NASA Launch Manager Tim Dunn of the Launch Services Program recapped today’s launch attempt. The hydraulic system problem developed en route, after takeoff, in the last 25 minutes prior to the initial 8:30 a.m. launch time. The hydraulic system in question was not for the L-1011 aircraft itself, but for the system that allows the Pegasus XL rocket to release from the aircraft. That system was not meeting its prescribed pressures, indicating a problem with the hydraulic pump.

“The team did a lot of valiant troubleshooting in the air,” Dunn said. “Everyone wanted to have another launch attempt today, so we continued right up until the L-4 minute point.”

Weather also posed problems at times during the countdown, Dunn pointed out.

“The pilots flew around, under and over a lot of precipitation and bad clouds,” he said.

Should the team resolve the hydraulic pump issue in time for a Tuesday morning launch attempt, the launch window is the same as today’s, and weather is improved, with an 80 percent “go” forecast.