Attention sky watchers in the U.S. Southwest and northwestern Mexico... Brian Webb provides the following Launch Alert: An Atlas V rocket carrying a classified payload is scheduled for launch from Southern California’s Vandenberg AFB on Thursday evening, December 11. The Atlas is set to lift-off from Space Launch Complex-3 (SLC-3) on south base at 19:17 PST, the presumed start of a classified launch window. Following lift-off, the Atlas will climb vertically for several seconds, then gradually nose over and head out to sea. Although the planned direction of flight is unknown, the vehicle will probably fly toward the south-southwest, south, or south-southeast. The Atlas V uses liquid propellant first and second stages. For this launch, four solid rocket motors are strapped to the first stage for added thrust. The first stage booster engine and strap-on solid rocket motors will ignite on the launch pad. The solid rocket motors will burn for about the first minute or two of flight before running out of fuel and being jettisoned at about +1:56. The first stage liquid propellant booster engine will continue burning until booster engine cutoff (BECO) at about +4:11. After a few seconds, stage 1/2 separation occurs followed by second stage ignition. Several minutes later, the second stage containing the NROL-35 payload will reach orbit. Weather permitting, the first few minutes of the launch could be visible to the unaided eye from all of California south of Sacramento, southwest Nevada, western Arizona, most of Baja California, and northwest Mexico. For the first few minutes of flight, the rocket will have a bright orange flame due to the solid rocket motors. When the solid motors burn out, the Atlas will decrease in brightness and resemble a moving star. The launch probably occurs too long after sunset for the Sun to illuminate the first stage exhaust. However, observers in dark locations may be able to see the rockets tenuous exhaust plume during the last minute or so of the first stage burn. Under good conditions, the launch could be visible to the unaided eye until first stage booster engine cutoff. Second stage ignition and the second stage burn will probably not be visible to most observers without optical assistance. To see the launch, you will need a location with an unobstructed horizon in the direction of Vandenberg AFB and the ocean south of the base. If possible, the location should also be far from city lights. Although the launch should be visible to the unaided eye, you will probably see more if you use binoculars (especially tripod-mounted binoculars) or a telescope. If you plan to drive to the mountains for the launch, allow yourself plenty of time to get there and drive very carefully. Mountain roads are dangerous and careless driving or parking can lead to tragedy. Also, be aware of your surroundings after you get out of your vehicle.
Posted on: Wed, 10 Dec 2014 18:16:47 +0000
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