First US lunar attempt. The first US Air Force lunar probe, using a Thor-Able booster. An explosion ripped it apart 77 seconds after launch.

Set distance record; failed to reach moon.

Pioneer 2 was launched from the Atlantic Missile Range, using a Thor-Able booster, the Air Force acting as executive agent to NASA. The 86.3-pound instrumented payload, intended as a lunar probe, failed to reach escape velocity.

Failed to reach moon; provided radiation data. Pioneer III, the third U.S.-IGY intended lunar probe under the direction of NASA with the Army acting as executive agent, was launched from the Atlantic Missile Range by a Juno II rocket. The primary objective, to place the 12.95 pound scientific payload in the vicinity of the moon, failed. Pioneer III reached an altitude of approximately 70,000 miles and revealed that the earth's radiation belt comprised at least two distinct bands.

The fourth U.S.-IGY lunar probe effort, Pioneer IV, a joint project of the Army Ballistic Missile Agency and Jet Propulsion Laboratory under the direction of NASA, was launched by a Juno II rocket from the Atlantic Missile Range. Intended to impact on the lunar surface, Pioneer IV achieved earth-moon trajectory, passing within 60,200 km of the moon before going into permanent orbit around the sun.

An intended lunar probe launched from the Atlantic Missile Range by an Atlas-Able booster disintegrated about 45 seconds later when the protective sheath covering the payload detached prematurely. The probe was sponsored by NASA, developed by the Jet Propulsion Laboratory, and launched by the Air Force Ballistic Missile Division.

Solar research. Solar Orbit (Heliocentric). Spacecraft engaged in research and exploration of the upper atmosphere or outer space (US Cat B).

An attempt to launch a Pioneer satellite into lunar orbit failed when one of the upper stages of the Atlas- Able rocket malfunctioned.

The final launch in the Pioneer lunar probe program was unsuccessful; the Atlas-Able booster rocket went out of control and exploded at an altitude of 12,200 m off Cape Canaveral.

Measured solar wind, Sun's magnetic field. Solar Orbit (Heliocentric). Spacecraft engaged in research and exploration of the upper atmosphere or outer space (US Cat B).

Monitored solar wind, cosmic rays. SOLAR ORB. Spacecraft engaged in research and exploration of the upper atmosphere or outer space (US Cat B).

Solar radiation data. Solar Orbit (Heliocentric). Spacecraft engaged in research and exploration of the upper atmosphere or outer space (US Cat B).

Solar radiation data. Solar Orbit (Heliocentric). Spacecraft engaged in research and exploration of the upper atmosphere or outer space (US Cat B).

Jupiter flyby December 1973; first man-made object to leave solar system. The spacecraft achieved its closest approach to Jupiter on December 3, 1973, when it reached approximately 2.8 Jovian radii (about 200,000 km). As of Jan. 1, 1997 Pioneer 10 was at about 67 AU from the Sun near the ecliptic plane and heading outward from the Sun at 2.6 AU/year and downstream through the heliomagnetosphere towards the tail region and interstellar space.

Jupiter flyby December 1974; Saturn flyby September 1979. Solar system escape trajectory. Pioneer 11 was the second mission to investigate Jupiter and the outer solar system and the first to explore the planet Saturn and its main rings. Pioneer 11, like Pioneer 10, used Jupiter's gravitational field to alter its trajectory radically. It passed close to Saturn and then it followed an escape trajectory from the solar system. During its closest approach, December 4, 1974, Pioneer 11 passed to within 34,000 km of Jupiter's cloud tops. It passed by Saturn on September 1, 1979, at a distance of 21,000 km from Saturn's cloud tops. The spacecraft has operated on a backup transmitter since launch. Instrument power sharing began in February 1985 due to declining RTG power output. Science operations and daily telemetry ceased on September 30, 1995 when the RTG power level was insufficient to operate any experiments. As of the end of 1995 the spacecraft was located at 44.7 AU from the Sun at a nearly asymptotic latitude of 17.4 degrees above the solar equatorial plane and was heading outward at 2.5 AU/year. Routine tracking and project data processing operations were terminated on March 31, 1997 for budget reasons.

The Pioneer Venus Orbiter was inserted into an elliptical orbit around Venus on December 4, 1978. After entering orbit around Venus in 1978, the spacecraft returned global maps of the planet's clouds, atmosphere and ionosphere, measurements of the atmosphere-solar wind interaction, and radar maps of 93 percent of the planet's surface. Additionally, the vehicle made use of several opportunities to make systematic UV observations of several comets. From Venus orbit insertion to July 1980, periapsis was held between 142 and 253 km (at 17 degrees north latitude) to facilitate radar and ionospheric measurements. The spacecraft was in a 24 hour orbit with an apoapsis of 66,900 km. Thereafter, the periapsis was allowed to rise (to 2290 km at maximum) and then fall, to conserve fuel. In 1991 the Radar Mapper was reactivated to investigate previously inaccessible southern portions of the planet. In May 1992 Pioneer Venus began the final phase of its mission, in which the periapsis was held between 150 and 250 km until the fuel ran out and atmospheric entry destroyed the spacecraft. With a planned primary mission duration of only eight months, the spacecraft remained in operation until October 8, 1992 when it finally burned up in Venus' atmosphere after running out of propellant.

The Pioneer Venus Multiprobe consisted of a bus which carried one large and three small `atmospheric probes. The large probe was released on November 16, 1978 and the three small probes on November 20. All four probes entered the Venus atmosphere on December 9, followed by the bus. The small probes were each targeted at different parts of the planet and were named accordingly. The North probe entered the atmosphere at about 60 degrees north latitude on the day side. The night probe entered on the night side. The day probe entered well into the day side, and was the only one of the four probes which continued to send radio signals back after impact, for over an hour. With no heat shield or parachute, the bus survived and made measurements only to about 110 km altitude before burning up. It afforded the only direct view of the upper Venus atmosphere, as the probes did not begin making direct measurements until they had decelerated lower in the atmosphere.