This post is written by guest blogger Jake Kaplow, an “engineer in training” at Boston University.
That crush you’ve had since eighth grade? It’s time to say how you feel. An asteroid the size of Manhattan’s headed straight toward Earth. In a few weeks, it’ll all be over.
“Baby, you’re my everything, you’re—”
Wait! Save it! NASA’s going to nuke the asteroid. Boy, that was close!
Sound familiar? It should, unless you’ve skipped out on about a dozen movies where that happens, namely Armageddon (1998), which did almost a half-billion at the box office. So, could an asteroid wipe us out? Could we detect and deflect it in time?
Asteroids have dealt damage in the past, like when one killed all of the dinosaurs. And while that didn’t wipe out life completely, it came pretty close. So, yes—a large asteroid, such as the one that caused the extinction of the dinosaurs (and many other animals) could impact the Earth. Well, what do we do?
Before we can nuke an asteroid, we need to find it first. NASA (and others) are looking for them, but it’s tricky. Early detection is key: if it’s close, it’s too late. If telescopes can identify an NEO (near-Earth object), then NASA and other astronomers can take pictures of the same spot over time and calculate the object’s trajectory. Thanks to the collaboration of observatories around the world, different perspectives and data combine to create a more complete picture of where an asteroid is headed, and more importantly, if it is a friendly passerby or a fateful foe.
But sometimes we can’t see asteroids. Dust, atmospheric occlusion, and low-light can obstruct our view and, consequently, our measurements. Imagine trying to follow a ball with binoculars at night during a sandstorm. Luckily, looking at something isn’t the only way to see it. What a time to be alive, right?
Using radio telescope arrays like the Very Large Array in New Mexico, the New Horizons space telescope, the recently retired Kepler telescope, and other tools, NASA can measure the orbits of celestial objects, such as planets, moons, and asteroids, in our cosmic neighborhood. Stars are far bigger than planets, but planets still exert gravitational force on them, which presents as wobbling. Asteroids have the same effect on planets and moons. Detecting a wobble or an anomalous orbit is a strong indicator of a nearby asteroid. But that’s just the first step: wobble alone is not enough to calculate an object’s trajectory.
NASA can combine measurements from both visual and radio telescopes on the ground and in space to better predict asteroids’ movements, but it’s still difficult to make predications with a high level of confidence.
No tried-and-true method exists for finding asteroids. Even NASA’s not too confident it could spot disaster in time: if an asteroid were on a collision course with Earth, “’the most likely warning would be zero,’” according to a NASA representative. “We would see nothing at all…then poof.” “Poof” is OK in a magic show, but not when we’re the ones disappearing.
Roughly once a year, a car-sized asteroid burns up in Earth’s atmosphere. Asteroids also pass by Earth regularly, “sneak[ing]” by us because they’re small, fast, often move erratically, and reflect light poorly, writes NASA reporter Elizabeth Howell. The number of existing NEOs makes it impossible to follow them all.
Despite the difficult nature of the problem, NASA is making progress toward a solid plan for asteroid detection. The NEOWISE spacecraft looked for NEOs in the infrared and found many over a four-month period. Other observatories worldwide spot new objects every day. NASA even pledged to track 90% of NEOs greater than one kilometer in size, which while impressive, still doesn’t cover objects farther away that could potentially impact Earth.
Say we identify an incoming asteroid: what then? If it’s due to hit us tomorrow or next month, it might be time to get out that bucket list. But if it will hit in the more distant future, we may have a chance.
In Armageddon, detonated nuclear bombs break up the killer asteroid into bite-sized chunks eaten up by the atmosphere. That may be a viable solution, but it’s a bit like hammering a nail with a brick: there’s a good chance you’ll bend the nail. Another technique might be more reliable.
NASA is working on a project called DART: Double Asteroid Redirection Test. Instead of detonating a nuclear bomb on an asteroid, NASA hopes this test will demonstrate a kinder approach: kinetic impactor technique. Just as you can hit a baseball with a bat to change its direction, you can fling heavy stuff at an asteroid to steer it from its course with Earth. Or we could land on the asteroid and fire some rockets, pushing the asteroid into a safer path.
Another technique requires no contact at all. By sending something sufficiently massive to the asteroid’s location, it may be possible to use gravity to drag the asteroid into a new orbit or trajectory. The biggest challenge is the amount of mass the probe or device would require to affect the asteroid. The bigger the asteroid, the more massive the probe would need to be. The more massive the probe, the more difficult and expensive it is to build, launch, and control.
But what if we’re not sure whether an asteroid’s going to hit us?
NASA tried to guess in 2004. They estimated that an asteroid named Apophis, either after the Egyptian god or a villain in a sci-fi TV show, had a 1 in 62 chance of impacting Earth in 2029. Just days later, that scary-high chance was downgraded to almost zero. Now the estimate is about 1 in 150,000. So how do we know when to devote the resources to redirection? Deploy them too soon, and it might be a total waste. Deploy them too late, and, well…
That’s when it’s time to finally tell that special someone: “—I want to spend the rest of my life with you. Who cares that we’re only 12?”