Year: 2026
Type: article
Abstract: Near-Earth asteroid (469219) Kamo‘oalewa is a uniquely stable quasi-satellite of the Earth and a target of the Tianwen-2 spacecraft mission. Here we report observations taken with JWST’s NIRSpec instrument in integral field unit (IFU) mode in 2026 February. The JWST reflectance spectrum is notably less red (more neutral) from 1.0 to 2.5 μ m than previous ground-based spectrophotometric observations. New observations made with the Large Binocular Telescope (LBT) in 2026 April, observed and processed similarly to the 2021 observations, find zJ colors in agreement with JWST. Kamo‘oalewa’s infrared colors appear more similar to typical silicate-rich asteroids and unlike the reddened, space-weathered lunar-like silicates suggested by previous observations. In agreement with the ground-based spectrum, we detect a faint silicate absorption feature at 0.93 ± 0.01 μ m. We do not detect a 2.0 μ m silicate absorption. Models of Kamo‘oalewa’s faint thermal emission (beginning near 4.5 μ m) find a mean diameter of D = 18 ± 2 m and best-fit visible albedo p V = 0.5 9 − 0.17 + 0.25 , with models as low as p V = 0.36 providing adequate model fits. This combination of color, albedo, and absorption bands is similar to oldhamite-bearing enstatite-rich compositions. Kamo‘oalewa’s brightness variations over the course of the JWST program provide independent confirmation of its rotation period of 27.9 minutes, with an axis ratio ∼1.4 ( D ∼ 15−21 m).
Language: English
Topic: Astro and Planetary Science
Subfield: Space and Planetary Science
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $2,400
OpenAlex ID: W7165759900