Launch Vehicle: Atlas-Agena B (no. 3 / Atlas D no. 121 / Agena B no. 6003)
Launch Site: Cape Canaveral, United States, launch complex 12
NASA Center: Jet Propulsion Laboratory
Spacecraft Mass: 330 kg
Spacecraft Instruments: 1) imaging system 2) gamma-ray spectrometer 3) single-axis seismometer 4) surface-scanning pulse radio experiment
References:
Deep Space Chronicle: A Chronology of Deep Space and Planetary Probes 1958-2000, Monographs in Aerospace History No. 24, by Asif A. Siddiqi

National Space Science Data Center, http://nssdc.gsfc.nasa.gov/

This was the first U.S. attempt to achieve impact on the lunar surface. The Block
II Ranger spacecraft carried a TV camera that used an optical telescope that would allow imaging down to about 24 kilometers above the lunar surface during the descent. The main bus also carried a 42.6-kilogram instrument capsule that would separate from the bus at 21.4 kilometers altitude and then independently
impact on the Moon.

Protected by a balsa-wood outer casing, the capsule was designed to bounce several times on the lunar surface before coming to rest. The primary onboard instrument was a seismometer.

Because of a malfunction in the Atlas guidance system (due to faulty transistors), the probe was inserted into a lunar transfer trajectory with an excessive velocity. A subsequent incorrect course change ensured that the spacecraft reached the Moon 14 hours early and missed it by 36,793 kilometers on 28 January. The central computer and sequencer failed and the spacecraft returned no TV
images.

The probe did, however, provide scientists with the first measurements of interplanetary gamma-ray flux. Ranger 3 eventually entered heliocentric orbit.