AAS Journal Author Series: Julien de Wit and Andy Rivkin on 2026ApJ..1003L..21D

Julien de Wit (Massachusetts Institute of Technology) and Andy Rivkin (Johns Hopkins University Applied Physics Laboratory) chat about their article presenting new JWST/NIRCam observations on near-Earth object 2024 YR4 from 2026 February 18 and 26 that extend the observational arc by 8 months, reduce the uncertainty in the 2032 lunar encounter by a factor greater than 30, and constitute the faintest detection of a near-Earth object to date, reaching V∼30.5 — beyond the V∼27 ground-based limit. The updated orbit solution yields a predicted miss distance of 22,900 ± 800 km (1σ) from the center of the Moon, thus ruling out a lunar impact. These observations extend the orbital arc at epochs when the object is not accessible from the ground, advancing the timeline for hazard assessment by 2 yr relative to the next feasible ground-based recovery. This capability is critical in an emerging regime of planetary defense characterized by the discovery of decameter-scale objects by next-generation surveys. JWST Observations of Asteroid 2024 YR4 Rule Out a 2032 Lunar Impact and Demonstrate a New Regime for Planetary Defense Follow-up https://scixplorer.org/abs/2026ApJ..1... Julien's web presence: https://eaps.mit.edu/people/faculty/j... https://www.disruptiveplanets.mit.edu Andy's web presence: https://www.jhuapl.edu/about/people/a... The intended audience for the AAS Journal Author Series is active researchers.