NASA’s Space Launch System core stage, the heavy-lift rocket with which the space agency is planning to send humans back to the moon, has been fully assembled at the Michaud facility in Louisiana and has been placed on a Pegasus barge. The barge will ship the rocket to the Stennis Space Center for a series of tests called the Green Run.
“The roughly 1.3-mile trip from the Michoud factory to the barge’s dock is just the start of the SLS flight hardware’s journey. Pegasus will ferry the SLS core stage from Michoud to Stennis, where the core stage will be lifted and placed into the historic B-2 Test Stand for the core stage Green Run test campaign that will begin later this year. The Green Run series is a comprehensive test campaign of the stage — from its avionics and propulsion systems to its four RS-25 engines — that will verify the core stage design ready for launch.”
When the SLS has finished its series of Green Run tests, it will be transported by barge again to the Kennedy Space Center in Florida. There, the core stage will be mated with its solid rocket engine strap-on boosters and a complete Orion command and service module. Then, likely in early 2021, the rocket will lift the uncrewed Orion into orbit around the moon, spending six to 20 days in a retrograde orbit that will take it as close as 60 miles from the lunar surface and then farther away than any vehicle designed to carry humans into deep space. After that time, while Orion’s systems are checked out, the spacecraft will blast out of lunar orbit and voyage back to Earth. The Orion will splashdown in the Pacific Ocean, much like the Apollo spacecraft did when they returned from the moon five decades ago.
The first mission of the Orion/SLS spacecraft has been designated Artemis 1, being part of the Artemis return to the moon program that was named after the sister of the Greek god Apollo. Artemis 2 will be a repeat of Artemis 1, but in this case will carry a crew of four around the moon, much like Apollo 8 did before the Apollo 11 moon landing.
Artemis 3 will, NASA hopes, take the “first woman and the next man” to the lunar surface, the first time human beings have landed on the moon since the flight of Apollo 17 in December 1972. Artemis 3 will lift off from Earth and will dock with a mini space station called the Lunar Gateway in the moon’s orbit. Then two of the astronauts will transfer to a lunar lander that had been prepositioned at the gateway and ride it down to the lunar surface. They will spend a week exploring the moon while two crewmates remain on the Lunar Gateway performing remote observations of the moon. The two astronauts on the moon will lift off at the end of their mission, dock at the Lunar Gateway, and then rejoin the two who remained behind to return to the Earth on the Orion.
The Space Launch System has been controversial since its inception. The rocket was mandated by Congress soon after President Barack Obama canceled the Constellation deep space exploration program. The SLS is comprised primarily with legacy systems from the space shuttle and Saturn V. Unlike several commercial rockets, such as the Falcon 9 and Falcon Heavy, the Space Launch System is totally expendable, meaning that pieces of it are discarded once they are done, Parts of the two Falcon launch vehicles are recovered and reused.
The development of the Space Launch System has been beset with cost overruns and schedule slippages, costing billions more and taking years longer than originally envisioned, Some critics have suggested that the project be scrapped and that humans can return to the moon using commercial rockets such as the Falcon Heavy or the still in development SpaceX Starship. However, the Space Launch System has powerful supporters in Congress, particularly Sen. Richard Shelby, R-Alabama, the chair of the Senate Appropriations Committee. Alabama happens to be the home of NASA’s Marshall Spaceflight Center where the Space Launch System is managed.
Each launch of the Space Launch System has been estimated to cost $2 billion. NASA Administrator Jim Bridenstine has disputed the figure and has vowed to bring the cost down to something less unreasonable.