NASA’s Space Launch System moon rocket moves into the Vehicle Assembly Building on Sept. 27. Credit: Stephen Clark / Spaceflight Now
NASA moved the Space Launch System moon rocket back into its hangar Tuesday to take shelter from Hurricane Ian, likely pushing back the next launch attempt for the agency’s long-delayed Artemis 1 lunar test flight until mid-November as Kennedy Space Center braces for high winds and flooding rains.
The 322-foot-tall (98-meter) moon rocket arrived in the Vehicle Assembly Building Tuesday morning, and NASA confirmed the rocket’s mobile launch platform was “hard down” on pedestals inside High Bay 3 at 10:05 a.m. EDT (1405 GMT). The arrival in the VAB wrapped up a nearly 11-hour rollback from Launch Complex 39B that began at 11:20 p.m. EDT (0320 GMT).
NASA officials decided Monday to proceed with the rollback to protect the $4.1 billion Space Launch System moon rocket, which is set to take off with an unpiloted Orion crew capsule on a flight around the moon. The Artemis 1 test flight is designed to verify the performance of the powerful rocket and crew capsule before astronauts strap in for future flights to the moon.
“We waited, I’d say, about as long as we could, but still had a window to the keep the vehicle safe and get back to the VAB,” said Jim Free, associate administrator for NASA’s exploration systems mission development, which oversees the SLS moon rocket and Orion programs.
The Space Launch System is not protected by a gantry when it’s on the launch pad, but NASA engineers have certified the rocket to withstand wind gusts up to 74 knots (85 mph). Managers waited through the weekend to monitor the changing forecast for Hurricane Ian, then decided Monday morning to move the rocket back to the hangar.
A small fire was reported on an electrical panel on the wall of High Bay 3 inside the Vehicle Assembly Building soon after the SLS moon rocket arrived back at the hangar. Janet Petro, director of Kennedy Space Center, said the VAB was evacuated and the fire was put out with no injuries to any personnel. She said the Artemis 1 moon rocket was not at risk from the fire, and workers returned to the VAB to resume their work.
Elsewhere at Kennedy Space Center and neighboring Cape Canaveral Space Force Station, teams are securing facilities and preparing power generators before Hurricane Ian’s impacts reach the spaceport. Regular work will be suspended at the space center, and a rideout team will remain on base during the storm to monitor infrastructure and assess damage.
“Safety of the workforce and property is the No. 1 priority, and this is reflected in all of our planning,” Petro said. “We have a hurricane plan that applies to all NASA and contractor organizations, as well as our launch partners and our NASA facilities located on the space force station.”
One of the most visible signs of preparing for the hurricane was the rollback of the SLS moon rocket. A diesel-powered crawler transporter carried the SLS moon rocket off the pad for the 4.2-mile (6.8-kilometer) journey back to the VAB on Tuesday. Reaching a top speed of 0.8 mph (1.3 kilometers per hour), the combined stack of the crawler, mobile launch platform, and moon rocket weighed more than 21 million pounds as it trekked back to the assembly building.
It was the sixth time the SLS moon rocket has moved between the VAB and the launch pad since March, and engineers prefer to minimize the moves to limit wear and tear on the rocket from the vibrations of riding on top of the crawler. But in the end, NASA decided it was more risky to leave the rocket on the pad with tropical storm or hurricane force winds possible at Kennedy Space Center this week.
NASA hoped to try to launch the Artemis 1 test flight this week, with a launch attempt penciled in for Tuesday. But that changed late last week as officials began preparations for rollback to the assembly building. The current Artemis 1 launch period closes Oct. 4, and another two-week launch period opens Oct. 17 and runs through Oct. 31.
Free said Tuesday it will be “difficult” to have the Artemis 1 moon rocket ready to fly by the end of the next launch period at the end of October. The next series of launch dates begin Nov. 12 and extend through Nov. 27.
The launch periods are primarily driven by the position of the moon in its orbit around Earth, along with concerns about shadowing of the Orion spacecraft’s solar panels, and a requirement for the mission trajectory to result in a daytime splashdown of the Orion spacecraft in the Pacific Ocean.
Engineers plan several tasks with the rocket back in the VAB, including swapping out batteries on the flight termination system, which range safety teams would use to destroy the launch vehicle if it flies off course after liftoff and threatens populated areas. The battery changeout work will require technicians to open an access door and enter the “intertank” section of the SLS core stage, the volume between the core stage’s liquid hydrogen and liquid oxygen tanks.
“Changing out the batteries, I won’t say it’s simple, but the team knows how to do it,” Free said.
The U.S. Space Force’s Eastern Range, which is responsible for public safety for all launches from Florida’s Space Coast, granted NASA a waiver last week to extend their certification of the flight termination system batteries long enough to enable Artemis 1 launch attempts through early October. The batteries were originally only certified for 25 days, long enough to allow Artemis 1 launch attempts through early September.
Changing out and re-testing the batteries is only possible with the rocket back inside the VAB.
NASA engineers will also spend the next few weeks assessing parts of the Space Launch System moon rocket and Orion spacecraft that could have lifetime limitations. NASA began stacking the rocket’s solid-fueled boosters on the mobile launch platform in November 2020, and capped off stacking of the rocket with the addition of the Orion spacecraft last October.
Engineers are analyzing the condition of pre-packed propellants inside the Space Launch System’s solid rocket boosters, which originally were only certified for 12 months once stacked on the launch platform. That lifetime limit has been extended by engineering reviews, and John Blevins, the SLS program’s chief engineer, recently said the boosters should be good for at least a few more months.
There is also a limit for how long hypergolic hydrazine and nitrogen tetroxide propellants can be loaded on the service module of the Orion spacecraft. The hypergolic propellants will be used for in-space maneuvers by the Orion propulsion system during the trip to the moon and back.
“We have a list of, I’d say, about 20 things that we’re looking at that have different durations in which we have to revisit them,” Free said. “We’re always looking at batteries in general. Obviously, we’re looking at some of the hypergol (propellant) storage on the service module. We want to make sure that we’re staying on top of and understanding the long term implications of that.”
Engineers are evaluating the conditions different components have been exposed to since stacking began on the Artemis 1 moon rocket, Free said.
“The limited life items are set by how often the engineering team decided they need to be revisited,” Free said. “So it could be every 30 days, 60 days, 365 days, so it’s kind of a running clock of things. Some of them are analytical, some of them are actual hardware measurements.”
The engineering reviews of “limited life” items, the flight termination system battery changeout, and any impacts from Hurricane Ian will drive the Artemis 1 schedule as NASA looks to set a new target launch date. Ground teams at Kennedy will also likely recharge batteries on some of the CubeSat ridehsare payloads on the SLS moon rocket, which will perform their own scientific missions in deep space, including observations of the moon, space weather, and an asteroid.
“If we’re looking at early next week for the team to come back (after Hurricane Ian), we’re talking Oct. 3, and our launch period opens back up on the 17th,” Free said. “It’s just a challenge of can we get in there, get the volumes open, and say we can turn and get back out there for another launch attempt. We don’t want to go out too fast, and then we’re stuck in a situation where maybe we didn’t get to all of the limited life items we wanted to look at because we’re trying to get back out there.”
With winter approaching in the northern hemisphere, most of of the Artemis 1 launch windows in the next few months will be at night. The first days of the November launch period all come with middle of the night launch times.
“I think our preference is to launch in the daylight,” Free said. “I think we feel like the visuals that we get from our long range tracking cameras are of benefit to us. We do have obviously some ways we can view the vehicle if we were to launch in the dark. I think we look at the risk versus benefit trade. So our preference is probably a daylight launch but we don’t rule out the nighttime launch either.”
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