The Pioneer 0 (also known as Thor-Able 1) probe was designed to go into orbit around the Moon and carried a TV camera and other instruments as part of the first International Geophysical Year (IGY) science payload. It was the first attempt by the USA at a lunar mission. On August 17 1958, the spacecraft was destroyed by an explosion of the first (Thor booster) stage 77 seconds after launch at 16 km altitude, 16 km downrange over the Atlantic. Failure was suspected to be due to a ruptured fuel or oxygen line. Erratic telemetry signals were received from the payload and upper stages for 123 seconds after the explosion, and the upper stages were tracked to impact in the ocean.
Spacecraft design
Pioneer 0 consisted of a thin cylindrical midsection with a squat truncated cone frustrum on each side. The cylinder was 74 cm in diameter and the height from the top of one cone to the top of the opposite cone was 76 cm. Along the axis of the spacecraft and protruding from the end of the lower cone was an 11 kg solid propellant injection rocket and rocket case, which formed the main structural member of the spacecraft. Eight small low-thrust solid propellant velocity adjustment rockets were mounted on the end of the upper cone in a ring assembly which could be jettisoned after use. A magnetic dipole antenna also protruded from the top of the upper cone. The shell was composed of laminated plastic.
The scientific instrument package had a mass of 11.3 kg and consisted of an image scanning infrared television system to study the Moon's surface, a diaphragm/microphone assembly to detect micrometeorites, a magnetometer, and temperature-variable resistors to record spacecraft internal conditions. The spacecraft was powered by nickel-cadmium batteries for ignition of the rockets, silver cell batteries for the television system, and mercury batteries for the remaining circuits. Radio transmission was at on 108.06 MHz through an electric dipole antenna for telemetry and doppler information and a magnetic dipole antenna for the television system. Ground commands were received through the electric dipole antenna at 115 MHz. The spacecraft was to be spin stabilized at 1.8 rps, the spin direction approximately perpendicular to the geomagnetic meridian planes of the trajectory.
The probe was supposed to be Pioneer (or Pioneer 1), but the launch failure precluded that name.
See Also