The Atlas V 551 Launch Vehicle is a part of the flight proven Atlas V 400/500 family that is being operated by United Launch Alliance. Atlas V rockets are flown since 2002 and have a near-perfect success rate (one flight was a partiel failure, however the mission was catalogued as a success). The Atlas V was developed by Lockheed Martin services. It is a part of the Evolved Expendable Launch Vehicle of the US Air Force. Launch sites for the Atlas V are the Launch Complex 41 at the Cape Canaveral Air Force Station, Florida and Launch Complex 3-E at Vandenberg Air Force Base, California.
The Atlas V uses a singe engine Common Core Booster with an RD-180 dual chamber engine. Up to 5 solid rocket boosters can be attached to the first stage of the launcher. A Centaur Upper Stage functions as the second stage of the rocket. Centaur can be powered by a single engine ot a dual engine system. To this date, only single engine Centaurs have flown on the Atlas V. The Centaur's engine can handle multiple start-ups in space, making it possible to insert payloads to a parking orbit before igniting the engine again to boost a spacecraft into GTO or GEO. Centaur provides the Inertial Navigation Unit that controls the entire stack (Atlas&Centaur) following liftoff. The unit also monitors and regulates propellant levels and propellant use.
The Atlas V 551 has five solid rocket boosters attached to its first stage.
Atlas V 551 has flown twice before. Once in 2006 to launch the New Horizons Mission to Pluto and in 2011 to deliver Juno on a path to Jupiter.
Every Atlas V version has a three digit ID-Number:
First Digit: Payload Fairing diameter: 4XX - 4m Diameter; 5XX - 5.4m Diameter
Second Digit: Number of Solid Rocket Boosters (0-5)
Third Digit: Number of RL-10A Engines on Centaur (1 or 2)
Centaur Upper Stage
Short Payload Fairing
Medium Payload Fairing