Workers are removing platforms in the Vehicle Assembly Building at the Kennedy Space Center, revealing the SLS ahead of its March 17 rollout. Credit: NASA

WASHINGTON — NASA is ready to roll out the first Space Launch System rocket this week for a countdown rehearsal ahead of a launch later this year.

Agency officials said at a March 14 briefing that they had completed reviews for the scheduled March 17 rollout of the SLS from the Vehicle Assembly Building (VAB) at the Kennedy Space Center to Launch Complex 39B several kilometers away. Rollout is scheduled to begin at approximately 5 p.m. Eastern and take 11 hours to reach the pad.

The SLS, with the Orion spacecraft mounted on it, will spend a few weeks at the pad for tests that culminate in a practice countdown called a wet dress rehearsal, where the core stage of the rocket is filled with liquid hydrogen and liquid oxygen propellants and goes through a countdown that stops just before the core stage’s four RS-25 engines would ignite.

“We are in very good shape and ready to proceed with this roll on Thursday evening,” Charlie Blackwell-Thompson, Artemis launch director at NASA, said at the briefing. Weather forecasts project acceptable conditions for the rollout.

Assuming the rollout and other tests at the pad remain on schedule, the formal countdown rehearsal will start with a “call to stations” for NASA personnel on April 1, she said. The fueling of the core stage and practice countdown will take place April 3.

The propellant loading process, which took about two and a half hours for the shuttle, will take eight hours for the SLS despite its use of shuttle-heritage hardware. “That’s for a couple of reasons. First, it’s a big ol’ stage,” Blackwell-Thompson said. A second reason is that the SLS has an upper stage that must also be fueled, requiring personnel to stagger the loading of the two stages.

The wet dress rehearsal will be the final major test before the first SLS launch on the Artemis 1 mission. NASA has not set a date for the launch but noted at a Feb. 24 briefing it was still keeping open an option for the “tail end” of a May launch window that runs from May 7 to 21. However, a launch in June or July is more likely.

After the dress rehearsal, NASA anticipates spending eight to nine days working on the vehicle for post-test operations and servicing before rolling it back to the VAB for final launch preparations. That schedule is subject to change, though, depending on what happens during the test, said Tom Whitmeyer, deputy associate administrator for exploration systems development.

NASA should then be able to set a more specific launch date for Artemis 1. “That’s the point where we’ll be in a good position as an agency to set a launch date,” he said. “We’re really getting close to being able to do that.”

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science...