Weather Notwithstanding, NASA Sticks with Tuesday for Next Artemis Launch Attempt

Weather Notwithstanding, NASA Sticks with Tuesday for Next Artemis Launch Attempt

NASA has decided at least for now to continue plans to launch the Artemis I Space Launch System rocket on Tuesday, September 27, despite an ominous weather forecast. A tropical disturbance is expected to grow into a major hurricane over this weekend with the Florida peninsula in its sights. NASA needs three days to get the rocket ready to roll back to the safety of the Vehicle Assembly Building and make the 4-mile trip, so can wait only until tomorrow to see how the storm evolves.

At a media briefing this afternoon, NASA officials said they will press on to launch on Tuesday while keeping an eye on the weather forecast. [UPDATE, September 24: NASA decided to delay the launch.]

NASA is determined not to roll the rocket back to the VAB unless there is no other choice. It wants to avoid placing any more stress than necessary on the SLS rocket and the Orion spacecraft as they travel atop the Crawler-Transporter. SLS/Orion made the journey three times already, in March and June for Wet Dress Rehearsal tests and for launch in August.

The Artemis I Space Launch System rocket and Orion spacecraft, attached to the Mobile Launcher, atop the Crawler-Transporter, on their way to Launch Complex-39B for the first time, March 17, 2022. Photo credit: NASA

NASA was ready to launch Artemis I on August 29, but the launch was called off when a faulty sensor indicated one of the four RS-25 engines wasn’t chilled sufficiently. A second attempt on September 3 was scrubbed because of a large liquid hydrogen leak in a Quick Disconnect fitting between the Mobile Launcher and the Core Stage.

NASA conducted another set of tests on Wednesday and although there were more hydrogen leaks, including one at the same fitting that scrubbed the launch on September 3 although it had different characteristics, the agency declared the test successful.

NASA already had identified September 27 as the next launch opportunity and today’s briefing was to announce if that is still the plan.

It is.

In addition to getting through the test, two other factors were in play.

First, NASA needed a waiver from the U.S. Space Force to avoid rolling the SLS/Orion stack back to the VAB to replace a critical battery in the Flight Termination System (FTS). The battery can only be reached when the SLS is surrounded by work platforms that allow access to different levels of the 322-foot tall rocket.

The Space Force controls all launches from the Eastern Range — Kennedy Space Center and the adjacent Cape Canaveral Space Force Station — and is responsible for public safety. If the rocket veered off course, a Space Force officer would activate the FTS to destroy it.

According to NASA, the FTS battery was only certified for 20 days and a waiver was needed for 5 additional days to cover the original three launch opportunities (August 29, September 2 and September 5).

Now it needed an extension for several more weeks to cover the new launch date of September 27 and a backup on October 2.

SLS Chief Engineer John Blevins said at today’s briefing that he worked closely with the Space Force and the waiver was extended.

Asked what convinced the Space Force the battery will be OK for so many weeks beyond the 20 days and if that means future launches will not have a 20-day limit, Blevins declined to explain beyond saying “they’ve done that analysis and they have confidence in our system for this time.”

“I don’t want to go into any details because they’re just not pertinent here. You know, to give those kinds of details, you know, would be silly because there’s just too many parameters that they look at for anybody to take that information and try to correlate it to anything that makes sense to them.

“So I’ll just say that they’ve worked with us all along. This is not the first time that we’ve been working with them. We worked with them not just during the shuttle program, but on this program for years. So they’re involved in evaluating our design qualification batteries and the testing that we do. They sit on console with us and so they’re part of our team. And so they have an incredible mission and they do a good job at it. And I’m really glad that we had enough information to provide the public safety assurance that they [needed]. So that’s all I have to say about the FTS.”

The third factor is weather and that remains an issue. Just before today’s press conference, the Space Force’s 45th Weather Squadron issued its “L-4” weather forecast four days before launch. It calls for an 80 percent “Probability of Violation” (POV) of weather rules, meaning there is only a 20 percent chance the weather will be acceptable.

The National Weather Service is warning that Tropical Depression 9 in the Caribbean is strengthening and its track currently is headed towards the Florida peninsula. Floridians are urged to begin hurricane preparations this weekend.

NASA officials at today’s briefing downplayed the weather risk, at least at this moment. Tom Whitmeyer, Deputy Associate Administrator for Common Exploration Systems Development at NASA Headquarters, said it is “not even a named storm yet.”

Hurricane forecasts this many days in advance are tricky, but NASA needs three days to get the rocket ready to roll back to the VAB and complete the trip. SLS can withstand gusts up to 74 knots while it’s on the launch pad, but sustained winds must be less than 40 knots while it is moving on the Crawler-Transporter.

NASA officials said they will reevaluate the situation this afternoon after NOAA updates its forecast at 5:00 pm ET and again tomorrow. They prefer to wait until tomorrow to make a decision.  If they do decide to bring SLS/Orion back to the VAB, that would mean doing it on Saturday, Sunday and Monday as the storm is arriving.

Eric Berger, a meteorologist and space reporter for Ars Technica, tweeted that he hopes NASA is thinking about its employees and making sure they have time to prepare for the storm themselves.

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