NASA delays SLS rocket rollout, says launch date is TBD

NASA officials on Wednesday said the agency would conduct an initial rollout of the massive Space Launch System rocket sometime in March, a multi-week delay attributed to “close-out” tasks that must be completed on the vehicle.

Until this week, NASA had been publicly targeting a February 15 rollout date, when a mobile tower would ferry the SLS rocket from the Vehicle Assembly Building to its launch site at Kennedy Space Center in Florida. Tom Whitmeyer, deputy associate administrator for exploration systems development at NASA Headquarters, said the agency is now targeting “mid-March” for the rollout, but he did not want to set a specific date.

Whitmeyer and other officials on a teleconference with reporters said they wanted to let the teams of NASA employees and contractors in Florida complete their work meticulously rather than being rushed.

“We’re going to process it correctly, and we’re going to get it launched, and we really take a lot of pride in our ability to process the flight hardware and to meet our commitments,” said Michael Bolger, who manages ground systems to support the rocket at Kennedy Space Center. “We’re finding that right balance of continuing to push to get this launched as soon as we’re ready, but not before.”

As recently as October, NASA officials were aiming to roll the SLS rocket to the launch pad at the end of December in preparation for a “wet dress rehearsal” test of the vehicle and its ground systems. At the time, they set an initial launch date for mid-February.

Now, the agency is refraining from setting a launch date at all. The NASA officials said they want to wait until the wet dress test is completed before feeling confident about any publicly announced launch date.

“We’d like to hold off and talk about that after we get to the wet dress,” Whitmeyer said. “We really want to see the result of that test before we can predict with any amount of confidence.”

That’s understandable, as the wet dress rehearsal is a cumbersome process designed to identify any flaws in the rocket or its ground systems prior to launch. During this test, the vehicle will be fully fueled with liquid hydrogen and liquid oxygen, and a countdown will be performed to about T-10 seconds. The interfaces between the rocket, spacecraft, and ground systems—along with all of the software to manage them—haven’t been tested in this manner before, and historically, this is where issues have arisen with new vehicles.

Although NASA declined to announce a launch date for the rocket, we can make some educated guesses. If NASA succeeds in rolling out the rocket to the launch pad in mid-March, the agency expects the wet dress procedure to take about two weeks, give or take a few days. That gets us to the end of March.

NASA has a launch window from April 8 to April 23. To make it, NASA would have to stick to the mid-March rollout, execute the wet dress test in a timely manner, and identify exactly zero significant issues that need to be fixed prior to launch. Should all of that happen, it’s conceivable that NASA could bring the rocket back to the Vehicle Assembly Building, outfit the SLS with its final pyrotechnics, and roll it back to the launch pad for a late April launch.

It’s also possible that unicorns could dance in a Florida flame duct sometime this spring.

In reality, NASA has held to virtually no published schedule since the SLS program began 11 years ago, with an initial launch target of 2016. So there is no reason to expect that situation to change. Assuming a relatively smooth wet dress procedure, therefore, NASA would feel pretty good about targeting a launch window from May 7 to May 21. But if there are issues that need to be addressed after the wet dress test on the launch pad, which seems likely, a summer launch of the Space Launch System is probably in the cards.

https://arstechnica.com/?p=1831265