Seen here is a photograph of Dimorphos as seen by the Hubble space telescope. The second tail is clearly visible. Credits: NASA, ESA, STScI, Jian-Yang Li (PSI); Image Processing: Joseph DePasquale.

Unexplained Force Adjusts Asteroids Orbit After DART Collision

Recent data from the DART mission to asteroid Dimorphous has scientists rethinking our understanding of asteroid behavior after collisions.


NASA’s DART mission, which saw an impact with asteroid Dimorphous in September 2022, led to a surprising outcome. Tons of rock were ejected from the asteroid’s surface, but more notably, DART’s collision altered Dimorphos’ orbital period, reducing it by 33 minutes.

However, subsequent observations a month after revealed that the orbital period had increased by 34 minutes. It appears that an unidentified force is slowing down the asteroid’s orbit post-collision, leaving astronomers puzzled. Current theories, as detailed in a preprint on arXiv, are yet to pinpoint the exact cause.

Defending Earth from Space Threats

DART’s main objective was to understand how asteroids react to impacts. The initially observed alteration in the asteroid’s orbital period was celebrated since using kinetic impact as a planetary defense technique is considered a viable solution to redirect Potentially Hazardous Asteroids. This data holds significance for agencies like NASA and ESA in planning asteroid deflection strategies.


Weighing 610 kg and traveling at around 22,530 km/h, DART’s impact on Dimorphos was profound. It created a crater, sending over 900,000 kg of debris into space, and even influencing the trajectory of Didymos, the moonlet’s parent asteroid. Scientists estimate that the impact displaced over two million pounds of rocky debris.

New Observations Challenge Previous Findings

Researchers, including Taylor Gudebski and Elisabeth Heldridge, utilized the 0.7m telescope at the Thacher Observatory in California for further observations. Their findings suggested a potential shortening in the asteroid’s orbital period soon after the initial data. One hypothesis is that the expansive debris cloud from DART’s collision could be influencing the asteroid’s orbit. However, this team believes the debris can’t fully explain the observed changes.

Moreover, even before DART’s impact, Dimorphos’ orbital period was already experiencing minor changes. But these were considerably smaller than the recent alterations.


The quest to understand DART’s true impact continues. It remains to be seen if the orbital period will keep reducing and how it might impact the future use of kinetic impactors. An upcoming mission, ESA’s Hera, launching in 2024, aims to closely study Dimorphos, potentially offering more insights into these mysterious behaviors.

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Written by Ivan Petricevic

I've been writing passionately about ancient civilizations, history, alien life, and various other subjects for more than eight years. You may have seen me appear on Discovery Channel's What On Earth series, History Channel's Ancient Aliens, and Gaia's Ancient Civilizations among others.

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