5.2. Atlas and Titan Rockets

Atlas and Titan were first developed as intercontinental ballistic missiles (ICBM), but were later converted into launchers. Let us review a little bit of history. In 1942, the development of the V-2 Rocket was declared first priority by Adolf Hitler. The V-2 rockets are approximately 14 meter tall and 1.65 meters; in diameter carrying a warhead of 750 to 980 kilograms with a range of about 320 kilometers. From September 1944 to March 1945 , 1,300 V-2 rockets were fired towards Britain killing more than 2,500 persons and injuring about 6,000. Then in January 1945 Germans fired successfully a winged version of the V-2, designed to be an upper stage of an ICBM for ultimate attack on North America. Americans had to respond to the threat. After the end of World War II, they shipped a hundred V-2 Rockets towards a Army base in New Mexico and brought more than one hundred German rocket engineers and scientists to work on their future intercontinental missile project. In April 1946, the Army started project MX-774 to study rockets capabilities leading to the ICBM, this project was later renamed ATLAS.

Among the legacies of World War II was a glittering array of new technologies spawned by the massive military effort. Atomic energy, radar, radio telemetry, the computer and the jet engine seemed destined to shape the world's destiny in the next three decades and heavily influence the rest of the century, but the ICBM was still much further down the technological road. More research was needed on liquid propellants, rocket engines, guidance systems for the missiles and thermonuclear bombs to minimize the weight of warheads. There was also a problem associated with the heat generated by warheads and other bodies reentering the Earth's atmosphere. Research done by H Julian Allen demonstrated the bluntbody shape as the most effective design for reentering bodies.

Another legacy of World War II was that not only the US, but also the Soviet Union had been transformed into a superpower, and they would test each other many times before a balance of power was reached. The Soviet Union was also working on rocket technology. As the years passed, the interest for space increased. It seemed now possible to send satellites and maybe men into space. The technology developed for the missiles was used to beat the USSR in the technological race for space. In 1955, when the US government decided to start the first satellite launcher project, Martin Company was awarded the contract to the VANGUARD launching vehicle using a booster based on an existing Viking ICBM. Viking was derived in great part from the V-2. The reason for the selection of this configuration was that it would make only minimum demands on the military ballistic-missile program. It appeared logical then to bypass Atlas which was far from being operational. In the same year, the Air Force's Titan ICBM was added to the list of the American rocket projects. One serious weakness of Atlas was the fact that all three of the Atlas engines were ignited on the ground before lift-off, with the two boosters dropping off later. A more efficient procedure is to fire only the first stage engines at lift-off, drop the entire stage, and then continue the flight with the second-stage engine, as chosen for Titan. This approach had been felt too risky to attempt in the earlier Atlas project because little experience had been build up at the time on igniting liquid-propellant engines at high altitudes.

The ICBM projects along with Vanguard were the US first priorities, their budgets were enormous, and Americans wanted to be the first to launch a satellite into orbit. On June 11, 1957, the first attempt to launch an Atlas missile at Cape Canaveral failed, so did the second Atlas rocket. And then on October 4, 1957, the Soviet Union announced that they had launched SPUTNIK 1 into orbit, with a total weight in orbit of 4,000 kilograms. And on November 3 of the same year, SPUTNIK 2, carrying a dog, was launched by the Soviet Union. It was obvious that the United States was loosing the battle. Finally in December 17, 1957, an Atlas booster was successfully launched, then in January of 1958, EXPLORER 1, the first US satellite, whose launcher had been developed by the Army Ballistic Missile Agency (ABMA) and Jet Propulsion Laboratory (JPL), redeemed the American honor. Its payload was only 900 grams versus 500 kilograms of Sputnik 2, but there was a scientific first; an experiment abroad the satellite showed the existence of a dense belt of radiation around the earth at an altitude of 400 kilometers (the Van Allen belt as the name of the scientist in charge of the experiment). American confidence perked up again when Vanguard 2 joined Explorer1 in orbit.

America needed a national space program; a civil program, lodged in a new agency, would pick up the existing space projects and forge an expanded program of space exploration in close concert with the military. This agency would not only design and build launch vehicles and satellites, but it would launch them, operate them, track them, acquire data from them, and interpret the data. NASA, the National Aeronautics and Space Administration, was created in 1958, taking over the 8,000 employees of the National Advisory Committee for Aeronautics (NACA). A week later, project MERCURY, America's first manned spaceflight program, started. Mercury would use Atlas as a launcher. Soon, ABMA and JPL laboratories and staff became part of NASA's resources.

Fig 1 Atlas II launch

Launch vehicles are divided roughly in four major groups. First are the so-called small Expendable, i.e. non recoverable, Launch Vehicles (ELV), derived from missiles and sounding rockets, such as Redstone and Viking, which produce less than 450 kn thrust. Second, there are those which have been developed by adding upper staging to intermediate range ballistic missile (IRBM), such as Jupiter and Thor. Next in scale come the ICBM-based launch vehicles with first stage ranking upward from 1300 to 4500 kn thrust, such as Atlas and Titan. Finally the largest ELV's have first-stage thrusts of well over 5000 kn and were conceived and designed from the start as launch vehicles, like Saturn which was used for the APOLLO program.

On December 18, 1958, the Atlas missile, with its new inertial guidance system, launched SCORE, a satellite capable of receiving messages and broadcasting them around the world. The next day, the whole world could hear the Christmas message from President Eisenhower transmitted by Score, this was the first time a human voice has been heard from space. On December 23 1958, the first attempt to launch a Titan vehicle at Cape Canaveral failed, but it was announced that Titan will soon be capable of manned circumlunar flight. In September 1959, the Atlas ICBM was declared officially operational and was taken over by the Strategic Air Command at Vandenberg Air Force Base. With an AGENA upper stage, Atlas orbited a 2,275-kg MIDAS reconnaissance satellite on its second try on May 1960. Its purpose was to provide early warnings of missile launchings through detection of their infrared radiation. Unfortunately, although the launch was successful, the satellite transmission system failed. Preparing for manned spaceflight, US launched several Mercury capsules/Atlas booster combination including a test with a Chimpanzee who survived a suborbital trajectory. On February 20, 1962, astronaut Lt. Col. John Glenn. Jr., aboard the Mercury-Atlas 6 capsule, completed the first US manned orbital flight. It is also an Atlas booster that carried the first Global Positioning System (GPS) Block I satellite into orbit. Atlas has been a workhorse since. There are nowadays many versions of Atlas rockets such as Atlas E and Atlas-Agena B and D and Atlas-Centaur, a description of their capabilities is given below.

In February 1959, a Titan ICBM flew for the first time. The next year, the Air Force placed a contract with Martin ( called Lockheed-Martin nowadays) for a new Titan II missile, designed to use storable fuel, an all-inertial guidance system and greater capacity for distance and payload. On January 2, 1962, NASA announced a new manned spaceflight project, GEMINI. Using the basic configuration of the Mercury capsule enlarged to hold a two-man crew, Gemini was to fit between Mercury and Apollo and give early answers to assist the design work on Apollo. The launch vehicle would be a Titan II missile. The mission was to rendezvous a target vehicle chosen to be Agena, launched by an Atlas first stage; the second stage Agena had a restartable engine that enabled it to have both passive and active roles. On March 23, 1965, Virgil L. Grissom and John W. Young were launched on the first Gemini mission, Gemini 3. This was the First US two person-flight and the first time a spacecraft's orbit was manually changed in space. The next Gemini missions all launched by Titan II boosters broke more records, including the longest human flight to date, the first docking of two orbiting spacecraft, the first tethered flight and more, putting the US at the top of the technological race against the Soviet Union, and preparing the field for Apollo and a lunar landing.

Titan IV launch

In 1963, the Air Force announced a plan to further increase the payload-carrying capability of its Titan II ICBM by adding solid-propellant rocket-boosters. The new configuration became known as Titan IIIC, capable of orbiting payloads weighing 2300 to 11,400 kilograms. In June 1966, it was launched and placed in a nearly circular orbit about 160 km high. Then, a Hohman transfer was programmed between altitudes of 160 km and 3400 km, changing at the same time from the original inclined orbit to a near-equatorial orbit-the greatest plane change completed up to that time by the US. Once in the final orbit, seven communications satellites and a gravity gradient satellite were ejected as part of a program to deploy a global system of communications satellites for the Defense Communication Agency (DSCS). Among the missions assigned to Titan III, was the Viking 1 mission which soft-landed on Mars July 20, 1976 to take soil samples of Mars and perform rudimentary analysis on them. In 1977, Titan III launched the Voyager space probes, which were programmed to fly by Jupiter and Saturn and most of their moons and then continue to Uranus and Neptune. They transmitted detailed views of Jupiter's swirling atmosphere, and interesting findings on Jupiter's 16 moons, permitted the discovery of 6 of Saturn's 24 moons and much more. In 1985, Lockheed Martin Astronautics was chosen once again by the Air Force to build a new generation of Titan launchers, Titan IV. Details of the different Titan and Atlas models still used nowadays are described below.