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Before its upcoming launch attempt to travel around the moon and back, the Artemis I gigantic moon rocket is getting ready for another test on Wednesday.

The Artemis I cryogenic demonstration test is scheduled to start at 7:15 a.m. ET on Wednesday, and NASA will stream live coverage of the event on its website. At Florida’s Kennedy Space Center, the Space Launch System rocket and Orion spacecraft are still parked on the launchpad.

According to NASA authorities, engineers have changed two seals on an interface for the liquid hydrogen fuel line between the rocket and mobile launcher after the second scrubbed launch attempt of the unmanned Artemis I mission on September 3. A significant hydrogen leak connected to these seals caused the launch attempt to be scrubbed.

According to Artemis mission manager Mike Sarafin, engineers discovered a “witness marker,” or depression on the seal associated with foreign object debris, when they changed the seal on an 8-inch (20-centimeter) quick disconnect line for hydrogen.

Although the team was unable to recover any debris, Sarafin said the dent was obvious and indicated a condition that may have led to the hydrogen leak.

Despite the small indentation (0.3 millimetres), pressurised gas can seep through, which can be quite dangerous given that hydrogen is flammable. The crew thinks the dent is connected to the leak, but the test findings may prove it.

According to Sarafin, the significant hydrogen leak on September 3 was two to three times the permitted limit.

Testing “kinder” methods
The cryogenic demonstration’s goals are to test the seals and load the supercold propellant using new, “kinder and gentler” loading techniques than what the rocket would encounter on launch day.

The cryo test of Artemis I focuses on a very specific stage of the countdown: inserting supercold liquid oxygen and liquid hydrogen into the rocket’s core stage and upper stage. This differs from the wet dress rehearsals, the previous tests of Artemis I that mimicked every stage leading up to launch.

According to Jeremy Parsons, deputy manager for NASA’s Exploration Ground Systems Program at Kennedy Space Center, the team does not intend to enter terminal count, or the last 10 minutes of the countdown before launch, during the test, which will leave the Orion spacecraft and rocket boosters unpowered.

In order to reduce the pressure and heat spikes seen during earlier launch attempts, a kinder and gentler loading approach was used. The team will gradually increase the pressure on the liquid hydrogen storage tank to achieve this. Parsons predicted that the slower method would only lengthen the process by no more than 30 minutes.

It will be a fairly gradual ramp, Parsons said. So our main goal is to lessen heat and pressure shock by gradually introducing some of those temperature variances.

The rocket is pumped with liquid oxygen, which has a density similar to that of water. According to Tom Whitmeyer, deputy associate administrator for NASA’s common exploration systems development, hydrogen is extremely light, therefore it is transferred using pressure rather than a pump.

The new loading procedures, according to Whitmeyer, will use a slower rate of pressure and more gradual temperature increases.

Today at 3 p.m. ET is the call to stations for the test, which starts when all of the teams involved with the mission report to their consoles and say they are prepared. Around 7 a.m. ET on Wednesday, the mission crew anticipates getting the all-clear to start propellant loading on the rocket. According to Parsons, if everything goes according to plan, the test should be finished by 3 p.m. ET that day.

An engine bleed will also be performed as part of the test to cool the engines before launch. The first Artemis I launch attempt was cancelled on August 29 in significant part because of a sensor problem that developed during this bleed.

The test’s forecast currently appears positive. In case Hurricane Fiona affects whether or not the rocket stack needs to be brought back into the Vehicle Assembly Building, a process that can take three days, the Artemis crew is briefed on it every day.

Getting ready for launch
The next launch attempt might happen on Tuesday, September 27, with a 70-minute window that opens at 11:37 a.m. ET if the cryo test goes well. On September 25, the mission management will gather to go through the test data and decide on a likely launch date.

If Artemis I takes off on that day, it will travel for 39 days before landing on Earth on November 5. On October 2, a backup launch is conceivable. Although NASA has suggested these launch dates, the team ultimately rely on the US Space Force’s choice, which would need to grant a launch waiver.

All rocket launches from the East Coast of the United States, including NASA’s Florida launch facility, are still under the control of the US Space Force, a branch of the military. This region is referred to as the Eastern Range.

Making sure there is no harm to people or property with any launch attempt is the responsibility of the range staff.

The Artemis team is still in “constructive and collaborative” communication with the Eastern Range, and NASA is providing more specific data that the Space Force has asked for assessment.

According to Whitmeyer, the team is moving forward step by step and wants to pass the test before making any more decisions.

When we are prepared to leave, Sarafin stated, “We will.” However, we have stated from the outset that this is the first of a series of flights that will get progressively more difficult, and it is a deliberate stress test of the rocket in terms of the reward for flying this flight.

The Artemis program’s first mission will launch a period of NASA space exploration that aims to send crewed missions to Mars and land diverse astronaut crews in previously unexplored areas of the moon in the Artemis II and Artemis III missions, which are scheduled for 2024 and 2025, respectively.