He is credited with the original idea that the Pioneer probes should carry a message for extraterrestrial intelligences.

November 1 - NASA loses contact with the Pioneer 11 probe.

The flybys of the two Pioneer probes, Pioneer 10 and 11 in 1973 and 1974, provided the first accurate measurement of Io's mass and size.

Three different designs of Pioneer lunar probes were flown on three different modified ICBMs.

Between 11 March and 12 June 1960, it tracked the Pioneer 5 probe.

The Pioneer probe to the Moon launched on Oct. 11, 1958, documented the outer part of the belts.

Once again, he knew that the Pioneer 1 probe was set for launch on October 11, but again decided to wait.

As the work at the JPL changed from military rockets to spacecraft, he worked on the Pioneer 4 lunar probe and other missions.

December 4 - The Pioneer 11 probe passes Jupiter and captures famous images of the Great Red Spot.

Tucked away in a display about communication, for instance, was a copy of the plaque that was affixed to the Pioneer 10 probe.