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Ionizing radiation exposure on Arrokoth shapes a sugar world
Chaojiang Zhang1,2, Vanessa Leyva3, Jia Wang1,2
1Department of Chemistry, University of Hawaii at Mānoa, Honolulu, HI 96822.
Summary
Galactic cosmic rays (GCRs) transform methanol ice on Arrokoth into sugars and polycyclic aromatic hydrocarbons (PAHs), explaining its reddish color. This discovery reveals Arrokoth as a "sugar world" with implications for prebiotic chemistry on early Earth.
Area of Science:
- Astrochemistry
- Planetary Science
- Organic Chemistry
Background:
- The Kuiper Belt object (KBO) Arrokoth exhibits a reddish surface with methanol spectral features.
- The formation pathways for Arrokoth's surface organic molecules remain unclear.
Purpose of the Study:
- To investigate the abiotic formation of complex organic molecules on Arrokoth's surface.
- To explain the origin of Arrokoth's distinctive reddish color.
Main Methods:
- Laboratory simulations of methanol ice exposed to galactic cosmic ray (GCR) proxies at 40 K.
- Spectroscopic characterization of irradiated ices.
Main Results:
- Methanol ice irradiated at 40 K produced sugars (e.g., glucose, ribose) and polycyclic aromatic hydrocarbons (PAHs).
- These molecules replicate Arrokoth's observed color slopes.
- Abundant sugar-related molecules and PAHs were identified, explaining the surface's reddish appearance.
Conclusions:
- Arrokoth can be characterized as a "sugar world" due to the abundance of sugar-related molecules.
- GCR irradiation of methanol ice provides a plausible abiotic pathway for generating biorelevant molecules on KBOs.
- These findings offer insights into the delivery of prebiotic molecules to early Earth.
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