Fitted with the third spacecraft to continue building out the U.S. Air Force's Advanced Extremely High Frequency communications satellite system, the United Launch Alliance Atlas 5 rocket has arrived at its launch pad after completing the first one-third of a mile of a journey to supersynchronous transfer orbit.

The voyage resumes Wednesday at 3:04 a.m. EDT (0704 GMT) with liftoff of the two-stage Atlas 5 rocket. Wednesday's launch window extends for two hours.

The countdown will begin at 8:04 p.m. EDT Tuesday (0004 GMT Wednesday), leading to activation of the rocket, final testing and system preps. Fueling operations start at 1:11 a.m. EDT (0511 GMT).

"My thanks to the entire team for its dedication in bringing AEHF 3 to launch and to the Air Force for trusting ULA to deliver this critical national security capability to orbit," said Jim Sponnick, ULA's vice president of Atlas and Delta programs.

The weather forecast from the Air Force's 45th Weather Squardon calls for 60 percent chance of violating launch constraints.

The outlook predicts scattered and broken cloud decks at 2,500, 14,000 and 30,000 feet with showers and isolated thunderstorm activity. Winds will be out of the east at 15 to 20 knots with a temperature of approximately 77 degrees Fahrenheit.

The primary concerns for Wednesday morning are violating the thick cloud and the cumulus cloud rules.

"On launch day increasing onshore low level flow and persistent tropical moisture will keep probabilities of showers and cloudy conditions high," meteorologists wrote in a forecast synopsis. "Expect showers, cloudy skies, and a chance for an isolated thunderstorm in the vicinity. Breezy onshore easterly winds gusting into the upper teens/low 20s (230 feet) are also expected."

If the launch gets pushed back to Thursday, a drier airmass should take hold over Central Florida. The probability of violating weather constraints Thursday is 40 percent.

Quelle: SN

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CAPE CANAVERAL AIR FORCE STATION, Fla., Sept. 16, 2013 – The U.S. Air Force's third Advanced Extremely High Frequency (AEHF) military communications satellite, designed and built by a Lockheed Martin [NYSE: LMT] team, is ready to launch aboard a United Launch Alliance Atlas V rocket from Cape Canaveral Air Force Station, Fla. Launch is set for Sept. 18 with a two-hour launch window opening at 3:04 a.m. EDT.

The AEHF system provides vastly improved global, survivable, highly secure, protected communications for strategic command and tactical warfighters operating on ground, sea and air platforms. The system also serves international partners including Canada, the Netherlands and the United Kingdom. Canada was the first of these nations to connect to AEHF during tests with multiple terminals, and Lockheed Martin announced last week that the Netherlands is now using the system.

 “Thanks to a focused government-industry team, the third AEHF satellite is ready to launch,” said Mark Calassa, vice president of Protected Communication Systems at Lockheed Martin. “We’ve increased affordability while maintaining a focus on mission success. Our AEHF-1 and -2 satellites are delivering improved capability during on-orbit testing, having already connected three allies and 10 terminal types. From suppliers to engineers to launch operators, we are committed to our customer and this mission.”

A single AEHF satellite provides greater total capacity than the entire legacy five-satellite Milstar constellation. Individual user data rates will increase five-fold, permitting transmission of tactical military communications, such as real-time video, battlefield maps and targeting data. In addition to its tactical mission, AEHF provides the critical survivable, protected and endurable communications links to national leaders, including presidential conferencing in all levels of conflict.

Lockheed Martin is under contract to deliver six AEHF satellites and the Mission Control Segment. AEHF-1 and AEHF-2 are on orbit, and AEHF-4 through -6 are progressing on schedule. All satellites are assembled at the company’s Sunnyvale, Calif., facility.

Headquartered in Bethesda, Md., Lockheed Martin is a global security and aerospace company that employs about 116,000 people worldwide and is principally engaged in the research, design, development, manufacture, integration, and sustainment of advanced technology systems, products, and services. The Corporation’s net sales for 2012 were $47.2 billion.