Pioneer P-30

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Pioneer P-30 (also known as Atlas-Able 5A, or Pioneer Y) was intended to be a lunar orbiter probe, but the mission failed shortly after launch on September 25, 1960. The objectives were to place a highly instrumented probe in lunar orbit, to investigate the environment between the Earth and Moon, and to develop technology for controlling and maneuvering spacecraft from Earth. It was equipped to estimate the Moon's mass and topography of the poles, record the distribution and velocity of micrometeorites, and study radiation, magnetic fields, and low frequency electromagnetic waves in space. A mid-course propulsion system and injection rocket would have been the first United States self-contained propulsion system capable of operation many months after launch at great distances from Earth and the first U.S. tests of maneuvering a satellite in space.

Contents

Mission

The spacecraft was launched on an Air Force-Convair Atlas D intercontinental ballistic missile coupled to Thor-Able upper stages including a Hercules ABL solid propellant third stage. The first stage burned normally for 275 seconds, the two Atlas booster engines were jettisonned as planned after ~250 seconds. At an altitude of about 370 km (230 mi) the first stage separated from the second stage. When the second stage was ignited telemetry showed abnormal burning and the stage failed due to a malfunction in the oxidizer system. The vehicle was unable to achieve Earth orbit, re-entered and was believed to have come down somewhere in the Indian Ocean. Signals were returned by the payload for 1020 seconds after launch. The mission was designed to reach the Moon approximately 62 hours after launch. Although the mission was a failure, ground controllers fired Able VA’s onboard liquid propellant hydrazine rocket engine — the first time that an onboard motor was fired on a space vehicle. [1]

Spacecraft design

Pioneer P-30 was almost identical to the earlier Pioneer P-3 satellite which failed, a 1 meter diameter sphere with a propulsion system mounted on the bottom giving a total length of 1.4 meters (55 inches). The mass of the structure and aluminum alloy shell was about 30 kg (65 lb) and the propulsion units roughly 90 kg (200 lb). Four solar panels, each 60×60 cm (24×24 inches) and containing 2200 solar cells in 22 100-cell nodules, extended from the sides of the spherical shell in a "paddle-wheel" configuration with a total span of about 2.7 meters (105 in). The solar panels charged nickel-cadmium batteries. Inside the shell, a large spherical hydrazine tank made up most of the volume, topped by two smaller spherical nitrogen tanks and a 90 N injection rocket to slow the spacecraft down to go into lunar orbit, which was designed to be capable of firing twice during the mission. Attached to the bottom of the sphere was a 90 N vernier rocket for mid-course propulsion and lunar orbit maneuvers which could be fired four times.

Around the upper hemisphere of the hydrazine tank was a ring-shaped instrument platform which held the batteries in two packs, two 1.5 W UHF transmitters and diplexers, logic modules for scientific instruments, two command receivers, decoders, a buffer/amplifier, three converters, a telebit, a command box, and most of the scientific instruments. Two dipole UHF antennas protruded from the top of the sphere on either side of the injection rocket nozzle. Two dipole UHF antennas and a long VLF antenna protruded from the bottom of the sphere. The transmitters operated on a frequency of 378 megahertz.

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