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Researchers analysing data from NASA’s Double Asteroid Redirection Test (DART) mission have found that the mission not only altered the orbit of the asteroid moonlet Dimorphos around its parent Didymos but also slightly changed the binary system’s orbit around the Sun. The findings provide new insights into planetary defence.
Background
The DART mission, launched in November 2021, was the first full‑scale test of a technology designed to deflect potentially hazardous asteroids. In September 2022, the DART spacecraft deliberately crashed into Dimorphos, a 160‑metre‑wide moonlet orbiting the larger asteroid Didymos. The impact was intended to shorten Dimorphos’s orbital period around Didymos and demonstrate that kinetic impacts can alter asteroid trajectories.
Initial measurements showed that the impact reduced Dimorphos’s orbital period by about 33 minutes. In March 2026, further analysis revealed that ejecta from the collision imparted additional momentum, causing the entire Didymos–Dimorphos system to lose enough angular momentum to shorten its solar orbit by roughly 0.15 seconds per year. Although the change is tiny, it confirms that momentum carried away by debris contributes to deflection, an important consideration for future planetary‑defence missions.
Key points and significance
- First successful deflection test: DART proved that a spacecraft impact can measurably change an asteroid’s orbit, validating a key technique for planetary defence.
- Momentum enhancement: Debris and dust produced by the collision carried additional momentum, amplifying the deflection effect beyond the direct impact.
- Implications for future missions: Understanding ejecta dynamics helps scientists plan kinetic‑impactor missions to protect Earth from potential asteroid threats.
- International cooperation: The mission involved international observatories and collaborations, illustrating the global nature of planetary‑defence efforts.
Source: Moneycontrol – NASA’s DART mission slightly altered asteroid’s orbit around Sun
