NASA targets Tuesday to fly Artemis 1, despite weather outlook
While keeping a weather eye on the horizon, NASA has opted to proceed with a launch attempt for Artemis 1 on Sept. 27 following the completion of a tanking test two days ago.
NASA performed a tanking test on the massive Space Launch System rocket on Sept. 21 to verify the seals that were replaced on the quick disconnect umbilical between the liquid hydrogen fuel feed line and the rocket. According to the agency, all objectives were met for the cryogenic demonstration test, despite suffering additional hydrogen leaks. A hydrogen leak was the reason for the scrub of the Sept. 3 launch attempt.
During the tanking test, the liquid hydrogen and liquid oxygen tanks in both the SLS core stage and Interim Cryogenic Propulsion Stage were filled. However, as soon as liquid hydrogen entered a “fast fill” mode, a leak once again cropped up. It was about the same magnitude at the same location and time as the one that caused the previous scrub — about 7% concentration at the liquid hydrogen quick disconnect.
NASA’s launch safety limit for hydrogen is 4% concentration.
Engineers worked to solve the problem, which involved warming up the fuel line before very slowly cooling it back down in an attempt to re-seat the seal. It mostly worked. The leak was brought back down to 0.5%.
These were part of the “kinder and gentler” loading procedures that the launch team had developed over the previous weeks. Teams also conducted a kick-start bleed test on the RS-25 engines and a pre-pressurization test on the core stage.
“The new cryogenic loading procedures and ground automation were designed to transition temperature and pressures slowly during tanking to reduce the likelihood of leaks that could be caused by rapid changes in temperature or pressure,” a NASA update reads on Sept. 21. “After encountering the leak early in the operation, teams further reduced loading pressures to troubleshoot the issue and proceed with the demonstration test. The pre-pressurization test enabled engineers to calibrate the settings used for conditioning the engines during the terminal count and validate timelines before launch day to reduce schedule risk during the countdown on launch day. “
During a Sept. 23 teleconference, NASA announced an extension for the flight termination system battery certification, which expired after 25 days on Sept. 6. Now the Space Force’s Eastern Range has granted a waiver to allow the rocket to launch as late as Oct. 2 before needing to be returned to the Vehicle Assembly building to recertify the batteries.
The flight termination system is only used in the event the rocket veers off course during a launch anomaly.
NASA is now targeting a 70-minute window that opens at 11:37 a.m. EDT (15:37 UTC) Sept. 27 to launch the Artemis 1 SLS mission from Launch Complex 39B at Kennedy Space Center in Florida. However, the 45th Weather Squadron’s launch forecast for the 27th calls for an 80% probability of weather violating constraints.
There is a backup opportunity penciled in Oct. 2. The window for that day is 109 minutes long and opens at 2:52 p.m. EDT (18:52 UTC).
A launch on Sept. 27 would see Orion return on Nov. 5, while launching on Oct. 2 would see the capsule return Nov. 11.
Artemis 1 tropical weather watch
Looming on the horizon, however, is the potential for tropical weather to interfere with NASA’s attempts to get Artemis 1 off the ground.
In the Southeastern Caribbean Sea, just north of Venezuela, is Tropical Depression Nine, which has a very good chance of intensifying into a tropical storm, and eventually a hurricane, which would likely be named Ian.
“Early next week the system is forecast to move near or over western Cuba as a strengthening hurricane and then approach the Florida peninsula at or near major hurricane strength, with the potential for significant impacts from storm surge, hurricane-force winds, and heavy rainfall,” the National Hurricane Center’s Advisory No. 2 reads. “While it is too soon to determine the exact magnitude and location of these impacts, the residents in Cuba, the Florida Keys, and the Florida peninsula should ensure they have their hurricane plane in place and closely monitor forecast updates through the weekend.”
According to NASA, the SLS rocket can safely remain at the pad as long as wind gusts are under 74 knots (85 miles per hour). The agency said it will meet again tonight and make a decision tomorrow morning or afternoon on whether to roll back or stay the course. The limit for rollback is 40 knots (46 miles per hour) of sustained winds while the crawler-transporter is in motion.
In the event that the tropical system starts to move toward the Space Coast, NASA said it would need to make a decision to roll the SLS rocket back to the Vehicle Assembly Building about two to three days before the winds would become a problem.
If NASA opts to return the rocket to the VAB, it would have to wait until at least the Oct. 17-31 window to launch the Artemis 1 mission to the Moon.
Videos courtesy of Orbital Velocity
Derek Richardson has a degree in mass media, with an emphasis in contemporary journalism, from Washburn University in Topeka, Kansas. While at Washburn, he was the managing editor of the student run newspaper, the Washburn Review. He also has a website about human spaceflight called Orbital Velocity.