Pioneer H is an unlaunched

unmanned space mission A robotic spacecraft is an uncrewed spacecraft, usually under telerobotic control. A robotic spacecraft designed to make scientific research measurements is often called a space probe. Many space missions are more suited to telerobotic rather ...

that was part of the US

Pioneer program The Pioneer programs were two series of United States lunar and planetary space probes exploration. The first program, which ran from 1958 to 1960, unsuccessfully attempted to send spacecraft to orbit the Moon, successfully sent one spacecraft to ...

for a planned 1974 launch. Had this mission and spacecraft been launched, it would have been designated Pioneer 12; that designation was later applied to the

Pioneer Venus Orbiter The Pioneer Venus Orbiter, also known as Pioneer Venus 1 or Pioneer 12, was a mission to Venus conducted by the United States as part of the Pioneer Venus project. Launched in May 1978 atop an Atlas-Centaur rocket, the spacecraft was inserted into ...

History

As planning for the Pioneer 10 and 11 missions progressed, mission scientists found themselves desiring a third probe. In 1971, a formal mission study was proposed for a spacecraft to be launched to

Jupiter Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but slightly less than one-thousand ...

in 1974, where it would use the gas giant as a gravitational slingshot to travel outside the

ecliptic The ecliptic or ecliptic plane is the orbital plane of the Earth around the Sun. From the perspective of an observer on Earth, the Sun's movement around the celestial sphere over the course of a year traces out a path along the ecliptic agains ...

. This was the first Out-Of-The-Ecliptic mission (OOE) proposed, for Jupiter and solar (Sun) observations. NASA/Ames Research Center would have managed the project. The

NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeedin ...

contractor TRW Systems Group (formerly Space Technology Laboratories) would have constructed Pioneer H from the flight-qualified spare components intended for the Pioneer F and G probes (designated

Pioneer 10 ''Pioneer 10'' (originally designated Pioneer F) is an American space probe, launched in 1972 and weighing , that completed the first mission to the planet Jupiter. Thereafter, ''Pioneer 10'' became the first of five artificial objects to ac ...

and

Pioneer 11 ''Pioneer 11'' (also known as ''Pioneer G'') is a robotic space probe launched by NASA on April 5, 1973, to study the asteroid belt, the environment around Jupiter and Saturn, solar winds, and cosmic rays. It was the first probe to encoun ...

after launch). NASA management did not approve the mission proposal, and it was never launched. In 1976 NASA transferred the craft (without RTG) to the

Smithsonian Institution The Smithsonian Institution ( ), or simply the Smithsonian, is a group of museums and education and research centers, the largest such complex in the world, created by the U.S. government "for the increase and diffusion of knowledge". Found ...

. In January 1977, Pioneer H was moved to the

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 N ...

, where it was eventually displayed as a replica of Pioneer 10.

Successor missions

The Pioneer H mission concept was finally realized with the Ulysses mission, which achieved the OOE orbit originally envisioned for Pioneer H. The Juno mission, currently at Jupiter in a polar orbit, is taking the

magnetometer A magnetometer is a device that measures magnetic field or magnetic dipole moment. Different types of magnetometers measure the direction, strength, or relative change of a magnetic field at a particular location. A compass is one such device, ...

observations of Jupiter's poles that Pioneer H would have performed.

Current location

Pioneer H hangs in the Milestones of Flight Gallery at the

in Washington, D.C., serving as a stand-in for the Pioneer 10 probe. While described in official Smithsonian records as a "replica", the spacecraft was considered fully functional by Pioneer mission planners (though its RTGs were never installed). Mark Wolverton quotes

James Van Allen James Alfred Van Allen (September 7, 1914August 9, 2006) was an American space scientist at the University of Iowa. He was instrumental in establishing the field of magnetospheric research in space. The Van Allen radiation belts were named aft ...

in ''The Depths of Space'':

We mounted an intensive campaign to launch the flight-worthy spare spacecraft and its instrument complement on a low-cost, out-of-ecliptic mission via a high-inclination flyby of Jupiter. However, our case fell on deaf ears at NASA headquarters, and the spare spacecraft now hangs in the main gallery of the National Air and Space Museum, at 1 AU and zero ecliptic latitude.

References

External links

The Depths of Space: The Story of the Pioneer Planetary Probes, Mark Wolverton, 2004

* ttps://web.archive.org/web/20070609082915/http://www.nasm.si.edu/research/dsh/artifacts/SS-pioneerX.htm Assembling for NASM the Pioneer 10 replica
International Solar Polar mission, 1979
{{NASA space program Cancelled spacecraft Pioneer program Individual spacecraft in the collection of the Smithsonian Institution Missions to the Sun