Space Launch System

A hydrogen leak near the connection between NASA’s Space Launch System moon rocket and its mobile launch platform foiled another attempt Thursday to pump cryogenic propellants into the towering mega-booster at the Kennedy Space Center.

NASA tried for the third time Thursday to load cryogenic liquid hydrogen and liquid oxygen propellants into the Space Launch System moon rocket at the Kennedy Space Center, after ground system issues cut short a countdown rehearsal on two occasions earlier this month. But a hydrogen leak in the connection between the launch platform and the core stage again forced officials to call off the countdown.

NASA restarted a two-day dress-rehearsal countdown Tuesday for the agency’s new Space Launch System moon rocket after a series of unrelated glitches, mostly involving ground systems, blocked two earlier attempts to fully fuel the huge launcher to verify its readiness for flight.

A problem with a helium valve on the Space Launch System moon rocket’s upper stage will require ground teams to only partially load the giant launcher with cryogenic propellants during an upcoming countdown dress rehearsal, NASA officials said Saturday. NASA also confirmed teams now targeting Thursday for the next try to complete the test.

NASA launch controllers called off plans to load super-cold liquid hydrogen and liquid oxygen into the first fully-assembled Space Launch System moon rocket Sunday for a countdown dress rehearsal, giving time for ground teams to troubleshoot problems with fans used to ventilate the giant rocket’s mobile launch structure at the Kennedy Space Center.

This timeline covers major countdown activities planned during the NASA’s wet dress rehearsal for the Artemis 1 mission. The wet dress rehearsal will include loading of more than 700,000 gallons of cryogenic liquid hydrogen and liquid oxygen into the Space Launch System moon rocket on launch pad 39B at the Kennedy Space Center in Florida.

NASA started loading liquid oxygen into the Space Launch System’s core stage Monday, but scrubbed a countdown dress rehearsal before pumping propellants into the rocket’s remaining propellant tanks. A previous fueling attempt was scrubbed Sunday due to a ground system issue at the Kennedy Space Center. The cryogenic tanking operation is part of a full-up countdown dress rehearsal ahead of the launch of unpiloted Artemis 1 moon mission.

NASA commenced a two-day countdown dress rehearsal for the agency’s huge Space Launch System moon rocket Friday, with clocks ticking down to a critical milestone Sunday, when the heavy-lifter will be fueled and pressurized on the launch pad for the first time.