An Expensive Software Bug

NASA’s Venus Flyby

In 1962 NASA failed its first attempt to explore Venus in a whopping $18.5m software bug. A loss that today would be around $150m. What happened?

The Mariner 1

The Mariner 1 mission, NASA’s first attempt to explore Venus, was lost due to a software glitch caused by a typographical error in the launch vehicle’s guidance software.

The Error

The devastating loss was all due to a missing superscript overbar for the radius symbol R (R instead of R̅) that was not carried over from the handwritten equations to the code. The overbar was a crucial part of the mathematical notation in the spacecraft’s guidance system algorithm. The omission led to incorrect guidance signals being sent to the spacecraft and its rocket veered off course.

The Correction

This ultimately forced in the Range Safety Officer (RSO) to send the destruct command in order to avoid damage and casualties as it’s projected crash trajectory was in the North Atlantic shipping lanes or possibly in an inhabited area.

The RSO sent the command less than 5 minutes into the launch and with only 6 crucial seconds left before the separation of the rocket and spacecraft would occur and destruction to prevent a crash would no longer be an option.

Lessons Learned

While NASA didn’t reveal their lessons learned or corrective actions, this incident does highlight how even minor oversights can lead to significant failures. It is important for individuals developing crucial, complex, and critical systems to apply rigorous attention to detail in every project phase from planning to testing.

NASA learned from their mistakes, implemented the corrections and successfully performed a series of Mariner explorations, which resulted in our vast knowledge of Venus today. To learn about Venus, visit https://nssdc.gsfc.nasa.gov/planetary/factsheet/venusfact.html and for more details on Mariner 1, visit NASA’s Mariner 1 page.