Completed 60 years ago

America's first attempt to explore Venus up close was lost to a software glitch. Investigators found a single missing superscript bar caused a fault in Mariner 1's guidance software. The out-of-control spacecraft and booster were destroyed for safety. Reporters at the time called it The press described “the most expensive hyphen in history.”

Mission Type
Venus Flyby
5 minutes
July 22, 1962
06:53:14 UT
Destroyed by Range Safety
July 22, 1962
T+294.5 seconds

Overview: Mariner 1

In formulating a series of early scientific missions to Venus in early 1961, NASA originally planned two missions, P-37 and P-38, to be launched on Atlas Centaur rockets, each spacecraft weighing about 1,246 pounds (565 kilograms).

By the time NASA formally approved the plan in September 1961, problems with the Atlas Centaur necessitated a switch to the Atlas Agena B with a reduced payload. By that time, NASA's Jet Propulsion Laboratory (JPL) had prepared three spacecraft based on the design of the Ranger Block 1 series (therefore named Mariner R) to fly by Venus in late 1962.

Each spacecraft carried a modest suite (about 20 pounds or 9 kilograms) of scientific instrumentation but had no imaging capability. The spacecraft included 54,000 components and was designed to maintain contact with Earth for 2,500 hours—an ambitious goal given that the (still unsuccessful) Ranger was designed for only 65 hours contact.

Mariner 1 would have flown by Venus at a range of about 18,000 miles (29,000 kilometers) on Dec. 8, 1962.

Due to an incorrect trajectory during launch, at T+294.5 seconds, range safety sent a signal to destroy the Atlas Centaur booster and its payload.

The failure was traced to a guidance antenna on the Atlas as well as faulty software in its onboard guidance program, which was missing a single superscript bar. The press described it as “the most expensive hyphen in history.”

Spacecraft and Technology

Nation United States of America (USA)
Objective(s) Venus Flyby
Spacecraft P-37 / Mariner R-1
Spacecraft Mass 447 pounds (202.8 kilograms)
Mission Design and Management NASA / JPL
Launch Vehicle Atlas Agena B (Atlas Agena B no. 5 / Atlas D no. 145 / Agena B no. 6901)
Launch Date and Time July 22, 1962 / 09:21:23 UT
Launch Site Cape Canaveral Fla. / Launch Complex 12
Scientific Instruments
  1. Microwave Radiometer
  2. Infrared Radiometer
  3. Fluxgate Magnetometer
  4. Cosmic Dust Detector
  5. Solar Plasma Spectrometer
  6. Energetic Particle Detectors
  7. Ionization Chamber

Key Source

Siddiqi, Asif A. Beyond Earth: A Chronicle of Deep Space Exploration, 1958-2016. NASA History Program Office, 2018.

Mariner 1 News