Any of a series of U.S. expendable space launch vehicles.
The Atlas was originally designed as a liquid-fueled ICBM and first tested in an operational version in 1959. Early versions launched most of the Mercury manned missions and, coupled with upper-stage rockets, a number of Ranger , Surveyor , Mariner , and Pioneer probes on lunar and planetary missions. Later generations have become workhorses of the U.S. space program and carry a wide variety of scientific, military, and commercial spacecraft.