I've got a few reasons for picking "Space Truckin" by Deep Purple for today. On August 20, 1975, NASA launched the Viking 1 probe onto it's way toward the planet Mars. Then, on August 20, 1977, Voyager 2 was sent out to go beyond Mars to investigate planets further out. Both were highly successful in their missions. Also, quite a few actors that appeared in the classic Doctor Who television series were born on an August 20.
Birthdays on August 20: 1932 - English actor Anthony Ainley (Upstairs, Downstairs, 'The Land That Time Forgot', Doctor Who), 1941 - English musician and singer Dave Brock (Hawkwind), 1942 - American singer, musician and actor Isaac Hayes (The Rockford Files, Stargate SG-1), 1943 - Scottish actor of all mediums Sylvester McCoy (The Last Place On Earth, Doctor Who, King Lear), 1948 - English vocalist Robert Plant (Led Zeppelin), 1949 - Irish singer, songwriter and musician Phil Lynott (Thin Lizzy) born in England, 1962 - English actress and television presenter Sophie Aldred (Doctor Who, Corners, Dimensions In Time), and in 1971 - English comedian, writer and actor David Walliams (Little Britain, Marple, 'A Cock And Bull Story').
Deep Purple - "Space Truckin" Live in New York, NY (1973).