Ten, nine, eight.
NASA Launch Commentator Josh Finch: Seven, six, five, four, three, two, one, zero.
Liftoff of the mighty Delta IV Heavy rocket with NASA’s Parker Solar Probe, a daring
mission to shed light on the mysteries of our closest star, the Sun.
[engine noise]
Telemetry officer: Three RL-68s look good in
the full-thrust mode.
[engine noise]
Telemetry officer: Twenty-five seconds into flight.
Chamber pressures continue to look good on all three boosters.
Now 35 seconds in.
Chamber pressure on the core booster is throttling down to the partial-thrust mode.
Response looks good.
Telemetry officer: Now 50 seconds into flight.
Strap-on boosters look good in the full-thrust mode.
Core booster looks good in the partial-thrust mode.
Now one minute into flight.
Vehicle trajectory looking good, right down the middle of the range track.
One minute, ten seconds into flight.
Coming up on one minute, 19 seconds into flight.
Max Q, maximum dynamic pressure, and Mach 1.
Delta IV is now supersonic.
One minute, 30 seconds into flight.
Port and starboard booster engines continue to look good in full-thrust mode.
Core booster looks good in the partial-thrust mode.
One minute, 45 seconds into flight.
Trajectory continuing to look good, right down the middle of the range track.
ACS press valve has been opened.
ACS pressure response looks good.
Two minutes, 10 seconds in.
Strap-on boosters continue to look good in the full-thrust mode.
Core booster looks good in the partial-thrust mode.
And Delta IV has gone to closed-loop guidance.
Two minutes, 30 seconds into flight.
And at two minutes, 39 seconds into flight, the Delta IV rocket now weighs just one-half
of what it did at launch, burning propellant at a rate of almost 5,000 pounds per second.
And launch vehicle is now 33 miles in altitude, 49 miles downrange distance, traveling at
4,500 miles per hour.
Three minutes into flight.
RL-68A engines in the port and starboard boosters continue to look good in the full-thrust mode.
Core booster looks good in the partial-thrust mode.
Three minutes, 15 seconds into flight.
Trajectory continuing to look good down the middle of the range track.
Approximately two minutes remaining in the boost stage of flight.
Chamber pressures continuing to look good on all three boosters – port and starboard
boosters in the full-thrust mode, core booster continuing in the partial-thrust mode.
And standing by for strap-on booster throttle-down momentarily.
Port and starboard boosters have begun to throttle down.
And we have jettison of both strap-on boosters.