24.05.2022

NASA unveils Artemis 1 moon mission launch windows through mid-2023

                     NASA's first Space Launch System, the Artemis 1 moon rocket, stands atop Launch Pad 39B during sunrise in this photo taken March 23, 2022. (Image credit: NASA/Ben Smegelsky)                                                                        

While Artemis 1's rocket and spacecraft are back in the shop for a few more weeks, NASA has released all the launch opportunities the mission has in 2022.

The Artemis 1 moon rocket could lift off for a round-the-moon mission as soon as July 26, although the agency has plotted out dozens of launch possibilitiesbetween then and December 22, with even more launch options to the moon through June 2023.

These dates are assuming the Space Launch System passes its wet "dress rehearsal" that simulates fueling operations, and overcomes the problems that required a rollback from the launch pad to the Kennedy Space Center's Vehicle Assembly Building (VAB) on April 26.

Engineers are working to address the hydrogen leak in the umbilical lines and found a damaged O-ring seal that underwent replacement, NASA said in a blog post May 13.

Per NASA, below is the full list of opportunities under consideration on this pathfinder mission to get ready for crewed missions to the moon later in the 2020s. All dates following the July 26 to Aug. 10 window are based on preliminary analysis of the factors needed to get the launch moving to the moon and back, and are subject to change. You can also download NASA's full Artemis 1 launch window calendar as a PDF.

Here's a look at the launch windows remaining in 2022.

• July 26 – Aug. 10: 13 launch opportunities, excluding Aug. 1, 2, and 6;
• Aug. 23 – Sept. 6: 12 launch opportunities, excluding Aug. 30, 31, and Sept. 1;
• Sept. 20 – Oct. 4: 14 launch opportunities, excluding Sept. 29;
• Oct. 17 – Oct. 31:11 launch opportunities, excluding Oct. 24, 25, 26, and 28;
• Nov. 12 – Nov. 27: 12 launch opportunities, excluding Nov. 20, 21, and 26;
• Dec. 9 – Dec. 23: 11 launch opportunities, excluding Dec. 10, 14, 18, and 23;

And here are the launch windows for Artemis flights in 2023.

• Jan. 7-20: 10 launch opportunities, excluding Jan. 10, 12, 13 and 14;
• Feb. 3-17: 14 launch opportunities, excluding Feb. 10;
• March: 19 launch opportunities between March 1-17 and March 29-31, excluding March 11 and March 18-28;
• April: 14 launch opportunities between April 1-13 and April 26-30, excluding April 2, 3, 7, 9 and 14-25;
• May: 14 launch opportunities between May 1-10 and May 26-31, excluding May 8 and May 11-25;
• June:  13 launch opportunities from June 1-6, on June 20 and from June 24-30, excluding June 5, 7-19 and 21-23;

                     NASA's Artemis 1 mission, stacked at the launch pad as seen from space by the Pléiades Neo satellite, operated by the European aerospace company Airbus. (Image credit: Airbus)                                                                           

"In addition to the launch opportunities based on orbital mechanics and performance requirements, there also is an operational constraint driven by infrastructure at NASA's Kennedy Space Center in Florida," NASA noted of the launch dates when they were released on May 16.

"Because of their size, the sphere-shaped tanks used to store cryogenic propellant at the launch pad can only supply a limited number of launch attempts depending on the type of propellant," the agency added. Essentially, any week only has three maximum launch attempts available due to the core stage tanking process.

Because liquid oxygen and liquid hydrogen are loaded into the core stage and upper stage on launch day, engineers must wait 48 hours to make a second launch attempt. A third attempt must wait an additional 72 hours, "due to the need to resupply the cryogenic storage sphere with more propellant from nearby sources," NASA said.                    

NASA outlined four main constraints when it comes to planning launch dates, aside from the fueling operations.

The first is to make sure that the moon is within reach of the massive SLS rocket's upper stage, which will perform a trans-lunar injection to move the Orion spacecraft towards the moon. Orion will then fly in a distant retrograde orbit. (Retrograde means that it will orbit the moon in the opposite direction to that in which the moon spins.)

The second constraint is making sure Orion's solar panels are not out of the sun for more than 90 minutes, so that the spacecraft has enough electricity to operate and to stay at a healthy temperature range. Orbital dynamicists must take into account the positions of the Earth, moon and sun (which pull upon the spacecraft with their gravity) as well as the "state of charge" on the battery to plot this out properly.                                                                                     NASA is sending a manikin on its Artemis 1 mission to gather data about how astronauts will experience the flight around the moon. It is called "Commander Moonikin Campos" after Arturo Campos, who assisted with bringing Apollo 13 safely back to Earth in 1970. (Image credit: NASA)                                                                           The third constraint is making sure Orion can perform a "skip entry" when returning to Earth, which is only allowable with certain launch dates. Orion will use the upper part of Earth's atmosphere, along with its inherent lift, to slow down a bit while skipping deliberately out of the atmosphere temporarily. Then it will re-enter for final descent and splashdown.                                                                                                                                   

"The technique allows engineers to pinpoint Orion's splashdown location and on future missions, will help lower the [gravity] loads astronauts inside the spacecraft will experience, and maintain the spacecraft's structural loads within design limits," NASA stated.

Lastly, Orion must launch at a time to allow for daylight recovery conditions after splashdown to assist in recovery operations. This will be especially crucial when people are on board.                                                                    

The launching date of the mission will also determine how long Orion is in space. The mission will either be between 26 and 28 days long, or between 38 and 42 days.

"The mission duration is varied by performing either a half lap or 1.5 laps around the Moon in the distant retrograde orbit, before returning to Earth," NASA said.

Quelle: SC 

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Update: 31.05.2022

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Next SLS countdown rehearsal scheduled for June 19

 

WASHINGTON — NASA has tentatively scheduled the next attempt to fuel the Space Launch System and go through a practice countdown for June 19, two weeks after the vehicle returns to the launch pad.

At a May 27 briefing, NASA officials said they were wrapping up work on the rocket in the Vehicle Assembly Building at the Kennedy Space Center. The rocket returned to the VAB a month ago after three attempts to complete a wet dress rehearsal (WDR) at Launch Complex 39B in the first half of April.

Cliff Lanham, senior vehicle operations manager for NASA’s Exploration Ground Systems program, said a “call to stations” for the rollout is scheduled for the evening of June 5. The rollout will start at around midnight Eastern June 6. That is about six hours later than the first rollout in March, which he said is intended to make it less likely thunderstorms will interfere with the rollout.

That would set NASA up to make its fourth WDR attempt no earlier than June 19, depending on weather and any potential range constraints, he said.

NASA hopes this fourth attempt will be successful, filling both the core stage and the upper stage with liquid hydrogen and liquid oxygen propellants and going through a countdown that stops just before the core stage’s engines would ignite. However, Tom Whitmeyer, deputy associate administrator for common exploration systems development, said the agency will “add a little schedule this time around to make sure if we have to do more than one wet dress rehearsal attempt, we’re ready to support that.”

Whitmeyer and Lanham said they felt confident workers had fixed the problems experienced during the April WDR attempts, including replacing a helium check valve in the upper stage and tightening flange bolts on an umbilical believed to be the source of a hydrogen leak. “All the things we’ve seen so far have been very positive in terms of the actual performance of the hardware,” Whitmeyer said.

While the SLS was back in the VAB, Air Liquide, the contractor that runs the nitrogen gas distribution system at the center, completed an upgrade to increase the amount of gas available for SLS operations, an issue that cropped up during the earlier WDR attempts. That upgraded system completed a 34-hour test that exceeded the requirements for SLS, said John Blevins, NASA SLS chief engineer.

NASA also used the vehicle’s time to perform some work that was scheduled for after the WDR. That included opening up the Orion spacecraft and installing some of the payloads it will carry on the uncrewed Artemis 1 mission and removing instrumentation on the SLS used to measure the loads on it during the first rollout.

Thar work, Lanham said, “will really help us from the standpoint of the volume of work” that will need to be done after WDR to get the vehicle ready for launch. He didn’t give an estimate of how much time NASA saved by doing that work early, but noted doing it now avoided delays from “nonconformances” technicians encountered.

“It allows us to lessen the demand on our resources when we do get back in the VAB and, I feel, lessen the risk on our overall schedule for rolling back out for launch,” he said.

Agency officials have previously stated they will wait until after the WDR is complete to set a formal launch date for Artemis 1, but Whitmeyer reiterated recent statements by officials, including NASA Administrator Bill Nelson, that NASA hopes to launch the mission in August. NASA has published launch windows for the mission of July 26 through Aug. 10, excluding Aug. 1, 2 and 6, as well as Aug. 23 through Sept. 6, excluding Aug. 30, 31 and Sept. 1.

Quelle: SN

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Update: 7.06.2022

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NASA’s SLS moon rocket returning to launch pad today for more testing

NASA’s first Space Launch System moon rocket rolled out to its launch pad early Monday at the Kennedy Space Center for another attempt later this month to fully load it with super-cold propellants, the culmination of a countdown rehearsal officials aim to complete before moving forward with launch later this summer.

The towering 322-foot-tall (98-meter) rocket began the journey at 12:15 a.m. EDT (0415 GMT) Monday with first motion out of High Bay 3 inside the Vehicle Assembly Building, the iconic hangar at Kennedy originally built to stack and service Saturn 5 moon rockets during the Apollo program.

The SLS moon rocket and its mobile launch platform rode to pad 39B on a diesel-powered crawler-transporter. The 4.2-mile (6.8-kilometer) journey took about 10-and-a-half hours to complete. The lowering of the moon rocket’s platform onto support posts at the launch pad marked the official conclusion of the journey at 10:47 a.m. EDT (1447 GMT), according to a NASA spokesperson.

The full stack weighed about 21.4 million pounds for rollout.

The huge rocket is the largest ever built by NASA, and is the centerpiece of the agency’s Artemis moon program, which aims to return astronauts to the lunar surface later this decade. NASA is preparing the first SLS moon rocket for the Artemis 1 test flight, a demo mission to send an unpiloted Orion crew capsule around the moon and back to Earth on a shakedown cruise before it flies with people.

In the run-up to the Artemis 1 launch, NASA teams at Kennedy have stacked the SLS moon rocket and rolled the launcher to pad 39B for the first time March 18 in advance of a “wet dress rehearsal” to test out countdown procedures and fully load the rocket with more than 750,000 gallons of super-cold liquid hydrogen and liquid oxygen propellants.

But a series of technical snags prevented NASA’s launch team from completing the countdown rehearsal in April.

A problem with ground equipment at the launch pad delayed the test a day from April 3, then encountered issues with the supply of nitrogen gas to the launch pad. The nitrogen is used to purge compartments inside the SLS moon rocket.

A fueling attempt April 4 was cut short by concerns about the temperature of liquid oxygen flowing into the rocket’s core stage, then engineers discovered problem with a helium valve on the SLS upper stage.

The helium valve issue prevented the launch team from pumping propellants into the upper stage on the next fueling attempt. But NASA tried again April 14 to load cryogenic propellants into the core stage, but ran into more problems with the nitrogen supply. After temporarily overcoming the nitrogen issue, the launch team detected indications of a hydrogen leak near an umbilical connection at the bottom of the core stage.

NASA officials then decided to return the rocket to the VAB for repairs.

The Artemis 1 launcher rolled back to the hangar April 26, and technicians inside the high bay tightened seals on the umbilical connection in hopes of fixing the hydrogen leak. Workers also swapped out the balky helium valve on the upper stage, which failed due to rubber debris stuck in the mechanism. NASA said teams inside the VAB also worked to ensure no more debris would pose a problem for the new valve.

Meanwhile, upgrades at an off-site nitrogen gas plant near the Kennedy Space Center were completed to expand the system’s capacity for the SLS moon rocket. The nitrogen facility is operated by Air Liquide.

With the troubleshooting behind them, NASA teams have returned the Artemis 1 moon rocket to pad 39B for another countdown dress rehearsal, or WDR, later this month. If all goes according to plan, the next attempt to fully load the SLS moon rocket with propellant is scheduled for June 19.

Before then, ground teams at the space center will ready the rocket for the practice countdown. Those tasks will include loading the steering, or gimbaling, mechanism on the rocket’s two solid-fueled boosters with hydrazine fuel, which feeds hydraulic power units in the booster thrust vector control system.

The countdown test will end with a cutoff just inside T-minus 10 seconds, before ignition of the rocket’s four core stage engines.

If the launch team is able to accomplish the WDR, NASA will roll the Space Launch System back to the assembly building for final closeouts and testing. NASA will haul the rocket to pad 39B again for the real launch campaign, currently scheduled for no earlier than August.

The agency is not setting an official target launch date until successfully completing the WDR.

Quelle: SN

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Update: 17.06.2022

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Fourth SLS countdown test set for June 20

 

PASADENA, Calif. — NASA is gearing up for a fourth attempt to perform a fueling test and practice countdown of its Space Launch System ahead of a launch now no earlier than the latter half of August.

During a June 15 call with reporters, agency officials said they were ready to proceed with a wet dress rehearsal (WDR) of the SLS at Launch Complex 39B. The test will begin with a “call to stations” for personnel at 5 p.m. Eastern June 18. Loading of liquid oxygen and liquid oxygen into the rocket’s core stage and upper stage will begin at 7 a.m. Eastern June 20, with the countdown ticking down to a T-0 at 2:40 p.m. Eastern that day.

The overall approach of the WDR will be similar to three attempts to complete the test in April. That includes counting down to T-33 seconds, recycling and then counting down to about T-10 seconds, stopping just before the core stage’s engines would ignite.

The three earlier attempts never reached the terminal stage of the countdown, running into a series of technical problems. NASA rolled the SLS back to the Vehicle Assembly Building (VAB) to perform repairs that included replacing a helium check valve in the rocket’s upper stage and fixing a hydrogen leak in ground equipment.

NASA also refined procedures for loading propellants into the core stage after running into issues with both liquid oxygen (LOX) and liquid hydrogen. “We saw some things with LOX when we loaded, and hydrogen,” said Jim Free, NASA associate administrator for exploration systems development. “Our team was able to go back in, in that time we had back in the VAB, to automate those procedures, which we know will help us,”

The changes are intended to prevent pressure fluctuations seen during loading in previous attempts, said Charlie Blackwell-Thompson, Artemis launch director. “Some of it was demonstrated last time as well but we were able to automate some of it, and then we’re also able to look at some other ways in which we might be able to do that,” she said.

NASA also promised to provide more real-time information for the upcoming WDR. During the three attempts in April, the agency provided only occasional blog posts and tweets, saying it could not provide more detailed technical information because of export control concerns, even though the agency provided such information during the shuttle program.

For the upcoming test there will be commentary during the fueling and countdown, Free said, along with “fantastic” graphics, although the agency will still not release the same level of detail as during the shuttle program. “We are trying to be more transparent,” he said.

Even if the upcoming WDR goes as planned, which was not the case the first three attempts, Free said a launch in the next available window, which opens July 26 and closes Aug. 10, is unlikely. “That late July/early August launch period is very difficult for us to hit,” he said, given the work needed after the WDR to return the vehicle to the VAB, make final preparations, and return to the pad. “I think we’re probably looking at the latter part of August.” That window opens Aug. 23 and closes Sept. 6, although there are no launch opportunities on Aug. 30, 31 and Sept. 1.

That schedule also assumes there are no major issues during the upcoming test. “This is the first time that we’re flying this vehicle, and I think we need to understand everything we can before we commit to launch,” he said when asked if NASA would proceed with a launch even if it did not complete every part of the WDR. “We’re going to understand what every situation is and run it to ground before we would press to commit to launch.”

Quelle: SN

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Update: 22.06.2022

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NASA fuels moon rocket for 1st time in countdown rehearsal

NASA has fueled its huge moon rocket for the first time and completed a countdown test despite a fuel line leak

CAPE CANAVERAL, Fla. -- NASA fueled its huge moon rocket for the first time Monday and went ahead with a critical countdown test despite a fuel line leak.

This was NASA’s fourth crack at the all-important dress rehearsal, the last major milestone before the moon rocket’s long-awaited launch debut.

The previous attempts in April were thwarted by a fuel leak, as well as stuck valves and other technical issues.

Another leak — this time in an external fuel line — almost curtailed Monday's test at Kennedy Space Center. But NASA managers decided to do the countdown test anyway.

Launch director Charlie Blackwell-Thompson said they pushed ahead to see “how the team performed, how the hardware performed, and they both performed very well."

Engineers wanted to get all the way down to the 9-second mark — just short of engine firing — to validate all the systems and procedures. But it cut off at 29 seconds. NASA spokesman Derrol Nail said it wasn't immediately known why the countdown stopped.

Earlier, nearly 1 million gallons of super-cold liquid hydrogen and oxygen were loaded into the 322-foot (98-meter) rocket known as the Space Launch System, or SLS.

The testing delays have pushed the actual launch — with an empty Orion capsule flying around the moon and back — to the end of August at the earliest. This test flight is crucial before astronauts climb aboard.

Blackwell-Thompson said it was too early to say what NASA's next step might be.

The second SLS flight, planned for 2024, would send a crew around the moon and back. The third mission — no earlier than 2025 — would have astronauts actually landing on the moon.

Astronauts last walked on the moon in 1972 during NASA’s Apollo program. The new program is named Artemis, Apollo’s twin sister in Greek mythology.

Quelle: abcNews

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NASA nearly completes SLS countdown test

 

Updated 7:45 a.m. Eastern to correct the source of the leak.

WASHINGTON — NASA came within 20 seconds of completing a full countdown rehearsal of its Space Launch System rocket June 20, although it was not immediately clear if the agency got enough data from the test to be able to proceed with a launch.

After five hours of delays caused by various technical issues, the countdown for the fourth wet dress rehearsal (WDR) of the SLS at Launch Complex 39B made it to T-29 seconds, several seconds beyond the point where control was transferred from ground to flight computers, before the computer saw a “flag” and stopped the countdown at about 7:37 p.m. Eastern.

NASA originally hoped to get the countdown to a manual cutoff point of T-9.3 seconds, just before, on an actual launch, the vehicle would ignite the four RS-25 engines in its core stage. However, NASA TV commentary stated that they expected to see a flag at the 29-second point in the countdown.

That terminal count took place about five hours later than planned because of technical issues, including a liquid hydrogen leak in a “quick disconnect” fitting for a bleed line that transfers that propellant from the core stage back to the pad. Efforts to stop the leak, including warming then cooling the fitting in the hopes of resealing the connection, failed. After lengthy deliberation, NASA managers elected to proceed with the terminal countdown from a preplanned T-10 minute hold after taking steps to mask, or hide, the warnings about the leak from computers.

“We were always protected in the flight software so we knew that we had protections there,” launch director Charlie Blackwell-Thompson said on NASA TV shortly after the end of the test, when asked about the decision to proceed with the countdown despite the leak. Launch personnel were monitoring the vehicle closely. “I felt like we were in a really good configuration to continue to get into terminal count and see how the hardware performed.”

The hydrogen leak, which was not related to the leak seen in a previous WDR in April, was the most serious but not the only issue that came up during this test. NASA delayed the start of tanking of the core stage by about two hours because of a problem with a valve in a backup gaseous nitrogen line serving the pad. Later, loading of liquid oxygen into the SLS upper stage was halted for a time after hitting a pressure limit. There was also a small grass fire near a flare stack in the vicinity of the pad used to burn off excess hydrogen.

Those problems and the delays they caused led to changes in the countdown rehearsal, scrapping a plan to stop the countdown at T-33 seconds, recycling, then going again to T-9.3 seconds. However, this WDR got far closer to completion than three previous attempts in April, and marked the first time the vehicle was completely filled with liquid oxygen and liquid hydrogen propellant at the pad.

“That was a big milestone for us,” Blackwell-Thompson said of fueling the vehicle. “Definitely a good day for us and a very exciting day as well.”

It’s unclear if the day was good enough to meet all of NASA’s requirements for the WDR and allow the vehicle to go back to the Vehicle Assembly Building to prepare for a launch that could take place as soon as late August. She declined to speculate on what this test meant for launch plans, saying the launch team was focused on reviewing the data.

At a June 15 briefing, Jim Free, NASA associate administrator for exploration systems development, was asked what NASA would do in a scenario like this, where it could perform only one of the two planned terminal countdowns. “We need to understand everything we can before we commit to launch,” he said. “My first caution is to say we’re going to understand what every situation is and run it to ground before we would press to commit to launch.”

“To me, it would depend on what the scenario was,” Blackwell-Thompson said at that earlier briefing, noting the agency would evaluate the data and any “residual risk” from not completing the full WDR. “It’s hard to speculate without the specifics.”

Quelle: SN

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Update: 26.06.2022

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NASA declares SLS countdown rehearsal complete

WASHINGTON — NASA managers say they have completed testing of the Space Launch System after a recent countdown rehearsal and are ready to move into preparations for a launch as soon as late August.

In a briefing June 24, agency officials declared the test campaign for the SLS complete after a fourth wet dress rehearsal (WDR) of the vehicle at Launch Complex 39B four days earlier. That test stopped at T-29 seconds, about 20 seconds early, because of a leak in a hydrogen bleed line.

Phil Weber, senior technical integration manager for NASA’s Exploration Ground Systems program, said at the briefing that despite the early cutoff, only 13 of 128 planned “commanded functions” were not successfully completed during the terminal phase of the countdown. Most of those 13, he said, had previously been tested, such as retracting umbilicals.

Of the remainder, NASA plans to perform one additional test at the pad of hydraulic power units used to gimble the nozzles of the vehicle’s solid rocket boosters. “The component is extremely robust, but the function is extremely important, so we just want to spin that up,” said John Blevins, SLS chief engineer.

The other functions not tested involved de-energizing ground power supplies before disconnecting umbilicals, a step intended to avoid igniting any leaks of hydrogen. Weber said he was not worried about not testing that since the risk of ignition requires multiple failures. “That was really the only set we didn’t get validated,” he said.

The decision to conclude the WDR campaign has the concurrence of agency leadership, including Jim Free, NASA associate administrator for exploration systems development. Free said in a June 15 briefing that he believed NASA needed “to understand what every situation is and run it to ground before we would press to commit to launch.”

“We did go through that with Jim and he did give is the go-ahead to proceed,” said Tom Whitmeyer, deputy associate administrator for common exploration systems development.

NASA plans to roll the mobile launch platform carrying SLS back to the Vehicle Assembly Building (VAB) early July 1, weather permitting. Once back in the VAB, crews will spend several weeks preparing the vehicle to return to the pad for the Artemis 1 launch.

That work includes inspecting and repairing a quick-disconnect fitting on the core stage that was the source of the hydrogen leak in the most recent WDR. Weber said they will likely replace a Teflon seal in that connector that has been there since the Green Run tests of the vehicle at the Stennis Space Center in 2020 and 2021. “It’s got some run time on it, as well as a couple trip to the pad, so we’re expecting we’re going to go in and change out those softgoods,” he said.

He acknowledged that might not correct the problem. If the hydrogen leak persists once the vehicle returns to the pad, the connection is in area that can be accessed while at the pad, enabling repairs without having to return the VAB.

Cliff Lanham, senior vehicle operations manager for NASA’s Exploration Ground Systems program, said he expected the vehicle to spend six to eight weeks in the VAB for the quick-disconnect repairs and other final work on SLS and Orion. That assumes the work doesn’t find any additional issues that require more work while in the building.

Once SLS returns to the pad, Lanham estimated it would take about 10 to 14 days to get ready for a launch, although it may be possible to condense that schedule somewhat based on the experience with the wet dress rehearsals.

That schedule, officials said, could still allow a launch in a window that runs from Aug. 23 through Sept. 6, although with no launch opportunities on Aug. 30, 31 or Sept. 1. The next window opens Sept. 19 and runs through Oct. 4.

“We think we’re really in good shape and we’re not working any major technical issues at this time. It’s strictly vehicle processing and getting ready to do a launch attempt,” said Whitmeyer.

He said it was too soon to set a window, citing upcoming reviews and assessment of work on the vehicle in the VAB. A launch in late August “is still on the table,” though, he added.

Quelle: SN

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Update: 4.07.2022

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In a step closer to launch, NASA’s Artemis 1 moon rocket rolls back to hangar

NASA’s powerful new Space Launch System moon rocket was hauled from its launch pad back to the Vehicle Assembly Building at the Kennedy Space Center Saturday for final repairs, testing and closeouts, moving closer to liftoff later this summer after completing a fueling demonstration last month.

The 322-foot-tall (98-meter) moon rocket rolled off its posts at pad 39B at 4:12 a.m. (0812 GMT) Saturday, about five hours behind schedule to allow time for extra inspections. A diesel-powered crawler-transporter carried the Space Launch System rocket down the ramp and along the rock-covered crawlerway on the 4.2-mile (6.8-kilometer) journey back to the Vehicle Assembly Building.

The launcher rolled into High Bay 3 of the iconic assembly hangar around 2 p.m. EDT (1800 GMT), and was secured inside the VAB about a half-hour later.

The return of the SLS moon rocket to the Vehicle Assembly Building moves the Artemis 1 mission a step closer to launch on a test flight around the moon. After a decade in development costing more than $20 billion, the Artemis 1 mission will mark the first flight of the huge SLS moon rocket, sending an Orion crew capsule on a course to orbit the moon.

The test flight will not carry astronauts, but will be the first launch of a human-rated rocket and spacecraft to the moon since the Apollo program. If the Artemis 1 flight goes according to plan, NASA intends for the next SLS/Orion mission — Artemis 2 — to carry a crew of around on a loop around the far side of the moon and back to Earth in 2024, marking the first astronaut voyage to the moon since 1972.

Future Artemis missions will incorporate a commercial crew lander to ferry astronauts between the Orion spacecraft in lunar orbit and the surface of the moon.

NASA’s launch team fully loaded the moon rocket with cryogenic liquid hydrogen and liquid oxygen propellants during a practice countdown June 20, accomplishing a major test objective managers wanted to complete before proceeding with final launch preps.

A series of practice countdown runs in April were plagued by technical problems that prevented the full fueling of the rocket.

The June 20 countdown rehearsal was not free of trouble. Engineers detected a hydrogen leak in a quick-disconnect fitting near the bottom of the rocket’s core stage, in a line that dumps excess hydrogen overboard from the system to thermally condition the four RS-25 main engines for ignition.

The launch team overcame the problem and continued the countdown to T-minus 29 seconds, about 20 seconds before the time engineers wanted to reach in the dress rehearsal. One of the final test objectives not accomplished June 20 was a hot-fire of hydraulic pumps powering the steering mechanisms on the rocket’s two solid-fueled boosters, which provide 80% of the steering control for the first two minutes of launch.

NASA ground teams successfully activated the hydraulic power units during a separate test June 25, paving the way for crews to prep the rocket for rollback to the Vehicle Assembly Building.

The return to the rocket hangar was supposed to begin late Thursday, but NASA pushed back the move by a day to complete work on the slope of the crawler way leading to the launch pad. Teams completed grating, or sifting, the crawlerway using heavy equipment before going ahead with rollback Friday night.

The crawler reached a top speed of nearly 1 mph during the trip back to the VAB. The combined stack of the SLS moon rocket, its mobile launch platform, and the crawler vehicle weighs about 21.4 million pounds.

NASA’s ground team briefly stopped the crawler and the SLS moon rocket outside the VAB around midday Saturday, allowing time for the crew access arm on the mobile launcher tower to move into position next to the Orion crew capsule on top of the vehicle.

The access arm is retracted against the mobile launcher tower while it is in motion, and can’t be extended once the rocket is inside the assembly building.

With the arm extended, the crawler continued moving through the vertical door of High Bay 3. The transporter’s jacking and leveling system lowered the mobile launch platform onto pedestals inside the VAB to complete the journey from pad 39B.

The space agency has not formally set a target launch date for the first SLS moon rocket, but officials are aiming to have the launcher ready to blast off on the Artemis 1 test flight in late August or early September, when the alignment of the moon, the sun, and the Earth will enable the mission to meet all its objectives.

A launch period opens Aug. 23 and runs until Sept. 6. NASA has another launch period available beginning Sept. 19 and extending until Oct. 4, followed by three more two-week launch periods through the end of the year. Depending on when the Artemis 1 mission takes off, the Orion test flight could last roughly 26 days or as long as 42 day. The mission duration hinges on the location of the moon relative to Earth, allowing the Orion spacecraft to complete a half-orbit or one-and-a-half distant orbits around the moon.

The launch periods are constrained by a number of considerations, including the position of the moon in its orbit around Earth, limits on how long the Orion spacecraft can fly in shadow without direct sunlight on its solar arrays, and re-entry and splashdown rules, including a requirement for a daytime return to Earth to aid in recovery operations in the Pacific Ocean.

The launch windows for the Aug. 23-Sept. 6 window are posted below. Aug. 30, Aug. 31, and Sept. 1 not viable launch dates because not all of the launch window constraints are met for those days.

Once the rocket is back inside the assembly building, workers will extend 10 sets of access platforms to reach various levels of the launch vehicle, and erect an access stand to reach the leaky hydrogen line.

Aside from already-planned work to ready the rocket for launch, technicians will repair the leaky hydrogen connector discovered during the fueling demonstration last month. Workers will replace Teflon seals on quick-disconnect fittings in the tail service mast umbilical, the connection that routes cryogenic propellants between the mobile launch platform and the SLS core stage.

Officials believe one of those seals loosened in the 4-inch quick-disconnect that started leaking during the June 20 countdown rehearsal. Phil Weber, an integration manager on the Artemis ground operations team, said last week that workers will also likely change out a similar seal on a larger 8-inch propellant fill and drain line as a pre-emptive measure.

Other work inside the VAB will include changing out an avionics box on the SLS upper stage, and a software load on the upper stage computer. The ground crew will also stow final equipment inside the pressurized cabin on the Orion spacecraft, and install flight batteries on the core stage, boosters, and second stage, according to Cliff Lanham, the Artemis 1 flow director on NASA’s ground operations team at Kennedy.

“Then, ultimately, we want to do our flight termination system testing, and once that’s complete, we’ll be able to perform our final inspections on all the volumes of the vehicle and do our closeouts,” Lanham said in a June 24 press briefing.

The flight termination system consists of pyrotechnic charges on the rocket that would be fired to destroy the vehicle if it veered off course and threatened populated areas.

The ground crew inside the VAB will arm the flight termination system and perform an end-to-end test, demonstrating the ability of the Space Force’s range safety team to send a destruct command to the SLS moon rocket. The flight termination system is only certified for 20 days after completion of the test, and the rocket would need to be hauled back to the VAB to revalidate the destruct mechanisms.

According to Lanham, work on the SLS moon rocket inside the Vehicle Assembly Building will take about six to eight weeks.

Weber said the ground crew will be “hustling” to roll the rocket back to pad 39B after the flight termination system check. The rocket will need to spend 10 to 14 days on the pad before the first launch attempt, and the schedule currently shows the Artemis 1 team could fit in three launch attempts before the 20-day flight termination system certification clock expires.

NASA officials are expected to set a target launch date as soon as next week.

Quelle: SN

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Update: 21.07.2022

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NASA to Discuss Status of Artemis I Moon Mission

NASA will hold a media teleconference at 11 a.m. EDT Wednesday, July 20, to discuss next steps for the Artemis I mission with the Space Launch System (SLS) rocket and Orion spacecraft at the agency’s Kennedy Space Center in Florida.

Audio of the call will livestream on NASA’s website.

Inside the Vehicle Assembly Building at Kennedy, technicians continue to prepare SLS and Orion for Artemis I. The first in a series of increasingly complex missions, Artemis I will be an uncrewed flight test that will provide a foundation for human exploration in deep space and demonstrate our commitment and capability to extend human existence to the Moon and eventually Mars.

Teleconference participants include:

• Jim Free, associate administrator, Exploration Systems Development Mission Directorate, NASA Headquarters in Washington
• Cliff Lanham, senior vehicle operations manager, Exploration Ground Systems Program, Kennedy
• Mike Sarafin, Artemis mission manager, NASA Headquarters

To participate by telephone, media must RSVP no later than two hours prior to the start of the event to: ksc-newsroom@mail.nasa.gov.  

Through Artemis missions, NASA will land the first woman and the first person of color on the Moon, paving the way for a long-term lunar presence and serving as a steppingstone to send astronauts to Mars.

Quelle: NASA

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Update: 23.07.2022

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NASA to Host Media Activities in Houston Ahead of Lunar Mission