Atlas 2A vehicle data
Posted: June 26, 2000
The Atlas 2A is a two-and-one-half stage rocket capable to lifting payloads of 3,070 kg (6,760 lb) into a geostationary transfer orbit. It features no strap-on solid rocket boosters and is the least powerful version of the Atlas family.
The Atlas 2A is a two-and-one-half stage launch vehicle. The Centaur upper stage is mounted on top of the one-and-one-half stage Atlas booster.
Atlas booster propulsion is provided by the Rocketdyne MA-5A engine system, which includes the sustainer engine and booster engine system. All engines are ignited before liftoff and develop a total sea-level-rated thrust of 490,000 pounds. The section containing the booster engine is jettisoned (booster package jettison [BPJ]) at an axial acceleration of 5.0 g. Flight continues powered by the sustainer engine ("sustainer phase" flight) until propellant depletion.
The Atlas is connected to the Centaur by the interstage adapter. This aluminum structure provides the structural link between Atlas and Centaur. The Atlas is separated from the Centaur by a flexible linear-shaped charge system attached to the forward ring of the interstage adapter.
Centaur Upper Stage
Centaur avionics packages, mounted on the equipment module, control and monitor all vehicle functions. Centaur avionics perform the inertial guidance and attitude control computations for both Atlas and Centaur phases of flight, and control Centaur tank pressures and propellant use.
The Centaur propulsion system uses two RL10A-4-1 engines with extendible nozzles manufactured by Pratt & Whitney. Each engine is has a rated thrust of 22,256 pounds. The Centaur engines are restartable and are capable of multiple firings in space, separated by coast phases.
The stub adapter and equipment module are attached to the forward end of the Centaur. The stub adapter is bolted to the forward ring of the Centaur tank and supports the equipment module and payload fairing. The equipment module attaches to the forward ring of the stub adapter and provides for mounting of the Centaur avionics and the spacecraft adapter.
The payload fairing is a two-half-shell structure constructed of aluminum with vertical, split-line longerons. It consists of a cylindrical section topped by a conical nose cone and a spherical cap.
The conical section external surface of the fairing is insulated with cork to limit temperatures to acceptable levels. Non-contaminating thermal control coatings are used on internal surfaces to reduce incident heat fluxes to the spacecraft.
Approximately 1 minute after Atlas booster jettison, the payload fairing is jettisoned.
In transfer orbit, the Centaur issues separation commands to release and separate the spacecraft from the forward adapter.
Vehicle: Atlas 2A (AC-139)
Payload: NASA's TDRS-H
Launch date: June 30, 2000
Launch window: 1238-1318 GMT (8:38-9:18 a.m. EDT)
Launch site: SLC-36A, Cape Canaveral, Fla.
TDRS-H - Description of the satellite to be launched on AC-139.
History of TDRSS - Past launches of TDRS satellites and their current status.
Launch timeline - Chart with times and descriptions of events to occur during the launch.
Launch windows - Available windows for possible future launch dates of AC-139.
MISSION STATUS CENTER