Carbonaceous Chondrite Impact Melts

Collisions between planetary bodies (such as asteroids colliding with one another or with planets) have played a role in the geologic evolution of our Solar System since the formation of planetesimals, the earliest kilometer-scale bodies. Shock damage from collisional impacts leaves evidence on surviving planetary materials that range in scale from kilometer-sized craters to nanometer-sized mineral structural defects.

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Aqueous Alteration and Accretion of Chondrite Parent Bodies: When and Where

Events such as the Shoemaker−Levy 9 comet impact into Jupiter (July 1994) and the Chelyabinsk meteorite impact in Russia (February 2013) are reminders of the dynamic processes that were part of the formation of our Solar System from a protosolar molecular cloud of interstellar and circumstellar dust and gas. High-temperature (up to 2000 K) transient heating events (e.g. shock waves, current sheets, lightning, etc.) resulted in thermal processing (evaporation, condensation, and melting) of the primordial molecular cloud matter. In general, however, the ambient temperature of the disk decreased radially from the proto-Sun. When temperatures fell below 160 K, water vapor condensed directly into water ice, forming a front known as the “snow line”. The snow line likely did not reside at a single location in the disk, but rather migrated as the luminosity of the proto-Sun, mass accretion rate, and disk opacity all evolved with time. Some models suggest that the snow line could be located at about 5 astronomical units (1 AU = average distance between Earth and the Sun) early in disk evolution, which is not far from Jupiter’s current orbit, but is likely to have been present at 2−3 AU when the disk was just 2−4 My old (Ciesla and Cuzzi 2005).

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NASA’s Cosmic Dust Program: Collecting Dust Since 1981

Cosmic dust refers to particles that originate from the interplanetary medium and that have a diameter of ~100 µm or smaller (Brownlee 1985). This material, also known as interplanetary dust particles (IDPs), can be collected directly from Earth’s atmosphere. NASA has collected particles in the stratosphere for nearly three decades.

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Qarabawi’s Charm: Looking Beyond the Science

If you have been reading CosmoELEMENTS over the last few years, you will have realized that much of our understanding of Solar System history, including its earliest events, is derived from the study of meteorites. Scientifically, they are exceptionally valuable samples and, as such, it is sometimes hard to take a step back and realize that some meteorites have a cultural and historical value that is even greater. Back before the cosmic origins of meteorites were accepted, it is understandable that any material that fell from the heavens was the subject of some debate; historically, meteoritic material was often viewed as especially rare and valuable, as a gift from the Gods, or even cursed.

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