 |
| © United Launch Alliance 120818-abort.jpg |
An attempt to launch a classified National Reconnaissance Office spy
satellite atop a heavy-lift Delta 4 rocket at Vandenberg Air Force Base
northwest of Los Angeles was aborted at the T-minus 7.5-second mark
Saturday evening when a problem was detected by computers orchestrating
the terminal countdown.
Flares had already ignited at the base of the 23-story-tall rocket to
burn away excess hydrogen gas, a routine safety precaution, when the
abort was ordered. It came a half second before the first of the Delta 4
Heavy's three side-by-side Common Booster Core engines was scheduled to
ignite and throttle up to full thrust, followed two seconds later by
the center and left-side CBCs.
Instead, a flight controller called
out "hold, hold, hold" as the countdown came to a halt. Flames from the
hydrogen igniters rose from the base of the rocket as they continued to
burn for a few moments, a somewhat scary sight given the
1.6-million-pound rocket was loaded with 465,000 gallons of liquid
hydrogen and oxygen propellants.
But United Launch Alliance
engineers quickly "safed" the vehicle and re-cycled the countdown to the
T-minus 4-minute mark while they reviewed telemetry. A few minutes
later, the flight was scrubbed for the day, and engineers begin
off-loading the Delta's load of fuel.
ULA did not set a new launch
date or provide any immediate details about what triggered the abort.
As a result, it was not immediately known what sort of inspections or
repairs might be needed before a second launch can be attempted.
This
was set to be ULA's ninth launch of 2018 and the second in a row of the
huge Delta 4 Heavy. The identity of the satellite payload, known as
NROL-71, is classified, but independent analysts speculate it may be an
advanced imaging reconnaissance spacecraft bound for an unusual
near-polar orbit.
COMMENTS