September 3 – The Kennedy Space Center
NASA failed to get their Space Launch System, or SLS rocket off the ground once again Saturday afternoon. This time the trouble started much earlier in the countdown however as a persistent leak kept the team from being able to pump the launch vehicle full of liquid hydrogen. An eight inch line that carries the liquid hydrogen into the rocket kept leaking at the inlet or quick disconnect that leads to the vehicle.
As hard as the tried the launch team at Kennedy Space Center was unable to get the leak resealed and keep levels of excess hydrogen at a safe level. Three separate times they tried to no avail, finally LD (Launch Director) Charlie Blackwell-Thompson called a halt to the mission, ending the day at 11:17 am E.T. still hours ahead of the launch window, but hours behind on their mission timeline.
For many who were around during the shuttle days, this felt eerily similar. Hydrogen was a constant issue which delayed and scrubbed shuttles. Hydrogen is one of the most abundant elements in our universe and one of the lightest as well. Because it is so small it can easily squeeze through the smallest of gaps. At ambient temperatures this is not such a problem but when the element is super chilled and at a high pressure it will easily slip from any available opening of any system. During the launch process propellant lines must remain attached to the launch vehicle until the moment of lift off in order to keep the booster’s tank completely topped off. In that final second when the shuttle would ignite that quick disconnect, disconnects and the lines break free as the vehicle moves skyward. Since the whole idea of this system is to quickly unfix from the vehicles they are not tightly bolted together, making sealing the components together extremely difficult.
There is also the issue of the flight termination system and its batteries. They are powered independently of the rocket and are only rated for twenty-five days from leaving the VAB (Vehicle Assembly Building). If their is hope of fixing the rocket on the pad and trying to reach the launch window of Sept. 19 through Oct. 4 they would have to extend the rating and are expected to discuss with range officials soon. If the rocket is rolled back inside the VAB, which currently looks like the most likely route NASA will take, they will have to service that flight termination system.
So if you’re now wondering why NASA still uses liquid hydrogen if they had continuous issues during the shuttle program, the answer is relatively simple. Liquid hydrogen is extremely fuel efficient, this means more bang for you buck so to speak, or better gas mileage. The real kicker though is that Congress mandated that NASA continue to use space shuttle main engine parts as part of the SLS rocket program back in 2010. When the bill was authorized for NASA to create the Space Launch System it directed them to utilize existing contracts, investments, workforce, industrial base, and capabilities from the Space Shuttle, Orion, and Ares I projects, including existing United States propulsion systems.