People have a bottomless appetite for all things space these days. Some space news is truly mind-blowing, like the first image of a black hole last year or this year’s time lapse of said black hole’s dancing shadow. Then there’s news of the less mind-blowing variety. Second only to full coverage of every supermoon are headlines of near (but harmless) misses by asteroids. However, while a supermoon isn’t too much more breathtaking than a run-of-the-mill full moon—those harmless near-misses actually do hint at something more significant. As our planet plows through space, its orbit inevitably crosses the orbits of other inhabitants of the solar system. Among this group are asteroids of all sizes. Most of these are so small they’d be vaporized by the atmosphere, but others are big enough to impact the surface and do serious damage. Infamously, an asteroid the size of a city crashed into Mexico’s Yucatán Peninsula some 66 million years ago. The blast was enormous. It sent mega-tsunamis racing across the ocean and dug a roughly 93-mile-wide crater, throwing much of that material into the atmosphere where it blocked and dimmed the sun for years. Many scientists believe the Chicxulub impact was the prime culprit behind the extinction of the dinosaurs and 75% of life on the planet at the time. There’s been no repeat performance in the last 66 million years, and the day-to-day risk of a major impact is very, very low. But it’s a near certainty that another large object will at some point in the future collide with our planet—unless we do something about it. Luckily, while the last killer space rock dropped out of the sky with no warning, we have a few tools the dinosaurs didn’t. In addition to telescopes to chart potentially hazardous asteroids, we can visit and, theoretically, divert an asteroid’s course before it reaches us. Now, the world’s space agencies are teaming up to take planetary defense beyond theory. This month, the European Space Agency (ESA) approved and funded their part of the Asteroid Impact Deflection Assessment (AIDA), a joint mission with NASA and other space agencies to, for the first time, attempt to alter the orbit of a sizeable asteroid in deep space. The missions aim to yield the first hard data in humanity’s quest to avoid the fate of the dinosaurs. Desperately Seeking NEOs Of course, to divert an asteroid, you have to find it first. In 1998, NASA launched a program to chart 90% of all the asteroids and comets in our neighborhood—known as near-Earth objects (NEOs)—larger than a kilometer in diameter. NASA hit this mark in 2010, but by then, the space agency had already been re-tasked to find 90% of all NEOs larger than 140 meters by the end of 2020. The new mandate would include objects that can wreak significant global havoc—as in the case of Chicxulub—but also smaller strikes that would nonetheless do serious damage to the regions they impact. To date, we’ve charted 9,334 NEOs larger than 140 meters (including comets). But that number is only a little more than a third of the total estimated population of 25,000. While current telescopes have done a great job, a space-based, infrared telescope would speed progress. So, it’s good news that, after years awaiting approval, the NEO Surveillance Mission (previously NEOCam) won first funding to kick the search into high gear with such a telescope. The mission aims to round out our list of 90% of NEOs bigger than 140 meters within a decade of launch. Of course, it doesn’t end there. Once we’ve found a killer asteroid or comet, it’d be nice to be able to do something about it—like, you know, gently (or not so gently) take it by the elbow and usher it from our planet’s path. So, how does one move a mountain in space? All It Takes Is a (Maybe Nuclear) Nudge There are many ideas about how to avoid asteroidal Armageddon. Most well-known of these is the nuclear option, where we’d detonate a nuclear explosive (or multiple explosives) near,...
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