NASA’s Artemis 1 moon mission completed a pre-flight milestone today (June 20) with a series of two-day tests known as a wet suit rehearsal.
These tests included feeding the huge rocket of the Artemis 1 space launch system (SLS) and performing a simulated countdown that took NASA’s Orion vehicle and capsule through most of the progressions they would suffer on the day. of the launch before the engine is started. The simulated countdown came to an end at 7:37 pm EDT (2337 GMT), ending the wet suit.
Not everything went perfectly well. The Artemis 1 team noticed a hydrogen leak during today’s feeding and intentionally “masked” the data associated with the problem to allow the countdown to continue. (During a real launch countdown, this data would have raised red flags, NASA officials said.) This change meant that the countdown stopped at T-29 seconds before the “takeoff”. instead of T-9 as originally planned.
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But this hiccup did not diminish the enthusiasm of the Artemis 1 team.
“It’s a great day for our team,” Charlie Blackwell-Thompson, Artemis launch director for NASA’s Kennedy Space Center (KSC) Earth Systems Exploration Program in Florida, said during a webcast of the wet suit just after finishing it. “Very proud to work during loading operations and work with terminal counting.”
KSC ground crews are likely to spend the next few days preparing the Mobile Launch Platform (MLP) and the Artemis 1 stack for transportation from the 39B Launch Platform to the Vehicle Assembly Building (VAB), where technicians they will analyze the results of the test series.
The wet suit was the last major milestone Artemis 1 had to complete before launch. On the actual mission, the SLS rocket will launch an unmanned Orion on a trip of about a month to the moon and back. Artemis 1 will be the first in a series of expeditions to the moon that NASA hopes will lay the groundwork for a permanent human presence on the lunar surface, one of the agency’s main goals. Artemis program.
Artemis 1 will be the first flight of the SLS, conducting more than a decade of research, development, and manufacturing to advance NASA’s human exploration plans beyond low Earth orbit (LEO). If Artemis 1 goes well, NASA plans to fly astronauts aboard Artemis 2 and Artemis 3, with the latter mission destroying the astronauts. the moon in four years or so.
Agency officials have repeatedly expressed optimism for the release of Artemis 1 in late August, but those hopes always depended on a soft, wet test. Now, this launch window seems much closer to reality.
Proceedings on rocket and MLP systems on Pad 39B began on Saturday (June 18) with a call to ground equipment stations at 17:00 EDT (2100 GMT). This started a countdown clock to a simulated launch time of 2:40 pm EDT (1840 GMT) today, which then went back to 4:38 pm EDT (2038 GMT).
True to its name, one of the first major protocols for testing the SLS wet suit was to fill the water tanks for the pad sound suppression infrastructure. The system pours nearly half a million gallons (1.9 million gallons) of water into the launch pad and flame trenches during a real takeoff and works to absorb the sound energy expelled from the engine ignition.
Then in the process came the initiatives of the vehicle stage. Operators started this Saturday night, starting Orion systems first. The central stage of the SLS was then launched on Sunday morning (June 19), followed by a series of system checks to confirm the connections between the spacecraft, the ground infrastructure and the control tables. the mission.
With the first stage rocket systems active, the final preparations for all four of the vehicle RS-25 engines they completed their own set of inspections and tests, which ended Sunday morning.
NASA officials met Sunday to assess the progress of tests and receive information on meteorologists’ weather with the US Space Force Space Launch Delta 45, which predicted favorable weather conditions for today’s tank procedures. In an official blog post, NASA stated that ground crews on Sunday afternoon were “performing a pre-launch rocket walk to make sure the space launch system is ready for upcoming propellant loading operations.” “.
Burning oil at midnight, so to speak, NASA crews turned on the power in the upper SLS stage, known as the Provisional Cryogenic Propulsion (ICPS) stage, just before 2 p.m. : 00 am EDT (0600 GMT) today. At 2:40 am (0640 GMT), all non-essential personnel were removed from the launch pad.
Artemis 1 made its full debut in mid-March, when the vehicle and MLP first rolled from the VAB to the platform for a dress rehearsal that began on April 1st. But the technicians encountered problems during this attempt; Three separate attempts to complete the wet suit were cleared due to complications during SLS feeding operations.
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The Artemis 1 team threw the Artemis 1 stack return to the GVA on April 25th, then spent about a month making repairs and improvements to pave the way for another wet dress test. Load errors during the first wet suit put a predominant focus on these systems during this morning’s cryogenic feeding procedures.
An integrated countdown has come into effect this morning and was expected to last 1.5 hours. During this time, mission directors conducted briefings on the weather and vehicle tank and had originally received a “go” from Blackwell-Thompson, but retention was extended when operators encountered a problem with a supply valve to the redundant gaseous nitrogen system of Pad 39B. According to Derrol Nail, a NASA spokesman on the agency’s live broadcast for the wet suit, the valve “would not shut down,” although the malfunction “was not with the valve itself, but with the controller.” .
Technicians were unable to immediately determine the cause of the problem, but they did replace the valve. The affected gas nitrogen line was initially designated as a redundant pellet supply. However, after replacing the valve, the engineers reassigned this leg for main use and the unaffected line as a new backup. “The new manual test of this valve works well, depending on the equipment available,” Nail said during the broadcast.
Nitrogen gas is used in Pad 39B to purge fuel tanks, umbilical cords, and other cavities within the SLS, both before and after the tank. Artemis 1’s time back at the VAB after the first attempt at wet dressing allowed some planned updates to the pad to move ahead of schedule. One of those upgrades included improving the supply capacity of nitrogen gas from the pill, which almost doubled in capacity.
“It simply came to our notice then [the gaseous nitrogen upgrades] We supported all of our needs prior to launch, “Blackwell-Thompson told Space.com during a press conference on June 15.” We reviewed all flow profiles, verified all pressures, and verified all timelines with a bit of margin. to ensure that our flow and needs can be supported during our wet suit rehearsal. “
Launch Deputy Director Jeremy Graeber joined the NASA broadcast for an update after the valve was resolved, informing listeners that the “problem has been cleared and we are in a good position to pick it up with the cryocharge. [and] It is no longer restricted. 9:28 am EDT (1300 GMT).) To a tight T-0 at 16:38 EDT (2038 GMT).
Both stages of the SLS rocket are powered by liquid oxygen (LOX) and liquid hydrogen (LH2). The loading process involves super cooling of the thrusters and cooling of the associated hardware before storage. Technicians carefully monitor load speeds, starting with a slow fill flow and increasing to maximum flow once umbilical connections and fuel tanks acclimatize to extreme cold temperatures. Once almost full, transfers decrease at a “higher” rate before shifting to an even slower flow, proportional to the boiling of the fuel leading to disconnection and umbilical release.
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LOX’s slow fill charge for the SLS center stage began this morning at 10:08 (14:08 GMT) and reached fast filling flows fifteen minutes later. In what is known as the “stern strut restriction,” it refers to the stress placed on the connection points for the bottom of the solid rocket thrusters of the SLS, according to Nail, the LOX tank of the center stage cannot fill more than 49% until LH2 tank exhaust sensors are completely covered.
To accommodate part of the lost time in the morning, mission operators were able to speed up LH2 cooling procedures for the umbilical and propellant lines. This cooling also included ventilation valves for the ICPS, which experienced pressure spikes during the first Artemis 1 wet suit. After this test, NASA technicians added these components to the pre-filling cooling procedures. LH2 for the main stage.
Operators were able to begin slow filling of the LH2 at 10:42 am EDT (1442 GMT). At 11:30 am EDT (15:30 GMT), once the exhaust sensors at the bottom of the tank were submerged, the LH2 transfer rates were changed to fast flow, putting the two fuel tanks in the tank. first stage on the way to reach the T-0 target at 16:38 EDT (2038 GMT).
Although the LH2 tank of the central stage is the largest of the rocket, with 537,000 gallons (2 million liters), it was also the tank that had to be completed first. The LH2 transfer from the central stage of the SLS began its replenishment flow at 12:42 pm (1642 GMT), allowing operators to begin cooling LH2 to the ICPS about 20 minutes later.
The first-stage LOX tank has a capacity of 196,000 gallons (740,000 liters), less than half the volume of the LH2 tank, but the vehicle’s liquid oxygen is …