SLS at Launch Complex 39B at the Kennedy Space Center in Florida. Photo: NASA
After three failed attempts to complete a wet rehearsal of its space launch system, NASA has decided to return its giant rocket to the vehicle assembly building. The relocation is likely to further delay the unarmed Artemis 1 mission to the moon.
The place is difficult – we understand it – but the recently unfinished wet rehearsal of SLS was just sad.
In fact, NASA could not even complete a modified rehearsal for the launch last Thursday, in which ground crews tried to load the main stage of the rocket with cryogenic propellants. A small leak of hydrogen on the tail service mast was blamed for stopping the test, and NASA said it would conduct a re-modified launch test earlier this week. However, the space agency quickly changed its plans, announcing on Saturday that the 322-foot (98-meter) rocket would return to the vehicle assembly building at the Kennedy Space Center for repairs.
The rehearsal for launching the SLS in a wet dress is taking place before the upcoming Artemis 1 mission, in which NASA will try to launch an unmanned Orion capsule to the moon and back without landing on the moon. Standing at launch complex 39B at the Kennedy Space Center in Florida, the rocket had to be fully refueled and the countdown stopped just before its four RS-25 engines ignited, but none of that happened. This is not a fantastic result, as SLS is a critical component of the Artemis program, which seeks to land American astronauts on the moon later this decade.
In a press release, NASA said the decision to return the SLS and Orion capsule back to VAB was “due to the need to upgrade a supplier off-site of the nitrogen gas used for the test.” The nature of these upgrades and the time required to implement them have not been revealed, but the space agency said it would “take the opportunity” to land the rocket directly in the hangar.
In particular, NASA needs to replace a defective helium check valve that prevented ground crews from loading supercooled liquid oxygen and liquid hydrogen into the rocket’s second stage during the second wetsuit attempt. The 3-inch valve can only be accessed when the rocket is inside the VAB. NASA will also use this time to repair the leaking navel, review test results, review its schedule, and decide on the remaining list of SLS test requirements.
It seems likely that NASA will have to hold another wet rehearsal now. Space officials said there was nothing wrong with the rocket and that they simply had to deal with minor or “unpleasant” problems. This may be the case, but the sheer volume of problems and the constant way in which refueling has taken place seem problematic.
The SLS wet dress started on April 1, but a constant series of problems prevented the test from continuing until its end. These problems include defective ventilation fans on the mobile launcher, improperly configured manual ventilation valve, excessively low temperatures and freezing during refueling, and the aforementioned problem with a third-party nitrogen gas supplier. A thunderstorm on April 2 and the Axiom Space mission to the International Space Station, which launched from the Kennedy Space Center on April 8, also contributed to the delay.
Charlie Blackwell-Thompson, Artemis’ launch director, said it would take ground crews about 10 days to prepare the SLS for its creeping 4-mile (6.4-kilometer) trip back to VAB, which will take about 12 o’clock. A second period for a full wet rehearsal, if it happens, is not inevitable. As for the Artemis 1 mission, the next three launch windows are from 1 to 16 June, from 29 June to 17 July and from 26 July to 9 August.
NASA has scheduled a media teleconference for 15:00 EDT today to discuss in more detail the state of the SLS and the wet dress. We will update this article with new information as it becomes available.
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