The dramatic mission to alter an asteroid’s trajectory created a debris trail stretching tens of thousands of miles behind the “moonlet” Dimorphos, according to NASA.
Scientists say the “ejecta” was largely generated by the asteroid’s recoil from being hit by a DART spacecraft in September.
“The investigation team has been digging into the implications of how this planetary defense technique could be used. … This has included further analysis of the ‘ejecta’ — the many tons of asteroidal rock displaced and launched into space by the impact,” NASA reported Dec. 15.
“Scientists estimate DART’s impact displaced over two million pounds (one million kilograms) of the dusty rock into space — enough to fill six or seven rail cars,” NASA says. “Solar radiation pressure has stretched the ejecta stream into a comet-like tail tens of thousands of miles in length.”
NASA scientists are continuing to study data and did not address the implications of the debris trail. However, the debris is not considered a threat to Earth.
The DART (Double Asteroid Redirection Test) mission was “the world’s first planetary defense technology demonstration.”
It’s goal was to see if a spacecraft could be used to alter the path of a potentially dangerous asteroid, should one threaten Earth.
It worked from that perspective: DART’s 14,000 mph collision with Dimorphos slowed its rotation by 33 minutes, NASA says.
Dimorphos — a minor-planet moon orbiting the asteroid Didymos — did not pose a threat to Earth, which made it a good test subject, experts say.
“Now we can start to apply this knowledge,” DART investigation team co-lead Andy Rivkin said in the news release. “Studying the ejecta made in the kinetic impact — all of it derived from Dimorphos — is a key way of gaining further insights into the nature of its surface.”
Calculations show “the ejecta contributed to moving the asteroid more than the spacecraft did,” NASA says.
Understanding this “momentum transfer” will play a key role in creating a strategy to defend Earth from asteroids, NASA says.
The DART craft was built and operated by Johns Hopkins APL for NASA’s Planetary Defense Coordination Office, officials say.