NASA got a late start on fueling the rocket overnight when a thunderstorm came within five miles of the launchpad around midnight Eastern time. Once the storm passed, crews began fueling the rocket: First, the liquid oxygen, which was going well, and then the liquid hydrogen. That’s when sensors at the base of the rocket detected a leak. NASA stopped the fueling, then started and stopped again in a fitful effort to keep the launch on track.
The supercooled liquid hydrogen is extremely light and kept at minus-423 degrees Fahrenheit, which makes it a difficult propellant to control. It’s so cold that when the 130-foot-tall hydrogen tank in the main booster stage is fully fueled with 538,000 gallons of liquid hydrogen, it shrinks six inches, according to NASA.
A little before 5 a.m. Eastern time, NASA started filling the upper-stage tanks and, shortly thereafter, the main-stage tanks had been fully fueled without additional leaks.
“The team did fantastic job working through that problem and get us past it,” Jeremy Graeber, the Artemis I assistant launch director, said during NASA’s live broadcast.
In the meantime, NASA has been pressing ahead. The problems are likely to force NASA to move the launch time to later in the two-hour window. But the agency has not set a new launch time.
“We have a lot of work to get to that point,” Graeber said.
Later, NASA commentator Derrol Nail said NASA was investigating a crack on a part of the rocket that connects the liquid hydrogen and liquid oxygen tanks, and serves as a connection point for the rocket’s solid rocket boosters.
“The intertank is built differently from the rest of the core stage,” according to NASA’s website. “It is bolted together, not welded, with ribs on the outside for strength.”
Engineers are also working a problem with one of the booster’s engines that is not at the correct temperature that would allow it to launch.
