NASA’s wet dress rehearsal for the new “space rocket mega rocket”, the space launch system (SLS), has officially ended – at least for now. A series of problems, mostly with ground equipment, focused on the dress rehearsal this week. Initially, the test launch was scheduled to begin on April 1 and was to last about 48 hours.
Recent problems have emerged: NASA’s inability to locate a leak in the hydrogen supply line, a defective valve, and the need to improve nitrogen flow to the substrate where SLS has been sitting for days. The purpose of the wet dress rehearsal was to test the operations, procedures and equipment needed for the first launch of the world’s most powerful missile, which is still planned for later this year.
For the Artemis 1 mission, the first in a series of gradual steps that will bring humans back to the lunar surface, the SLS is equipped with an unmanned Orion capsule and a handful of cubes. In the not-too-distant future, nearly 50 years after Apollo’s last mission, SLS aims to successfully deliver these payloads to lunar orbit.
Artemis 1 takes a step back
With the rehearsal for the wet dress rehearsal delayed, NASA now plans to return the rocket to the massive Vehicle Assembly Building (VAB) on April 26. While there, workers will try to eliminate the hydrogen leak, as well as deal with a problem valve that prevented the upper stage of the rocket from loading. NASA will then decide if it wants to do additional work on the SLS while they have it in store, which will inform their next step.
One possibility is for NASA to prepare the SLS for flight, take it back, conduct a successful wet rehearsal, and then leave the vehicle on the site to launch when celestial mechanics cooperate. The earliest optimistic start-up window is probably this summer, from June 29 to July 12. However, given the extensive history of SLS delays, creating this window can be a challenge.
Despite the problems, the wet rehearsal has achieved most – but not all – of its goals, NASA officials say. The team partially refueled the SLS cryogenic fuels while checking the health and safety of the Orion crew capsule, command and communications, and range safety checks. The start-up team also gained fluency in the procedures for starting and stopping the countdown and troubleshooting, and even quickly devised new refueling procedures.
Notable missed goals for the Artemis 1 dress rehearsal include refueling at the top stage and testing three teams for the operation, according to Artemis Launch director Charlie Blackwell-Thompson.
Number after number
Even before this week, the wet rehearsal of Artemis 1, which started in early April and was supposed to last one weekend, had several attacks and starts.
Initially, mobile starter fans, which were used to prevent the accumulation of hazardous gases, failed. This meant that personnel could not refuel the rocket’s super-cold fuels – liquid oxygen and liquid hydrogen – in its main stage and the intermediate stage of cryogenic propulsion. The technicians were forced to wait for the equipment to thaw before continuing. Also related to the mobile starter, someone mistakenly left the refueling valve switch closed instead of open. These early problems prompted the dress rehearsal team to temporarily give way to launch the Axiom-1, the first all-private mission to the International Space Station.
Another problem with the valves also appeared on the rocket itself, the only problem with the equipment of the vehicle. The helium non-return valve did not work as specified, which meant that the upper stage of the rocket could only be partially refueled. This problem cannot be corrected until SLS returns to VAB. But the good news is that once there, it should be an easy solution.
Driving the last dagger into the dress rehearsal on April 14, one of the umbilical cords attached to the rocket caused a hydrogen leak that again halted progress.
Artemis 1 presses
“We will be ready when we go through the test program… We are investing several long hours,” Artemis mission manager Mike Sarafin told reporters.
History has shown us that launching rockets capable of transporting crews to the moon is not easy. According to William Harwood of CBS, the first simulated countdown of the Apollo Saturn V rocket took almost three times longer than originally planned, at 17 days instead of six.
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