Expendable Launch Vehicle Operations
While development of the lunar program moved forward, unmanned launches continued unabated from Cape Canaveral. Part of the original Vanguard Naval Research Laboratory team became the Launch Operations Branch of the Goddard Space Flight Center after NASA was established in 1958. This team became a part of the Kennedy Space Center in October 1965.
The team completed its planned series of Vanguard launches while NASA was developing more powerful vehicles. Because they could be used only once and their components were not recoverable, these unmanned rockets also were referred to as expendable launch vehicles (ELVs). In April 1959, NASA awarded a contract to the Douglas Aircraft Co. for the design, fabrication, testing and launch of an improved version of the three-stage Thor-Able expendable booster, to be called Thor-Delta (later simply the Delta). The first stage was a Thor Intermediate Range Ballistic Missile and the second and third stages were modifications of the second and third stages of the Vanguard. The Goddard group was given the responsibility for supervising the checkout and launch of Delta vehicles. They were still performing these tasks when phased over into KSC.
The Delta became the "workhorse" of NASA's ELV family, undergoing a number of upgrades in power until it could place 2,800 pounds (1,270 kilograms) in geosynchronous transfer orbit, more than 20 times its original payload capability. Of the 182 Delta launches NASA conducted through 1988, 170 were successes.
While the Cape was the primary Delta launch site, many were also launched from the West Coast. NASA used launch pads at Vandenberg Air Force Base in California to achieve polar or other north-south orbits required for certain meteorological and Earth resources satellites, as well as cosmic explorer spacecraft.
The second vehicle added to the NASA unmanned medium launch vehicle category was the Thor-Agena. The Agena was a powerful upper stage developed for the Air Force by the Lockheed Propulsion Co. It used liquid propellants and had inflight shutdown and restart capabilities. A test flight on Jan. 15, 1962, achieved most of its objectives. After two test flights, a Thor-Agena placed the huge Echo 2 balloon into orbit on Jan. 25, 1964. This spherical balloon, 135 feet (41.1 meters) in diameter, remained in orbit for two years and was the object of numerous early communications experiments by scientists from the United States, the United Kingdom, and the Soviet Union. The Thor-Agena remained in service until April 1970, with a total of 12 operational missions. This was the first NASA vehicle to be launched from Vandenberg Air Force Base. It was also the first NASA vehicle to have solid propellant rockets strapped to its first stage for additional thrust-a technique that became standard with the Delta.
Almost concurrently with the Thor-Agena, NASA developed the Atlas-Agena, a much more powerful vehicle. The Atlas stage had been developed as an Intercontinental Ballistic Missile by General Dynamics/Convair for the Air Force. When mated with the Agena, the vehicle had the capability of placing spacecraft in lunar or interplanetary trajectories. The first operational launch was on Jan. 30, 1964, a Ranger mission to impact on the Moon and take photographs during the descent to the surface. The vehicle performed well, but the Ranger camera system failed. The second Ranger mission was a success, however, returning the first close-up photographs of the lunar surface. There were 19 Atlas-Agena missions in all-including four Rangers to the Moon; five Lunar Orbiters, the first spacecraft from the United States to enter orbit around and photograph another planetary body; the first Mariner spacecraft sent to Venus and Mars; the first three Applications Technology Satellites in Earth orbit; the first Orbiting Astronomical Observatory; and three Orbiting Geophysical Observatories. The last NASA Atlas-Agena was launched on March 4, 1968.
The Air Force also continued work on vehicle development programs, though its aims and capabilities were dissimilar to those of NASA. One early project was a hydrogen-burning stage called Centaur, that would be far more powerful than those using less-volatile kerosene fuel. The service had inherited this project as an engine development effort from the National Advisory Committee for Aeronautics, NASA's predecessor. On July 1, 1959, the Air Force transferred the Centaur development program to NASA, in effect returning it to its originators. Marshall Space Flight Center was assigned management responsibility initially. The project was transferred to the Lewis Research Center between the first and second launches.
The Atlas-Centaur required new facilities, and Launch Complex 36, with two pads, was built on Cape Canaveral to accommodate it. The Atlas-Centaur development program was one of the most difficult in NASA history. The first launch on May 8, 1962, was a failure. Three of the next five missions, although trouble-plagued, were successes; one was a failure and the other only partially successful. After each flight, the analysis of system failures contributed to an overall understanding of vehicle performance. Engineering modifications and changes in the checkout procedures were instituted to correct the problems. Atlas-Centaur 8 failed in that the Centaur engines did not ignite for a second burn after a coast period of several minutes in low Earth orbit. But the design engineers and launch operations people were so certain they could correct the problem that the next flight, Atlas-Centaur 10, was scheduled for an important mission. On May 30, 1966, this vehicle carried the first Surveyor spacecraft to a spectacular accomplishment-the first soft landing of an American spacecraft on the Moon.
After that tremendous success, the overall record of the new vehicle became quite good. Atlas-Centaur achieved seven successful launches of the Surveyors, of which five went on to land safely on the Moon. The vehicle sent Mariner spacecraft to Venus, Mercury and Mars and Pioneer spacecraft to Jupiter and Saturn-feats that incredibly enriched our understanding of the solar system. It also carried into Earth orbit many spacecraft too heavy for the other available vehicles. These included the very heavy Orbiting Astronomical Observatories, INTELSAT communications satellites, the larger Applications Technology Satellites, and many more.
In 1970, NASA planners foresaw a need for an unmanned launch vehicle with greater capability than the Delta or Atlas-Centaur. Several planned future missions-specifically the Viking automated laboratories to explore the Martian surface and atmosphere and two Voyagers to observe Jupiter and Saturn-would require a spacecraft too heavy for the Delta or Atlas-Centaur to carry. At that time the Space Shuttle was only a future possibility for NASA. After studying various alternatives, NASA decided that the fastest, most economical way to obtain the new heavy lift vehicle required would be to combine two existing systems. The planners decided to replace the small third stage on the Air Force's Titan IlIC vehicle with the far more powerful Centaur upper stage of the Atlas-Centaur. The new combination, called the Titan-Centaur, became the most powerful vehicle available in the United States' unmanned space program at that time.
In addition to the Vikings and Voyagers, Titan-Centaur launched two Helios spacecraft to study the Sun.
The launches of the two Voyager spacecraft to the outer planets in 1977 were the final assignments for Titan-Centaurs. Launch Complex 41, an Air Force launch site on Cape Canaveral, was borrowed by NASA from 1974 until 1977 for Titan-Centaur launches. Martin Marietta was the contractor for the Titan stages, and General Dynamics/Convair for the Centaur. Complex 41 later became the launch site for the most powerful unmanned U.S. rocket, the Titan IV, developed by Martin Marietta for the Air Force.
Launch of an expendable rocket did not carry the risk associated with placing humans in orbit. Nevertheless, it was a complex task involving many people and costing tens of millions of dollars. Integration and checkout of a NASA unmanned booster and its payload required that launch directorate personnel work closely with the spacecraft designers to prepare needed ground support systems. This was a process that began not just days or months, but sometimes years ahead of the actual launch date.
The careful advance preparation continued when the spacecraft was delivered to Cape Canaveral well ahead of the scheduled liftoff date, so it could be assembled and checked out by the manufacturer or owner. On scientific spacecraft, the scientists responsible for individual instruments and experiments often participated in the spacecraft checkout and launch activities.
Expendable launch operations personnel also had to determine radar and photographic requirements. Support provided by the Eastern and Western Test Ranges, operated by the U.S. Air Force, had to be coordinated.
Companies which built the launch vehicles were an integral part of the ELV launch team. The test conductor was always a contractor employee, while the launch director was always from NASA. Both NASA and contractor engineering staffs were on hand to resolve technical problems. Overall direction came from the launch director, while the test conductor manned the key console and provided detailed instructions to the launch team.
The ELV program also involved a close working relationship between KSC and other NASA centers. One of these was the Goddard Space Flight Center in Greenbelt, Md., which oversaw the design and development of the Delta for NASA. Goddard also supervised the design and packaging of many scientific and technological satellites, and continues to perform this activity today. The Lewis Research Center in Cleveland oversaw the design and development of the Atlas family of vehicles, as well as the Centaur upper stage.
The Jet Propulsion Laboratory at Pasadena, Calif., was and still is the control facility for the Deep Space Network used for tracking planetary exploration spacecraft such as the Voyagers, Vikings and Mariners. The Ames Research Center near San Francisco also plays an important part in planetary investigations. This has included designing and developing the Pioneer spacecraft which returned the first detailed information on the planets Venus, Jupiter and Saturn. The Langley Research Center in Hampton, Va., managed the design and construction of the Viking Landers, two spacecraft that sent back fantastic imagery and physical measurements from the surface of Mars, and the Lunar Orbiters whose photography of the Moon paved the way for the Apollo astronauts.
The original experienced launch team KSC inherited from Vanguard has gained and lost personnel through the years, and policy surrounding NASA expendable launch vehicle operations has undergone periodic redefinition. One noticeable change that occurred was the emergence of a large number of "reimbursable" launches-those undertaken for commercial customers, foreign governments or agencies, and other branches of the U.S. government.
These "customers" would usually buy or supply their own spacecraft, purchase the launch vehicle and service from NASA, and pay the expenses associated with launching their payload. Although NASA did not make a profit from these services, the numbers involved enabled the production lines to operate at a relatively high rate, resulting in mass production efficiencies which reduced the cost of each stage. Those which NASA purchased for its own use were then less expensive than they would be otherwise.
The owner assumed control of the satellite after it was placed in orbit. Most of the reimbursable missions involved applications satellites, derived from initial scientific investigations performed by NASA. The percentage of such missions peaked in 1980, when 83 percent of the spacecraft were launched on a reimbursable basis.
Manned space flight also had an impact on the unmanned payloads field. In January 1979, following a management reorganization, the unmanned launch operations directorate was assigned the added responsibility of processing payloads for the then nascent Space Shuttle program.
With the advent of the manned Shuttle, NASA envisioned that reliance on expendable launch vehicles would decline. The Shuttle concept offered a unique advantage over expendable launch vehicles-it was a reusable resource.
The first Shuttle flight occurred in April 1981. As one successful mission followed another, NASA implemented a corresponding phase-down in ELV launches.
An alternate role for expendable launch vehicles began to emerge in the early 1980s. In January 1983, the administration of President Ronald Reagan announced that the federal government would encourage private industry to build and operate ELVs to deliver commercial payloads -- such as communications satellites -- into orbit. Government facilities, including those at Cape Canaveral and Vandenberg, would be made available to private industry on a cost-reimbursable basis. The military also now regarded unmanned rockets as an invaluable backup to the Shuttle.
Further influencing government policy regarding ELVs was the Space Shuttle Challenger accident in January 1986. Six months later, NASA gave the commercial ELV industry a needed boost when the agency announced that commercial payloads such as communications satellites would no longer be deployed from the Shuttle.
About the same time, the Air Force announced plans to use unmanned vehicles for many of its future payloads. These decisions opened the door wide, not only to the big three American ELV manufacturers -- General Dynamics, builder of the Atlas family of vehicles, Martin Marietta, the Titan, and McDonnell Douglas, the Delta -- but other entrepreneurial firms eager to join the space race. These firms would not have to compete against the Space Shuttle to launch commercial payloads, although formidable competition was emerging from established or developing foreign firms and agencies.
NASA reassessed its own policy toward unmanned expendable rockets. The agency concluded that a mixed fleet of launch vehicles, rather than reliance on a single system, the Shuttle, was the best approach. In 1987, NASA announced its mixed fleet plan. "Expendable vehicles will help assure access to space, add flexibility to the space program, and free the Shuttle for manned scientific, Shuttle-unique, and important national security missions," NASA Administrator Dr. James Fletcher said.
The plan calls for procuring ELV launch service competitively whenever possible, except for a transitional first phase covering launches through 1991. During this transition, NASA will procure ELV launch service non-competitively to address a backlog of space science missions. The agency's role will be the same throughout both phases, however: oversight of vehicle manufacture, preparation and launch, rather than direct management of it, as was the case in the past.
Under the transitional first phase, NASA will go through either the Air Force or directly to the vehicle manufacturer to obtain the best match between vehicle and payload for the time frame in which each will be needed. Vehicles being produced under contracts for the military, such as the Titan 11, Titan IV, Delta 11, Atlas E and Atlas 11, will be procured via the Air Force.
If NASA should buy a commercially available vehicle, the manufacturer will provide not only the vehicle, but launch service as well. Failing into this category are several variants of expendable rockets originally designed and built for either the Air Force or NASA and now being marketed commercially, such as the Titan III and Atlas I (formerly the Atlas-Centaur). Some vehicle types, like the Delta II and Atlas II, are simultaneously being produced under contracts to the Air Force and offered for commercial launch service.
An already strong legacy will gain greater luster in the next decade when a number of exciting and vital space science missions are launched for NASA on ELVs as part of the first phase. A Delta 11 booster procured through the Air Force will carry into space the Roentgen Satellite (ROSAT), an X-ray telescope that, once in orbit, will allow scientists to study such phenomena as the high X-ray luminosity of stars that otherwise appear to be identical to the sun. ROSAT will build on data provided by the High Energy Astronomy Observatory series, launched in the late 1970s on Atlas-Centaurs. West Germany is providing the telescope and the spacecraft, and the United Kingdom one of the focal instruments. The United States is procuring the launch vehicle and services, and also will provide one focal instrument.
NASA-sponsored exploration of the red planet, Mars, will resume with the Mars Observer mission in the early 1990s aboard a commercial Titan III rocket. Mars Observer will circle the planet for two years in a low, near-circular polar orbit, mapping the planetary surface as it changes with the seasons. Eight instruments will measure and investigate characteristics such as elements, minerals, cloud composition, and the nature of the Martian magnetic field.
Long-range plans call for NASA to purchase through the Air Force the most powerful American-made unmanned booster, the Titan IV-Centaur. The agency wants to launch two Titan IV-Centaurs in the mid-1990s as part of an ongoing program of solar system exploration.
The first planned mission is the Comet Rendezvous and Asteroid Flyby (CRAF), which will yield new insights into two types of smaller bodies in our solar system. En route to its rendezvous with the comet Knopff, CRAF will fly by the asteroid 449 Hamburga. It will take photographs. and scientific measurements of the asteroid, which is only 55 miles (88.5 kilometers) in diameter. Once at Knopff, CRAF will spend three years flying alongside the comet. Scientists will be able to study a body of what could be some of the original matter left behind when our solar system was formed nearly 5 billion years ago.
The second Titan IV-Centaur is slated for the Cassini mission, named after a French-Italian astronomer who discovered several of Saturn's moons. Cassini will carry out a four-year tour of Saturn and its moons. It will also send a probe through the dense atmosphere surrounding Titan, the largest of Saturn's satellites, to collect data and provide a preliminary map of its surface. Cassini will be a joint effort between NASA and the European Space Agency.
In the second phase of the mixed fleet plan, ELV launch manufacturers will compete to launch a class of payload in a particular weight category-small, medium, intermediate and large. As in the transitional phase, the winning company will provide complete launch service, from building the ELV to launching it.
General Dynamics was the first ELV builder to receive an order under the second phase. In October 1987, NASA announced that it had chosen the Atlas I over Martin Marietta's Titan booster to launch a series of meteorological satellites for the National Oceanic and Atmospheric Administration (NOAA). At least three of the Geostationary Operational Environmental Satellite (GOES) spacecraft will be launched on Atlas Is from Launch Complex 36, and the number could reach five. Also in 1987, General Dynamics completed negotiations with NASA for use of the Launch Complex 36 facilities for commercial launches.
The two NASA centers which oversaw design and development of the Delta and Atlas rockets will still be involved with ELVs, but with a different slant. Goddard Space Flight Center is managing both competitive and non-competitive procurement of ELV launch services in the small payload class, which includes the Scout (not launched from Cape Canaveral), and medium weight payload class, which includes the Delta. In July 1989, Goddard announced that Delta manufacturer McDonnell Douglas had been competitively selected to negotiate a contract for three firm and 12 optional missions in the latter category.
Lewis Research Center will manage competitive and non-competitive procurement of ELVs capable of launching intermediate class payloads, which includes the Atlas-Centaur, and large class, which includes the Titan IV.
At KSC and Cape Canaveral, control of civilian unmanned launches is gradually being shifted from NASA to the private sector. In October 1988, Martin Marietta and NASA announced an agreement under which Martin will use some KSC facilities to support its Titan III commercial launches. Earlier the same year, a 28-year era drew to a close when NASA launched a Delta rocket for the last time from Launch Complex 17 on the Cape. In November the following year, the last Delta in the NASA inventory was launched on the West Coast. It carried the Cosmic Background Explorer (COBE) into orbit from Vandenberg AFB. In July 1988, Launch Complex 17 was formally turned over to the Air Force, which will allow Delta manufacturer McDonnell Douglas to conduct commercial launches from the same complex.
The Air Force also will assume control of Launch Complex 36; one of the two pads will be used by General Dynamics for commercial launches. In September 1989, NASA conducted its final launch of an Atlas-Centaur from the Cape. Atlas-Centaur 68, carrying the last in a series of Fleet Satellite Communications (FItSatCom) spacecraft, was originally scheduled for launch in 1987. The mission was postponed when the Centaur's liquid hydrogen tank was accidentally punctured by a work platform.
KSC will continue to be involved with ELV launches of U.S. civil payloads, but, as is the case with Goddard and Lewis, the slant will be different. In early 1989, KSC was assigned oversight responsibility for all unmanned launches carrying NASA payloads from both the Cape and Vandenberg AFB.
The NASA unmanned launch operations team has completed many historic launches. These space flights far exceed in number the manned missions of the Mercury, Gemini, Apollo, Skylab and Apollo-Soyuz programs. More than 300 unmanned launches were conducted from 1958 through the end of 1989, with a high rate of success. Unmanned spacecraft have returned volumes of scientific data, much of it not otherwise obtainable. The effects on scientific knowledge as a whole are incalculable. Technological benefits from applications spacecraft have provided better weather forecasting, accurate storm tracking, a superb international communications system that permits live television coverage from almost anywhere in the world, highly accurate navigation for ships and planes, and inventories of the resources of land and ocean. The unmanned space program already has more than repaid the nation's investment in time, money and technical talent as it enters its fourth decade.
The following table provides launch dates and brief descriptions of some of the more significant missions.
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