NASA's Asteroid Deflection Mission May Spark an Artificial Meteor Shower

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NASA's DART mission will attempt to deflect a small asteroid off-course as a proof-of-concept demonstration for defending Earth against much larger threats. (Photo: NASA)

A proof-of-concept demonstration by NASA to determine whether we could save Earth from a doomsday asteroid by literally knocking it off course may end up causing the first human-generated meteor shower.

Called the Double Asteroid Redirection Test (DART), the unprecedented mission will begin with the launch of an 1,100-pound NASA probe aboard a SpaceX Falcon 9 in 2021. It will then travel roughly 6.6 million miles for a dramatic rendezvous with a binary asteroid system called Didymos in late September 2022. Instead of targeting Didymos, which measures nearly 2,600 feet across, DART will set its sights instead on a smaller, 500-foot-wide orbiting object nicknamed "Didymoon." Traveling at a speed of 13,500 mph, DART's collision with Didymoon is expected to generate enough force to change the small rock's orbit.

"The collision will change the speed of the moonlet in its orbit around the main body by a fraction of one percent, but this will change the orbital period of the moonlet by several minutes — enough to be observed and measured using telescopes on Earth," NASA states on the mission website.

A new manmade meteoroid stream

An illustration of the DART spacecraft just before its collision with 'Didymoon."
An illustration of the DART spacecraft just before its collision with Didymoon. (Photo: NASA/Johns Hopkins University Applied Physics Laboratory)

When DART collides with Didymoon, the resulting explosion is expected to create a 30-foot-wide crater in the asteroid and, according to The New York Times, eject anywhere from 22,000 to 220,000 pounds of centimeter-sized debris. While the vast majority of these tiny meteoroids will envelope the Didymos system like a cloud, an unknown number will be ejected into space. Due to the asteroid's orbit passing by Earth only a few days after the collision, it's likely that some will burn up in the atmosphere as part of the first meteor shower caused by human activities in space.

According to Paul Wiegert, an astronomy professor at the University of Western Ontario, this precedent is as much a warning as an opportunity. In a new paper published in The Planetary Science Journal he writes that while the vast majority of the ejecta created by DART won't cross paths with Earth for potentially thousands of years, the experiment still proves that we need to be careful –– particularly in regards to spacecraft safety –– and understand the repercussions of violent actions in space.

An illustration of the probe's collision with the asteroid.
An illustration of the probe's collision with the asteroid. (Photo: European Space Agency)

"Though one is tempted to dismiss the problem as negligible at this time, it is reminiscent of the problem of space debris in low Earth orbit," he writes. "Neglected initially, we are now reaching a point where we may be denied the full use of valuable portions of near-Earth space because of orbital debris build-up. Much future expense and risk could be averted if the same story does not unfold with asteroidal debris production."

Wiegert adds in the paper that future instruments, such as the mirrors on the upcoming James Webb Space Telescope, could be critically damaged by artificially-generated meteoroid streams. He urges researchers to monitor not only the results of the collision, but also the path of the debris field. Setting such a precedent could help protect future missions from increased human activity elsewhere in our solar system.

"Though it is unlikely to occur in the case of the DART impact, future human asteroid operations such as planetary defense tests or asteroid mining, could conceivably produce debris streams whose meteoroid particle content rivals or exceeds naturally occurring meteoroid streams," he warns.