The cover of the October 2014 issue of Physics Today recently caught my eye. I fondly remember participating in the early discussions and conferences to find a physical medium to capture the high-velocity particles that would be encountered during NASA’s Stardust mission. It was clear from the beginning that a low-density material, some type of foam, was necessary. In 1987 Peter Tsou of NASA’s Jet Propulsion Laboratory visited me at Los Alamos National Laboratory to see some of the foams that we were producing for our physics experiments. Most were opaque and polymeric. Included, however, were some silica-based aerogel foams. It was readily apparent that although the aerogel foams did not have the mechanical tenacity and capture capability of the polymeric foams, they had two unmatched properties: The first was very low carbon and hydrogen content as a result of the preparative process. The second was transparency, the property that would lead to aerogel’s ultimate selection. The trajectory of the captured particle could easily be determined and the particle could be found at the end of the visible capture track.
It was gratifying to be recognized for my role in the development of the stardust capture media when Tsou wrote about the history of the search and testing of various foam media and the ultimate selection of aerogel to perform the task.1
