Pioneer 2

Launch data: Designation  F00049 / 58F19 Launch date 08 Nov 1958 - 7:30:21 UT Launch site CC, LC-17A Launch vehicle Thor-DM18 Able-1 (#129/DM-1812-6) Mission Lunar orbiter Decay 08 Nov 1958

NASA photo of the Pioneer 2 probe

Specifications:

Description:

• Pioneer 2 was nearly identical to Pioneer 1. It consisted of a thin cylindrical midsection with a squat truncated cone frustum 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 total mass of the spacecraft after vernier separation but before injection rocket firing was 39.5 kg.

• The scientific instrument package had a mass of 15.6 kg (34.4 lb) and consisted of an STL image-scanning television system (which replaced the image scanning infrared television system on Pioneer 1), a proportional counter for radiation measurements, an ionization chamber to measure radiation in space, a diaphragm/microphone assembly to detect micrometeorites, a spin-coil magnetometer to measure magnetic fields to 5 microgauss, 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 108.06 MHz through a magnetic dipole antenna for the television system, telemetry, and doppler. Ground commands were received 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.

• ionization chamber
• magnetometer
• temperature sensor
• micrometeoroid sensor
• proportional counter
• imaging system

Mission details:

• Pioneer-2, or Able-3 was the last of the three project Able space probes designed to probe lunar and cislunar space. It was launched on November 8, 1958 and was very similar to Pioneer-1, but it had some important modifications: the NOTS (Naval Ordnance Test Station) infrared camera was replaced by a lighter, visible light camera built by STL (Space Technology Laboratories), which offered also a better resolution. Its place was moved from the waist to the lower cone. A cosmic ray counter was added and the batteries were replaced with a new model due to the problems on Pioneer 1. The Thor Able launcher received some modifications to the staging system and a new system of integrating accelerometers.
• Pioneer 2, like its predecessors, never reached its target. A signal from the ground shut down the Thor launch vehicle’s stage 2 earlier than planned. Additionally, when the X-248 thirdstage engine separated, it failed to fire. As a result, the probe burned up in Earth’s atmosphere only 45 minutes after launch. During its brief mission, it reached an altitude of 1,550 kilometers and sent back data that suggested that Earth’s equatorial region had higher flux and energy levels than previously thought. The information also indicated that micrometeoroid density was higher near Earth than in space. Investigators concluded that the third-stage engine had failed to fire because of a broken wire.