Constraining the Birthplace of Asteroids: Many primitive meteorites originating from the asteroid belt once contained abundant water that is now stored as OH in hydrated minerals. Alexander et al. (p. 721 , published online 12 July) estimated the hydrogen isotopic compositions in 86 samples of primitive meteorites that fell in Antarctica and compared the results to those of comets and Saturn's moon, Enceladus. Water in primitive meteorites was less deuteriumrich than that in comets and Enceladus, implying that, in contradiction to recent models of the dynamical evolution of the solar system, the parent bodies of primitive meteorites cannot have formed in the same region as comets. The results also suggest that comets were not the principal source of Earth's water.

Abiotic Martian Organics: Understanding the sources and the formation mechanisms of organic carbon compounds on Mars has implications for our understanding of the martian carbon cycle. Steele et al. (p. 212 , published online 24 May) present measurements of organic material in 11 martian meteorites, including the Tissint meteorite, which fell in the Moroccan desert in July 2011. Ten of the meteorites contain complex hydrocarbons encased within igneous minerals. The results imply that the organics formed as the magma melt crystallized and are thus of abiotic origin.

The study of organic matter in a well-preserved meteorite provides insight into processes that affected its parent asteroids.

Martian meteorites are the only direct samples from Mars, thus far. Currently, there are a total of 262 individual samples originating from at least 11 ejection events. Geochemical analyses, through techniques that are also used on terrestrial rocks, provide fundamental insights into the bulk composition, differentiation and evolution, mantle heterogeneity, and role of secondary processes, such as aqueous alteration and shock, on Mars. Martian meteorites display a wide range in mineralogy and chemistry, but are predominantly basaltic in composition. Over the past 6 years, the number of martian meteorites recovered has almost doubled allowing for studies that evaluate these meteorites as suites of igneous rocks. However, the martian meteorites represent a biased sampling of the surface of Mars with unknown ejection locations. The geology of Mars cannot be unraveled solely by analyzing these meteorites. Rocks analyzed by rovers on the surface of Mars are of distinct composition to the meteorites, highlighting the importance of Mars missions, especially sample return. The Mars 2020 Perseverance rover will collect and cache—for eventual return to Earth—over 30 diverse surface samples from Jezero crater. These returned samples will allow for Earth‐based state‐of‐the‐art analyses on diverse martian rocks with known field context. The complementary study of returned samples and meteorites will help to constrain the evolution of the martian interior and surface. Here, we review recent findings and advances in the study of martian meteorites and examine how returned samples would complement and enhance our knowledge of Mars.