NASA plans to take another shot at a crucial refueling test of its Space Launch System (SLS) megarocket on June 19.
SLS will make its debut at the next Artemis 1 mission, which will send an uncrewed Orion capsule on a trip around the moon. But before Artemis 1 can lift off, its SLS and Orion must complete a crucial series of pre-launch tests known as “wet dress rehearsal.”
In a call with reporters on Friday afternoon (May 27), NASA officials announced that they plan to begin shooting Artemis 1 from the massive Vehicle Assembly Building (VAB) at the Kennedy Space Center (KSC). from NASA in Florida to Launch Pad 39B at around midnight EDT (0400 GMT) on June 6.
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It won’t be the first Artemis 1 launch. NASA’s first run in a wetsuit Artemis 1 began on April 1, about two weeks after the Moon rocket initially launched from the VAB. Following a similar schedule for vehicle reviews on the platform this time, NASA officials said they expect to start the roughly 48-hour wet dress on June 19.
Several technical problems emerged on the platform during last month’s wet dress, including a stuck valve and a hydrogen leak in one of the “umbilical” lines connecting the SLS to its mobile launch tower. The Artemis 1 team tried to power the SLS three times, but ended up scrubbing the wet dress, finally rolling the Artemis 1 stack back into the VAB for repairs on April 25.
NASA officials outlined several of these solutions during Friday’s call. For the leaky umbilical, for example, it was found that the flange bolts had inadvertently loosened, compromising its seal.
“Those seals age over time,” explained John Blevins, chief engineer for the SLS program at NASA’s Marshall Space Flight Center in Alabama.
“We had previously tightened them and we hadn’t done … torque checks over the period of time we’ve now found those seals to age,” he added. Blevins expressed confidence in the repair work, saying members of the Artemis 1 team have taken steps to prevent leaks.
Replaced a helium check valve and related hardware in the upper stage of the SLS, which is called the Interim Cryogenic Propulsion Stage (ICPS). Modifications were also made to the ICPS umbilical boots, which are involved in the quick disconnect between the SLS and the mobile launch tower during takeoff. Additional leak detectors have also been added to components of the system responsible for handling liquid hydrogen, NASA officials said.
Cliff Lanham, senior vehicle operations manager for KSC’s exploration ground systems program, highlighted some of the work on Artemis 1 that NASA has started ahead of schedule thanks to the reversion of SLS to VAB. For example, teams installed payloads partially inside the Orion capsule and replaced the remaining ground system plates with flight plates to cover the vehicle’s instrumentation. That fit, Lanham said, will give the vehicle better protection from Florida’s hot, humid and often rainy weather, especially during the summer months.
While the SLS has been undergoing maintenance at the VAB, the Pad 39B has also received some much-needed updates. Part of the SLS dress rehearsal requires fueling and draining the rocket propellant to simulate the procedures leading up to an actual launch. Gaseous nitrogen is used on the platform to purge rocket cavities and dry umbilicals, and platform 39B was able to receive a capacity increase in recent weeks.
“Because it’s such a large rocket, we require a commensurate number of products … There are a lot of different functionalities on the vehicle that require nitrogen gas,” said Tom Whitmeyer, NASA deputy associate administrator for common exploration systems, during the Friday call.
The increased capacity will allow SLS to undergo more extensive checks on the launch pad, including a 32-hour test run of the nitrogen system to simulate rocket consumption during launch, as well as ground systems and avionics.
“The vehicle itself is a very simple vehicle, but any time you go into cryogenic loading operations, it’s something you have to take one step at a time,” Whitmeyer said.
If the wet dress works this time, the Artemis 1 team can begin preparing for a real liftoff. NASA officials have said their goal is to launch Artemis 1 this August, though they won’t set an official target date until wet dress is complete and all data has been analyzed.
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