Robert M. Walker (February 6, 1929 – February 12, 2004) was an American physicist, a planetary scientist, the founder and director of McDonnell Center for the Space Sciences at Washington University in St. Louis, noted for his co-discovery of the etchability of nuclear particle tracks in solids, as well as his conjecture that meteorites and lunar rocks contain a record of the ancient radiation history of various stars including the Sun.Asteroid 6372 was named Walker in his honor by the International Astronomical Union.Walker was a member of the National Academy of Sciences.Walker was also a fellow of the American Physical Society, the American Geophysical Union, the Meteoritical Society and the American Association for the Advancement of Science. He was also a founder and the first preside