# Q-type asteroids: Possibility of non-fresh weathered surfaces

## TL;DR

This study proposes that Q-type asteroids may have weathered surfaces lacking fine particles, supported by laboratory experiments showing large weathered particles match Q-type asteroid spectra.

## Contribution

It introduces a new hypothesis that Q-type asteroids have non-fresh weathered surfaces with few fine particles, challenging previous assumptions.

## Key findings

- Large (over 100 μm) weathered chondritic particles match Q-type asteroid spectra.
- Q-type asteroids may have non-fresh, weathered surfaces rather than being freshly exposed.
- Laboratory experiments support the hypothesis with spectral analysis.

## Abstract

Itokawa particles, which are the recovered samples from the S-complex asteroid 25143 Itokawa by the Hayabusa spacecraft, demonstrate that S-complex asteroids are parent bodies of ordinary chondrite meteorites. Furthermore, they clarify that the space weathering age of the Itokawa surface is of the order of several thousand years. Traditionally, Q-type asteroids have been considered fresh-surfaced. However, as the space weathering timescale is approximately three orders of magnitude lesser than the conventionally considered age, the previously proposed formation mechanisms of Q-type asteroids cannot sufficiently explain the surface refreshening. In this study, we propose a new hypothesis on the surface state of Q-type asteroids: Q-type asteroids have a non-fresh weathered surface with a paucity of fine particles. For verifying this hypothesis, laboratory experiments on the space weathering of ordinary chondrites are performed. Based on the results of these experiments, we found that large (more than 100 {\mu}m) ordinary chondritic particles with space weathering exhibit spectra consistent with Q-type asteroids.