5.04.2022

Ground system problem halts Artemis 1 countdown dress rehearsal

NASA launch controllers called off plans to load super-cold liquid hydrogen and liquid oxygen into the first fully-assembled Space Launch System moon rocket Sunday for a countdown dress rehearsal, giving time for ground teams to troubleshoot problems with fans used to ventilate the giant rocket’s mobile launch structure at the Kennedy Space Center.

The practice countdown, known as a wet dress rehearsal, started Friday and was supposed to culminate in the pumping cryogenic propellants into the 322-foot-tall (98-meter) Space Launch System rocket Sunday on launch pad 39B.

But the SLS launch team scrubbed the simulated countdown shortly before noon EDT (1600 GMT), prior to the start of propellant loading. The countdown was paused much of Sunday morning while the launch team evaluated problems with fans needed to pressurize, or ventilate, the mobile launch tower.

The fans blow air into the mobile launcher to ensure hazardous gases don’t build up during tanking, reducing the risk of a fire or other emergency, according to Charlie Blackwell-Thompson, NASA’s Artemis launch director.

One of the fans ran into trouble early Sunday, so officials paused the countdown to allow a team to go back to the launch pad to troubleshoot the problem. The launch team switched to a backup fan and prepared to continue the countdown, but then the second fan encountered a different issue, Blackwell-Thompson told reporters Sunday afternoon.

“The purpose of that pressurization is to prevent hazardous gas intrusion during load, so it provides a positive pressure,” she said. “So in the event that you were to have a leak or have some sort of hazardous commodity out of at pad, that you didn’t have, those gases intrude into those areas and potentially cause a fire hazard.

“So we decided that we wanted to really understand (the fan problems), given it was the first-time loading of the vehicle, and we made the decision to stand down to get in a configuration to go troubleshoot that, and then to be ready to make another run at it tomorrow,” Blackwell-Thompson said.

The mobile launcher stands 370 feet (113 meters) tall, with retractable umbilical arms to route gases and propellants to the rocket, and a crew access arm to allow astronauts to board the Orion spacecraft for future Artemis moon missions.

The ventilation fans are located in a building along the perimeter of pad 39B, a few hundred feet away from the rocket and mobile launcher. Air from the fans is routed through ducting in the launch pad’s environmental control system.

Blackwell-Thompson said engineers do not believe the cause of the malfunctioning fans is related to four lightning strikes observed inside the perimeter of pad 39B during a thunderstorm late Saturday afternoon. However, ground teams were still troubleshooting the fans when she spoke with reporters Sunday, and NASA officials weren’t sure of the reason the fans ran into problems.

Engineers determine the lightning strikes did not impact the Space Launch System or ground facilities. Three of the strikes hit the launch pad’s lightning towers, and another struck the catenary wiring system used to route electricity away from the rocket while it is exposed at the pad.

NASA is testing the Space Launch System for its first test flight, known as Artemis 1. The countdown rehearsal at Kennedy is a full-up practice run for launch day. Once the countdown proceeds into the final steps before liftoff, the clock will stop at T-minus 9.3 seconds, just prior to main engine ignition.

If ground teams at Kennedy are able to resolve the fan problems overnight, NASA’s mission management team will meet at 6 a.m. EDT (1000 GMT) Monday to give a “go” or “no go” for the start of propellant loading.

That propellant loading should begin shortly after 7 a.m. EDT (1100 GMT) for the giant Boeing-built core stage, covered in orange foam insulation to prevent ice build-up on the rocket’s outer skin.

Liquid oxygen, chilled to minus 297 degrees Fahrenheit (minus 183 degrees Celsius) will begin loading first into the core stage. Then liquid hydrogen, stored at minus 423 degrees Fahrenheit (minus 253 degrees Celsius), will start pumping into the rocket’s main stage at pad 39B.

It will take about three hours to load liquid oxygen into the core stage, and an hour-and-a-half for liquid hydrogen. In flight, the propellants will feed the rocket’s four RS-25 main engines, leftovers from the space shuttle program, for a burn lasting more than eight minutes.

Then the launch team will move on to loading hydrogen and oxygen into the rocket’s cryogenic upper stage, powered by a single Aerojet Rocketdyne RL10 engine. Here’s a breakdown of the propellants that will be loaded into the rocket Sunday:

• Core Stage liquid oxygen: 196,000 gallons

• Core Stage liquid hydrogen: 537,000 gallons

• Upper stage liquid oxygen: 5,000 gallons

• Upper stage liquid hydrogen: 17,000 gallons

Another 30-minute build-in hold is planned when the countdown reaches the T-minus 10 minute mark Sunday afternoon. After a final “go/no go” pre-launch readiness poll, NASA launch director Charlie Blackwell-Thompson will give approval for the countdown clock to resume.

If all goes according to plan, the countdown will target a simulated launch time of 2:40 p.m. EDT (1840 GMT) Monday. In the final 10 minutes of the countdown, the core stage and upper stage propellant tanks will be brought to flight pressure, the boosters will be armed, and the rocket will be switched to internal power.

The countdown will cut off at T-minus 33 minutes and recycle to the T-minus 10 minute hold. NASA’s launch team plans a second run through the terminal countdown later Sunday afternoon, culminating in a hold at T-minus 9.34 seconds, just prior to ignition of the main engines.

Then the core stage and upper stage will be drained of cryogenic propellants, and NASA engineers will evaluate the rocket’s performance during the dress rehearsal, before eventually rolling the rocket back to the Vehicle Assembly Building for final pre-launch testing and closeouts.

NASA plans to announce a target launch date for the Artemis 1 mission after the wet dress rehearsal is complete. The launch dates currently under consideration are in June.

The Artemis 1 mission will send an Orion crew capsule into orbit around the moon, where mission control will run the spacecraft through a series of demonstrations before astronauts fly on the next SLS/Orion flight, named Artemis 2, on a looping trajectory around the moon.

Future missions after Artemis 2 will attempt to land astronauts on the moon with a commercial lunar lander, and build out a mini-space station near the moon called the Gateway.

Quelle: SN

----

Update: 6.04.2022

.

After weather and hardware issues, NASA starts SLS moon rocket fueling test

Update: NASA is now targeting sometime after Friday, April 8, to complete the SLS rocket's wet dress rehearsal. The shift makes way for SpaceX's Axiom-1 mission to fly from Kennedy Space Center at 11:17 a.m. ET Friday.

---

More technical issues forced NASA teams at Kennedy Space Center to delay a countdown rehearsal for the agency's Space Launch System moon rocket Monday, pushing critical fueling milestones to later in the week.

In an update posted at 5 p.m. Monday, NASA said a valve located on the 322-foot rocket's mobile launch tower failed to open properly, forcing managers to delay key portions of the practice countdown known as the "wet dress rehearsal." The 45-hour test that began Friday is designed to simulate a launch countdown and is called "wet" because it includes fueling the rocket with liquid propellants at pad 39B.

"Due the vent valve issue, the launch director has called off the test for the day," NASA said in an update. "The team is preparing to offload liquid oxygen and will begin discussing how quickly the vehicle can be turned around for the next attempt. A lot of great learning and progress today."

The SLS rocket's space shuttle-era RS-25 engines will not fire during the test. If all goes well, the rocket will be rolled back to the Vehicle Assembly Building for more work. An updated launch timeline is expected next week, though NASA will be unable to fly anytime before June.

"There is no substitute for testing with flight hardware versus models," NASA said in explaining why a wet dress rehearsal is needed.

The test originally designed to last about 45 hours began at 5 p.m. Friday and was scheduled to wrap up by Sunday, but a lightning strike within the pad 39B's perimeter and a fueling system issue forced teams to rework the timeline. Pad systems had to be inspected for damage after the lightning strike, too.

SLS is the NASA-branded rocket built for the Artemis program, which aims to put two astronauts on the lunar surface no earlier than 2025. The rocket is slated to fly an uncrewe Orion capsule on a multi-day trip to orbit the moon and return to Earth – a mission known as Artemis I. 

Artemis II plans to do the same but with astronauts in the Orion capsule; Artemis III, meanwhile, will go all the way down to the lunar surface with two yet-to-be-named astronauts.

The updates coming from NASA are limited only to text form via Twitter and the agency's website. Officials last week said national security concerns forced them to not allow media or the public to listen to mission managers conducting the test. The agency is also not offering commentary on NASA livestreams despite TV crews also rehearsing coverage of the event.

Quelle: Florida Today

----

Update: 7.04.2022

.

NASA further delays SLS moon rocket's big test to after SpaceX launch

NASA will wait until after Florida's next launch to resume a critical test of the Space Launch System rocket tasked with taking the agency back to the moon from Kennedy Space Center.

Teams last Friday kicked off what should have been a 45-hour launch countdown rehearsal, but had to delay some operations to Monday due to weather and hardware issues at pad 39B. The operation is called a "wet dress rehearsal" because it includes a detailed recreation of the real countdown and liquid propellant loading.

NASA officials said Monday's attempt to close out the remaining checklist items – loading the rocket's stages with liquid oxygen and hydrogen being chief among them – was also scrubbed due to a few technical issues. Teams are expected to work the issues while giving room for SpaceX to launch a Falcon 9 rocket and four private passengers to the International Space Station on Friday, April 8. Nearby pad 39A will host the 11:17 a.m. EDT liftoff.

A specific date for the next attempt at fueling the 322-foot rocket remains uncertain. It's tasked with launching Artemis I with an uncrewed Orion capsule around the moon, which should be followed by a crewed version called Artemis II no earlier than next year.

"We haven't run into any fundamental design flaws or design issues," Mike Sarafin, Artemis mission manager, told reporters Tuesday. "These are what I will characterize as nuisance or technical issues where we're learning features and systems."

Quelle: Florida Today

----

Update: 9.04.2022

.

Artemis I Wet Dress Rehearsal Update 

----

Update: 15.04.2022

.

Fuel leak thwarts NASA's dress rehearsal for moon rocket

NASA's latest attempt to fuel its huge moon rocket for a countdown test has been thwarted by a hazardous hydrogen leak

CAPE CANAVERAL, Fla. -- NASA's latest attempt to fuel its huge moon rocket for a countdown test was thwarted Thursday by a hazardous hydrogen leak, the latest in a series of vexing equipment trouble.

The launch team had just begun loading fuel into the core stage of the rocket when the leak cropped up. This was NASA's third shot at a dress rehearsal, a required step ahead of a test flight to the moon.

This time, the launch team managed to load some super-cold liquid hydrogen and oxygen into the core stage of the 30-story Space Launch System rocket, but fell far short of the full amount. Liquid hydrogen is extremely hazardous, with officials noting that the systems had been checked for leaks prior to the test.

Technicians deliberately left the smaller upper stage empty, after discovering a bad valve last week. The helium valve inside the upper stage cannot be replaced until the rocket is back in its hangar at Kennedy Space Center.

Two previous countdown attempts were marred by balky fans and a large hand-operated valve that workers mistakenly left closed at the pad last week.

Officials said via Twitter that they're assessing their next steps.

NASA had been targeting June for the launch debut of the 322-foot (98-meter) SLS rocket. The empty Orion capsule on top will be sent on a four- to six-week mission around the moon and back.

Astronauts will strap in for the second test flight around the moon, planned for 2024. That would be followed as early as 2025 with the first lunar landing by astronauts since 1972. NASA plans to announce the crews for these two missions this summer.

Quelle: abcNews

+++

Excitement palpable at Kennedy Space Center as NASA conducts last Artemis I moon rocket test

NASA teams at Kennedy Space Center are targeting this afternoon for the wrap-up of a series of tests and rehearsals for the agency's Space Launch System moon rocket, marking an end to their first time interacting with the massive vehicle on the launch pad.

But what might seem like a longer-than-planned test from the public's perspective continues to be a source of excitement for employees and officials, some of whom have waited more than a decade to see the 322-foot rocket at pad 39B. The test's timeline also reflects what NASA officials saw during the Apollo program and showcases differences in hardware development philosophies like those practiced by SpaceX.

"I've been seeing the excitement build with every milestone met and we especially feel it here in the firing room," Chance Belloise, a master console operator at KSC, told FLORIDA TODAY. "Things have been super busy lately. Subsystems have been working hard at their consoles, our (communications channels) are always buzzing, and it's even starting to get hard to find parking around here."

The "wet dress rehearsal," called that because it includes fueling the rocket with liquid propellants, was expected to take about 45 hours starting April 1 but had to be put on hold due to inclement weather and technical issues. Managers arrived at their consoles Tuesday afternoon and kicked off their third rehearsal countdown at 5:30 p.m. ET.

Excitement for the test and eventual launch of the rocket on Artemis I, now slated for its uncrewed flight around the moon no earlier than June, actually crystallized in March when the fully stacked rocket made its first public appearance. Thousands of officials, employees and their families, media, and others watched as the rocket exited the Vehicle Assembly Building on its slow trek to pad 39B. Some even hosted small picnics while others threw footballs to pass the time leading up to rollout.

"Standing there with family, friends, and co-workers who have been working on this years and years was a very sobering moment," Belloise, who works directly for ERC and joined the team last year, said. "It was truly a monument to all the years of work that have gone into it."

This afternoon, teams will keep a close eye on ground equipment as it pumps propellants into the first stage booster's tanks. Then, acting as if in a mock countdown, managers will command the process to stop just before the clock hits T-0.

Fueling of the rocket's second stage will not be part of the process due to a misbehaving check valve, which allows one-way flow for liquids or gases, but block backwards flow. Officials this week said that issue will need to be fixed once the WDR is complete and SLS is rolled back to the Vehicle Assembly Building. Whether or not that means another rehearsal will be necessary was not immediately clear.

The wet dress rehearsal has allowed teams to refine timelines; work together for the first time with the fully integrated rocket and ground equipment; troubleshoot hardware issues; work around inclement weather like lightning; and generally gain experience so as to not walk into the Launch Control Center on launch day without having practiced the process.

If all goes according to plan, this specific SLS rocket will fly from pad 39B without astronauts on a trip around the moon known as Artemis I. If successful, that will pave the way for Artemis II no earlier than 2023, which will be an identical mission but will carry astronauts. And if that goes well, Artemis III is expected to take two NASA astronauts to the lunar surface no earlier than late 2025.

"It will be almost like the night before Christmas," Belloise said of Artemis I's launch day. "And it honestly, it feels that way every time we come up to a major milestone like this."

Historical perspective

SLS isn't the first NASA-branded rocket to be put through its paces ahead of launch.

The first operational Saturn V moon rocket built for the Apollo program, for example, rolled out to nearby pad 39A – now leased by SpaceX for its vehicles – in August 1967, according to NASA. It was slated to go through a similar series of tests known as a Count Down Demonstration Test, or CDDT.

Just like with SLS, the Saturn V rocket was powered up and fueled at the pad. But the tests that were planned to take about six days actually needed 17 to be completed.

NASA archives credit the longer-than-anticipated testing phase as one of the key reasons behind the Apollo program's success. Rocco Petrone, director of launch operations at the time, said: "We learned a lot. The program came to fruition."

A few months later, Apollo 4 flew on a successful test flight without any crew onboard, just like SLS will do for its Artemis I mission no earlier than June.

Development philosophies

NASA's approach to rocket development stands in contrast to another organization that's gained worldwide popularity over the last two decades: SpaceX.

The company is famous for pushing the limits of its hardware, even as far as expecting explosive failures during first flights. Unlike NASA's approach, SpaceX puts fewer resources into prototypes and instead hopes to learn lessons along the way in a "fly-test-fix" approach.

NASA takes the opposite approach with SLS: the rocket must not fail, even during its two demonstration missions leading up to the lunar landing in 2025. The agency hopes to work out all the issues ahead of liftoff, which tends to front-load a lot of the work to earlier in the process.

NASA's approach also means the stakes are high for SLS' debut mission. Since everything has to go perfectly, the Artemis program could find itself in the crosshairs if a failure were to further push the already delayed timeline.

Quelle: Florida Today

----

Update: 17.04.2022

.

NASA to roll back SLS for repairs

Updated 10 p.m. Eastern after NASA decision to roll back SLS.

WASHINGTON — NASA announced late April 16 it will roll back the Space Launch System from the launch pad for various repairs, further delaying the rocket’s long-anticipated first launch.

In a statement late April 16, NASA announced it planned to roll back the SLS to the Vehicle Assembly Building (VAB) “due to upgrades required at an off-site supplier of gaseous nitrogen used for the test,” the agency said. Problems with the supply of gaseous nitrogen, used to support activities at the pad, had delayed two previous countdown rehearsals.

NASA did not state when the vehicle would go back from Launch Complex 39B, where it rolled out March 17, to the VAB. The agency said it will hold a briefing April 18 about its plans. The agency added it would use the time in the VAB to repair a faulty helium check valve in the SLS’s upper stage and a hydrogen leak detected shortly after starting to load liquid hydrogen into the rocket’s core stage during the April 14 attempt. It was the first time that controllers had reached that stage of the countdown after technical problems halted two previous attempts before liquid hydrogen could start loading.

The leak is on the ground side of an umbilical plate on the mobile launcher’s tail service mast, and not on the SLS itself. “The good news is that there’s only a few things in that purge enclosure and there’s a couple of discrete penetrations that could be the culprit,” said Charlie Blackwell-Thompson, Artemis launch director, during an April 15 briefing.

At that briefing, agency officials expressed some optimism about correcting the problem on the pad. Mike Sarafin, NASA Artemis mission manager, said those potential sources for the leak represented “low-hanging fruit” for fixing the problem and allowing another wet dress rehearsal as soon as April 21.

However, he suggested even then that rolling the SLS back the VAB was an option. “There are some more invasive options that require getting further into the hardware and potentially having to get into some extended troubleshooting,” he said, work he indicated might be best done in the VAB.

Sarafin said engineers also had to consider environmental issues of having the vehicle on the pad for an extended period, such as wind stresses on the towering vehicle. “The longer we stay at the pad, the more we stress the vehicle,” he explained. “Every time the wind blows against it, it creates a bending moment and, over time, that adds up.”

“We haven’t fully outlined all the options right now,” he said at the April 15 briefing. “The one that we’re pursuing with great vigor is the low-hanging fruit option and we’ll let the team come up with some other options.”

Blackwell-Thompson suggested one option would be to do another tanking test once the vehicle returns to the pad for the Artemis 1 launch. “You could certainly look at your schedule risk for launch countdown and make a decision whether or not you wanted to do a tanking prior to a launch countdown,” she said. In that scenario, the rocket would go through a tanking test and practice countdown and, if all went well, “some days later decide to go launch.”

Despite not getting through the countdown test in three attempts to date, and uncertainty about when the hydrogen leak will be fixed, Blackwell-Thompson said she was not particularly concerned. She noted there were five or six tanking tests before the first launch of the shuttle more than four decades ago. “Putting it into context, I would say we’re within family of our experience in the past for first-time ops,” she said.

Quelle: SN

+++