NASA engineers finally refueled the massive Space Launch System rocket Monday night and got through most of the final crucial test before its first flight. After reviewing their collection of data from the test, the team will decide this summer’s launch date for the world’s most powerful rocket, part of the first major mission in the Artemis lunar program.
After rolling the fully stacked mega rocket, with the Orion crew capsule on top, out to the launch pad at the Kennedy Space Center in Florida, the SLS team began running through an exercise countdown called the “wet dress rehearsal test.” While previous attempts in April were founded thanks to problems with defective valves, hydrogen leaks and lighthouse fans, the team has solved these problems and completely filled the rocket’s fuel tanks. They went through almost the entire countdown procedure and stopped at T-29 seconds at 19:37 Eastern time. That may be enough to complete the preparation of SLS and Orion for launch day.
“It was a long day for the team, but it was a very successful day, and it reached most of the goals we had not achieved in the previously wet dress,” said Charlie Blackwell-Thompson, Artemis’ launch director, at NASA’s press conference this morning.
Although the team actually achieved most of these goals, they did not quite follow the planned script. The firing controls encountered a couple of technical issues, including a new leak of liquid hydrogen – supercooled down to a cold -423 degrees Fahrenheit – in the wire that connects to the rocket’s core stage. If this was the launch day, such a leak would normally trigger the launch computer to keep the countdown. After failing to dim the power, the team decided to trick the computer into not seeing the leak warnings so they could continue counting down the exercise. They reached it further than ever before, but they did not quite reach the planned T-9.3 second mark, where, if they continued, the RS-25 engines of the core phase would fire up.
Now the team will review the data they have collected and in a few days they will make a decision on whether to go through the entire countdown test a fifth time or whether they have enough information to finally move on with the central Artemis 1 launch later in the summer.
The launch of the SLS rocket will only be part of a series of back-to-the-moon events starting this summer. As soon as this Saturday, NASA plans to launch Capstone, a tiny cubesat satellite that will travel the orbit intended for the Lunar Gateway space station, which is expected to be an intermediate station for astronauts traveling between Earth and the moon.
The next possible launch window for Artemis 1 opens between July 26 and August 10, followed by another launch window about two weeks later. The unmanned mission will fly a loop around the moon while deploying small spacecraft for secondary missions and technology demonstrations.
Four other Artemis missions are planned, with more potential on the way. After Artemis 1, the second mission will involve a manned lunar flight, and if the current schedule holds, by 2025, the long-awaited third mission will finally bring NASA astronauts back to the moon’s surface after 50 years since the Apollo program. Subsequent Artemis missions will build the Lunar Gateway.
At today’s press conference, members of the team said they feel confident about the rocket’s systems now that they have reached their most important milestones. “The team showed tremendous discipline, perseverance and perseverance,” said Mike Sarafin, Artemis’ mission leader. “Artemis 1 paves the way to the moon and establishes Orion and SLS as our crew and freight transportation system for the Artemis program, and yesterday set us on our way to Artemis 1.”