If SLS Won't Launch NASA's Moon Mission, What Will?

NASA's big next-gen rocket won't be ready in time for the agency's upcoming moon mission, meaning NASA will have to rely on someone else.

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NASA

NASA is going back to the moon. The agency has made their goal of a return moon mission clear over the past few years, building a new rocket to carry astronauts and planning a space station in orbit around the moon for the mid 2020s. But during a Senate hearing on Wednesday, NASA administrator Jim Bridenstine : while humans might be returning to the moon, it won't be NASA that gets them there.

According to Bridenstine, NASA’s Space Launch System rocket is not developed enough to meet the agency’s timeline for future moon missions. In other words, the SLS won’t be ready fast enough. “SLS is struggling to meet its schedule,” Bridenstine said in the hearing. “We are now understanding better how difficult this project is, and it’s going to take some additional time.”

NASA’s difficulties with the SLS haven’t exactly been a secret. Initially, the SLS was meant to be completed in 2016, but the project gets a new delay every year or so that pushes back the date again and again. Currently, the first test flight is scheduled for some time in 2020, but there’s plenty of time between now and then for yet another delay.

That’s a problem for NASA, because the agency has a mission coming up that it needs the SLS for called Exploration Mission-1, and it’s a first step toward landing humans on the Moon again. The mission would send NASA’s upcoming Orion crew capsule around the moon to test the capabilities of the system.

Exploration Mission-1 is supposed to launch in 2020 aboard an SLS rocket. But if the SLS is only beginning its first test flights at the same time, there’s no way it will be ready for an Orion capsule. That leaves NASA with two choices: delay the mission, or find some other rocket to go with. According to Bridenstine, the agency is preparing to go with option number two.

“I think we as an agency need to stick to our commitment,” Bridenstine said at the hearing. “If we tell you, and others, that we’re going to launch in June of 2020 around the Moon, I think we should launch around the Moon in June of 2020. And I think it can be done.”

So if NASA is going to launch Orion in 2020 anyway, what rocket is it going to use? There are no rockets that can actually replace the SLS, which is designed to be the largest rocket in history. Of the handful of heavy-lift rockets currently in operation, none of them can come close to matching the SLS.

The only two rockets that might be up to the task are the Delta IV Heavy and SpaceX Falcon Heavy, but neither can complete the mission as currently designed. So, the experiment will have to be modified. Instead of one launch, Exploration Mission-1 will use two: one for the Orion capsule, and another for an upper stage rocket to bring the capsule to the moon.

That’s not ideal for NASA, and not just because the agency won’t get to use its own rocket. Turning one launch into two increases the complexity and makes it more likely that something will go wrong. That could pose a big problem once humans start to fly in the Orion capsules in Exploration Mission-2.

Still, with the mission date fast approaching NASA doesn’t have very many other choices. Either NASA relies on a smaller private rocket, or they push the date of the mission back. Sometime over the next year we’ll find out for sure which path NASA chooses.

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