Retired aeronautical engineers Al Kuhn, left, and Manny Cherkas pose for a portrait with a model of the Apollo space craft at their retirement home in Palo
Retired aeronautical engineers Al Kuhn, left, and Manny Cherkas pose for a portrait with a model of the Apollo space craft at their retirement home in Palo Alto on Friday, July 19, 2013. Kuhn worked on Apollo 11 and Cherkas worked on the Pioneer Venus project. (Jim Gensheimer/Bay Area News Group) ( Jim Gensheimer )