Author Topic: Sighting 18/oct/09  (Read 1968 times)

Offline JonnyEnglish

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Sighting 18/oct/09
« on: 10/18/2009 08:23 PM »
Hello.
I just went out to get firewood. dark starry sky and I saw the following: 21:15 local time ( 19:15 GMT ) to 21:20 local time directly over my house near Toulouse, france. lat43.97long2.52. In a very clear sky, the usual satellite seen going overhead heading due north amongst the stars. This one very different. Usual apparent speed, like the space station I'd say but followed, say 5DEG later by a very  visible spearhead shaped cloud, about 1 or so deg wide. Then I noticed that it had a huge ring around it. like  the angle a rainbow subtends at the eye. Like you sometines see around a full moon but many times larger in angular terms. This bright, massive circle tracking the speed of the dot [+ it's cloud] and remaining visible after the dot, before my eyes, let out another cloud of gas and slowly faded to a cloud itself. The final view I had was as the ring 'set' over the northern horizon which for me is a valley wall, about 15DEG elevation. Spectacular. Did I see a satellite die, discuss. Jonathan

Offline edkyle99

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Re: Sighting 18/oct/09
« Reply #1 on: 10/19/2009 02:45 AM »
Hello.
I just went out to get firewood. dark starry sky and I saw the following: 21:15 local time ( 19:15 GMT ) to 21:20 local time directly over my house near Toulouse, france. lat43.97long2.52. In a very clear sky, the usual satellite seen going overhead heading due north amongst the stars. This one very different. Usual apparent speed, like the space station I'd say but followed, say 5DEG later by a very  visible spearhead shaped cloud, about 1 or so deg wide. Then I noticed that it had a huge ring around it. like  the angle a rainbow subtends at the eye. Like you sometines see around a full moon but many times larger in angular terms. This bright, massive circle tracking the speed of the dot [+ it's cloud] and remaining visible after the dot, before my eyes, let out another cloud of gas and slowly faded to a cloud itself. The final view I had was as the ring 'set' over the northern horizon which for me is a valley wall, about 15DEG elevation. Spectacular. Did I see a satellite die, discuss. Jonathan

You may have seen the AV-017 Centaur disposal burn, or the propellant blowdown.  Atlas V AV-017 launched into near polar orbit from Vandenberg AFB on October 18, 2009.  It lifted off at 16:12 UTC and deployed its payload 18 minutes later.  The Centaur stage was supposed to coast until about three hours after liftoff before performing a final disposal burn, meant to propel it into solar orbit, as it headed north over Northern Africa and Western Europe.  The burn was to be followed by a propellant blowdown.  The burn and blowdown are described in the mission summary at:
http://www.ulalaunch.com/launch/DMSP18/AV017_mob.pdf

Nice sighting!

 - Ed Kyle
« Last Edit: 10/19/2009 04:15 AM by edkyle99 »

Offline Proponent

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Re: Sighting 18/oct/09
« Reply #2 on: 10/19/2009 08:54 AM »
You may have seen the AV-017 Centaur disposal burn, or the propellant blowdown....  The Centaur stage was supposed to coast until about three hours after liftoff before performing a final disposal burn, meant to propel it into solar orbit....

Wow--a 220-second disposal burn?!  Is this a standard technique?  It just seems to be such a colossal waste of delta-V.  Couldn't you dispose of the stage in the ocean at a much lower delta-V?

Offline ugordan

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Re: Sighting 18/oct/09
« Reply #3 on: 10/19/2009 09:02 AM »
Wow--a 220-second disposal burn?!  Is this a standard technique?  It just seems to be such a colossal waste of delta-V.  Couldn't you dispose of the stage in the ocean at a much lower delta-V?

http://forum.nasaspaceflight.com/index.php?topic=13210.msg280781#msg280781
http://forum.nasaspaceflight.com/index.php?topic=13210.msg489923#msg489923

Re the sighting: did it look similar to this? http://spaceweather.com/archive.php?view=1&day=19&month=10&year=2009
« Last Edit: 10/19/2009 09:19 AM by ugordan »

Offline edkyle99

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Re: Sighting 18/oct/09
« Reply #4 on: 10/19/2009 02:23 PM »
You may have seen the AV-017 Centaur disposal burn, or the propellant blowdown....  The Centaur stage was supposed to coast until about three hours after liftoff before performing a final disposal burn, meant to propel it into solar orbit....

Wow--a 220-second disposal burn?!  Is this a standard technique?  It just seems to be such a colossal waste of delta-V.  Couldn't you dispose of the stage in the ocean at a much lower delta-V?

These DMSP satellites were originally designed for launch by Titan II augmented by a kick motor.  EELV has a lot of excess capacity for this mission.  In this case the excess was used to perform Centaur propellant settling experiments during the coast.  ULA wanted to do a depletion burn all the way to propellant exhaustion for test purposes as well.  It was determined, given the uncertain final MECO time of such a burn, that a final disposal burn to solar orbit was easier/safer than attempting a deorbit burn.

 - Ed Kyle
« Last Edit: 10/19/2009 02:50 PM by edkyle99 »

Offline JonnyEnglish

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Re: Sighting 18/oct/09
« Reply #5 on: 10/21/2009 08:58 AM »



Re the sighting: did it look similar to this? http://spaceweather.com/archive.php?view=1&day=19&month=10&year=2009

Hi,
Similar is a good word. Fortunately, we've little pollution and without clouds or moon, the contrast was impressive. I got to see what I now assume to be a ~500 km diameter sphere of spent/jetissoned fuel gases, following the event in space.

Do people think that their launches will all follow a similar trajectory and therefore, I live in a good place to see this again?

I'll take snaps next time

here's t'ISS going over in the meantime

Jonny

Offline kevin-rf

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Re: Sighting 18/oct/09
« Reply #6 on: 10/21/2009 12:25 PM »
Do people think that their launches will all follow a similar trajectory and therefore, I live in a good place to see this again?

I'll take snaps next time

I would bet on it. We on the US east coast over the last ten years have been able to watch TWO dumps at the end of east coast high inclination DOD missions. Always awesome to watch. Personally I enjoyed them more than the live launches. Though, there is something to be said for watching a launch with your feet in the surf over at jetty park.

« Last Edit: 10/21/2009 12:26 PM by kevin-rf »
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