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Atlas 3B ascent and fuel dump may be visible from N.East America



 
 
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  #1  
Old February 3rd 05, 12:40 AM
Ted Molczan
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Default Atlas 3B ascent and fuel dump may be visible from N.East America

An Atlas 3B rocket is scheduled to lift off from Cape Canaveral on 2005 Feb
03 at 07:41 UTC (2:41 AM EST). I expect the launch window to begin 14 min
earlier for each day of any launch delay. Coverage of the launch is
available he

http://www.spaceflightnow.com/atlas/ac206/status.html

http://streamvox.streamos.com/gemssv/ils012705/

Observers in parts of North America may be able to spot a couple of seldom
seen events: the ascent trajectory, and the Centaur upper stage's propellant
dump.

The ascent trajectory is unusual in that it will track toward the northeast,
not far off the east coast of the U.S.A. and Canada. The rocket is likely to
remain in Earth's shadow during all or most of the ascent, so the its plume
may not be very bright. I suggest scanning with 7x50 binoculars.

Here is an Excel spreadsheet containing a rough estimate of the ascent
trajectory, including formula's to compute azimuth and elevation for your
location:

http://satobs.org/seesat_ref/AC-206/...ook_angles.xls

You need only enter the lift-off time, and your latitude and longitude. The
lift-off time need not be UTC. The co-ordinates of the example are for
Washington, D.C.

I am not certain steeply the rocket will climb, so the spreadsheet covers
two scenarios: the one labelled "Low MECO1" assumes the vehicle will be 240
km above the Earth at main engine cut-off #1; "High MECO1" assumes it will
have climbed to 640 km. I suspect that the low scenario is correct.

The Centaur upper stage's propellant dump occurs less than 2 hours after
launch. When illuminated by the sun, Centaur propellant clouds have been
seen with the unaided eye at distances of tens of thousands of kilometres.

The Centaur propellant dump from the Atlas 2AS launched on 2004 Aug 31 UTC,
was visible to the unaided eye at ranges in excess of 8000 km, for about 10
min after it ended. I spotted it while in progress, at a range of about 6300
km, as a glowing cloud about the apparent diameter of the moon. Binoculars
revealed considerable structure in the plume.

The exact time of the Atlas 3B's propellant dump has not been published;
however, based upon typical practice, if the launch occurs on Feb 3, and on
time, it should be completed by about 09:35 UTC.

That would put the dump within Earth's shadow; however, it would pass into
sunlight about 4 min later, 09:39 UTC, near 53 N, 82 W, altitude 1161 km,
becoming visible to observers in the northeast. A cursory analysis indicates
some visibility at least as far west as Chicago, and at least as far south
as Washington D.C. Of course, if the dump occurs much earlier or later than
usual, then there would be little to see over North America.

To assist as many people as possible to see this event, Heavens-Above kindly
has agreed to host the estimated orbital elements. To run your own
predictions, go to this page:

http://www.heavens-above.com

Select or enter your site co-ordinates, then from the main page, click
"Select a satellite from the database", and enter 70999 in the box labelled
"US Space Command ID", and follow the instructions to generate custom pass
predictions. Be careful to ignore predictions for dates and times prior to
lift-off.

The estimated orbital elements should be accurate to within about 5 min of
time and several deg of arc, but it is a good idea to allow for even more
error.

For those who prefer to run their own predictions, here are estimated
elements, in 2-line format:

MES2 1010 X 1208 km
1 70999U 05034.37193286 .00000000 00000-0 00000-0 0 08
2 70999 63.4167 155.0000 0132437 179.7272 98.8000 13.39694040 03

Description of 2-line elements: http://www.satobs.org/element.html

I will update this information as events warrant.

Ted Molczan


  #2  
Old February 3rd 05, 05:39 PM
William R. Thompson
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Default

Ted Molczan wrote:

An Atlas 3B rocket is scheduled to lift off from Cape Canaveral on 2005 Feb
03 at 07:41 UTC (2:41 AM EST). I expect the launch window to begin 14 min
earlier for each day of any launch delay.


(snip)

To assist as many people as possible to see this event, Heavens-Above kindly
has agreed to host the estimated orbital elements. To run your own
predictions, go to this page:


http://www.heavens-above.com


I wondered why that "Atlas 3B launch" had appeared there without a
matching launch. I looked for the satellite but saw nothing (which
at least proves I'm not troubled by creative eyesight).

The predicted orbital elements are similar to the ones given
for recent NOSS launches, so there may be two satellites associated
with this launch.

--Bill Thompson
  #3  
Old February 4th 05, 04:32 PM
Impact9
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Default

When I was a kid in I think 1988 me and my friends were outside during
summer break playing hide and seek in the dark. Over the southwest
horizon I seen what appeared to be a meteor getting very bright moving
very fast. I yelled for my parents to come outside and we watch this
thing that looked like a balastic missle flying across the sky. You
could even tell it had some giant letters down the side. You could
actually hear it flying through the air since everything was dead quite
with this missle overhead. About a minute later it disappeard across
the north west horizon. Didn't see no bright flash or mushroom cloud so
we went inside and watched the news. =) Come to find out it was a
russian booster rocket reentering the atmosphere and burned up before
impact. It was very cool and VERY scary.

 




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