NASA (National Aeronautics and Space Administration) an American Civil Space Program, who is a global leader in space exploration, keeps experiencing severe delays in her proposed Artemis Moon Launch project which has been in inception since 2017.
The Artemis programme is a series of ongoing space missions run by NASA, with Launch vehicle of Space Launch System (SLS); Commercial launch vehicles, with Crew Modules of Lunar Gateway, Orion, Human landing system (HLS). The Artemis Launch involves three Artemis Missions which are currently in progress and fully run by NASA. Artemis 1 an uncrewed test flight around and beyond the Moon. Artemis 2, a crewed flight beyond the Moon which will take humans the farthest they’ve ever been in space. And Artemis 3, a mission that will land the first female astronaut and first Astronaut of colour on the Moon to spend a week performing scientific studies on the lunar surface, and it was proposed to be the US space agency’s first crewed Moon landing mission since Apollo 17 in 1972.
The Causes of the Delay
By now NASA should have sent her Artemis 1 uncrewed astronaut capsule winging around the Moon, but the big new rocket remains on its launch pad after the launch attempt scheduled for August 29 and September 3 2022 were canceled respectively.
The delay germinated through an observed leak in the fuel lines that feed liquid hydrogen to the rocket. On NASA’s first try, on 29 August, lightning near the launch pad delayed work to fill the rocket’s fuel tanks. Then two hydrogen leaks appeared. Finally, a sensor indicated that one of the SLS’s four main engines was not chilled to the temperature necessary to receive fuel before lift-off. That caused NASA to halt the launch attempt — although it later found that the sensor was probably faulty and the engine was as cold as it needed to be.
This delay is reminiscent of similar struggles with hydrogen leaks when NASA flew its space shuttles between 1981 and 2011. The agency hopes to overcome the challenge and soon send the SLS and its accompanying capsule on a test flight, known as Artemis I — a major milestone in a programme that aims eventually to return astronauts to the Moon.
On the second try, on 3 September, a large hydrogen leak appeared in one of the previous leaky locations, a ‘quick disconnect’ seal on a fuel line. This leak was much larger than the previous one, to the point that the gas, which is flammable, built up to dangerous levels.
Why does NASA keep using Hydrogen if it leaks
Jim Free NASA’s associate administrator for exploration-systems development explained that for rocket propellant, liquid hydrogen is lightweight and powerful when combined with liquid oxygen, it produces the highest specific impulse — a measure of the thrust it can generate — of any rocket fuel. So NASA has continued using it even though it can be extremely finicky and prone to leaks. John Blevins, the SLS chief engineer with NASA, at an 8 September media briefing said “Hydrogen is a challenging molecule, but it’s worth it.” He noted that the current missions that NASA is embarking on beg for constant fuel usage. And US congress essentially ordered NASA to use hydrogen for the SLS when it authorized the rocket’s development in 2010, so the agency could keep the infrastructure and jobs that were developed during the space shuttle era.
Although, other Aerospace companies such as SpaceX of Hawthorne, California have experimented with other propellants using methane for the engines that will power its planned deep-space rocket, Starship. It was observed that Methane burns more cleanly and is cheaper than the fuels SpaceX has used previously, such as kerosene. But it does not provide as much specific impulse as hydrogen.
The Next Launch
According to the Artemis Fact website, it was displayed that the next launch attempt will come up by late September or October (TBC) because NASA Engineers are currently working to fix the hydrogen leaks while the SLS is still on the launch pad at the Kennedy Space Center in Florida. But there are many constantly changing factors that dictate when and how NASA might next try to launch. For instance, the rocket contains a safety system that is designed to destroy it if it veers off course. The system’s batteries need to be refreshed regularly, according to rules set by the US Space Force, a branch of the US military that is in charge of safety at the launch pad.
Also, the logistical complexity restricted NASA to only launching the rocket on certain dates, due to Physics laws constraints of getting spacecraft off the rotating Earth around the Moon and back to Earth, while satisfying requirements such as making sure the capsule splashes down into the Pacific Ocean during daylight, at the end of its journey. And NASA doesn’t want to launch the SLS in the days around 3 October, when a commercial spacecraft is slated to take four astronauts to the International Space Station.
Readmore: Nature Journal: why Why NASA’s Artemis Moon launch is delayed — and what’s next. doi: https://doi.org/10.1038/d41586-022-02867-6