After the SLS Core Stage hot fire test that aborted just over a minute into the test, it was uncertain what objectives were met and if they would need to do a second test fire. During the second press conference Tuesday afternoon, concerns arose about the Core Stage reaching its cryo-cycling limit before the launch but today NASA shares the Core Stage and Artemis 1 timeline may be in better shape than first thought.
It was said Tuesday afternoon that the SLS Core Stage could only be fueled up with cryogenic propellant 9 times before it reaches its limit. This wasn’t fully explained and it left many reporters confused why it was so small after the Space Shuttle’s external tank, which the Core Stage is based on, could be fueled up to 13 times. NASA shared today that 9 was the allocation of attempts given to the Green Run tests at Stennis Space Center and overall, the Core Stage can be cryo-cycled up to 22 times.
This gives rest to the weary that were concerned over Artemis 1 not launching due to reaching that limit. NASA also allocated 13 cryo-cycles to NASA Kennedy Space Center for dress rehearsal and launch attempts.
Another item given was that even though the test was cut short, the test might have completed many of the 23 objectives set out for the hot fire. Between NASA teams, Boeing, Aerojet Rocketdyne, and other contractors they are continuing to look over the data to determine what objectives were fully met, what were partially met, and if any require a retest. This is good news for the Artemis program if the Core Stage can skip another test fire and be shipped directly to Florida for integration with the rest of the SLS stack.
Either way, if they need to do another test or launch the four RS-25 engines need to go through a drying and refurbishment phase which was said is already underway. This could take a couple of weeks and longer if they find anything that needs to be replaced but initial inspections show that the engines are in excellent condition.
Currently, the Artemis 1 launch attempt is still set for November of 2021 which doesn’t leave much room for several launch attempts if they need to launch the SLS’s Solid Rocket Boosters by the beginning of January to stay within their “Best By Date”.