The spacecraft consisted of a thin cylindrical midsection with a squat truncated conefrustum of high on each side. The cylinder was 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 a 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 and was painted with a pattern of dark and light stripes to help regulate temperature. The scientific instrument package had a mass of and consisted of:
A diaphragm/microphone assembly to detect micrometeorites. A micrometeorite hitting the diaphragm would generate an acoustic pulse that would travel through the diaphragm to the microphone. The microphone contained a piezoelectrical crystal that rang at 100 kc under influence of the acoustic pulse. A bandpass amplifier would amplify the signal, so it could be detected.
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 on 108.06 MHz, a standard frequency used by satellites in the International Geophysical Year, 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 revolutions per second, the spin direction approximately perpendicular to the geomagnetic meridian planes of the trajectory.
Launch and failure
Pioneer 0 was launched on Thor missilenumber 127 at 12:18:00 GMT on 17 August 1958 by the Air ForceBallistic Missile Division, only 4 minutes after the scheduled launch time. It was destroyed by an explosion of the first stage of the Thor booster, 73.6 seconds after lift-off at 15.2 km altitude, 16 km downrange over the Atlantic Ocean. The failure was suspected to be due to a turbopump bearing that came loose, causing the liquid oxygen pump to stop. The abrupt loss of thrust caused the Thor to lose attitude control and pitch downward, which caused the LOX tank to rupture from aerodynamic loads and resulting in complete destruction of the launch vehicle. 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. The original plan was for the spacecraft to travel for 2.6 days to the Moon at which time a TX-8-6 solid-propellant motor would fire to put it into a 29,000 km lunar orbit which was to nominally last for about two weeks. Air Force officials stated that they were not surprised at the failure, adding that "it would have been more of a shock had the mission succeeded". It was the only mission in the Project Able-1 Probes entirely run by the Air Force Ballistic Missile Division, as subsequent missions were conducted by NASA.
