THE TITAN/CENTAUR LAUNCH VEHICLE
The two Voyager spacecraft were carried into space and accelerated toward Jupiter by the Titan III-E Centaur rocket, the largest launch vehicle in the NASA arsenal after the retirement of the Saturn rockets in 1975. The Titan and Centaur vehicles were originally developed separately and have been used with other rocket stages for many NASA launches. They were first combined for the two Viking launches to Mars in 1975, and this powerful four-stage launch vehicle was used again in 1977 for Voyager.
The Titan/Centaur stands nearly 50 meters tall, about the height of a fifteen-story building. Fully fueled, it weighs nearly 700 tons. At takeoff, the thrust of the two solid-propellant Stage-0 motors is about 10.7 million newtons. These motors, which burn for 122 seconds, use powdered aluminum as fuel and ammonium perchlorate as oxidizer. Together, they have a mass of 500 tons.
The first stage of the liquid propellant core of the Titan rocket ignites about 112 seconds after takeoff. The propellant is hydrazine as fuel and nitrogen tetroxide as oxidizer. The first stage is 3 meters in diameter and 20 meters tall. Fueled, it has a mass of 130 tons. The motor provides a thrust of 2.5 million newtons for a duration of 146 seconds.
About 4.3 minutes after takeoff the Titan Stage II liquid propellant motor begins to fire, and the first stage is separated and falls back into the Atlantic. The second stage is 3 meters in diameter and more than 7 meters long, with a fueled mass of 35 tons. The single liquid fuel motor burns for 210 seconds with a thrust of half a million newtons. During the second stage burn, the shroud covering the Voyager spacecraft is jettisoned.
The Centaur and Titan vehicles separate 8 minutes into the flight, and the Centaur main engine begins its burn. The Centaur is nearly 20 meters tall and 3 meters in diameter, with a mass of 17 tons. The motors have a thrust of almost 200 000 newtons, operating on the most powerful chemical fuels known: liquid oxygen and liquid hydrogen. The Centaur burns for only 1 minute and 36 seconds as it attains Earth parking orbit; the engine then shuts down as the vehicle begins a half-hour coasting period that carries it nearly half way around the Earth. During this time, careful tracking of the spacecraft supplies the data needed for Earth-based computers to calculate the proper time to leave parking orbit and start the long trip toward Jupiter.
About 50 minutes after liftoff, from a position high above the Indian Ocean, the second burn of the Centaur main engine begins. Six minutes of additional thrust provides enough energy to break out of Earth’s orbit. The Voyager then separates from the Centaur for a final boost toward Jupiter. The solid rocket motor in the spacecraft propulsion module (acting as final stage of this five-stage launch sequence) fires for 45 seconds at a thrust of 68 000 newtons. Just an hour after liftoff, the Voyager spacecraft is on its way, coasting on an orbit toward Jupiter at a speed of more than 10 kilometers per second.
The Voyager spacecraft is dominated by the large 3.7-meter-diameter antenna used for communication with Earth. Here the spacecraft undergoes final tests before launch. The science instrument scan platform is folded against the spacecraft on the right; the three cylinders on the left are the RTG power sources. [260-108BC]
