A recent study suggests that asteroid Dimorphos is exhibiting unexpected changes in behavior after a collision with a NASA spacecraft last year. The asteroid, which is approximately 580 feet wide, was intentionally crashed into by a spacecraft as part of the Double Asteroid Redirection Test mission.
New observations indicate that Dimorphos may be spinning in its normal orbit around its parent asteroid, Didymos. This goes against NASA’s predictions, as it was expected to maintain a stable orbit.
Jonathan Swift, a high school teacher in California, and his students were the first to notice these unexpected changes while observing Dimorphos with their school telescope. Several weeks after the collision, NASA announced that the asteroid had decreased its orbit by approximately 33 minutes. However, Swift and his students observed an additional decrease of one minute per month after the impact, suggesting a continued decrease in velocity since the collision.
The DART team later confirmed that Dimorphos indeed continued to decrease its orbit until one month after the impact. However, their calculations showed a decrease of 15 seconds, rather than a full minute. The asteroid eventually reached a point of stability in its velocity decrease one month after the collision.
One possible explanation for this unexpected behavior is the presence of a cloud of space rocks. Observations revealed a series of scattered rocks around the area, which likely broke off from Dimorphos’ surface during the impact. It is speculated that some of these larger rocks fell back onto Dimorphos, causing a greater decrease in its orbit than initially anticipated.
The DART team plans to publish a more comprehensive report on these unexpected findings in the near future. However, a fuller understanding of the situation will be needed until the European Space Agency’s spacecraft Hera arrives at Dimorphos in 2026 to investigate the impact site up close.
Source: New Scientist