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Ten, nine, eight.

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00:00:04,440 --> 00:00:14,049
NASA Launch Commentator Josh Finch: Seven,
six, five, four, three, two, one, zero.

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Liftoff of the mighty Delta IV Heavy rocket
with NASA’s Parker Solar Probe, a daring

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mission to shed light on the mysteries of
our closest star, the Sun.

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[engine noise]

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Telemetry officer: Three RL-68s look good
in

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the full-thrust mode.

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[engine noise]

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Telemetry officer: Twenty-five seconds into
flight.

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Chamber pressures continue to look good on
all three boosters.

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00:00:45,480 --> 00:00:48,519
Now 35 seconds in.

12
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Chamber pressure on the core booster is throttling
down to the partial-thrust mode.

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Response looks good.

14
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Telemetry officer: Now 50 seconds into flight.

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Strap-on boosters look good in the full-thrust
mode.

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Core booster looks good in the partial-thrust
mode.

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Now one minute into flight.

18
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Vehicle trajectory looking good, right down
the middle of the range track.

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One minute, ten seconds into flight.

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Coming up on one minute, 19 seconds into flight.

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Max Q, maximum dynamic pressure, and Mach
1.

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Delta IV is now supersonic.

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One minute, 30 seconds into flight.

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Port and starboard booster engines continue
to look good in full-thrust mode.

25
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Core booster looks good in the partial-thrust
mode.

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One minute, 45 seconds into flight.

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Trajectory continuing to look good, right
down the middle of the range track.

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ACS press valve has been opened.

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ACS pressure response looks good.

30
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Two minutes, 10 seconds in.

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Strap-on boosters continue to look good in
the full-thrust mode.

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Core booster looks good in the partial-thrust
mode.

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And Delta IV has gone to closed-loop guidance.

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Two minutes, 30 seconds into flight.

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And at two minutes, 39 seconds into flight,
the Delta IV rocket now weighs just one-half

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of what it did at launch, burning propellant
at a rate of almost 5,000 pounds per second.

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And launch vehicle is now 33 miles in altitude,
49 miles downrange distance, traveling at

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4,500 miles per hour.

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Three minutes into flight.

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RL-68A engines in the port and starboard boosters
continue to look good in the full-thrust mode.

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Core booster looks good in the partial-thrust
mode.

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Three minutes, 15 seconds into flight.

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Trajectory continuing to look good down the
middle of the range track.

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Approximately two minutes remaining in the
boost stage of flight.

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Chamber pressures continuing to look good
on all three boosters – port and starboard

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boosters in the full-thrust mode, core booster
continuing in the partial-thrust mode.

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And standing by for strap-on booster throttle-down
momentarily.