Ein halbes Jahrhundert nach Ende der „Apollo“-Ära dient die Mission dazu, die komplexeste und leistungsstärkste Rakete der Welt unter realen Bedingungen einem strengen Stresstest zu unterziehen, bevor die SLS für den Transport von Astronauten zugelassen wird. Das Raumschiff „Orion“ fliegt dieses Mal unbemannt Richtung Erdtrabanten (siehe Grafik oben)
2025 sollen wieder Astronauten Mond betreten
Wenn alles nach Plan verläuft, stehen neue Missionen an: 2025 sollen zwei NASA-Astronauten auf dem Mond landen. „Ab 2025 bis 2030 sind dann wir Europäer mit dabei“, bestätigt Josef Aschbacher, Generaldirektor der Europäischen Weltraumorganisation (ESA).
Quelle: KronenZeitung
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Update: 31.08.2022
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Warning sign? NASA never finished a fueling test before today’s SLS launch attempt
"I am very proud of this launch team."
KENNEDY SPACE CENTER, Fla.—Despite all of the hard work by its engineers and technicians, NASA did not really get close to firing up the massive Space Launch System (SLS) rocket on Monday.
The rocket experienced several issues during the countdown early on Monday before running into a technical problem the launch team could not solve: an RS-25 rocket engine that did not properly chill down prior to ignition. Even if the engine problem had been resolved, weather along the Florida coast on Monday morning proved dicier than anticipated.
Space is hard, certainly. But Monday's attempt—which NASA had promoted heavily by inviting celebrities to the launch and which included a visit by Vice President Kamala Harris—was perhaps a bit rushed. Why? Because NASA rolled a rocket out to launch without accounting for all of the things that could go wrong.
To their credit, the launch controllers successfully worked through a host of issues on Monday prior to the scrub. For example, fueling operations started nearly two hours late due to lightning in proximity to the launch pad. This forced the team to push hard through a compressed timeline ahead of a launch window that opened at 8:33 am ET (12:33 UTC).
Once the launch team got into propellant loading, work to fill the large liquid hydrogen tank was stymied by a leak at an 8-inch inlet leading into the tank. This problem was ultimately resolved by stopping the process and then restarting propellant loading—yes, NASA resolved the problem by essentially turning off the SLS and turning it back on again.
After this, the countdown proceeded reasonably smoothly for about an hour until a problem with one of the rocket's four main engines. As part of the pre-launch process, cryogenic propellant is "bled" from the fuel tanks into the engines to chill them to about 5° Celsius prior to flight. (In responding to a question about the engine temperature, Artemis I Mission Manager Mike Sarafin actually gave the temperature as "500 Rankine.")
In troubleshooting this engine issue, launch controllers could not find a way to address what appears to have been a problem on the core stage side of the vehicle. So the launch attempt was scrubbed.
"I am very proud of this launch team," NASA Administrator Bill Nelson said during a briefing after the scrub.
And well he should be, given the hard work done late Sunday night and Monday morning during the final portions of the countdown. But should the flight controllers have been put in such a position?
Beginning in April of this year, NASA conducted four separate "wet dress rehearsal" tests during which the agency aimed to fully fuel the SLS rocket and countdown to T-10 seconds, ending the test before ignition of the main engines. Each of these four tests ultimately ended prematurely, although the fourth attempt in Junesaw engineers bring the rocket down to T-29 seconds.
However, to reach that late stage in the countdown, NASA had to "fool" the flight computer. During the test, a 4-inch hydrogen line—smaller than the problematic 8-inch line on Monday—had a leaky seal. To complete the wet dress test, NASA chose to mask the leak from the ground launch sequencer, the ground-side computer that controls the majority of the countdown.
Because of this masking, NASA could not complete the engine chill portion of the test. Had it done so, the agency may well have uncovered the problem that caused a scrub on Monday. In hindsight, therefore, NASA probably should have completed a full wet dress rehearsal before rolling the rocket out for a launch. Instead, the agency effectively attempted a fifth wet dress test on Monday, when the world was expecting a launch.
NASA's chief of human exploration systems development, Jim Free, defended the decision to attempt a launch on Monday without completing a wet dress test. "We felt, and still feel, like going for today was the right thing to do," Free said of the launch attempt.
Free said NASA is conscious of the wear-and-tear involved in rolling the SLS rocket to and from the launch pad for additional wet-dress tests and in pressurizing the tanks during fueling. Those risks must be balanced against challenges during the countdown.
Now, NASA may be rolling the rocket back to the Vehicle Assembly Building at Kennedy Space Center anyway. Agency officials said they were leaving open the possibility of a launch attempt at 12:48 pm ET on Friday, September 2. After a meeting on Tuesday afternoon to discuss possible fixes to the engine bleed issue, mission managers will announce a plan forward.
If the rocket cannot launch by September 5, it will need to go back to the hangar for additional work. Then, it's likely that the rocket would not launch before mid-October.
Quelle: arsTechnica
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Update: 20:00 MESZ
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NASA Artemis I preps for Saturday launch to the moon from Kennedy Space Center
NASA is now targeting this weekend for its next attempt at launching the Artemis I mission to the moon after a previous attempt was scrubbed due to technical issues with the rocket at Kennedy Space Center.
Officials Tuesday evening said teams are prepping for a 2:17 p.m. EDT Saturday, Sept. 3, liftoff of the Space Launch System rocket and Orion capsule from pad 39B. It will mark the opening of a two-hour window.
Multiple issues during a first launch attempt on Monday, Aug. 29, forced officials to call off the uncrewed test flight that will take Orion on a weeks-long journey to the moon and back. Weather caused delays right as fueling was set to begin, but several hardware issues also cropped up. Most were resolved, but attempts at chilling one of the four RS-25 main engines failed and officials decided to scrub for the day.
After giving teams time to rest, officials met early Tuesday to go over data from the attempt and decided to change the countdown process moving forward.
"We agreed on what's called Option 1, which is to operationally change the (propellant) loading procedure and start our engine chilldown earlier," Mike Sarafin, NASA's Artemis mission manager, told reporters Tuesday evening. "We also agreed to do some work at the pad to address a (hydrogen) leak that we saw."
"We are going to reconvene the mission management team on Thursday, Sept. 1, to review our flight rationale and overall readiness," Sarafin said.
Saturday wasn't originally one of the opportunities chosen by NASA in this late-August-to-early-September window, but teams opted to give SLS one more shot. Another backup is available at 5:12 p.m. EDT Monday, Sept. 5, but beyond that, SLS will not be able to fly without first rolling back to the Vehicle Assembly Building for hardware work and testing.
The next roughly two-week period to launch what will become the world's most powerful rocket opens Monday, Sept. 19.
Weather for Saturday's attempt, however, is questionable: the Space Force on Tuesday said conditions during the two-hour window will be roughly 40% "go."
"I'm optimistic that we'll have at least some clear air to work with during the afternoon attempt on Saturday," Mark Burger, a Space Force launch weather officer, said. "However, the probability of violation at any point during the countdown still looks rather high to me given the moist air mass and ... showers coming in off the ocean."
The probability of lightning near pad 39B was one of the factors that impacted Monday's attempt. Fueling the 322-foot rocket with liquid hydrogen and oxygen had to be delayed by about an hour as teams waited for weather to clear the area.
NASA's Artemis I engine issues
The first attempt was scrubbed primarily due to issues with engine temperatures. The four RS-25 main engines on the SLS rocket need to be chilled to minus 420 degrees during the countdown to prevent thermal shock at the time of liftoff, which could damage or destroy hardware as super-chilled propellants are rapidly pumped in.
Multiple attempts to fix the issue on engine No. 3 didn't pan out; NASA officials said it stayed about 30 to 40 degrees warmer than planned.
John Honeycutt, NASA's SLS program manager, said some progress has been made in isolating the issue and believes a faulty sensor might be giving incorrect temperature readings. Engineers observed cold liquid hydrogen flowing properly, so moving up the chilldown process to earlier in the window will give them more time to gather data about the process that might show the engine is actually chilling properly even if the sensor says otherwise.
"I think we've got enough data to put the story together, but we still need to put some pieces together," Honeycutt said. "We're questioning the fidelity of these (temperature) sensors ... we're a little bit concerned about one of those."
"We're really some goodness in the data and what the physics is telling us in that when we do establish that bleed flow ... we're seeing good, cold liquid hydrogen," he said.
If an engine sensor needs to be swapped out, that unfortunately means teams will need to roll the rocket back to the VAB. It takes nearly four days to prepare for that process. Including the time it takes to fix hardware, that likely means a multi-week delay.
The RS-25 main engine is actually leftover – but refurbished and updated – space shuttle hardware. All four engines launched previous missions before being tested and bolted to the bottom of the Boeing-built SLS core stage.
This Artemis I test flight is part of NASA's larger plan to put humans back on the moon. If the first mission goes well, Artemis II will do roughly the same with astronauts on board before III puts two people on the surface after more than 50 years. That's expected sometime after 2025.
