Our friend and colleague, Dr. David S. McKay, passed away peacefully in his sleep in the early morning hours yesterday, 20 February 2013. He had been battling serious health problems for some time, especially cardiac issues this past year. He was 77.

Dr. McKay was Chief Scientist for Astrobiology in the Astromaterials Research and Exploration Science Directorate at the NASA Johnson Space Center. He was the lead author on the 1996 paper in Science on the ALH84001 martian orthopyroxenite, arguing that it contains evidence for life on Mars. Although that claim was highly controversial, there can be no question that the appearance of that paper sparked significant changes in martian and planetary science, shaped the direction of NASA’s Mars Exploration Program to the present day, and prompted the establishment of the NASA Astrobiology Institute.