At any moment this could happen: We could detect an asteroid in an orbit that would pass the Earth. It may be small; It could be something big. Tomorrow may be; It could happen a thousand years from now. So what can we do about this?
We know rocks of all shapes and sizes hit Soil quite a lot since its founding. We see evidence of this moon: All these craters keep track of the damage. Craters are rarer on our planet, but only because wind and water erode evidence of recent craters and plate tectonics takes care of older ones.
Based on observed evidence from crater records asteroid By looking at populations, we can get a general picture of how often disasters befall our world. Every few years, an object about a dozen meters in diameter crashes into our planet. When it does this, it releases the energy equivalent of a decent-sized nuclear bomb. But most of them explode in the upper atmosphere of the open ocean, so we don’t tend to notice them.
Relating to: How many potentially dangerous asteroids narrowly miss Earth each year?
More broadly, kilometer-scale asteroids hit Earth approximately every 10 million years. These have the potential to cause global disaster – It didn’t turn out so well for the dinosaurs.. Fortunately, although these giant space rocks are destructive, they are extremely rare.
Between these extremes lies the sweet spot of danger: large asteroids that could destroy a city or damage a civilization; This will be, by far, the greatest disaster that can happen to us. Such objects hit the Earth every few thousand years. And that’s what we need to worry about.
To pursue and defend
The International Astronomical Union’s Minor Planet Center, which tracks such things, has counted 34,152 so far. near-Earth objects (NEOs), asteroids whose orbits bring them within 0.05 astronomical units (AU) of Earth’s orbit. (One AU is about 150 million kilometers, or 93 million miles—roughly the average distance between Earth and the sun.) These NEOs don’t necessarily pose a threat—the vast majority are almost always quite far from Earth—but they’re certainly ones we need to keep a close eye on.
This catalog is drawn from a collection of ground and ground observatories. spaceusually caught on loan, extra time. But next Vera C. Rubin Observatory It will provide a great boost to NEO detection as it will constantly monitor the sky and provide a complete catalog every few nights. With this observatory, astronomers expect us to detect three to 10 times the current number of known NEOs.
But identifying these objects is only one piece of the puzzle. We also need to know where the asteroids are going, which requires tracking their movements every night. And you can’t observe for a few nights and call it a day; Asteroids have a bad habit of changing their orbits frequently. This is due to their small, irregular size. Small gravitational pulls from giant planets can block transits as well as alter their orbits. Even their colors and shapes make a difference: Depending on the reflection and rotation speed of the asteroid, sun It could unevenly heat the surface of the space rock, causing a slight but permanent change in momentum.
It is only through strict and persistent monitoring that we can safely detect any potential threat to our home.
big guns
This is the first part of a logical process planet defense strategy. The second part actually does something about the threat.
One option is to do nothing: Let the object hit Earth and hope it doesn’t cause too much damage. This is not very attractive, thankfully we can take a more active approach.
If we detect the asteroid early enough, we can move it out of its current orbit. NASA demonstrated the feasibility of this approach. Success of the Double Asteroid Redirection Test (DART) missionA simple spacecraft crashed head-on didymossmall moon of asteroid dimorphos. Coup triggered measurable change Didymos’ orbitsuggests that we can only achieve this demonstration in the event of a real threat.
If a head-on impact seems a little too brutal, we can also adjust the asteroid’s orbit in more subtle ways. A “gravity tractor” could send a spacecraft into orbit around an asteroid; This spacecraft will slowly change the direction of the asteroid, and the gravitational effect will also change the direction of the asteroid. We can also paint the menacing rock so that it reflects a different amount of sunlight on one side, changing its orbit.
Related Stories:
—8 ways to stop an asteroid: Nukes, paint and Bruce Willis
—What would a planetary defense mission look like if an asteroid really threatened Earth?
—Protecting Earth from asteroids is complex and requires global cooperation
The key to doing all this work is early diagnosis. If we detect the asteroid too late, we cannot provide it with enough energy to change its course. Maybe we can change where on Earth the object hits – for example, we can try to aim it at the open ocean – but that’s the best we can hope for.
Therefore, when it comes to preventing the greatest disaster humanity has ever known, we must keep our eyes on the sky, be patient, and be alert to danger.