JWST sighting of decameter main-belt asteroids and view on meteorite sources

Abstract

Asteroid discoveries are essential for planetary-defense efforts aiming to prevent impacts with Earth, including the more frequent megaton explosions from decameter impactors. While large asteroids ($\ge$100 km) have remained in the main belt since their formation, small asteroids are commonly transported to the near-Earth object (NEO) population. However, due to the lack of direct observational constraints, their size-frequency distribution--which informs our understanding of the NEOs and the delivery of meteorite samples to Earth--varies significantly among models. Here, we report 138 detections of the smallest asteroids ($⪆$10 m) ever observed in the main belt, which were enabled by JWST's infrared capabilities covering the asteroids' emission peaks and synthetic tracking techniques. Despite small orbital arcs, we constrain the objects' distances and phase angles using known asteroids as proxies, allowing us to derive sizes via radiometric techniques. Their size-frequency distribution exhibits a break at $\sim 100$ m (debiased cumulative slopes of $q=-2.66\pm 0.60$ and $-0.97\pm 0.14$ for diameters smaller and larger than $\sim$100 m, respectively), suggestive of a population driven by collisional cascade. These asteroids were sampled from multiple asteroid families--most likely Nysa, Polana and Massalia--according to the geometry of pointings considered here. Through additional long-stare infrared observations, JWST is poised to serendipitously detect thousands of decameter-scale asteroids across the sky, probing individual asteroid families and the source regions of meteorites "in-situ".

Original version submitted to Nature in June 2024; see final accepted version at DOI: s41586-024-08480-z

References in corpus (24)

• Array Programming with NumPy
• astroquery: An Astronomical Web-Querying Package in Python
• Solar System evolution from compositional mapping of the asteroid belt
• Thermal emission from the Earth-sized exoplanet TRAPPIST-1 b using JWST
• No thick carbon dioxide atmosphere on the rocky exoplanet TRAPPIST-1 c
• "TNOs are Cool": A survey of the trans-Neptunian region VI. Herschel/PACS observations and thermal modeling of 19 classical Kuiper belt objects
• PHOTOMETRYPIPELINE: An Automated Pipeline for Calibrated Photometry
• NEOMOD: A New Orbital Distribution Model for Near Earth Objects
• Source regions of carbonaceous meteorites and NEOs
• Detection of a faint fast-moving near-Earth asteroid using synthetic tracking technique
• A roadmap for the atmospheric characterization of terrestrial exoplanets with JWST
• SPECULOOS Northern Observatory: searching for red worlds in the northern skies
• Sizes and albedos of Mars-crossing asteroids from WISE/NEOWISE data
• Spin Axes and Shape Models of Asteroid Pairs: Fingerprints of YORP and a Path to the Density of Rubble Piles
• The low surface thermal inertia of the rapidly rotating near-Earth asteroid 2016 GE1
• Asteroids seen by JWST-MIRI: Radiometric Size, Distance and Orbit Constraints
• Size distributions of bluish and reddish small main-belt asteroids obtained by Subaru/Hyper Suprime-Cam
• Report of the Working Group on Strategic Exoplanet Initiatives with HST and JWST
• GPU-based framework for detecting small Solar System bodies in targeted exoplanet surveys
• Constraining the Interiors of Asteroids Through Close Encounters
• Debiasing astro-Photometric Observations with Corrections Using Statistics (DePhOCUS)
• The Massalia asteroid family as the origin of ordinary L chondrites
• Young asteroid families as the primary source of meteorites
• Small body harvest with the Antarctic Search for Transiting Exoplanets (ASTEP) project

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