NASA’s Artemis 1 moon rocket at launch complex 39B earlier this month. Credit: NASA / Ben Smegelsky
Renouncing another countdown test, NASA plans to return the first rocket of the space launch system to its assembly hangar at the Kennedy Space Center next week to repair hydrogen leaks and continue preparations for takeoff of the mission to the moon Artemis 1.
Once the general countdown tests are complete, Kennedy’s ground crews prepare to roll the lunar rocket from the 98-meter-high space launch system to the vehicle assembly building. The return to VAB is expected to end with the Wet Dress Rehearsal, or WDR, campaign as NASA approaches the launch of the long-delayed test flight Artemis 1 around the Moon, sources said Wednesday in the late.
The launch of Artemis 1 will begin an unmanned demonstration mission of the powerful SLS lunar rocket and the Orion spacecraft before future Artemis flights take astronauts to the moon. The space launch system has been in development for more than a decade, costing more than $ 20 billion to date, making it one of NASA’s most expensive programs in its time.
NASA’s launch team encountered several technical issues that prevented the full loading of the SLS lunar rocket’s cryogenic propellant tanks into three practice countdowns in April. But a fourth general test on Monday deepened the countdown and the launch team filled the rocket with its supply of 755,000 gallons of super-cold liquid hydrogen and liquid oxygen for the first time.
But engineers discovered a hydrogen leak in a 4-inch quick-disconnect attachment on Monday, forcing the launch team to modify procedures in the final stages of the practice countdown.
NASA’s launch team originally wanted to go through the final 10-minute terminal countdown sequence, reaching the T-minus 9.3 seconds in the final run, just before the time when the engines main stage lights would light up during a real launch attempt. The engineers spent several hours assessing the hydrogen leak, and finally the administrators decided to continue the countdown with only one run during the final 10-minute sequence.
Engineers reconfigured the countdown sequencer to the ground to mask the hydrogen leak, which would normally cause the countdown clock to be cut off. With the alternative solution to tell the computer of the grounding sequencer to ignore the leak, the clock continued with T-minus 29 seconds, one second after the countdown control delivered from the ground controller to an automated sequencer aboard the SLS. moon rocket.
Rocket on-board computers ordered the T-29 to restrain seconds, when sensors showed that mid-stage engines were not ready for ignition, NASA officials said Tuesday. The leaking hydrogen connector discovered Monday is associated with a system for thermally conditioning, or cooling, the main stage RS-25 engines.
Despite leaking and counting back before reaching 9 seconds less T, NASA officials said the general rehearsal achieved most of its goals.
“I’d say we’re at the 90th percentile of where we should be in general,” Mike Sarafin, manager of NASA’s Artemis 1 mission, told a news conference with reporters Tuesday.
But Sarafin said there are still some “open items” left undone during Monday’s countdown rehearsal. One of them was the commissioning of the hydraulic power units of the SLS solid rocket propellants, which should have occurred in the last 30 seconds of the countdown to propel the reinforcing nozzles through a checking the direction of the cardan shaft with its thrust vector control mechanisms, according to John. Blevins, the chief engineer of the SLS program at the Marshall Space Flight Center.
Blevins said on Tuesday that engineers would assess the risk of proceeding with the launch without spending the last 20 seconds of the countdown test. The worst case scenario for continuing without another trial is a problem that causes an abortion in the last seconds of the countdown on release day.
“We will have a successful launch or a friction because we have protection in the system for those targets that we did not meet, in case they do not work properly on the day of the launch,” Blevins said. “So it’s not really about making the vehicle safer to fly. They’re really about to be able to reach the launch target of our window that’s optimal for our lunar mission.”
Tom Whitmeyer, NASA’s exploration systems manager, said Tuesday he was “very excited” about the outcome of the countdown test.
“We think we had a very successful rehearsal,” Whitmeyer said.
“There is a relative risk of continuing to exercise the hardware on the pad (for another test),” Whitmeyer said Tuesday. “This is not necessarily a risk-free situation.”
The powerful space launch system, powered by leftover space shuttle engines and propellers, is critical to planning NASA’s lunar mission. The rocket will send crews to the moon to the Orion capsule, which will be linked to a landing platform delivered into lunar orbit in a separate launch. The lander will transport the astronauts to the surface of the Moon and return to the Orion spacecraft to return to Earth.
The program’s first landing on the moon will take place after Artemis Flight 2, a mission that will send four astronauts on a journey beyond the far side of the moon and back to Earth. The Artemis 1 mission is a forerunner of Artemis 2.
Once the Artemis 1 rocket returns to the vehicle assembly building, the Artemis ground crew will fix the hydrogen plug problems detected on Monday. Technicians will also complete preparations for the flight completion system, which will be activated to destroy the rocket if it deviates from course after takeoff.
Final inspections and closures are also available within the VAB, and the ground crew will recharge the batteries for some of CubeSat’s secondary payloads mounted under the Orion spacecraft.
NASA has not set a target launch date for the Artemis 1 mission, but agency officials said last week that the flight could be ready for launch as early as possible in late August. NASA has Artemis 1 launch dates available in periods lasting about two weeks, when the moon is in the correct position in its orbit, and the trajectory ensures that the spacecraft’s power-generating solar panels Orion should not be shaded for more than 90 minutes at a time.
Other limitations include requirements to meet specific re-entry parameters and a splash of daylight from the Orion capsule at the end of the mission.
The next viable release period for Artemis 1 opens on August 23rd and closes on September 6th, after which there will be more launch opportunities available from September 19th.
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