NASA’s Giant SLS Rocket Is One Step Closer To Launch

NASA engineers finally fueled the massive Space Launch System rocket Monday night, passing most of the final crucial test before its inaugural flight. After reviewing their wealth of data from the test, the team will decide the launch date this summer for the world’s most powerful rocket, part of the first major mission of the Artemis lunar program.

After rolling the fully-stacked mega-rocket, with the Orion crew pod on it, to the launch pad at the Kennedy Space Center in Florida, the SLS team began a practice countdown called the wet dress rehearsal test. While previous efforts failed in April due to issues with faulty valves, hydrogen leaks and launch tower fans, the team addressed these issues and fully loaded the rocket’s fuel tanks. They went through almost the entire countdown, stopping at T-29 seconds at 7:37 PM Eastern Time. That may be enough to get the SLS and Orion ready for launch day.

“It was a long day for the team, but it was a very successful day, and it achieved a majority of the goals we hadn’t achieved in the previous wet dress,” Artemis launch director Charlie Blackwell-Thompson said on NASA’s press conference this morning.

While the team did indeed meet most of those goals, they didn’t quite follow the planned script. The launch controllers encountered a few technical issues, including a new leak of liquid hydrogen — supercooled to an icy -423 degrees Fahrenheit — into the line connecting to the missile’s core stage. If this were launch day, such a leak would normally prompt the boot computer to hold the countdown. After failing to stop the power, the team decided to trick the computer into not seeing the leak warnings so they could continue the workout countdown. They got further than ever before, but they didn’t quite make it to the planned T-9.3 seconds where, if they had gone ahead, the core stage RS-25 engines would start.

Now the team will review the data they’ve collected and decide in a few days whether they need to go through the entire countdown test a fifth time or if they have enough information to finally get through with the pivotal Artemis 1 launch later this summer.

The launch of the SLS rocket will be just one part of a series of back-to-the-moon events that kick off this summer. NASA plans to launch Capstone this Saturday, a small cube satellite that will navigate the orbital path intended for the Lunar Gateway space station, which is expected to be a staging post for astronauts traveling between the Earth and the Moon.

The next viable launch window for Artemis 1 opens between July 26 and August 10, followed by another launch window about two weeks later. That unmanned mission will loop around the moon while small spacecraft will be deployed for secondary missions and technology demonstrations.

Four more Artemis missions are planned, with more potential ones in the works. After Artemis 1, the second mission will include a manned lunar flight, and if the current schedule holds in 2025, the highly anticipated third mission after 50 years since the Apollo program will finally bring NASA astronauts back to the lunar surface. Subsequent Artemis missions will build the Lunar Gateway.

At today’s press conference, members of the team said they are confident in the missile’s systems as they have reached their key milestones. “The team showed tremendous discipline, perseverance and fortitude,” said Mike Sarafin, Artemis’ mission manager. “Artemis 1 is paving the way forward to the Moon and firmly establishing Orion and SLS as our crew and cargo transportation system for the Artemis program, and set us on the road to Artemis 1 yesterday.”