[sac-forum] Re: Last Night's Fuel Dump at Sentinel
- From: "Spencer, Darrell" <DSpencer@xxxxxxx>
- To: <sac-forum@xxxxxxxxxxxxx>, <az-observing@xxxxxxxxxxxxx>
- Date: Mon, 12 Nov 2007 05:58:44 -0800
I found this to be a fascinating event at Sentinel. Here's a blurb from
Cloudy Nights (part of a now larger thread) from _before_ the event.
This guy drove 200+ miles to find clear sky just to see this separation
and fuel vent.
Thanks,
Darrell Spencer
**********
Early Sunday morning a couple of transient naked-eye "nebulae" or
"comets" are expected to be observable, weather permitting, from all of
the western hemisphere at the end of the launch sequence of DSP 23.
The launch window is 8:39 - 10:41 PM EST Saturday night (1:39 - 3:41
Sunday UTC) from Cape Canaveral, Florida.
Just about six hours after launch (i.e., 2:39-4:41 AM EST, 7:39-9:41
UTC), when the payload and Centaur upper stage have reached very near to
geostationary height, there will be a three-minute burn to change the
orbital inclincation and circularize the orbit. This will occur at about
longitude 90 west, plus or minus some degrees, close to the celestial
equator. This will be the first nebula/comet. (I believe but am not
certain that this will be the fainter of the two.)
Spacecraft separation will occur just about 6.5 minutes after the end of
the burn. Not long after spacecraft separation excess fuel and oxidizer
will be vented from the Centaur. This will be the second nebula/comet --
the brighter one, I think (but am not sure).
The burn itself (i.e., the flame) may be visible with a telescope. At
least one of the nebulae/comets may be as bright as first magnitude.
As these events will occur very near geostationary height, they will not
move very much in the sky. The burn cloud may move at nearly sidereal
rate. The venting cloud may be nearly stationary as the stars move by.
But both of them may move to the north or south, as the nominal final
orbital inclination is four, not zero.
DSP satellites themselves are very faint unless specular reflections off
their four solar panels are observed. They are spin-stabilized at 6 RPM.
I've seen at least two geostationary cloud events like this one (one DSP
and one Milstar) as well as one from a launch into a Molniya orbit. They
are very interesting and also rare.
Obviously a dark site is preferred. Presumably there will be quite a few
people at star parties.
Here are links for more launch and payload information:
http://www.spaceflightnow.com/delta/d329/status.html
<BLOCKED::http://www.spaceflightnow.com/delta/d329/status.html>
http://www.ulalaunch.com/index_launch_info.html
<BLOCKED::http://www.ulalaunch.com/index_launch_info.html>
http://www.ulalaunch.com/docs/DSP-23msnBk10_24final.pdf
<BLOCKED::http://www.ulalaunch.com/docs/DSP-23msnBk10_24final.pdf>
________________________________
From: sac-forum-bounce@xxxxxxxxxxxxx
[mailto:sac-forum-bounce@xxxxxxxxxxxxx] On Behalf Of Richard Harshaw
Sent: Sunday, November 11, 2007 7:50 PM
To: sac-forum@xxxxxxxxxxxxx; az-observing@xxxxxxxxxxxxx
Subject: [sac-forum] Last Night's Fuel Dump at Sentinel
Folks, there is a nice article on Spaceweather.com today about last
night's observed fuel dump in Orion.
Dick Harshaw
Phoenix, AZ
"Astronomy is something like the ministry. No one should go into it
without a call." -- Edwin P. Hubble, 1889-1953
Other related posts:
