SLS dress rehearsal Monday … Watch live here!

SLS dress rehearsal Monday … Watch live here!

2022-06-20 0 Por ljxih

SLS dress rehearsal starts Monday, June 20

The SLS wet dress rehearsal countdown has resumed following a hold to resolve a technical issue. The launch control team has begun chill down operations and resumed the countdown clock ahead of flowing super cold liquid oxygen (LOX) into the core stage tank. The T-0 time for today’s test is now 4:38 p.m. EDT (20:38 UTC) on July 20 for the first of the two terminal count runs for the wet dress rehearsal. NASA is providing live commentary on event scheduling here.

After a successful rollout to historic Launch Pad 39B at Kennedy Space Center on June 10, 2022, the mighty Space Launch System, or SLS, is ready for a dress rehearsal. This is the rocket that’ll launch the Artemis moon mission. And NASA technicians will be putting the rocket through its paces on Monday, June 20. They’ll be pushing every button and flipping every switch, including filling the vehicle’s main fuel tanks … rehearsing each step except final ignition of the main engines, as NASA prepares for the Artemis 1 launch, hopefully to be later this summer.

The space agency’s Artemis blog offers this quick rundown of Monday’s activities:

The rehearsal will run the Artemis I launch team through operations to load propellant into the rocket’s tanks, conduct a full launch countdown, demonstrate the ability to recycle the countdown clock, and also drain the tanks to give them an opportunity to practice the timelines and procedures they will use for launch.

The NASA blog post also includes a minute-by-minute breakdown of each step of the SLS’s Wet Dress Rehearsal (WDR), which mimics exactly the actual ignition countdown.

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Third time’s a charm

This is the third time NASA has attempted to complete the Wet Dress Rehearsal. Two previous attempts – one in December 2020 and a second just months ago in March 2022 – both fell short of completing the shakedown of the moonship.

Once the SLS – NASA’s most powerful vehicle to date – is deemed fit to fly, its Orion spacecraft will make an uncrewed trip around the moon, a critical first step toward humanity’s return to the lunar surface and eventually Mars. The first crewed mission, Artemis 2, is scheduled for 2024. Artemis 3, which will put astronauts on the moon for the first time in 50 years, will fly no earlier than 2025.

The Artemis launch schedule depends on completing the critical Wet Dress Rehearsal.

SLS dress rehearsal: Tall rocket with capsule atop and two booster rockets attached to the sides.
NASA’s Space Launch System (SLS) rocket at Launch Pad 39B at the agency’s Kennedy Space Center in Florida on March 18, 2022. The rocket, with the Orion capsule at the top, awaits a wet dress rehearsal ahead of the uncrewed Artemis 1 launch. Image via Kim Shiflett/ NASA/ Wikipedia.

Expect the unexpected

While NASA is confident in its latest and most powerful manned space vehicle, the two prior attempts to ready the ship for flight were cut short of the full WDR. Since NASA is looking for problems, it may actually find some, which can lead to alterations in the testing schedule.

NASA cautions those watching along that the listed times for WDR milestones are approximate, and delays may happen:

During the test, the timing for some events on account of several planned operational demonstrations tied to specific capabilities and test objectives may differ from the day of launch countdown. These demonstrations include tests on the cryogenic systems and an approximately three-minute hold inside the terminal count, which would not normally occur on launch day. If needed, the test team may also hold as necessary to verify conditions before resuming the countdown, or use the test window or extend beyond it, if consumables and resources allow them to complete test objectives.

Fill ‘er up!

Filling of the SLS’s fuel tanks should start at 7:35 a.m. ET following a “go” or “no-go” call by the launch director and the mission management team chair. Getting the entire fuel load aboard is scheduled to take five hours, ending at 12:40 p.m. ET.

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A 30-minute built-in hold will stop the countdown at 2 p.m. ET for the final NASA test director briefing. The launch director’s poll of each launch team division for “go” or “no-go” is set for 2:25 p.m. ET.

If all lights are green on every control board, the WDR Run 1 countdown will resume at 2:30 p.m. ET at T-10 minutes and counting.

At 2:34 p.m. ET, the Orion ascent pyros are armed and the vehicle shifts to internal power. Seven minutes later, at 2:41 p.m. ET, the ground launch sequencer will send the “cut-off” command, ending the countdown at T-33 seconds.

The countdown will then be reset to T-10 minutes for WDR Run 2, with the second countdown ending just 10 seconds before main engine ignition.

Following the tests, the vehicle will be returned to safe mode and cryogenic fuel drain operations will begin.

Bottom line: NASA is attempting a third Wet Dress Rehearsal of the Space Launch System on Monday (June 20, 2022). Watch it live here.

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