How Diffractive Solar Sails Could Stop a Killer Asteroid at 100 km/s– www.universetoday.com
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EXCERPT:
Asteroids don’t come with a warning label that they might one day hit Earth. While we don’t know of any currently on course to do so, we are finding thousands of new ones each year, and there’s always a potential that one could. We proved a viable technique for dealing with that eventuality – the DART mission successfully moved a small asteroid using a “kinetic impactor” – basically a big rod designed to push the asteroid off its trajectory. But DART had one big flaw – it was traveling in the same direction as the asteroid, and approached it from behind, eventually hitting it with an impactor launched while in orbit around it. That technique might work if we have enough warning, but would require years of orbital mechanical maneuvering to pull off. An alternative, proposed by researchers at Beihang University, is to use a new type of solar sail to deflect a potentially hazardous asteroid by hitting it head on.
Deflecting an asteroid using an impactor comes down to one simple factor – energy. The more energy transferred from the impactor to the asteroid, the more the asteroid will move. And the great thing about energy is that it increases with the square of velocity. In other words, the faster you hit something, the more energy you impart to it.
DART smashed into Dimorphos, its target asteroid at about 6 km/s – a respectable speed, but limited by the fact that it was coming from the same direction. According to the new paper, an impactor using a solar sail can come at an approaching asteroid from the opposite direction – akin to a wrong-way highway driver – and smash into its target at around 100 km/s – imparting something like 230 times the force per kilogram of impactor mass than the DART test did.
Fraser talks about how we could potentially stop a killer asteroid.
