Mars’ rocks
- The O isotope ratios show some of the rocks are from the Moon
- i.e. ALH 81005, p. 448 of Seeds
- recall formation of impact crater Fig. 22-5
- debris is ejected
- forms the radial rays seen around many lunar craters
- some will have escape velocity
- go into orbit around the sun
- much later can run into Earth
- Some isotope ratios different than Earth, Moon, or asteroidal Meteorites, but exactly equal to those of Mars.
- Viking measured Mars isotope ratios in ‘76
- we should have some new samples following the 2005 Mars mission
Mars rock ALH (Alan Hills) 84001 Fig.23-24
- O isotope ratios imply a Mars origin
- rocks age is 3.6-4 billion y.