By Irene Klotz
CAPE CANAVERAL, Florida (Reuters) - An unmanned Atlas 5 rocket blasted off from Cape Canaveral Air Force Station on Friday to deliver the second member of an advanced U.S. military communications satellite network into orbit.
The 197-foot (60-metre) tall rocket, built by United Launch Alliance, blasted off its seaside launch pad at 2:42 p.m. EDT, piercing partly cloudy skies as it headed into orbit.
Sealed inside the rocket's protective nosecone was the second Advanced Extremely High Frequency (AEHF) military communications satellite.
The satellite, built by Lockheed Martin Corp, is part of a planned four-member constellation designed to provide global, high-speed, secure and jam-resistant communications for the U.S. military and international partners from the United Kingdom, Canada and the Netherlands.
?"Launch is the critical first step to getting this capability to our troops around the world," Air Force Lieutenant Kristin Hoover, a member of the AEHF team, said during a webcast of the launch.
The first AEHF satellite was launched on August 14, 2010, but took 13 months to reach operational orbit due to a problem with the spacecraft's propulsion system. Investigators determined that a piece of debris had prevented the satellite's liquid-fueled booster engine from firing.
Ground control teams spent more than a year coaxing the spacecraft into position 22,300 miles above the equator using its smaller thruster engines.
AEHF-1 was turned over to the military's operations squadron two weeks ago.
The AEHF network is a follow-on to the Milstar communications satellites. Each of the new spacecraft has 10 times the capacity of a single Milstar satellite, launch commentator Don Spencer said.
The AEHF satellites, which cost more than $1 billion apiece, are designed to last 14 years.
The launch was the 30th of an Atlas 5 rocket, all flown successfully. The rocket is in the process of being upgraded to fly astronauts as well.
(Editing By Tom Brown and Eric Beech)