We’re probably going to die. That was the unofficial, whispered consensus during a high-stakes meeting in April 2021 when a group of experts from NASA and ESA (European Space Agency) realized they couldn't stop a fictional space rock from leveling a massive chunk of Europe. It wasn't real, obviously. It was a tabletop exercise. But the panic—that feeling of "oh, we're actually not ready for this"—was very, very real.
Space is big. Like, mind-bogglingly empty. But every so often, a piece of leftover solar system junk decides to cross our orbit. When NASA runs an asteroid simulation hitting earth, they aren't just playing a fancy version of a video game. They are trying to find the holes in our planetary defense strategy before a real rock finds them first.
The Time We "Destroyed" New York and Europe
Every two years, the International Academy of Astronautics (IAA) hosts the Planetary Defense Conference. It's basically a gathering of the smartest people on the planet—engineers, physicists, legal experts, and emergency management folks—who spend a week role-playing the end of the world.
In the 2019 scenario, they simulated a 140-to-260-meter asteroid named 2019 PDC. The "impact" was set for New York City. They tried to send a fleet of kinetic impactors (basically high-speed space bullets) to knock it off course. They hit it, but a 60-meter fragment broke off. That "small" piece kept screaming toward Manhattan. The result? A simulated fireball that would have vaporized everything within a 15-mile radius. There was no way to stop it.
Then came 2021.
The 2021 asteroid simulation hitting earth was even more brutal. The team was given six months of "simulated time" to react. That sounds like a long time until you realize that launching a rocket usually takes years of planning. They concluded that with only six months of warning, no existing technology on Earth could stop the impact. The asteroid eventually "hit" near the border of Germany, the Czech Republic, and Austria. The lesson was simple: we need more time.
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Why do we keep failing these tests?
It’s not because the scientists are bad at their jobs. It's because the physics of moving a billion-ton rock are incredibly stubborn. You can’t just "nuke it" like in the movies. If you blow an asteroid into a thousand smaller pieces, you might just turn one big bullet into a cosmic shotgun blast. Now you have a thousand radioactive rocks hitting the planet instead of one. Great.
Actually, the biggest hurdle isn't even the science. It's the bureaucracy. In these simulations, the legal experts often get stuck on questions of liability. If we try to nudge an asteroid so it misses Russia, but we accidentally nudge it too much and it hits London instead, who is responsible? Who pays for the damage? We don't have an international treaty for that yet. Kind of terrifying, right?
The DART Mission Changed the Game
While the simulations were looking grim, 2022 gave us a massive win. NASA’s Double Asteroid Redirection Test (DART) was the first real-world test of our ability to move a space rock. They aimed a refrigerator-sized spacecraft at a small moonlet named Dimorphos, which orbits a larger asteroid called Didymos.
They hit it. Hard.
The goal was to change Dimorphos's orbital period by at least 73 seconds. It actually changed by 32 minutes. This was huge. It proved that "kinetic impact" works. If we see a rock coming decades in advance, we can just bump it. A tiny nudge ten years away becomes a miss by thousands of miles by the time it reaches Earth.
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NEO Surveyor and the Hunt for the "City Killers"
The problem is that you can't hit what you can't see. We are currently "blind" to about 60% of the asteroids large enough to level a city. Most of these are hiding in the glare of the sun.
That’s where the NEO Surveyor comes in. This is a space telescope scheduled to launch in the mid-2020s. Unlike ground-based telescopes that can only look up at night, this one will sit in space and use infrared to spot the "dark" asteroids that don't reflect much sunlight. Honestly, this is probably the most important piece of hardware being built right now. If we don't find them, the next asteroid simulation hitting earth won't be a simulation at all.
What Happens During a Realistic Impact?
If a 100-meter rock (a "city killer") were to hit today without any deflection, the sequence of events is pretty standard across all simulations.
- The Entry: The asteroid enters the atmosphere at roughly 40,000 miles per hour. It compresses the air in front of it so fast that the air turns into plasma.
- The Airburst: Most smaller asteroids don't even hit the ground. They explode in mid-air due to the intense pressure. This happened in Chelyabinsk, Russia, in 2013. That was only a 20-meter rock, and it shattered windows across an entire city.
- The Thermal Pulse: If the rock is big enough (like 100+ meters), the heat from the entry can start fires for miles before the shockwave even arrives.
- The Shockwave: This is what does the most damage. It flattens buildings and knocks over trees like toothpicks.
In a simulation, the Federal Emergency Management Agency (FEMA) uses this data to figure out evacuation routes. How do you move 10 million people out of Los Angeles in three days? You basically can't. That’s why the focus is shifting from "surviving the hit" to "preventing the hit."
The Logic of the "Gravity Tractor"
If a kinetic impactor is too risky because it might break the asteroid, scientists have another idea: the Gravity Tractor. Basically, you fly a heavy spacecraft next to the asteroid and just... sit there. The tiny gravitational pull of the spacecraft will slowly, over years, tug the asteroid off its path. It’s slow. It’s boring. But it’s incredibly precise.
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We haven't tested this in a real simulation yet because we don't have a spacecraft heavy enough to make a dent, but the math is solid. It’s the "gentle" approach to planetary defense.
The Real Danger is Complacency
People often ask why we spend millions on an asteroid simulation hitting earth when we have "real" problems like climate change or pandemics. The answer is simple: an asteroid is the only natural disaster we can actually, 100% prevent. We can't stop a hurricane. We can't stop an earthquake. But we can stop an asteroid.
The 2023 simulations focused a lot on "late-stage" detection. What if we only have two years? The experts explored "terminal intercept" options, which involve launching a nuclear device to vaporize the surface of the asteroid. The goal isn't to crack it open, but to use the outgassing from the explosion like a rocket engine to push it away. It’s a last-ditch effort, and it’s controversial.
Actionable Steps for Staying Informed
While you don't need to build a bunker in your backyard, staying informed about the reality of planetary defense is actually helpful for public support of these missions.
- Follow the Minor Planet Center: This is the global clearinghouse for all asteroid observations. If something is actually coming, it will show up in their database first.
- Support the NEO Surveyor Launch: Public funding for infrared space telescopes is the number one way to ensure we aren't blindsided by a "sun-grazer" asteroid.
- Watch the ESA Hera Mission: Launching recently to visit the site of the DART impact, Hera will perform a "crime scene investigation" to see exactly how much we moved that asteroid. This data will be fed into the next major asteroid simulation hitting earth to make it more accurate.
- Understand the "Torino Scale": If you see a news headline about an asteroid, check its Torino Scale rating. A "0" or "1" means there is effectively zero risk. Don't fall for the clickbait unless it hits a 3 or higher.
We are the first generation of humans in 4 billion years of Earth's history that actually has the technology to prevent our own extinction from a space impact. The simulations might show us failing, but that’s the point. We fail in the simulation so we can succeed when it actually counts. The "deadly" simulations of 2019 and 2021 were a wake-up call that moved planetary defense from a niche hobby to a global security priority.