NROL-24 Centaur propellant dump may be visible

NROL-24 Centaur propellant dump may be visible
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NROL-24 Centaur propellant dump may be visible molczan 12-09-2007
Posted by on December 9, 2007, 5:04 pm
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NROL-24 is scheduled for launch on 2007 Dec 10 at 22:04 UTC (17:04
EST), from Cape Canaveral, aboard an Atlas V-401 rocket.

Observers located in roughly the eastern half of North America may be
able to see the Centaur upper stage's propellant dump, about 100 min
after launch. It should be readily visible to the unaided eye as a
small, slow-moving, luminous cloud.

I estimate that the dump will be visible east of a line from very
roughly Winnipeg through Kansas City, Tulsa and New Orleans. If the
launch occurs late in the launch window, which I guess is about 30 min
in duration, then the zone of visibility will extend up to about 7 deg
further west.

Here is my estimate of the Centaur's planned orbit, in "2-line
elements" format, which can be used to generate an ephemeris with
appropriate software:

1 79001U 07344.97850452 .00017925 00000-0 14828-2 0 07
2 79001 57.3981 310.1520 5327478 293.4985 20.3013 5.13214280 05

For those unfamiliar with 2-line elements, I have also created an MS
Excel spreadsheet to generate az/el and RA/Dec at one minute
intervals. Simply enter your site coordinates, and the date/time of
launch:

http://satobs.org/seesat_ref/misc/NROL-24_Centaur_look_angles.xls

The file has been set up for launch at the above scheduled date and
time, so you may only need to enter your latitude and longitude. In
the event of a launch delay, you will need to update the time and
possibly the date. The planar launch window opens 4 to 5 min earlier
for each day of delay.

Spaceflight Now is an excellent source of current information about
the launch:

http://www.spaceflightnow.com/

Based on a previous similar launch (NROL-1, in Aug 2004), and assuming
an on-time launch, the dump should be visible by about 23:42 UTC
(18:42 EST). It will occur several thousand kilometres above the
Earth, hence the wide area of visibility.

CAUTION: Both the orbit and the timing of the dump are somewhat
uncertain. Ephemerides made using the above search elements could
easily be off by at least 5 deg in position, and quite a few minutes
in time, so it is best to scan along the predicted track with the
unaided eye. The timing of the dump is also somewhat uncertain, so I
recommend allowing at least +/- 10 min.

Once the cloud has been spotted, binoculars or a telescope will reveal
its complex shape. The Centaur and possibly the payload may be visible
near the cloud's apparent point of origin.

Ted Molczan

Posted by marika on January 11, 2008, 7:48 pm
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show/hide quoted text

Small world!! That's pretty funny.
sorry i missed it

show/hide quoted text
Probably.



mk5000



"You just killed a helicopter with a car!"-- Matt Farrell: "Live Free or Die
Hard"






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