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.
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