Mission Type: Flyby
Launch Vehicle: Atlas-Agena D (no. 11 / Atlas D no. 289 / Agena D no. AD68/6931)
Launch Site: Cape Canaveral, United States, launch complex 13
NASA Center: Jet Propulsion Laboratory
Spacecraft Mass: 260.8 kg
Spacecraft Instruments: 1) imaging system; 2) cosmic dust detector; 3) cosmic-ray telescope; 4) ionization chamber; 5) magnetometer and 6) trapped radiation detector
Spacecraft Power: 28,244 solar cells mounted on four panels
Maximum Power: 700 W
Total Cost: Total research, development, launch, and support costs for the Mariner series of spacecraft (Mariners 1 through 10) was approximately $554 million.
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/

NASA approved two probes for the Mariner-Mars 1964 project in November 1962.

The primary goal of the two spacecraft was to photograph the Martian surface using a single TV camera fixed on a scan platform that could return up to twenty-one pictures after an eight-month journey.

During the launch of Mariner 3, the first of the two probes, the booster payload shroud failed to separate from the payload. Additionally, battery power mysteriously dropped to zero (at T+8 hours 43 minutes), and the spacecraft's solar panels apparently never unfurled to replenish the power supply. As a result, ground control lost contact with the spacecraft, which eventually entered heliocentric orbit.

A later investigation indicated that the shroud's inner fiberglass layer had separated from the shroud's outer skin, thus preventing jettisoning.