VOLATILES IN CHONDRITES AND ACHONDRITES
M. Bose1, T. M. Hahn2, Ziliang Jin3
1
School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287
2Jacobs, Johnson Space Center, Houston, TX 77058
3
Macau University of Science and Technology, Macau.
(*Correspondence: Maitrayee.Bose@asu.edu)

The abundance and distribution of volatiles in Solar System objects are vital for understanding planet
formation and evolution. The presence of water and organic molecules is critical for the emergence of life
and the habitability of planetary environments. Although some information on volatiles can be obtainedfrom analysis of meteorites, they are prone to alteration and exchange in Earth’s environment. Additionally,lack of context, i.e., which specific asteroid body, sampling location within the asteroid etc. results in an
incomplete understanding. Returning samples allows for the use of state-of-the-art laboratory analyses,
providing extremely high-precision, high-sensitivity, and high-resolution. More importantly, returned
samples can be placed into geologic context and provide complementary information with other studies ofthe parent object.
A successful sample return mission from asteroid Itokawa by JAXA’s Hayabusa spacecraft led to ourexcellent understanding about the parent bodies of ordinary chondrite meteorites. Minute details of theasteroid’s history was gleaned through thorough and detailed laboratory investigations including
compositions, mineralogy, and chronology. One such investigation led to the measurement of hydrogenisotopes and water in tiny Itokawa particles, which show that the silicate minerals can contain between 400800 ppm of water and translated to up to 0.5 Earth’s oceans to be delivered to proto-Earth by S-type
asteroids1. On the other hand, the proportions of various chondritic materials accreted to form Mars are
distinct from those for Earth. Recent accretion models for terrestrial planets using chondritic components
suggests that S-type asteroids (specifically, H chondrites) would have contributed up to 50% the mass ofproto-Mars2. Based on analysis of recent confirmed falls, Chelyabinsk and Benenitra, we ascertained that
only about ½ of water contained within the martian mantle can be explained by accretion of S-type
asteroids; We speculate that pebble accretion may have played a significant role in forming Mars3.
Asteroids Bennu and Ryugu are the targets of ongoing sample return missions from C-type asteroids. The
spectral features are similar to those of aqueously altered CM-type carbonaceous chondrites (CCs).
Murchison and Aguas Zarcas are CM2 chondrite falls and potential meteorite analogs for Bennu and Ryugu.
We studied these two CCs and their components to constrain the evolution of hydrogen in C-type asteroids4.
In addition, we studies stones from Ureilites and Brachinites5, primitive achondrites that are likely better
planet forming starting materials because of their early accretion ages. I will discuss the data, and discuss
how both chondrites and achondrites that formed in the inner solar system could be the source of volatiles
during the early accretion stages of terrestrial planets.
References.
(1) Jin Z. and Bose M. (2019) Science Advances 5:eaav8106.
(2) Mah J. and Brasser R. (2021) Icarus 354: 114052(3) Jin Z. and Bose M. (2020) LPS XXXXI, Abstract #1470.
(4) Bose M., Hahn Jr. T. M., and Jin Z. (2021) 84th Annual Meeting of the Meteoritical Society, Abstract#6078.
(5) Bose M., Hahn Jr. T. M. (2021) 84th Annual Meeting of the Meteoritical Society, Abstract #6227.