NASA’s Artemis 1 lunar mission is back on the launch pad.
Technicians at NASA’s Kennedy Space Center (KSC) in Florida began rolling the Artemis 1 stack – one Space Launch System (SLS) topped with an Orion crew capsule – out of the Vehicle Assembly Building (VAB) at approximately 12:10 a.m. EDT (0410 GMT) Monday morning (June 6), again taking the mega moon rocket on the 4-mile (6.4 kilometer) hike to historic Launch Complex 39B.
The overnight trip took approximately 10 hours, with Artemis 1 arriving at the pad just before 10:00 a.m. EDT (2:00 p.m. GMT). Now the vehicle battery and ground systems are waiting for another attempt to power the rocket and simulate a launch countdown for a critical series of tests known as the wetsuit rehearsal, which is scheduled to begin on June 19.
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Artemis 1 will be the highly anticipated maiden voyage of SLS, whose development has been marred by multiple delays and cost overruns. (Orion flew once before, during a trip to Earth orbit in 2014.)
The mission will fly an uncrewed Orion the moon and back in preparation for the future Artemis missions, which aim to return humans to the moon for the first time since 1972. NASA is therefore taking all necessary precautions to ensure the success of the rocket’s debut, including choosing to scrub the first wet dress rehearsal in April to let time for additional maintenance after three failed attempts to load the SLS with cryogenic fuel.
The first deployment of Artemis 1 from VAB to Pad 39B took place on March 17, followed by a wet dress rehearsal which began on April 1. Unable to complete the full range of tests, NASA made the decision to taxi the vehicle and its Mobile Launch Platform (MLP) return to VAB for repair April 25. Technicians looked into the root causes of the initial wet dress chafing, and they also used the time spent in the VAB to expedite the implementation of other scheduled upgrades.
During the first wetsuit test, ground crews experienced fuel loading issues in the SLS’s Interim Cryogenic Propulsion Stage (ICPS), which is responsible for Orion’s orbital insertion and injection burns trans-lunar. Loose flange bolts contributed to hydrogen leakage in the umbilicals connecting the MLP to the ICPS. NASA’s investigation found that the joints of these bolts deteriorated to some degree as they aged and implemented torque controls to tighten the affected hardware.
Other repairs were also aimed at fixing SLS’s cryo-loading issues. A helium check valve was replaced on the ICPS and modifications were made to the umbilical boots responsible for the rapid disconnection of the MLP arms from the SLS during takeoff.
With the Artemis 1 stack missing from Pad 39B for the past five weeks, launch complex upgrades were able to move ahead of schedule. Most notably, the NASA contractor providing the infrastructure that manages and supplies nitrogen gas to the launch pad was able to nearly double the capacity of the facility by adding a second method to produce the gas.
Huge amounts of nitrogen gas are used during the wet dress rehearsal as well as the launch itself. For one thing, gas is cycled through all fuel tanks and pipes in the rocket and ground infrastructure to help purge the ship’s cavities before and after refueling. The new upgrades will allow the systems to reach full design capabilities and facilitate fueling tests for up to 32 hours, NASA officials said.
The next wetsuit rehearsal for Artemis 1 is scheduled to begin on June 19 and last approximately 48 hours. The countdown simulation will see the rocket go through pre-flight and refueling procedures until just before engine ignition.
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KSC ground crews will coordinate with mission control personnel from NASA’s Johnson Space Center in Houston, engineers from Marshall Space Flight Center in Huntsville, Alabama, as well as Space Force Eastern Range in Cape Canaveral, Florida. to perform loading operations of more than 700,000 gallons (2.65 million liters) of cryogenic fuel between the rocket and the launch pad infrastructure.
A series of countdown, hold and abort rehearsals, as well as different simulated weather scenarios will test ground crews’ abilities to load and unload propellants under a number of different launch conditions. Several days after a successful wet dress, teams will return the SLS and Orion to the VAB to analyze test data, determine the vehicle’s flight readiness, and hopefully begin preparing the rocket for an actual launch.
NASA officials refrained from picking a firm date for the Artemis 1 mission, citing the need to review the outcome of the dress rehearsal, but expressed optimism for a late August window, which could be possible if all is going well. the next weeks. Should SLS experience additional issues, NASA has preemptively issued a list of future launch opportunities which run until 2023.
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