Spaceflight Now Home


Sign up for our NewsAlert service and have the latest news in astronomy and space e-mailed direct to your desktop.

Enter your e-mail address:

Privacy note: your e-mail address will not be used for any other purpose.

Atlas 5 rocket to receive its satellite passenger today

Posted: August 5, 2010

Bookmark and Share

An advanced satellite for relaying secure U.S. military communications and the Atlas 5 rocket that will launch the craft into space next week are being brought together inside a Cape Canaveral assembly building today.

AEHF emerges from Astrotech. Credit: Spaceflight Now
Already packed within the Swiss-made nose cone, the Air Force's first Advanced Extremely High Frequency satellite made a middle-of-the-night departure from its processing hangar in Titusville for a trailer-ride to the rocket's Vertical Integration Facility at Complex 41.

Cranes will hoist the AEHF 1 spacecraft into position atop the rocket for attachment to the Centaur upper stage later in the day.

The satellite had spent the past two months at the commercial Astrotech campus being checked out and fueled for flight. The final days of work there included encapsulating the 13,600-pound craft within the two-piece launch fairing and setting the payload aboard the transporter for its trip to join the Atlas 5 rocket.

In the early morning hours today, the satellite was hauled across the river, up through the Kennedy Space Center and over to Complex 41 where the Atlas awaits on a mobile launching platform.

AEHF drives through Kennedy Space Center. The space shuttle hangars are visible in the background. Credit: Spaceflight Now
Once AEHF is installed, the fully stacked rocket will stand 197 feet tall. The United Launch Alliance vehicle features a Russian-designed main engine fed with refined kerosene and liquid oxygen, three strap-on solid propellant boosters, the liquid hydrogen-powered cryogenic Centaur and a composite payload shroud 16 feet in diameter.

"The Atlas 5-531 configuration with three solid rocket motors is one of the most powerful Atlas 5 vehicles we launch," said Bob Winn, ULA's AEHF 1 mission manager.

Liftoff had been targeted for August 12 at 7:14 a.m. EDT, but the launch could be sliding a day or two. Schedules became increasingly tight when the satellite's milestone move to the assembly building was delayed a few days, eating up the slack in the pre-flight timeline.

As of late Wednesday, the Air Force had not announced any official decisions on the launch rescheduling plans.

Between now and launch day, a combined test for the rocket and its payload will be conducted to verify systems are operating in sync for ascent.

Also upcoming is the review process to give the "go" for sending the Atlas 5 and satellite aloft. The Flight Readiness Review will assess the status of preparations and the subsequent Launch Readiness Review culminates in clearance for rolling the rocket out to the pad August 11 and beginning the countdown.

The daily launch window extends two hours each morning and shifts about four minutes earlier per day.

The Atlas flight sequence will last 51 minutes from liftoff until deployment of AEHF 1 from the booster. The craft will be delivered into a highly elliptical geosynchronous transfer orbit with a high point of 22,236 statute miles, a low point of 119 statute miles and inclination of 27 degrees.

The AEHF 1 satellite. Credit: Lockheed Martin
In the subsequent weeks and months, the satellite's own conventional and exotic ion propulsion systems will circularize the orbit to approximately 22,300 miles over the equator at 90 degrees West longitude for testing.

This maiden AEHF bird should be ready, if all goes well, to enter service early next year from an orbital location dictated by the needs at that time, officials said.

"AEHF will provide tactical and strategic support to a wide variety of Army, Navy, Marine and Air Force users," said Col. Michael Sarchet, commander of the Protected Satellite Communications Group at the Space and Missile Systems Center.

The U.S. military purchased a series of AEHF satellites for launches in the coming years to replace the aging Milstar communications spacecraft that link the national leadership and warfighters.

"AEHF is a very sophisticated satellite because it is built to provide the highest levels of protection for our nation's most critical users. Encryption, low probability of intercept and detection, jammer resistance and the ability to penetrate the electro-magnetic interference caused by nuclear weapons are essential features when communication can be of the highest priority," Sarchet said.