Summary

The cartoon outline in Figure 1 encapsulates the fundamental relationship that meteorites have with the other members of the Solar System family. Populations of interstellar grains in primitive asteroidal meteorites reveal the constituency of the neighbourhood in which the Sun initially formed, helping to constrain astrophysical models of stellar evolution. Chondrites mark the change that took place between simple aggregates of interstellar dust and their accumulation into parent bodies as a protoplanetary disk formed and then evolved into the Solar System. The presence of the decay products of short-lived radionuclides within components in chondritic meteorites provides a chronology for the formation of the earliest solid materials within the nebula. Primary mineral assemblages in chondrites trace the heterogeneity of the solar nebula, whilst secondary minerals reveal the extent of hydrous and thermal alteration on the parents. Differentiated meteorites record the extent, timing and duration of melting and subsequent magmatic activity on their parents, indicating the short timescale on which parent bodies aggregated, then differentiated. Iron and stony-iron meteorites act as markers for iron-silicate segregation and core formation. Turning from asteroidal meteorites to those from other sources: lunar meteorites extend the range and diversity of materials available for study from Earth's only natural satellite, whilst the families of martian meteorites assist in interpretation of magmatic and fluvial processes on Mars, and have stimulated studies into the potential existence (extinct or extant) of life on Mars.

Meteorites are the only physical objects that can be analysed directly in the laboratory, hence they are an unparalleled resource for Solar System, and Galactic, exploration. Past, and future space missions to comets, asteroids and Mars rely on measurements from meteorites to aid in interpretation of returned data. Astronomers studying interstellar and circumstellar dust by both ground- and space-based techniques are turning more frequently to results from meteorites, and the grains separated from them, to help with understanding the size, shape and composition of the dust. Direct measurement of the isotopic composition of the several populations of interstellar grains isolated from meteorites, and the gases trapped within them, are enabling astrophysicists to model more accurately stellar evolutionary sequences, and to confirm (or refute) predictions made from these models. All in all, and again with reference to Figure 1, meteorites are not at the bottom of a hierarchy of stellar and planetary objects, rather they are the foundation on which all theoretical, observational and experimental data rest, the root that underpins and firmly anchors our comprehension and appreciation of nebular history.

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