An unmanned rocket has launched a new U.S. military satellite into orbit.

The Atlas V (five) rocket lifted off Tuesday afternoon from Cape Canaveral Air Force Station carrying the second satellite of four planned in the Space-Based Infrared System.

The spacecraft will provide early missile warning, missile defense, battlefield reconnaissance and technical intelligence for the US military and its allies.

The satellites will move at the same speed as the earth's orbit. More satellites will be added at a later date.

The full complement of satellites, built by Lockheed Martin, cost $15 billion.