NASA may fly humans on the less powerful version of its deep-space rocket

NASA can make some major changes to the first flights of its future deep space rocket, the Space Launch System, after receiving a recent push from Congress to build a new launch pad. When humans fly over the rocket for the first time in the 2020s, they can use a less powerful version of the vehicle than NASA expected. If the changes go forward, it could reduce the first manned mission to deep space in more than 45 years.

The SLS has been in development for the last decade, and when it is complete, it will be the main NASA rocket to carry astronauts. to the Moon and to Mars NASA has long planned the debut of the SLS with two crucial test missions. The first flight, called EM-1, will unscrew and send the smallest planned version of the rocket on a three-week trip around the Moon. Three years later, NASA plans to launch a larger and more powerful version of the rocket around the Moon with a team of two people, a mission called EM-2.

But now, NASA can delay the update of the rocket and fly the same small version of the SLS for the flight with crew instead. If that happens, NASA would have to devise a different type of mission for the crew, since they will not use the most powerful version of the vehicle. "If EM-2 flies that way, we would have to change the profile of the mission because we can not do what we could do if we had [larger SLS]," said Robert Lightfoot, the acting administrator of NASA, during a hearing on Yesterday's Congress.

NASA clarified that astronauts would still fly around the Moon on the second flight. However, the rocket could not carry additional scientific cargoes like NASA had originally planned. "The main objective of EM-2 is to demonstrate critical functions with the crew on board, including mission planning, system performance, crew interfaces and navigation and orientation in deep space, which can be achieved in a SLS of Block 1, "said a NASA spokesman in a statement to The Verge .

The modification of these first flights is only possible now thanks to an unexpected influx of cash obtained by NASA in the recent spending law of 2018. The space agency received an additional $ 350 million to build a second launching platform for the SLS. And it gives NASA more flexibility in conducting the first rocket missions.

The SLS is designed to take off from a portable launch pad, known as a mobile launch pad, at NASA's Kennedy Space Center in Florida. To prepare for the first rocket flight, NASA has been updating an old platform it originally built for the canceled Constellation program, an initiative by President Bush to send humans to the Moon. However, the updates took a while and cost more than $ 400 million, according to the Planetary Society. First, it is more money than was needed to build the platform.

A graph of the evolution of SLS
Image: NASA

But NASA had a problem: the agency realized that, once all the updates were complete, the structure could only support releases of the version smaller of the rocket, what is called Block 1. The larger version of the SLS that is supposed to carry crew – called Block 1B – is much higher and heavier; the platform could not support the new height and weight of the vehicle. That meant that the platform would have to go through another round of updates once the first SLS unmanned flight was completed.

NASA faced a programming disaster. The space agency predicted that the update of the mobile launch platform would again take at least 33 months, or almost three years. And during that time, the SLS could not fly. The platform would be out of service, so the rocket would be too. In addition, any delay in updating the platform would further delay the first manned flight in deep space. Finally, NASA did not officially request funds for the additional platform, citing costs.

So Congress decided to intervene. It gave NASA the money to build a second mobile launch platform from scratch, one that would admit the largest version of block 1B of the rocket. If the space agency starts building the platform now, it could be ready before the planned launch date for 2023 for the crew flight. And NASA would not have to wait for updates to be released for the second time.

Now that NASA has this cash, the agency is becoming creative. It will have two platforms: one for the smaller SLS and one for the larger version of the rocket. That means NASA can continue to launch the smaller Block 1 vehicle until the larger SLB Block 1B is ready. And NASA is taking advantage of that option, because it may take a while until Block 1B can fly. That version of the SLS requires a large and critical piece of hardware known as the Exploration Upper Stage, which sits on top of the rocket. It's what will give the SLS its extra boost of power, but it's a piece of complicated machinery NASA had never built before. And NASA has already encountered many delays in programming with the preparation of the SLS, a consequence of creating a new vehicle from scratch.

The current mobile launch platform at the Kennedy Space Center
Image: NASA

Then, the smaller version of SLS could shorten the time between the first two missions, something Lightfoot admitted at the hearing. "Now that we know we're going to build the second mobile launcher, I can keep this mobile launcher in place, buy another [Block 1] and keep flying," he said. But that means that a manned mission in Block 1 will not carry any additional cargo, only crew. Lightfoot says the mission will still be enough to certify the SLS for human missions. "That still puts humans in orbit and that still allows us to verify all the systems that we would not review in EM-1," he said at the hearing.

Meanwhile, it is also possible that the second flight of the SLS will not carry crew at all. NASA must also launch its next mission to Jupiter's moon, Europa, very soon. Known as Europa Clipper, the mission is required by Congress to fly in the SLS in 2022. Lightfoot mentioned that Europe Clipper could be presented before the first manned flight of the SLS. It only depends on whether the Orion crew capsule, which will transport astronauts in the SLS, will be ready before Europe Clipper is ready. If the Europa spacecraft comes first, it could also fly in the small rocket of block 1.

In general, Lightfoot stressed in Congress that NASA now has many different options: "It allows us to have the ability to fly SLS when we are ready with any payload that is ready to go. "

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