HISTORY WRITTEN FOR CAS NEWS & USED WITH PERMISSION
NASA officials have cleared the agency’s Artemis lunar rocket for the start of another countdown early Monday, but engineers must resolve questions about hurricane-damaged insulation before the massive propellant may be cleared to take off on an unpiloted moonshot.
After multiple delays due to hydrogen leaks and other issues, as well as the rocket’s biting brush with Hurricane Nicole last week, NASA officials met on Sunday to review preparations. kickoff and agreed to kick off a 47 hour and 10 minute countdown at 1:54. am Monday EST. The launch is scheduled for 1:04 a.m. Wednesday.
But Nicole’s high winds caused a thin strip of putty-like material known as RTV to delaminate and drift away from the base of the Orion crew capsule’s protective nose cone at the top. of the rocket.
The material is used to fill a slight indentation where the fairing attaches to the capsule, minimizing aerodynamic heating during ascent. The fairing fits over the Orion capsule and is jettisoned once the rocket is out of the dense lower atmosphere.
“It was an area about 10 feet long (windward side) where the storm blew through,” mission chief Mike Sarafin said. “It’s a very, very thin layer of RTV, it’s about two inches or less…thick.”
Engineers do not have access for repairs to the pad and must develop a “flight justification”, i.e. a justification to fly despite the delaminated RTV, in order to proceed with the launch. Officials want to ensure that any additional material that flies away in flight will not impact and damage downstream components.
The question recalls a debate following a foam debris incident in October 2002 that damaged an electronic assembly at the base of a shuttle booster. In this case, NASA elected to continue flying while engineers developed a fix. Two flights later, another foam impact fatally damaged the Columbia shuttle’s left wing.
Sarafin said the SLS rocket, performing an unmanned test flight, “is a fundamentally different vehicle design.”
“The vehicle in this case is bigger, and we have to take that into account,” he said. “But in terms of hitting the critical components… the physics are the same, the analysis is very similar, but where the critical components are (is) just fundamentally different.”
Either way, NASA’s mission management team plans to meet again on Monday to review the rationale for the flight and determine if the countdown can continue to launch.
If all goes well, the launch team will begin pumping 750,000 gallons of super-cold liquid oxygen and hydrogen into the massive rocket’s tanks from just before 4 p.m. Tuesday, using techniques revised “softer and smoother” to control temperatures and minimize sudden pressure surges. prevent leaks in critical joints.
If any issues arise, engineers will have two hours to resolve them before the launch window closes.
But the weather is 90% “ok” and if refueling procedures work as planned, the 322-foot-tall Space Launch System rocket’s four main shuttle engines and extended-strap solid-fuel boosters should finally roar. at 1:04 a.m. Wednesday morning, ushering in a new era in American spaceflight.
Briefly turning night into day as it climbs atop 8.8 million pounds of thrust, the 5.7 million pound SLS will accelerate rapidly as it consumes propellant and loses weight, going through the speed of sound in less than a minute.
The two strap thrusters, which provide the lion’s share of the rocket’s initial thrust, will burn out and drop about two minutes and 10 seconds after liftoff. The four hydrogen engines powering the core stage will shut down six minutes later, placing the Orion capsule and the SLS second stage into an initial elliptical orbit.
After raising the low point of orbit, the single engine powering the Interim Cryogenic Propulsion Stage, or ICPS, will fire again about 90 minutes after launch to break out of Earth orbit and head for the moon. The Orion capsule and its service module will separate a few minutes later to continue the rest of the journey alone.
The goal of the Artemis 1 mission is to send the Orion spacecraft on a looping trajectory past the moon in a critical test of the vehicle’s propulsion, navigation and solar power systems before returning to Earth for a 5,000 degree reentry and splashdown in the Pacific Ocean west of San Diego.
If the Artemis 1 flight goes well, NASA plans to launch four astronauts atop a second SLS for a lunar shakedown mission – Artemis 2 – in late 2024, followed by an astronaut landing mission in the period. 2025-26.
But that’s assuming the Artemis Flight 1 goes well. As Jim Free, director of exploration systems at NASA Headquarters, said on Friday, “we’ll never get to Artemis 2 if Artemis 1 doesn’t make it.”