How do scientists tell which parent body a meteorite came from?
Mainly by oxygen isotopes, which act like a fingerprint, together with chemistry, mineralogy and other isotope systems that group meteorites from the same source.
Meteorites do not come with labels, so scientists use a combination of tests to group them by parent body.
Oxygen isotopes. Oxygen has three stable isotopes: oxygen-16, oxygen-17 and oxygen-18. Their ratios vary between meteorite groups in a way that cannot be produced by ordinary processes such as melting and evaporation. Each parent body seems to have inherited its own mixture. On a graph of oxygen-17 against oxygen-18, meteorites from the same body cluster together. For example, all HED meteorites, thought to come from Vesta, plot along a single line, while Martian meteorites plot along another.
Chemistry. Ratios of elements, such as iron to manganese in pyroxene, or the abundances of nickel, gallium, germanium and iridium in iron meteorites, distinguish groups. Iron meteorites are classified into chemical groups this way.
Mineralogy and texture. The minerals present and their compositions, such as the iron content of olivine, help classify meteorites.
Other isotopes. Isotopes of chromium, titanium, molybdenum and others reveal whether material formed in the inner or outer Solar System.
Age. Martian meteorites are much younger than most others; lunar meteorites match Apollo samples.
When enough meteorites share a set of features, they form a group, and each group is thought to represent a separate parent body. Linking a group to a specific asteroid in space is harder and relies on telescope spectra, orbits from fireball networks and spacecraft visits.