Overview
- The system’s along-track velocity decreased by about 11.7 micrometers per second, shortening its roughly 770-day orbit by about 0.15 seconds and shrinking its orbital radius by around 360 meters.
- Researchers derived the effect using 22 stellar occultations recorded between October 2022 and March 2025, nearly 6,000 ground-based astrometric measurements, radar data, and DART navigation observations.
- Escaping impact ejecta roughly doubled the effective impulse, yielding a momentum-enhancement factor near two beyond the spacecraft’s direct push.
- Combined heliocentric and local orbital changes point to contrasting densities, with Didymos near 2.6 tons per cubic meter and Dimorphos about 1.5 tons per cubic meter, consistent with a porous rubble-pile moonlet.
- The binary remains no threat to Earth, and ESA’s Hera spacecraft is scheduled to arrive in November 2026 to provide independent in-situ verification and refined physical measurements.