spaceSpace and Physics

What Could We Do If There Was An Asteroid On A Collision Course With Earth?


Dr. Alfredo Carpineti


Dr. Alfredo Carpineti

Senior Staff Writer & Space Correspondent

Alfredo (he/him) has a PhD in Astrophysics on galaxy evolution and a Master's in Quantum Fields and Fundamental Forces.

Senior Staff Writer & Space Correspondent


We recently posted about an asteroid that flew dangerously close to our planet, and many followers have been wondering what one can do in case a space rock does come plummeting towards our heads.

While our natural inclinations will push us to scream in fear and/or appeal to our favorite deity, there’s a lot that can be done to prepare, react, and maybe even stop threatening objects on a collision course with our planet.


Step One, Don’t Panic

Asteroids and comets are a threat. They are a real and present danger to our planet. That said, we have not been sitting idling. NASA’s Spaceguard survey has mapped the position and trajectories of 90 percent of the largest near-Earth objects (NEOs), those larger than 1 kilometer (0.62 miles). The impact from any of these objects would cause worldwide devastation, global cooling, and mass extinctions.

The good news is that none of these appear to be a threat, so at least on that front we can rest easy. We know of about 15,000 NEOs out of a likely 1,000,000, and both NASA and the European Space Agency have programs dedicated to discovering as many of them as possible.

NASA is now aiming to discover 90 percent of the NEOs larger than 140 meters (460 feet). These NEOs are a little bit more worrying, as we have so far discovered only about 8,000 objects between 100 and 1,000 meters (0.06 and 0.62 miles), with many still missing from the roll-call. If one of these bad boys were to hit land, they could create a crater as large as a small city. If they hit an ocean, they would generate a tsunami.


Smaller objects wouldn’t be too dangerous on water, but they could be problematic on land. They’d most likely burn up in the atmosphere, but the shockwave could be still very dangerous. The Chelyabinsk meteor that fell in Russia in 2013 caused damage to over 7,200 buildings and injured 1,491 people. And it was only 20 meters (65 feet) in diameter.

Initiatives like Asteroid Day were created with the precise intention to raise awareness of such a danger.

content-1484239864-shutterstock-55135175Meteor Crater panoramic view in Winslow, Arizona, USA. Shutterstock/Nikolas_jkd 

Getting Ready For The Worst


While the threat is there, the odds appear to be in our favor. The largest object that will have a close shave with our planet is Apophis in 2029 and then again in 2036. There’s only a 1-in-250,000 chance that it would hit Earth, but the first close encounter might alter its orbit a bit, making it more dangerous.

So, if we were to discover NEOs heading to Earth, would we have the capabilities to defend ourselves? A panel of experts discussed this very topic last December, and they concluded that humanity is currently not ready to destroy or deflect a threat of this kind.

Our main enemy is time. While we might have the technology ready to deploy, we might not have enough time to launch it. Currently, scientists are studying the best strategies to deal with asteroids in order to have the best plan ready to defend ourselves.

Of the various possibilities so far, there’s the nuclear option, there’s the option of using lasers, hooking the NEO and dragging it away, or having a fast rocket simply slam into it. But we can’t just get up and do it. We need to take into account many variables (size, density, distance from us, etc.) before contingency plans can be drafted.


“We are very carefully doing our homework before finals week," Dr Catherine Plesko stated during a conference. "We don’t want to be doing our calculations before something is coming. We need to have this work done."

Lacking defenses doesn’t leave us helpless, though. NASA and the Federal Emergency Management Agency (FEMA) have already run three simulated scenarios on how to intervene if we were put in such peril. The two agencies are building a portfolio of scenarios for potential future use, in order to ensure they have information that would be critical in such an emergency.

Some may find these plans futile, but remember real life is not going to be like Deep Impact or Armageddon. We won’t be able to fly a spaceship to the NEO and land on it to plant the bomb so it can be detonated at the last second. If we can land a crew there, it’s already too late. It would be too close.

Also, landing a crew would be incredibly difficult. Asteroids and comets are tiny. Rosetta’s comet 67P has a gravitational acceleration almost a million times smaller than Earth. The landing of the probe Philae was a phenomenal feat of engineering and even that one didn’t go exactly according to plan. Philae bounced three times before settling down.


So don’t land on an NEO and please don’t send a group of untrained civilians to blow it apart. They might destroy your space station, and by blowing it apart, you might end up with hundreds more large fragments heading for Earth on unpredictable orbits.

content-1484240123-comet-on-17-august-20Comet 67P/Churyumov-Gerasimenko as seen by Rosetta. ESA

What To Do In The Mean Time

There’s no reason to lose sleep on the possibility of a potential asteroid impact, but at the same time, we can’t bury our heads in the sand. So what can all of us do to prepare? Worry less about stocking up on tin goods and do more to raise awareness of the problem.


Join an activity for Asteroid Day, write to your political representative about it, and make sure that the threat is discussed with level-headedness.

Ideally, we want a dedicated space observatory to monitor these objects and a rocket (or several) ready to go if necessary. Both are expensive, but if there’s enough political will, we can be ready.

Disaster movies always show humanity coming together and working hard even in the face of impossible odds. Perhaps that’s the most realistic parts of them.


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