THE NEW SPACE RACE: Moon mission fueling test concludes with no major problems.

NASA and contractor engineers pumped more than 750,000 gallons of supercold propellants into the agency’s huge Space Launch System rocket Thursday without any signs of hydrogen leaks or any other significant problems in a major step toward launching four astronauts on a flight around the moon as early as March 6.

The practice countdown began Tuesday night, kicking off a carefully choreographed series of steps to ready the world’s most powerful operational rocket for what amounted to a simulated launch Thursday at 8:42 p.m. EST. Controllers then carried out additional tests to make sure the team can recycle, hold and restart an actual launch countdown as needed to handle unexpected problems.

The initial stages of the rehearsal countdown went well and at 9:35 a.m. Thursday, Launch Director Charlie Blackwell-Thompson gave her “go” to begin the multi-hour process of pumping 196,000 gallons of liquid oxygen and 537,000 gallons of liquid hydrogen fuel into the SLS rocket’s first stage. The second stage was loaded with another 22,500 gallons of oxygen and hydrogen propellants.

Unlike the rocket’s first fueling test earlier this month, when hydrogen leaks forced the team to call off the countdown, sensors detected no significant leaks the second time around and the rocket’s tanks were topped off without incident.

Well, good.