NASA makes third attempt to partially fuel moon rocket in practice countdown
CBSN
NASA on Tuesday restarted a two-day dress rehearsal countdown 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.
The lone rocket-related problem — trouble with a one-way helium pressurization valve in the booster's second stage — cannot be fixed at the launch pad, and engineers will be unable to pump supercold cryogenic propellants into the stage during fueling operations Thursday as originally planned.
Instead, the team will concentrate on loading the SLS core stage with 537,000 gallons of liquid hydrogen fuel and 196,000 gallons of liquid oxygen Thursday morning, testing their ability to monitor and control the flow of propellants, verifying control room commanding and validating software through two terminal countdown test runs.
