August 9, 2021
In 1973 on this date, the Soviet Union launched its Mars 7 probe. Instead of a soft landing on Mars, the probe missed the planet by 1,300 kilometers. A history of the Soviet space program may be found here.
If Mars 7 was successful, I would have landed near Ritchey Crater south of Valles Marineris. Image credit NASA; Map credit: USGS