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Expendable Launch Vehicles

All Expendable Launch Vehicles use the same basic technology to get into space – two or more rocket-powered stages, which fall away when their engine burns are completed. Whatever a launch vehicle carries above the final discarded stage is considered the payload.

A payload’s weight, orbital destination and purpose determine what size launch vehicle is required. A small ELV like Pegasus can place a low-weight spacecraft into near-Earth orbit, while an expendable vehicle like the massive Saturn V was required to send manned Apollo spacecraft to the Moon.

The powerful Titan/Centaur combination carried large and complex robotic scientific explorers, such as the Vikings and Voyagers, to examine other planets in the 1970s. Among other missions, the Atlas/Agena vehicle sent several spacecraft to photograph and then impact the Moon. Atlas/Centaur vehicles launched many of the larger spacecraft into Earth orbit and beyond.

To date, Delta launch vehicles have carried more than 200 NASA scientific, wind and communications payloads into orbit, or to other planets. NASA used the Athena I and II vehicles to launch scientific satellites from VAFB, CCAFS and Kodiak Island. The Pegasus, an Orbital Sciences fleet vehicle, is the only airborne launch vehicle in the ELV fleet. The Taurus vehicle, also built by Orbital Sciences, may be used for future NASA launches.

ELV Services Fleet

Atlas/CentaurThe Atlas/Centaur vehicles first became operational in 1966. Lockheed Martin used the Atlas II and III vehicles to launch military, commercial and scientific payloads into space from Space Launch Complex 36 at CCAFS and Space Launch Complex 3E at VAFB. More than 580 Atlas flights have taken place, including 170 flights with the Centaur stage added to create the Atlas/Centaur vehicle.

When launched by NASA through 1989, the Atlas/Centaur was the standard vehicle for intermediate payloads that carried about 8,200 pounds (3,700 kilograms) to Geosynchronous Transfer Orbit (GTO). The Centaur was the first high-energy, liquid-hydrogen/liquid-oxygen launch vehicle stage, and it provided the most power for its weight of any proven stage then in use.

The Atlas/Centaur was the launch vehicle for Surveyor I, the first U.S. spacecraft to soft-land on the Moon. Other spacecraft launched by Atlas/Centaurs include the Orbiting Astronomical Observatories; Applications Technology Satellites; the Intelsat IV, IV-A and V series of communications satellites; Mariner Mars orbiters; a Mariner spacecraft that made a flyby of Venus and three flybys of Mercury; Pioneers, which accomplished flybys of Jupiter and Saturn; and Pioneers that orbited Venus and sent probes plunging through its atmosphere to the surface. Most recently, NASA launched the Tracking Data and Relay Satellite-J communication satellite Dec. 4, 2002, on an Atlas IIA from CCAFS.

Lockheed Martin developed the Atlas III launch system that debuted in 2000. This vehicle can carry more than 8,819 pounds (4,000 kilograms) to geosynchronous transfer orbit. The Atlas V system, the newest of Lockheed Martin’s fleet, first launched Aug. 21, 2002, carrying a commercial communications satellite. The AtlasVcan carry from 8,700 pounds (3,946 kilograms) to 19,100 pounds (8,663 kilograms) to GTO from Space Launch Complex 41 at CCAFS.


Delta rockets have been built and launched since 1960. Delta's origins go back to the Thor intermediate-range ballistic missile, which was developed in the mid-1950s for the U.S. Air Force. The Thor, a single-stage, liquid-fueled rocket, was modified to become the Delta launch vehicle, which later evolved into the Delta II.

Known as the "workhorse" of the launch industry, the Delta II comprises a group of expendable rockets that can be configured as two- or three-stage vehicles and with three, four or nine strap-on graphite epoxy motors (GEMs) depending on mission needs.

Delta IV was developed in partnership with the U.S. Air Force EELV program and is the most advanced family of Delta rockets. Delta IV blends advanced and proven technology to launch virtually any size medium-to-heavy class payload to space.


On April 5, 1990, Orbital began a new era in commercial space flight when our Pegasus rocket was launched for the first time from beneath a NASA B-52 carrier aircraft in a mission that originated from Dryden Flight Research Center in California. In the decade since its maiden flight, Pegasus has become the world's standard for affordable and reliable small launch vehicles. It has conducted 38 missions, launching 78 satellites.

The three-stage Pegasus is used by commercial, government and international customers to deploy small satellites weighing up to 1,000 pounds into low-Earth orbit. Pegasus is carried aloft by our "Stargazer" L-1011 aircraft to approximately 40,000 feet over open ocean, where it is released and then free-falls in a horizontal position for five seconds before igniting its first stage rocket motor. With the aerodynamic lift generated by its unique delta-shaped wing, Pegasus typically delivers satellites into orbit in a little over 10 minutes.

This patented air-launch system reduces cost and provides customers with unparalleled flexibility to operate from virtually anywhere on Earth with minimal ground support requirements. Pegasus launches have been conducted from six separate sites in the U.S., Europe and the Marshall Islands, the first time a space launch vehicle has demonstrated such operational flexibility.


The Taurus rocket offers an affordable, reliable means of launching small satellites into low-Earth orbit. Developed under the sponsorship of the Defense Advanced Research Projects Agency (DARPA), Taurus was designed for easy transportability and rapid set-up and launch. Since its debut flight in 1994, Taurus has conducted six of seven successful missions launching 12 satellites for commercial, civil, military, and international customers.

Taurus is a ground-based variant of our air-launched Pegasus rocket. The four stage, inertially guided, all solid propellant vehicle can deploy 1,350-kilogram (3,000 pound) satellites into low-Earth orbit. Two fairing sizes offer flexibility in designing a particular mission, and with the addition of a structural adapter, either can accommodate multiple payloads, resulting in lower launch costs for smaller satellites "sharing" a mission.

A cornerstone of the Taurus program is a simplified integration and test capability that includes horizontal integration of the rocket's upper stages and offline encapsulation of the payload within the fairing. The upper stages and the encapsulated cargo are delivered to the launch site, where they are mated. The whole assembly is then stacked on the first stage using a mobile crane.

The Taurus launch system includes a complete set of ground support equipment to ensure the ability to operate from austere sites. Thus far, Taurus has launched from the U.S. Government's Western range at Vandenberg Air Force Base (VAFB) in California. Taurus is also approved for launch from Cape Canaveral Air Station (CCAS) in Florida, Wallops Flight Facility (WFF) in Virginia, and Kodiak Launch Complex, Alaska.


The Titan was used by NASA to launch interplanetary missions from CCAFS. An earlier version of the Titan vehicle, the Titan III-E/Centaur, built by Martin Marietta and General Dynamics, was used to launch two Helios missions to the Sun, two Viking missions to Mars, and two Voyager missions to Jupiter and Saturn beginning in the 1970s. One of the Voyagers also continued on to Uranus and Neptune. All of the missions provided remarkable new scientific data about our Solar System and spectacular color photographs of the planets they explored, as well as some of their moons.

The Titan IV launched NASA’s Cassini spacecraft to Saturn in 1997. The Titan III sent NASA’s Mars Observer on its journey in 1992. The Titan II was used This Titan IVB/Centaur rocket launches Oct. 15, 1997, carrying the Cassini launch many National Oceanic and Atmospheric Administration (NOAA) weather satellites. Most recently, a Titan II launched NASA’s NOAA-M satellite June 24, 2002, from VAFB.

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Tim Reckart
NASA Official: Thomas St. Onge
Last Updated: February 3, 2011
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