The SM-65B Atlas, or Atlas B, also designated X-12

X-plane

The X-planes are a series of experimental United States airplanes and helicopters used for the testing and evaluation of new technologies and aerodynamic concepts...

was a prototype of the Atlas missile. First flown on 19 July 1958, the Atlas B was the first version of the Atlas rocket to use the stage and a half design.

Ten flights were made. Nine of these were sub-orbital test flights of the Atlas as an Intercontinental Ballistic Missile

Intercontinental ballistic missile

An intercontinental ballistic missile is a ballistic missile with a long range typically designed for nuclear weapons delivery...

, with five successful missions and four failures. The seventh flight, launched on 18 December 1958, was used to place the SCORE

Project SCORE

Project SCORE was the world’s first communications satellite. Launched aboard an Atlas rocket on December 18, 1958, SCORE provided a first test of a communications relay system in space, as well as the first successful use of the Atlas as a launch vehicle...

 satellite into low Earth orbit

Low Earth orbit

A low Earth orbit is generally defined as an orbit within the locus extending from the Earth’s surface up to an altitude of 2,000 km...

, the first orbital launch conducted by an Atlas rocket.

All Atlas-B launches were conducted from Cape Canaveral Air Force Station

Cape Canaveral Air Force Station

Cape Canaveral Air Force Station is an installation of the United States Air Force Space Command's 45th Space Wing, headquartered at nearby Patrick Air Force Base. Located on Cape Canaveral in the state of Florida, CCAFS is the primary launch head of America's Eastern Range with four launch pads...

, at Launch Complexes 11

Cape Canaveral Air Force Station Launch Complex 11

Launch Complex 11 at Cape Canaveral Air Force Station, Florida, is a launch complex used by Atlas missiles between 1958 and 1964. It is the southernmost of the launch pads known as missile row...

, 13

Cape Canaveral Air Force Station Launch Complex 13

Launch Complex 13 at Cape Canaveral Air Force Station, Florida is a deactivated launch complex used by Atlas rockets and missiles between 1958 and 1978. It is the third-most southern of the complexes known as missile row, between LC-12 and LC-14...

 and 14

Cape Canaveral Air Force Station Launch Complex 14

Launch Complex 14 is a launch site at Cape Canaveral Air Force Station, Florida. LC-14 was used for various manned and unmanned Atlas launches, including the Friendship 7 flight aboard which John Glenn became the first American to orbit the Earth....

.

Launch history

Date	Time (GMT)	Pad	Serial	Apogee	Outcome	Remarks
			3B	10 kilometres (6.2 mi)	Failure
1958-08-02	22:16	LC-13	4B	900 kilometres (559.2 mi)	Success
1958-08-29	04:30	LC-11	5B	900 kilometres (559.2 mi)	Success
1958-09-14	05:24	LC-14	8B	900 kilometres (559.2 mi)	Success
1958-09-18	21:27	LC-13	6B	100 kilometres (62.1 mi)	Failure
1958-11-18	04:00	LC-11	9B	800 kilometres (497.1 mi)	Failure
1958-11-29	02:27	LC-14	12B	900 kilometres (559.2 mi)	Success	First full-range test flight
1958-12-18	22:02	LC-11	10B	N/A	Success	Placed SCORE Project SCORE Project SCORE was the world’s first communications satellite. Launched aboard an Atlas rocket on December 18, 1958, SCORE provided a first test of a communications relay system in space, as well as the first successful use of the Atlas as a launch vehicle... satellite into 185km x 1,484km x 32.3° orbit
1959-01-16	04:00	LC-14	13B	100 kilometres (62.1 mi)	Failure
1959-02-04	08:01	LC-11	11B	900 kilometres (559.2 mi)	Success