increase the pressure in the tank in order to establish the hydrogen purge”, but that “the vent valve did not cooperate”. That was the straw that broke the camel’s back, and the team “decided it was appropriate to declare the scrub because we just weren’t going to do the two-hour window,” said Sarafin, adding that it was “one of those situations where we just knew we needed more time. He insisted that the problem was not with the engine itself, but rather with the” purge system which thermally conditions the motor”.

The engine bleed issue is one of an unknown number of items that were not tested during wet rehearsals. At the end of the last wet dress held in June, NASA officials said 90% of all test goals have been met, without disclosing details of the remaining 10%. The last wet dress was not finished due to an unresolved hydrogen leak related to a faulty quick coupler. For this rehearsal, NASA officials had hoped to run the countdown to T-10 seconds, but it never exceeded T-29 seconds, leaving many doubts about the final launch phase.

After the partial completion of the third wet dress in April, SLS was returned to the Vehicle Assembly Building for repair, returning to Launch Pad 39B in early June. Over the course of four rehearsals, engineers recorded a host of seemingly minor issues, a list that includes faulty ventilation fans on the mobile launcher, an incorrectly configured manual ventilation valve, overly cold temperatures, and frost while charging the launcher. thruster, a small hydrogen leak on the umbilical tail service mast, problems with the nitrogen gas supplier, and a faulty helium check valve that needed to be replaced.

That said, it was during the fourth wet dress that SLS was finally fully loaded with propellants, with over 755,000 gallons of liquid oxygen and liquid hydrogen added to both rocket stages. Although it did not meet 10% of the test goals, Tom Whitmeyer, NASA Exploration Systems Manager, said “we think we had a really successful rehearsal”, and that there were risks in making a fifth try.

Speaking to reporters yesterday, NASA Associate Administrator for Exploration Systems Development Jim Free echoed that earlier sentiment, saying another wetsuit rehearsal was unnecessary. “We would have taken another round of deployment and return,” he said, and that would have introduced other risks, including attrition. “We won’t know until we do, but we won’t know until we try,” Free added. “We felt in the best position to try.”

Keith Cowing, editor and former NASA rocket scientist, said the space agency treated Artemis 1’s first launch attempt as essentially the fifth wetsuit rehearsal. Cowing, who spoke to me on the phone, said NASA should have done all the required testing in advance to avoid these new issues.

“These things happen,” Cowing said. “But it’s heritage material, with different pieces of rockets that have flown before.” By legacy hardware, Cowing refers to the fact that the current SLS configuration “uses existing Space Shuttle inventory hardware, as much as possible, to reduce cost and accelerate schedule.” according at NASA. These elements include the main stage thrusters and motors, as well as the integrated spacecraft and payload element. “NASA shouldn’t expect everything to work as planned because there will be integration issues,” Cowing told me. To which he added: “Testing is good, and it has to be done methodically, so when you finally try to launch, you know what you tested, instead of using launch attempts as In fact wet dresses.

Cowing worries about the state of the program and the already archaic nature of SLS. Unlike SpaceX rockets, which can be modified and repaired on the launch pad, SLS must return to the Vehicle Assembly Building for hardware adjustments (this could be the case with the aforementioned leaky vent valve, but we’ll have to wait for official word from NASA). And at an estimated cost of $4.1 billion per launch, Cowing predicts that SLS launches will be rare events, citing NASA Inspector General Paul Martin, who earlier this year described the price as “unsustainable”.

NASA officials are probably feeling the pressure, hence the desire to finally get SLS off the ground. It does create some awkward theater though, with Monday’s scrub being a good example. The chances of a launch were exceptionally low (at least that’s how I assessed it), but NASA had no qualms about publicizing the event and inviting a host of dignitaries and guests famous.

The mega-rocket doesn’t seem ready to launch, yet NASA is doing its best to convince us that it is. Unfortunately, the “simulated” launch attempt earlier this week is unlikely to be the last.

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