When NASA crashed a spacecraft into the asteroid moon Dimorphos in 2022, it changed Dimorphos’ orbit around its parent asteroid, Didymos, and the two objects’ orbit around the Sun, according to new research. NASA’s Jet Propulsion Laboratory (JPL) said in a press release that it is “the first time a man-made object has measured the path of an astronomical body around the Sun.” This is a promising result as scientists work to find a viable way to protect Earth from dangerous space objects.
The Double Asteroid Redirect Test (DART) mission was designed to demonstrate a possible way to deflect such an object by targeting the non-hazardous moon Dimorphos, which is approximately 560 feet wide. NASA immediately declared it a success as its initial analysis showed that the planned collision narrowed Dimorphos’s orbit around Didymos, the larger of the two objects in the binary asteroid system. In a follow-up study published in 2024, a team from NASA’s JPL reported that Dimorphos’ orbital period was reduced by about 33 minutes, because its path was about 120 feet closer to Didymos than before. Now the latest study indicates that not just Dimorphos, but the entire binary system was affected.
Didymos and Dimorphos have an orbital period of 770 days around the Sun, which lead author Rahil Makadia said results in a variation of “about 11.7 microns per second, or 1.7 inches per hour”. This may not seem like much, but according to Makadia, “over time, such a small change in the asteroid’s speed could make the difference between a dangerous object hitting our planet or missing out.”
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