Antarctic micrometeorite composed of CP and CS IDP‐like material: A micro‐breccia originated from a partially ice‐melted comet‐like small body

Abstract

Asteroids and comets are thought to form in the inner and outer solar systems, respectively. Chondritic porous and smooth interplanetary dust particles (CP IDPs and CS IDPs, respectively) in the stratosphere are regarded as dust grains from comets and hydrated asteroids, respectively. Here, we describe an Antarctic micrometeorite (AMM) composed of lithologies of both CP and CS IDPs. In addition to the CS IDP-like compact lithology that experienced severe aqueous alteration, the CP IDP-like porous lithology shows evidence of very weak aqueous alteration. The structure of the organic matter in the porous lithology varies from that in the CP IDPs to aromatic-rich organic matter. In contrast, the structure of the organic matter in the compact lithology is homogenous, which is consistent with higher degrees of aqueous alteration. Its structure is more similar to that of CP IDPs and Wild 2 samples than that of meteoritic insoluble organic matter, suggesting that the compact lithology formed from the porous lithology. Some CP IDPs are related to cometary dust streams, such as those originating from 26P/Grigg-Skjellerup. In addition, the presence of this AMM indicates an additional origin of the CP IDPs and their equivalent AMMs. The mineralogy and organic chemistry of this AMM suggest that its parent body was composed of the same building blocks as those of the comets, and later experienced incomplete aqueous alteration. The AMM probably formed as microbreccia in the regolith layer composed of materials from a CP IDP-like crust and a hydrated interior.

Transport of dust across the Solar System: Constraints on the spatial origin of individual micrometeorites from cosmic-ray exposure

“…This finding is further corroborated by oxygen isotope measurements and indicates an asteroidal origin [11]. Porous anhydrous, volatile-rich MMs with high deuterium/hydrogen ratios and ultracarbonaceous MMs are assumed to derive from comets [12–14].…”

“…Determining the cosmogenic radionuclide concentration of, e.g. 10 Be, 14 C, 26 Al, 36 Cl, 41 Ca, 53 Mn and 60 Fe, with half-lives of ~1,000 years up to a few million years, of individual MMs can potentially be used to calculate the cosmic-ray exposure duration (i.e. age) that each particle has experienced before reaching Earth and, hence, allows us to derive the approximate heliocentric distance of its origin.…”

AFM-IR nanospectroscopy of nanoglobule-like particles in Ryugu samples returned by the Hayabusa2 mission

“…They were then rediscovered by Nakamura et al (2002) and Garvie & Buseck (2006), who dismissed the idea of these structures being of biogenic origin. Nanoglobules are present in primitive meteorites (e.g., De Gregorio et al 2013), in Stardust's samples returned from the comet 81P (Wild2) (De Gregorio et al 2010), in micrometeorites (Maurette et al 1995), UCAMMs (Bradley & Ishii 2017;Yabuta et al 2017), and in chondritic anhydrous IDPs and micrometeorites (Messenger et al 2008;Bradley et al 2022;Noguchi et al 2022).…”