Formation of chondrule analogs aboard the International Space Station

Chondrules are thought to play a crucial role in planet formation, but the mechanisms leading to their formation are still a matter of unresolved discussion. So far, experiments designed to understand chondrule formation conditions have been carried out only under the influence of terrestrial gravit...

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Bibliographic Details
Published in:Meteoritics & planetary science 2021-09, Vol.56 (9), p.1669-1684
Main Authors: Koch, Tamara E., Spahr, Dominik, Tkalcec, Beverley J., Lindner, Miles, Merges, David, Wilde, Fabian, Winkler, Björn, Brenker, Frank E.
Format: Article
Language:English
Subjects:
Analogs
Arc discharges
Chondrule
Cooling
Cooling rate
Crystal structure
Crystallization
Crystallography
Crystals
Dust
Dust particles
Electric arcs
Experiments
Forsterite
International Space Station
Microgravity
Morphology
Multinational space ventures
Planet formation
Preferred orientation
Space stations
Spherules
Terrestrial environments
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Summary:Chondrules are thought to play a crucial role in planet formation, but the mechanisms leading to their formation are still a matter of unresolved discussion. So far, experiments designed to understand chondrule formation conditions have been carried out only under the influence of terrestrial gravity. In order to introduce more realistic conditions, we developed a chondrule formation experiment, which was carried out at long‐term microgravity aboard the International Space Station. In this experiment, freely levitating forsterite (Mg2SiO4) dust particles were exposed to electric arc discharges, thus simulating chondrule formation via nebular lightning. The arc discharges were able to melt single dust particles completely, which then crystallized with very high cooling rates of >105 K h−1. The crystals in the spherules show a crystallographic preferred orientation of the [010] axes perpendicular to the spherule surface, similar to the preferred orientation observed in some natural chondrules. This microstructure is probably the result of crystallization under microgravity conditions. Furthermore, the spherules interacted with the surrounding gas during crystallization. We show that this type of experiment is able to form spherules, which show some similarities with the morphology of chondrules despite very short heating pulses and high cooling rates.
ISSN:1086-9379
1945-5100
DOI:10.1111/maps.13731