---
title: 'Can Humanity Stop a Planet-Killing Asteroid?'
source: 'https://youtube.com/watch?v=dKm7T13X7n4'
video_id: 'dKm7T13X7n4'
date: 2026-07-20
duration_sec: 763
channel: 'Kurzgesagt – In a Nutshell'
---

# Can Humanity Stop a Planet-Killing Asteroid?

> Source: [Can Humanity Stop a Planet-Killing Asteroid?](https://youtube.com/watch?v=dKm7T13X7n4)

## Summary

This video explores humanity's ability to defend against asteroid impacts, from small city-killers to massive planet-killing comets. It explains the limitations of current deflection methods and introduces a new concept using tungsten penetrators to destroy asteroids. The video concludes that while small asteroids can be handled, a planet-killer discovered today would be unstoppable, though a combined penetrator-nuke strategy could work with advance preparation.

### Key Points

- **Asteroid Impact Threat** [00:13] — A stadium-sized asteroid hitting Earth would release energy equivalent to 4,000 Hiroshima bombs, flattening cities.
- **Late Detection Examples** [00:37] — In 2019, asteroid OK (30-story building) was discovered one day before grazing Earth. In 2023, asteroid MK was spotted 13 days before passing closer than the Moon.
- **Traditional Deflection Methods** [01:06] — Methods like landing thrusters or crashing spacecraft into asteroids are compared to deflecting a cargo ship with a bag of potatoes—they work but require years of advance notice.
- **Asteroid Composition** [01:48] — Most asteroids are not solid rocks but rubble piles of pebbles, minerals, and dust, making them easier to pulverize than nudge.
- **Challenges with Nuclear Bombs** [02:17] — Head-on nuke collision fails because the asteroid destroys the bomb before detonation. Exploding at a distance loses energy in vacuum. Burying a nuke requires risky landing and slow drilling.
- **Penetrator Concept** [04:08] — Instead of nukes, use dense tungsten penetrators placed in the asteroid's path. At 70,000 km/h relative speed, the impact releases immense energy, vaporizing rock and destroying the asteroid.
- **Timing and Distance** [05:05] — Destruction must occur about one day before impact (2 million km away) to avoid fragments hitting Earth together. A single 2.5-tonne penetrator suffices for a 100 m asteroid.
- **Planet Killer Comets** [06:31] — Comets from the outer solar system, like NEOWISE (discovered 4 months before approach), are massive, fast (140,000 km/h), and harder to track. They carry energy equivalent to tens of thousands of nuclear arsenals.
- **Challenges for Planet Killers** [07:55] — Simply breaking a planet killer into pieces is insufficient; fragments must miss Earth entirely. This requires destruction far away (beyond Mars) and hundreds of thousands of penetrators, needing 24,000 super-heavy rockets—currently impossible.
- **Combined Penetrator-Nuke Strategy** [08:44] — A feasible plan: launch a single rocket with 5 penetrators (including a 300-megaton nuke) to hit the comet sequentially, drilling a tunnel and detonating inside to shatter it. This uses existing technology but requires unprecedented precision and a one-way astronaut mission.

### Conclusion

Humanity can stop small asteroids with tungsten penetrators, but planet-killing comets remain a formidable threat. A combined penetrator-nuke strategy could work with current technology, but requires advance preparation and precision.

## Transcript

Our first ever PC game, Star Birds, is out now in Early Access!  Find out more at the end of this video! Imagine: a stadium sized asteroid is going to hit Earth in two weeks.
Even at this moderate size, a fireball brighter than the Sun tears through the atmosphere at 60 times the speed of sound and the destructive power of 4,000 Hiroshima bombs flattens cities,
Many killer asteroids were only spotted at the last moment. In 2019, asteroid OK, as big as a 30-story building, was discovered just one day
before it grazed earth closer than some of our satellites. Last year, the even larger asteroid MK was spotted 13 days before it passed us closer than the Moon. If they had hit Earth, they would have unleashed the destructive power of 3,000 and 9,000 Hiroshima bombs.
Scientists have devised all kinds of tricks to push dangerous asteroids away landing thrusters to steer it,
or even crashing spacecraft into it. They are the equivalent of trying to deflect a cargo ship by throwing a bag of potatoes at it
– they do move the asteroid, but only by a tiny bit. With these methods, you need to act years or even decades in advance to make an asteroid miss the Earth. But very recently scientists have developed  a new spectacular way to destroy killer asteroids
Let’s see how this works with our 100 m asteroid heading for Earth! For a long time, people imagined asteroids as being gigantic stones.
But it turns out, most of them aren’t like that. – heaps of pebbles, precious minerals and dust, barely held together.  Which means that instead of just nudging them,  we can do something better – pulverize them.
And the obvious choice is, of course, a nuke! We load up a nuclear warhead,  launch, aim at our deadly asteroid and…
Oh. The asteroid destroyed the nuke! Asteroids can approach Earth at 70,000 km/h  – enough to cross the Atlantic in 5 minutes. So if we go for a head-on collision, the asteroid will wreck the nuke before it even has a chance to explode.
Ok easy, let’s explode the bomb  before it touches the asteroid. Scientists have estimated the optimal  distance, which for our 100 m killer friend Launch, set the timer and…
Unfortunately in space there is no air to carry a shockwave, so most of the explosion’s energy is lost. The rock will still hit us in two weeks, only a few kilometers to the left.
is like hitting our cargo ship with a washing machine instead of potatoes Ok, let’s go the movie route – land someone on the asteroid, drill a hole and bury a nuke inside to avoid all of these problems!
And indeed this is possible in theory, albeit suicidal in practice.   Even on fairly big Mars, whose surface we know almost perfectly, roughly 70% of our attempts have failed.
So imagine the chances of landing a crew and a nuclear bomb on a small and extremely fast asteroid Even if we succeeded, drilling in microgravity is painfully slow, since there is no downward pull to help you.
So we’d need an agonizing amount of time that we don’t have. We have to think less like Hollywood and more like a lumberjack. If you want to split a log, you don’t hit it with a rock.
You use an axe – a dense and perfectly shaped tool designed to break things apart. And just in the same way, scientists have found a new tool to destroy asteroids: We won’t even have to shoot them!
A few meters long, slim and made of tungsten,  a metal way denser and harder than rock. You just put the penetrators in the way of  the asteroid, to float silently in space.
From the perspective of the asteroid, you  wouldn’t see a few tiny bullets sitting still.   You’d see them rushing at you at 70,000 km/h! It doesn’t matter who stands still and who is fast!
But this speed means that by far the longest part  of this mission is to get to the asteroid in time. We can’t destroy it too close to Earth because its fragments will slam into the atmosphere all at once Our atmosphere can absorb isolated chunks
– but if thousands of them strike together,  their shockwaves will add up and kill millions. So instead we need to get it one day before impact, when the asteroid will be nearly 2 million kilometers away, A vast distance, but doable.
We’ll send just one penetrator, about 2 meters long and weighing 2.5 tonnes. Once our rocket arrives, it puts the  penetrator in place to cause maximum damage
A tiny speck of light appears in the vast distance, and then suddenly it's here, We’ll slow down time to see exactly what happens.
The asteroid crashes into the penetrator so fast and with so much violence that the power of 120 metric tons of TNT is released into the asteroid.   The rock vaporizes and the tungsten melts away,  carving a wound that tunnels through the asteroid.
The damage is too much, and with all of this energy looking for a place to go, the asteroid is blasted into thousands of pieces. A day later the fragments hit Earth, dispersed over hundreds of thousands of square kilometers
and turning an apocalypse into a mostly harmless show of cosmic fireworks. spotting a killer asteroid with  two-weeks notice would be enough.
What if we face a cosmic mountain, a planet killer,   carrying the destructive power of  tens of thousands of nuclear arsenals. The non avian dinosaurs would tell you about it but they’re dead.
Planet killers are objects so vast and powerful that they would end most life on earth in a single strike. The most dangerous ones are comets from the outer fringes of the solar system,
so distant and dark that tracking them is impossible. Comets are dirty ice balls the size of mountains, more fragile than pure rock but also much faster and violent, traveling at around 140,000 km per hour.
In 2020 the comet NEOWISE, with the power of  6,000 times all the nuclear bombs on Earth, was discovered just 4 months before its closest approach to Earth. What if we find such a beast six months before it’s going to crash into Earth?
Unfortunately this would be extremely hard for a bunch of reasons. First of all our planet killer comet has so much more mass than a tiny killer asteroid,
that simply breaking it into millions of pieces would not help us that much. to set the sky ablaze and kill most life on Earth. So we need to make most if not all of its fragments completely miss Earth
– but to do that we need to destroy it much further away – as far away as Mars. And to destroy a mountain, we need way  more penetrators – hundreds of thousands. To travel this far and to transport this much payload, we need at least 24,000 super heavy rockets.
– and they’re not really finished yet. we would not finish in time. If we actually discovered a planet killer today, there is literally nothing we could do about it.
Maybe if we combine penetrators with a bit of Hollywood and our old friend, the nuclear bomb, there is still a way. For this plan to work we basically need  to have all the parts ready beforehand.
A rocket like NASA’s SLS – the one planned to take astronauts to the Moon As soon as the planet killer is spotted on its way to wipe us out we launch a single rocket to meet it.
For 5 long months it travels through the nothingness of space as life on Earth nervously continues. Finally it reaches its destination a bit beyond the orbit of Mars. Now we deploy 5 massive penetrators in sequence,  one perfectly lined up two kilometers after the other.
The engineering challenge of aligning and timing this correctly is horrendous and we only have one attempt. So a few very brave astronauts go on this one way trip to supervise the process, with no way home.
Nervous hours pass as all of humanity  watches the skies and screens. The icy mountain of death appears in full and then it’s already here!
The comet smashes into the first penetrator at 140,000 km/h, Ice, rock and tungsten liquify in an instant
as the energy of the impact eats itself dozens of meters deep into the mountain. Here is the second one, perfectly hitting the same spot punching directly into the crater, smashing, melting, drilling.
The third and fourth penetrators repeat the process again, now smashing a tunnel about 100 meters deep. But this time this is just a scratch on the surface of  the monster, the comet is not really damaged yet.
And then comes the final penetrator and its toxic load. 300 megatons in nuclear warheads – 20,000 times more energy than the bomb that destroyed Hiroshima. It travels deep into the tunnel and just before it hits the end, it explodes.
Instead of hitting nothing in the vacuum the energy of the explosion smashes into rock and gravel and ice. there is so much shock and push and punch that  a frozen world billions of years old dies from within.
Turning into a cloud of millions  of fragments spreading in all directions. To make this happen in reality would take  unprecedented planning and precision.
Not in a century with sci-fi technology. Just with the rockets, engineering, and knowledge we already have today.
Our first ever PC game, Star Birds,  is out now in Early Access! Join a brave flock of intergalactic birds as they venture into space to mine asteroids,
build production chains, and unlock new technologies that will help them thrive across the galaxy. Scan and claim nearby asteroids, build up your  production lines, and create a sprawling network
of floating space factories. Whether you're a seasoned strategy player or completely new to the genre, Star Birds welcomes you to explore, build, and discover at your own pace. together with the amazing team at Toukana Interactive, the creators of Dorfromantik.
And now, we’re incredibly excited to finally share it with you. So grab your space helmet and head over to Steam to start your adventure. From all of us at kurzgesagt and Toukana:  thank you for being part of this journey.  
We can’t wait to hear what you think and to keep  building Star Birds together with your feedback. See you in space!