# Thermophysical modeling of NEOWISE observations of DESTINY+ targets Phaethon and 2005 UD

## TL;DR

This study uses thermophysical modeling of NEOWISE data to determine physical properties of two near-Earth asteroids, Phaethon and 2005 UD, aiding in understanding their surface characteristics for the DESTINY+ mission.

## Contribution

It introduces a thermophysical model with a Monte Carlo Markov Chain approach to analyze NEOWISE observations of NEAs, providing detailed surface property estimates.

## Key findings

- Phaethon has an effective diameter of 4.6 km and a thermal inertia of 880.
- 2005 UD's diameter is about 1.2 km with less constrained properties.
- Results improve understanding of asteroid surface properties for mission planning.

## Abstract

Thermophysical models allow for improved constraints on the physical and thermal surface properties of asteroids beyond what can be inferred from more simple thermal modeling, provided a sufficient number of observations is available. We present thermophysical modeling results of observations from the NEOWISE mission for two near-Earth asteroids which are the targets of the DESTINY+ flyby mission: (3200) Phaethon and (155140) 2005 UD. Our model assumes a rotating, cratered, spherical surface, and employs a Monte Carlo Markov Chain to explore the multi-dimensional parameter space of the fit. We find an effective spherical diameter for Phaethon of $4.6^{+0.2}_{-0.3}~$km, a geometric albedo of $p_V=0.16\pm0.02$, and a thermal inertia $\Gamma=880$ $^{+580}_{-330}$, using five epochs of NEOWISE observations. The best model fit for (155140) 2005 UD was less well constrained due to only having two NEOWISE observation epochs, giving a diameter of $1.2\pm0.4~$km and a geometric albedo of $p_V=0.14\pm0.09$.