Tanki online

After a while, NASA again tries to launch a moon rocket

NASA’s Space Launch System rocket stands on its launch pad in Florida. (NASA Photo/Joel Kowsky)

NASA is counting down once again to the first-ever liftoff of its Space Launch System rocket for an uncrewed test flight around the moon that should set the stage for future lunar landings.

The launch from Kennedy Space Center in Florida is scheduled during a two-hour opportunity that begins at 2:17 p.m. ET (11:17 a.m. PT) Saturday.

Live online coverage of refueling operations is scheduled to begin at 2:45 a.m. PT on NASA television. Full launch coverage in English will begin at 9:15 a.m. PT, with Spanish coverage beginning at 10 a.m. PT. (See the full program.)

Liftoff of the SLS rocket — which outperforms Apollo-era Saturn V as the most powerful launcher ever built for NASA – should be a spectacular sight. But this is just the start of a 38-day mission marking the first time in nearly 50 years that a spacecraft designed to carry humans has traveled as far as the moon.

NASA’s mission plan calls for the SLS to send an Orion spacecraft on a looping journey that would approach 60 miles from the lunar surface and extend up to 40,000 miles beyond the moon.

This time, Orion won’t be carrying anyone. Instead, three sensor-equipped mannequins will collect data on radiation exposure and other environmental conditions inside the capsule. There will also be an Alexa-like virtual assistant dubbed Callisto, which is provided by Amazon in conjunction with Cisco and Lockheed Martin.

One of the mission’s key moments will come when the Orion spacecraft slams into the atmosphere at 25,000 mph on its way back toward a splash in the Pacific Ocean. This will put Orion’s heat shield to its severest test, in temperatures up to 5,000 degrees Fahrenheit.

If this test flight goes well, it would pave the way for NASA to send a crew of astronauts on a similar flight around the moon for Artemis 2 in 2024. The landmark lunar landing would come on Artemis 3 in 2025 or 2026.

NASA canceled its first launch attempt on Monday, primarily due to an issue involving the cooling procedure for the four Aerojet Rocketdyne RS-25 rocket engines on the Boeing-built SLS core stage.

The pre-launch procedure calls for “purging” some of the supercooled liquid hydrogen from the SLS tank to bring the engines temperature down to the required level of approximately 420 degrees below zero F. During the Monday’s refueling operation, a sensor indicated that one of the engines was not cooling enough.

Engineers were unable to fix the issue in time for launch, forcing a scrub. They later came to suspect that the problem was due to a faulty sensor rather than a failure in the cooling system itself.

For this attempt, the rules governing the procedure have been rewritten to account for a wider assortment of data from a variety of sensors – and ignore readings from the suspect sensor if necessary.

Additionally, the cool down procedure, also known as the “startup purge,” will be performed during an earlier phase of the refueling process, around 8 a.m. ET (5 a.m. PT). The Heads of Mission made this change because the procedure worked perfectly earlier in the countdown during a “Green Run” engine test in March.

Over the past few days, the launch pad workers have also been refining and fixing some of the components that caused other issues during Monday’s countdown – for example, a leak in rocket fuel supply lines.

Tank trucks deliver liquid hydrogen to storage tanks at Kennedy Space Center. (NASA Photo/Bill Ingalls)

Technical issues aren’t the only issues that could delay takeoff: stormy weather could also force a postponement. Forecasters estimate that there is a 60% chance of acceptable weather at the start of Saturday’s launch window, rising to over 80% by the end of the two-hour window.

“Every day, there’s about a 1 in 3 chance that we’ll scrub for some reason,” said Melody Lovin, weather officer for US Space Force’s Space Launch Delta 45. “Of those chances of us rubbing, there’s about a 50 per cent chance that it’s due to weather conditions.”

If Saturday’s launch attempt has to be called off, the next opportunity will present itself on Monday or Tuesday. If that opportunity is also missed, the SLS should be taken off the launch pad for a test of its end-of-flight safety system, said Jeremy Parsons, deputy director of ground exploration systems at Kennedy Space Center.

The Artemis Lunar Program, named after the mythological moon goddess who was Apollo’s sister, highlights NASA’s leading role in exploration beyond Earth. This role has been somewhat controversial in recent years, due to the years of delays and billions of dollars in cost overruns associated with the SLS-Orion program.

A successful mission would arguably raise the space agency’s profile against commercial space companies such as SpaceX and Blue Origin, while a less successful mission could heighten the debate over whether NASA should outsource its role more. to these business ventures. (SpaceX is already to provide a lunar lander for the Artemis 3 mission, based on its Starship rocket design.)

“Both Blue Origin and SpaceX have built heavy reusable rockets at their own expense and are already stomping on the government disposable rocket that receives billions of dollars from our tax dollars,” the former NASA associate administrator wrote. , Lori Garver, in her recently published article. memory, “Escape from gravity.”