NASA’s asteroid crash slightly shifted an entire solar orbit

When NASA intentionally crashed a spacecraft into an asteroid in 2022, the moment sounded like something straight out of a science-fiction movie. The mission, known as the Double Asteroid Redirection Test (DART), aimed to answer an important question: could humans deflect an asteroid if one ever threatened Earth? At the time, scientists focused mainly on how the collision changed the orbit of the small asteroid Dimorphos around its larger companion, Didymos.

Now, new findings suggest the impact may have had an even more remarkable effect. Fresh observations indicate that the crash slightly altered the entire asteroid system’s orbit around the Sun. Although the change is extremely tiny, scientists say it marks the first time a human-made spacecraft has measurably shifted the solar orbit of a natural celestial object.

How NASA’s DART impact affected a binary asteroid system

The DART spacecraft deliberately collided with Dimorphos in September 2022 at a speed of around 22,500 kilometres per hour. Dimorphos is a relatively small asteroid, measuring about 170 metres across, and it orbits a much larger asteroid called Didymos, which is roughly 805 metres wide. Together they form what astronomers describe as a binary asteroid system.

While Dimorphos circles Didymos, both bodies travel together around the Sun. Because they are gravitationally linked, any change to one can influence the motion of the entire system.

When DART struck Dimorphos, the collision blasted a massive cloud of rock and dust into space and altered part of the asteroid’s surface. Scientists expected debris, but the sheer amount that erupted surprised many observers. Researchers explain that the ejected material carried momentum away from the asteroid, creating an extra push on Dimorphos. This phenomenon, known as the “momentum enhancement factor,” meant the debris acted like a natural rocket exhaust that amplified the force of the spacecraft’s impact.

When the asteroid’s 12-hour orbit suddenly became shorter

Earlier studies had already confirmed that the collision significantly changed Dimorphos’ orbit around Didymos. Before the impact, the smaller asteroid took about 12 hours to complete one orbit. After the crash, that orbital period was shortened by roughly 33 minutes.

Scientists viewed this result as a major success because it demonstrated that a spacecraft could alter an asteroid’s motion.

However, new research indicates that the event produced an additional, far subtler effect. Observations suggest that the Didymos–Dimorphos system’s orbit around the Sun shifted by around 0.15 seconds. In astronomical terms, even such a tiny change can be meaningful. Researchers estimate the binary system’s speed changed by about 11.7 microns per second, which is roughly 1.7 inches per hour. Although the adjustment is almost unimaginably small, scientists say that over long timescales such shifts could eventually lead to significant orbital deflections.

Future of asteroid defence

The DART mission served as the first real-world test of asteroid-deflection technology, but it is only the beginning of planetary defence efforts.

NASA is already working on the Near-Earth Object Surveyor mission, a specialised space telescope designed to detect hard-to-spot asteroids. Many potentially hazardous objects are extremely dark and reflect very little sunlight, making them difficult to identify using traditional telescopes.