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Gravity Probe
B Launch Day Events
The Virtual Launch Control Center was activated
at
11:00 a.m. EDT
The Virtual Launch
Control Center was deactivated at
12:58
p.m. EDT. Please join us tomorrow at 10:45
a.m. EDT for the resumption of live coverage.
The launch of NASA's Gravity Probe B spacecraft aboard a
Boeing Delta II rocket has been scrubbed for 23 hours. A
hold was called approximately 3 minutes before liftoff after
it was determined that there was insufficient time to confirm
before launch that the correct wind profile had been loaded
aboard the Delta II based on the data from the final weather
balloon. The team was waiting on this final weather balloon
data due to the marginal upper level wind conditions that
were observed through the countdown.
All times
are in EDT unless otherwise stated.
12:58
p.m. - The Launch Director has called a hold. The launch
has been postponed until tomorrow due to upper level wind
restraints. Tomorrow's launch time is set for 12:57:24
p.m. EDT. Live coverage will resume tomorrow at 10:45
a.m. EDT.
12:57
p.m. - T-4 minutes and counting.
12:56
p.m. - End of T-4 hold approaching. The Mission Director
is ready to proceed with the count.
Did you know?
The Delta rocket will carry two video cameras which will record the separation of the 2nd stage of the launch vehicle from the GPB space vehicle.
12:50
p.m. - Final "Readiness To Proceed" poll is being conducted by NASA Launch Manager. Team is ready to proceed with final count.
12:47
p.m. - We have entered the T-4 minute hold. The spacecraft is on internal power and has been configured for launch.
12:43
p.m. - The next upper level wind data will not be available until the 10-minute, 4-second built-in hold at T-4 minutes. Upper level winds fall into the category of flight dynamics, as opposed to weather constraints.
12:39
p.m. - We are at T-12 minutes and counting.
12:31
p.m. - T-20 minutes and counting.
12:27
p.m. - The Mission Director has conducted a poll and
we are go to continue countdown.
12:25
p.m. - The weather team is monitoring upper level winds at this time.
12:23
p.m. - The Delta II's second stage engine will start about 277 seconds after launch, and fire for more than 6 minutes. The engine will then restart 62 minutes after launch and fire for about 16 seconds to fine tune the spacecraft's speed and location.
Did you know?
Data collection for GP-B won’t begin until 40 to 60 days after launch.
12:10
p.m. - The weather officer has dropped the chance of weather
constraint for the launch to 0% for ground weather.
12:00
p.m. - Engine slew begins. First is the "coast slew," then the "first stage slew." The engines are rotated on an x-y plane, back and forth.
11:58
a.m. - T-33 minutes and counting. L-time is the actual
amount of time until launch, while T-time
does not include the time set aside for built-in holds.
11:50
a.m. - At L-60, about 10 minutes from now, a winds
assessment will take place and the weather team will give
updated launch constraint chances. The seven factors affecting
weather constraints are lightning, cumulus clouds, anvil
clouds, debris clouds, disturbed weather, thick cloud layers
and smoke plumes.
11:41
a.m. - There will be six tracking stations following this spacecraft, ranging from an unmanned aircraft known as the NP-3D Orion, to a ground site in Malindi, Kenya.
11:32
a.m. - We are 17 minutes into liquid oxygen loading of the first stage of the Delta II vehicle.
Did you know?
There are three built
in holds during this countdown: T-150 for 60 minutes, T-20
for twenty minutes and T-4 for 10 minutes.
11:16
a.m. - T-75 minutes and counting. LOX loading has begun
on the Delta II launch vehicle.
As the liquid oxygen gets loaded the vehicle seems to change color from blue
to white.
11:12
a.m. - The team has given a go for liquid oxygen (LOX)
loading.
11:06
a.m. - The mission director has polled. The launch team
is ready to proceed.
11:05
a.m. - The cryo-tanking poll has just occurred, and
we are go.
Events that occured prior to activation of the Virtual
Launch Control Center:
10:55
a.m. -T-95 weather and lightning briefing was conducted.
There is no significant precipitation in the area. Winds
are primarily out of the east, and will become northwest
by the time of launch. Wind shear is light at all levels.
At the time of launch, there is a 20% chance of cumulous
cloud constraint.
10:51
a.m. - We have reached T-100 minutes and counting.
10:44
a.m. - The fueling process has completed, after 19 minutes and 4 seconds.
10:26
a.m. - The vehicle is now loaded with 2000 gallons
of RP-1, as fueling continues.
10:25
a.m. - Fueling has begun on the Delta II vehicle.
The rocket will be loaded with 9,950 gallons of
RP-1, which is a highly refined kerosene.
10:00
a.m. - The T-150 minutes count begins. The terminal
count is ready to proceed, and warning sirens have
been sounded for all personnel to clear the pad area.
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