Rocket Checks Prompt Launch Delay for NASA's Pluto Probe

NASA's New Horizons Pluto probe is prepared to be encased in its launch fairing at the Payload Hazardous Servicing Facility at the Kennedy Space Center in Florida. CREDIT: NASA/KSC.

The launch of NASA's Pluto-bound New Horizons spacecraft is being delayed so engineers can perform precautionary boroscope inspections of the Atlas 5 rocket's first stage fuel tank.

Liftoff had been scheduled for January 11 from Cape Canaveral. But the extra work will slip the launch to no earlier than January 17, eating up the first six days in the year's 35-day window to dispatch the probe from Earth.

The NASA-ordered inspections stem from a problem experienced in September during factory testing of an updated Atlas 5 tank design. Lockheed Martin says a test tank failed just under the "ultimate pressure" threshold it should withstand. That led to workers reinspecting all of the tanks that had been produced in the factory.

The Atlas 5 rocket to launch New Horizons passed its check successfully. But now NASA wants to inspect the propellant tank's interior one more time to be safe.

The tank already contains the flight load of RP-1 fuel to feed the rocket's RD-180 main engine during liftoff. The highly refined kerosene was pumped aboard the vehicle during a countdown dress rehearsal earlier this month. That fuel will have to be drained and the tank purged before the inspections can start.

Launch on January 17 will be possible during a two-hour window opening at 1:24 p.m. EST (1824 GMT). Despite the delay, New Horizons can still achieve the desired trajectory that swings past Jupiter for a sling-shot boost and reaches Pluto in 2015. The window for that scenario runs through January 28.

Liftoff between January 29 and February 2 would still include a Jupiter flyby but the arrival at Pluto would slip to 2016 or 2017 depending on the day of launch. More days are available for launch through February 14, but that would set up a direct route from Earth to Pluto that adds years to the trip because Jupiter will have moved out of alignment.

After mid-February the launch would have to wait a year before the next planetary opportunity lines up.

Meanwhile, the New Horizons craft was set to travel Friday night from its Kennedy Space Center processing facility to the Atlas 5 vehicle assembly building at Complex 41. The spacecraft will be mated atop the rocket on Saturday.