I've seen a couple Vandenberg launches from Stansbury and one for the Midvale Harmons. However, those were evening launches with the exhaust plume backlit. As Brian mentions this, being a morning launch, may not be as spectacular. But if the weather permits I'm going to give it a try just to see how a morning launch looks. Note that you can subscribe to receive Brian's messages at no charge. patrick Begin forwarded message:

LAUNCH ALERT

Brian Webb Ventura County, California kd6nrp@earthlink.net http://www.spacearchive.info

2009 December 9 (Wednesday) 19:59 PST ----------------------------------------------------------------------

TWILIGHT EFFECT

Regarding Friday's Vandenberg launch, space analyst Rick Baldridge wrote:

"From my calculations, the rocket gets into sunlight 3 minutes 15 seconds after launch (if launched about 6:09:33 am PST Dec. 11th) -- with MECO about 1 minute 10 seconds after entering sunlight."

Rick has been very accurate in the past, so it's likely that since Friday's launch occurs at dawn, we will see a Twilight Effect as the first stage's exhaust plume is illuminated by the Sun after the Delta II climbs out of the Earth's shadow.

However, since the sunlight will be reflecting off of the plume rather than shining through it (as would occur during a dusk launch), the display will probably be interesting, but not spectacular.

Refer to the following page for a photo of a similar Delta launch during dawn from several years ago:

www.spacearchive.info/delta-ii-iridium-ms-11.htm

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LAUNCH SUMMARY

Launch: Delta II/Widefield Infrared Survey Explorer (WISE)

Date: 2009 December 11

Launch Window: 06:09:33-06:23:51 PST (14:09:33-14:23:51 UTC)

Launch Site: Pad SLC-2W, Vandenberg AFB

Vehicle: Boeing Delta II with three strap-on solid rocket motors

Launch Heading: Toward the south (196° flight azimuth)

The following table is a listing of flight events for this launch:

Time Altitude (mm:ss) Event (nautical mi) ------- ------------------------------------- -------------

00:00 Liftoff 00:36 Mach 1 00:50 Maximum Dynamic Pressure 01:04 Solid Rocket Motors Burnout 8.8 01:39 Jettison Solid Rocket Motors 16.9 01:40 Begin Dog-Leg Maneuver 02:20 End Dog-Leg Maneuver 03:15 Vehicle Emerges from Earth's Shadow (probable Twilight Effect) 04:24 First Stage Main Engine Cutoff (MECO) 56.9 04:32 Staging 04:38 Second Stage Ignition 62.7 04:56 Payload Fairing Jettison 69.7

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RESOURCES

Please consult the following sources for information related to Friday's Delta II/WISE launch.

Launch Viewing Locations and Information

www.vandenberg.af.mil/questions/topic.asp?id=745

www.spacearchive.info/vafbview.htm

Launch Photography

www.spacearchive.info/vafbphoto.htm

Mission Background

www.nasa.gov/wise

Launch/Countdown Status

www.nasa.gov/wise

www.spaceflightnow.com

Launch Webcasts

www.nasa.gov/wise

www.nasa.gov/ntv (NASA TV)

NASA TV is reportedly available on Dish TV channel 213 and Direct TV channel 376.

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Copyright 2009, Brian Webb. All rights reserved. This newsletter may be distributed in its entirety without restriction. Excerpts may not be reprinted or posted elsewhere without prior permission.

Patrick Wiggins NASA/JPL Solar System Ambassador to Utah & NE Nevada http://utahastro.info paw@wirelessbeehive.com 435.882.1209