The Juno I was a four-stage American space launch vehicle, used to launch lightweight payloads into low Earth orbit. The launch vehicle was used between January 1958 to December 1959. The launch vehicle was a member of the Redstone launch vehicle family, and was derived from the Jupiter-C

sounding rocket A sounding rocket or rocketsonde, sometimes called a research rocket or a suborbital rocket, is an instrument-carrying rocket designed to take measurements and perform scientific experiments during its sub-orbital flight. The rockets are used to ...

. It is commonly confused with the

Juno II Juno II was an American space launch vehicle used during the late 1950s and early 1960s. It was derived from the Jupiter missile, which was used as the first stage. Development Solid rocket motors derived from the MGM-29 Sergeant were used ...

launch vehicle, which was derived from the PGM-19 Jupiter

medium-range ballistic missile A medium-range ballistic missile (MRBM) is a type of ballistic missile with medium range, this last classification depending on the standards of certain organizations. Within the U.S. Department of Defense, a medium-range missile is defined by ...

. In 1958, a Juno I launch vehicle was used to launch America's first satellite,

Explorer 1 Explorer 1 was the first satellite launched by the United States in 1958 and was part of the U.S. participation in the International Geophysical Year (IGY). The mission followed the first two satellites the previous year; the Soviet Union's ...

History

Developed as a part of the Explorer Project, the original goal for the launch vehicle was to place an artificial satellite into orbit. Following the Soviet Union's launch of

Sputnik 1 Sputnik 1 (; see § Etymology) was the first artificial Earth satellite. It was launched into an elliptical low Earth orbit by the Soviet Union on 4 October 1957 as part of the Soviet space program. It sent a radio signal back to Earth for t ...

on October 4, 1957 (and the resulting "

Sputnik crisis The Sputnik crisis was a period of public fear and anxiety in Western nations about the perceived technological gap between the United States and Soviet Union caused by the Soviets' launch of ''Sputnik 1'', the world's first artificial satelli ...

") and the failure of the Vanguard 1 launch attempt, the program received funding to match the Soviet space achievements. The launch vehicle family name was proposed in November 1957 by Jet Propulsion Laboratory (JPL) Director Dr. William Pickering, who proposed the name Juno, after the Roman goddess and queen of the gods, as well as for its position as the satellite-launching version of the Jupiter-C. The fourth stage for the Juno I launch vehicle was derived following the September 1956 test launch of a Jupiter-C for the Army Ballistic Missile Agency, which could have been the world's first satellite launch, had a fourth stage been loaded and fueled. This fourth stage would have allowed the nose cone to overshoot the target and enter orbit. The first launch of a Juno I launch vehicle was in early 1958, with the successful launch of

satellite on February 1, 1958, at 03:47:56 GMT, after the Soviet Union's

on October 4, 1957. The launch had been originally been scheduled for January 29, 1958, but was scrubbed twice. Explorer 1 was the first U.S. satellite, and became the first satellite to detect and discovered the Van Allen radiation belt. Following the first successful launch of the launch vehicle, five more Juno I launch attempts occurred, three successful, three failures. The final launch attempt was on October 23, 1958, from Cape Canaveral Launch Pad 5, which ended in failure.

Launch vehicle

The Juno I consisted of a Jupiter-C first stage, based on the Redstone missile; with three additional

solid fuel Solid fuel refers to various forms of solid material that can be burnt to release energy, providing heat and light through the process of combustion. Solid fuels can be contrasted with liquid fuels and gaseous fuels. Common examples of solid fuels ...

stages based on the Sergeant missile to provide the added impulse to achieve orbit. The fourth stage was mounted on top of the "tub" of the third stage, and fired after third-stage burnout to boost the payload and fourth stage to an orbital velocity of , with an acceleration of 25–51 g. The tub along with the fourth stage were set spinning while the launch vehicle was on the launch pad to provide gyroscopic force in lieu of a guidance system that would have required thrust vectoring, vernier thrusters, or a reaction control system. The booster guidance package (with the tub attached) separated from the first stage after burnout to provide attitude control until second stage ignition. This multi-stage system, designed by Wernher von Braun in 1956 for his proposed

Project Orbiter Project Orbiter was a proposed United States spacecraft, an early competitor to Project Vanguard. It was jointly run by the United States Army and United States Navy. It was ultimately rejected by the Ad Hoc Committee on Special Capabilities, whi ...

, obviated the need for a guidance system in the upper stages. It was the simplest method for putting a payload into orbit but having no upper-stage guidance, the payload could not achieve a precise orbit. Both the four-stage Juno I and three-stage Jupiter-C launch vehicles were the same height (), with the added fourth-stage booster of the Juno I being enclosed inside the nose cone of the third stage.

Launch history

Following the successful launch of

on February 1, 1958, the first U.S. satellite, Juno I made five more launches before being retired in favor of

. Although Juno I's launch of the

satellite was a huge success for the U.S. space program, only two of its remaining five flights were successful,

Explorer 3 Explorer 3 (Harvard designation 1958 Gamma) was an American artificial satellite launched into medium Earth orbit in 1958. It was the second successful launch in the Explorer program, and was nearly identical to the first U.S. satellite Explor ...

and

Explorer 4 Explorer 4 was an American satellite launched on 26 July 1958. It was instrumented by Dr. James van Allen's group. The Department of Defense's Advanced Research Projects Agency (ARPA) had initially planned two satellites for the purposes of stu ...

, giving the Juno I vehicle a mission total success ratio of 50%. The Juno I vehicle was replaced by the

in 1959. The American public was happy and relieved that America had finally managed to launch a satellite after the launch failures in the Vanguard and Viking series. With the relative success of the Juno I program, von Braun developed the

, using a PGM-19 Jupiter first stage, rather than a Redstone.

Gallery

References

External links

* Source: Data Sheet, Department of Astronautics,

National Air and Space Museum The National Air and Space Museum of the Smithsonian Institution, also called the Air and Space Museum, is a museum in Washington, D.C., in the United States. Established in 1946 as the National Air Museum, it opened its main building on the Nat ...

, Smithsonian Institution. {{US launch systems 1958 in spaceflight Space launch vehicles of the United States