Why we are Not Good at Detecting Astroids that Could Threaten Civilization

Let’s play a game. Imagine that you’re standing outside, blindfolded, and someone throws a rock at you every so often. Sometimes, you hear it whiz by. Most of the times, you only learn you were almost hit because it hits something. But every once in a while, a rock strikes you square in the face. Ouch.

Earths Last Big Astroid Impact

On February 15, 2013, a rock about the weight of the Eiffel Tower barreled toward Earth. It was going 19 kilometers per second. That’s 40 times faster than a bullet. Near Chelyabinsk, Russia, the asteroid struck with such speed that it compressed the air in front of it and blew up at an altitude of 30 kilometers. The blast was brighter than the sun. And it was silent. At least, for a while.

For a complete 90 seconds, the onlookers observed the mesmerizing fireball and the lengthy smoke trail in the sky but heard nothing. So they did what anyone would do. They quickly took out their phones and rushed to the nearest window. Then the shockwave hit!

Glass shattered in thousands of buildings. The explosion was so powerful that about 1,500 people were injured due to flying glass. And the worst part is that asteroid? We never saw it coming.

The Rock We Expected Wasn’t the One That Hit Us

Just 16 hours later, astronomers had predicted a flyby of an asteroid. A rock called Duende, which was about the same size as the Chelyabinsk impactor, passed just 27,000 km away from the Earth. While we were looking at Duende, another asteroid came out of nowhere to blindside us.

As it turns out, this type of cosmic sneak attack occurs all the time. More than 1200 asteroids bigger than a meter have struck earth (1988). Of those, we detected only five before impact. The best warning we ever got? Less than a day.

So, with all our satellites, telescopes and clever technology, why are we so rubbish at spotting killer space rocks before they hit us?

Asteroids: Space Debris from a Damaged Solar System

Near space objects(NEOs) are a real threat. Most asteroids minds their own business and hang out in the asteroid belt, between Mars and Jupiter. But the solar system is not a static place. Over time, gravity can pull objects in space out of their orbit resulting in them getting sent to the inner solar system. It’s the near-Earth objects that most concern us.

NEOs short for Near-Earth Objects are dangerous to Earth. Some cross our path regularly. Some of them drift quietly, unnoticed, until boom. A tiny change in trajectory caused by a planetary encounter, solar radiation or their own lopsided heating could turn a harmless stone into a city killer.

The biggest asteroids, ones that are at least 10 kilometers in size, are easy to keep track of, and fortunately for us, none are on collision course with us in the site next century. However, smaller asteroids are far more common, the hundreds-of-meters-wide kind that could flatten a city or trigger a massive tsunami, as scientists at MIT’s P.I. found. And we haven’t found them all yet.

Going back to the asteroid that exploded over Russia in 2013 and injured over a thousand people, Chelyabinsk, was 20-metre long only. If a rock that size came hurtling towards earth on a slightly different trajectory, it could have been catastrophic.

The real danger lies not in the asteroid killing dinosaurs. It’s the under-the-radar threats we should really be concerned about asteroids that are large enough to doom a city but small enough to go unnoticed. And one of them could already be on its way.

Why We Suck at Seeing Asteroids

Spotting an asteroid is not like spotting a bright star. Most asteroids are small, dark, and fast. They don’t emit light, they only reflect it. Even at this, they reflect only 15% of the light striking them. It’s hard to tell how the lump of charcoal was imagined flying through the night sky at 20 km/sec.

Our best chance to see asteroids is when they’re fully lit up by the Sun. Most of the asteroids detected are 85% found in a 45-degree slice of sky opposite to the Sun. The frightening portion, though, is that any asteroid coming from the direction of Sun is essentially invisible.

That’s exactly what happened with Chelyabinsk. Since Chelyabinsk came from the direction of the Sun, we have had no way to see it before it was too late.

The Ones That Got Away & Ones that are Coming

What Happens When a Big One Hits? Well, the universe doesn’t operate on human timescales. It takes a century for time to feel new, but the universe is old beyond measure. Asteroid impacts in universe are not accidents but clockwork of nature. They’re inevitabilities.

If a country gets hit by a 1km-wide asteroid, it won’t end civilization but will destroy the country which will become a crater. Moreover, it will cause massive firestorms and turbulence of planetary proportions. What if a 10-kilometer asteroid hits earth (the one which ended the life of dinosaurs)? It would deliver an impact with force equal to billions of nuclear bombs, and that would just be the beginning. Lava rock would be blasted into orbit and rain down igniting the whole sky The heat alone would cook the planet’s surface. The only survivors? The creatures that could survive underground or surf the ocean surface like the small mammals did 66 million years ago.

So, should we be worried? In the short term, no. All 10-kilometer asteroids with predicted impact trajectories towards Earth in the next hundred years have been mapped. None of them are on course for us. But this certainty is a trick of limited perspective. Since space is not stationary, likewise, is the asteroid orbit.

This is where dynamic disorder turns into a life-threatening concern. Asteroids don’t move in perfect, predictable ellipses; We observe that the orbits of asteroids aren’t set in stone, but··· Over decades, these slight effects add up, thus making long term predictions impossible. We are able to predict the path of an asteroid for a century, but beyond that the system goes into chaos and certainty disappears.

The 2013 Chelyabinsk meteor injured 1,500 people and was 20 meters wide; we were completely oblivious to the event. The bright star in the sky is actual the sun itself, which possibly can hide some asteroids. If an asteroid that could destroy cities was coming to earth today, we would probably not know until it was too late.

We can be confident that nothing large will hit us soon, but we cannot say the same for smaller asteroids the ones big enough to wipe out cities. The next one’s already out there being jostled around by gravity and other chaotic forces. And we don’t know where it is.

What Happens When a Big One Hits?

We like to believe that we are in control. That civilization is stable, that progress is inevitable. But space doesn’t care. A one-kilometer-wide asteroid strike wouldn’t wipe out humanity, but it surely would wipe out a country; Brazil, to be precise. Cities would be wiped out, firestorms would start, and tsunamis would travel the oceans. The dust would encase the earth and choke out the sun for months. Crops would fail. Supply chains would collapse. Millions, perhaps billions, would die.

But a 10-kilometer asteroid? That’s not a disaster, it’s an extinction event. Around 66 million years ago, a rock similar in size hit the Yucatán Peninsula. When it impacted, glowing rock was blasted into space, then fell back again, igniting the whole planet. For hours, Earth glowed red-hot. The dinosaurs were literally cooked alive before the real disaster even hit.

Then came the long winter. Dust from the asteroid impact blocked out so much sunlight it created a ‘nuclear winter’ type scenario. Photosynthesis collapsed. Ecosystems unraveled. All that was left were the little ones and those who hid the subterranean and the sea-dwellers. The big, dominant species? They were wiped out. With this absence, small mammals: our forefathers are at the helm.

So when we discuss various asteroid impacts, we won’t only be talking about blasts. We’re referring to evolutionary resets powers of nature that wipe the old world out and make way for the new. If we don’t put our act together, the next reset may not be in our favor!

What are the Odds of Another Dino-Killer Impact?

We live in an age of misplaced priorities. Every day, we worry about the latest crisis while the universe doesn’t seem to care. The more we technologically advanced, the more we think we can control things. Yet when it comes to doomsday events, those situations that could wipe out or reset civilization in a night, most of us are blind passengers on a ship we barely know how to steer.

So, what are the odds of another dino-killer impact? Not high. All of the known 10-kilometer asteroids, the type that killed the dinosaurs, have had their orbits completely mapped by scientists, and none of them are predicted to hit us in the next 100 years. You don’t have to panic; at least not in the way a gazelle in the Serengeti has to panic if it knows there are no lions near it.

But the real danger isn’t in what we know. It’s in what we don’t know.

An asteroid large enough to destroy a city is much more likely than one that could kill dinosaurs. We have not mapped them all. We don’t know their orbits with certainty. Those are the one which might slip through the net i.e. they might come from angles where we are not looking, shielded by the Sun’s glare till it’s too late. The 20m-wide Chelyabinsk exploded thousands of windows and injured more than a thousand people. Now picture an asteroid that’s ten times bigger coming in.

While a reset button for the planet is on its way but the smaller ones still remain a mystery. We know they’re out there. We just don’t know when one will arrive. By the time we see it, nothing is left to do but to witness.

Can We Stop an Asteroid? The Science (and Fiction) of Planetary Defense

This is the Hollywood Delusion. We have all seen it; humanity’s last hope shoots into space, drills into an asteroid, and blows it up with a nuke. The Earth is saved. Roll credits.

But reality isn’t a Hollywood script. If an asteroid is nuked, it will break up and while it won’t be a threat anymore, it would create thousands of other threats. A shotgun blast of destruction instead of a single impact. And even if breaking it up was not a problem, then we can’t really ignore the fact that we don’t have space nukes.

Deflect, Don’t Destroy

A smarter move would be nudging the asteroid off course. In a theoretical sense, rockets can be attached to it and zapped with lasers, and it’s possible to use a “gravity tractor,” which is a spacecraft that hovers nearby and pulls the asteroid off course using only gravity.

Sounds elegant, but in practice, it’s wildly impractical. We can’t use rockets because they aren’t strong enough, lasers don’t pack a punch, and a gravity tractor would take decades to work. If we find an asteroid six months before it hits, these ideas become science fiction.

Painting an Asteroid? Yes, Really

One of the most bizarre yet scientifically sound ideas is to change the colour of an asteroid. The Yarkovsky effect is when sunlight heats an asteroid unevenly, causing it to change trajectory. If we paint it white, it could go out of route a little to miss earth.

The problem? Painting it white may require years or decades and a very huge amount of paint.

The Foolproof Plan That’s No Plan At All

If all else fails, could we evacuate? Well, not really. Witness how disaster struck when millions tried to flee to the coast. The roads were blocked, there were no more gas, and some people died before the storm itself got there. Now scale that up to a city-killer asteroid. There’s nowhere to go. Panic would make everything worse.

The absolute best way to prevent disaster is to find these asteroids beforehand

The truth is, we can’t stop what we don’t see. At present, we haven’t found thousands of city-killer asteroids. Some lurking here and there, waiting for their time to hit us.

If we want to survive, early detection is everything. More space telescopes. Better tracking. There’s an asteroid out there that could hit Earth we just don’t know where.

What Can We Actually Do?

At this moment, the most essential thing we can do is find these asteroids. This means we have to fund the mapping of the skies, launch space telescopes specifically designed to find asteroids, and monitor any space rocks that could cross our orbit.

The asteroid that shall next hit the Earth is out there already. We just don’t know where it is.

Yet.

Stay curious. And don’t forget to look up.