100 years ago today (28th June 1911) the Nakhla meteorite was seen to fall from the sky in Egypt (allegedly killing a dog a the process!). This turned out to be an exciting find as Nakhla originated on Mars and provided the first evidence of processes involving water in a Martian meteorite (Bunch & Reid, 37th Meteoritical Society Meeting, 1974) indicating the presence of water on Mars.
Only around 30 Martian meteorites have been found on Earth so far. Clues that meteorites come from other planets and not asteroids include:
- younger ages
- high volatile contents
Definitive evidence that certain meteorites (including Nakhla) are from Mars came from the Viking spacecrafts that measured gases in the Martian atmosphere. The trapped gases in Nakhlar matched the gases measured by Viking.
All images courtesy of NASA.