Our colleague and friend Bishun Khare died quietly on August 20 at the age of 80.  Bishun is widely known for his early work on organic solid residues (tholins) related to the aerosols in planetary atmospheres and the interstellar medium, performed for many years at Cornell University in collaboration with Carl Sagan.  Their 1984 paper gave the optical constants of Titan tholin from the X-ray to microwave region, and has served as a fundamental input to modeling work that included planetary surfaces in addition to atmospheric aerosols.  That key paper has received well over 300 citations, and has stimulated much additional research on tholins, both in the US and in Europe.  In 1996, Bishun moved from Cornell to NASA Ames Research Center on a Senior National Research Council fellowship, and subsequently joined the SETI Institute.  He continued his research on many topics in his Ames lab, and mentored a great number of students, including supervising the thesis work of graduate students.  Bishun was a patient, kind, and sharing individual, who loved to talk about science, especially the organic materials in Nature and those he could synthesize in his lab.

Composed by D. Cruikshank