EXPOSURE HISTORY OF THE TORINO METEORITE

We determined He, Ne, Ar, Be-10, Al-26, Cl-36, and C-14 concentrations , as well as cosmic-ray track densities and halogen concentrations in different specimens of the H6 chondrite Torino, in order to constrain its exposure history to cosmic radiation. The Torino meteoroid had a r adius of similar to 20 cm and travelled in interplanetary space for 2. 5-10 Ma. Earlier, Torino was part of a larger body. The smallest possi ble precursor had a radius of 55 cm and a journey through space longer than similar to 65 Ma. If the first-stage exposure took place in a bo dy with a radius of >3 m or in the parent asteroid, then it lasted nea rly 300 Ma. The example of Torino shows that it is easy to underestima te first-stage exposure ages when constructing two-stage histories.