Some rather clever scientists at the Lawrence Livermore National Laboratory (which has a superb planetary defense contingent) worked out that, for a 90-meter asteroid, you need 10 years to confidently deflect it with a kinetic impactor to prevent an Earth impact. So, to deflect 2024 YR4, if it’s 90 meters long and we have just a few years of time, we’d probably need a bigger impactor spacecraft (but don’t break it!)—or we’d need several kinetic impactors to deflect it (but each has to work perfectly).
Eight years until impact is a little tight. It’s not impossible that the choice would be made to use a nuclear weapon to deflect it; this could be very awkward geopolitically, but a nuke would impart a bigger deflection than an equivalent DART-like spacecraft. Or, maybe, they’d opt to try and vaporize the asteroid with something like a 1 megaton nuke, which LLNL says would work with an asteroid this size.
Ars: So it’s kind of late in the game to be planning an impact mission?
Andrews: This isn’t an ideal situation. And humanity has never tried to stop an asteroid impact for real. I imagine that if 2024 YR4 does become an agreed-upon emergency, the DART team (JHUAPL + NASA, mostly) would join forces with SpaceX (and other space agencies, particularly ESA but probably others) to quickly build the right mass kinetic impactor (or impactors) and get ready for a deflection attempt close to 2028, when the asteroid makes its next Earth flyby. But yeah, eight years is not too much time.
A deflection could work! But it won’t be as simple as just hitting the asteroid really hard in 2028.
Ars: How important is NASA to planetary defense?
Andrews: Planetary defense is an international security concern. But right now, NASA (and America, by extension) is the vanguard. Its planetary defenders are the watchers on the wall, the people most responsible for not just finding these potentially hazardous asteroids before they find us, but also those most capable of developing and deploying tech to prevent any impacts. America is the only nation with (for now!) a well-funded near-Earth object hunting program, and is the only nation to have tested out a planetary defense technique. It’s a movie cliché that America is the only nation capable of saving the world from cosmic threats. But, for the time being—even with amazing planetary defense mission contributions from ESA and JAXA—that cliché remains absolutely true.
Article by:Source: Eric Berger
