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Asteroid approaching Earth

Asteroid heading towards Earth (guvendemir, iStockphoto)

STEM in Context

Could We Stop an Asteroid?

Let's Talk Science
Format
Video Text Images
Readability
7.32

Summary

If an asteroid were to hit the Earth it could be disastrous. Here are some ways we could protect ourselves.

Asteroids are rocky objects left over from when the Solar System first formed. When they hit Earth, they are called meteorites.

Most meteorites are small and pass unnoticed but bigger ones can be disastrous. After all, when a meteorite struck near Chicxulub, Mexico, the heat it produced wiped out around three quarters of the species on Earth—including the dinosaurs.

When an asteroid enters the Earth’s atmosphere, it’s called a meteor. Meteors burn up in Earth’s atmosphere without striking Earth. Have you ever seen a “shooting star”? Those aren’t stars at all. They’re meteors!

Types of space rocks
The differences between comets, asteroids, meteoroids, meteors and meteorites has to do with where you find them and what they are made of (© 2019 Let’s Talk Science).

In 2013, a meteor burst over Chelyabinsk, Russia. It injured over a thousand people and caused all kinds of damage to the town.

This photograph of the meteor streaking through the sky above Chelyabinsk, Russia, on Feb. 15, 2013, was taken by a local person
This photograph of the meteor streaking through the sky above Chelyabinsk, Russia, on Feb. 15, 2013, was taken by a local person (Source: © M. Ahmetvaleev via NASA).

 

If an asteroid is small enough, it will explode when it impacts the Earth’s atmosphere. That’s what happened with the Chelyabinsk meteor. It was only 20 metres in diameter.

But the bigger the asteroid, the more damage it can cause. According to Science educator Bill Nye, asteroids with diameters between 25 metres and 45 metres could wipe out an entire city or county. Asteroids with diameters of 100 to 140 metres could wipe out a whole country. Asteroids any bigger than that could wipe out an entire continent. And, as we know, really big asteroids can wipe out huge amounts of life.

Because space is so vast, astronomers estimate that there are many huge asteroids that humans have not detected. Some astronomers estimate that there are approximately 17 000 near-earth asteroids larger than 140 metres in diameter that are undetected. In December 2018, a meteor exploded over the Bering Sea. Nobody noticed it until it exploded!

Could we stop an asteroid? (2013) by ASAPScience and Bill Nye (7:07 min.).

To detect asteroids, Bill Nye suggests building a special satellite. This satellite would be positioned around the orbit of Venus. The satellite’s rear would point to the Sun. This way, it would be able to detect asteroids with infrared light.

Imagine this spacecraft detected an asteroid charging toward Earth. The next step would be to deflect it (change its direction), so that it wouldn’t strike Earth. One way to deflect an asteroid is to change its speed. If an asteroid is travelling 10 km/second, reducing its speed by 2 mm/second would be enough to deflect it. Since asteroids can be very large, changing its speed even a little can make it change course. 
Don’t forget, an asteroid can weigh 10 000 tonnes or even 100 000 tonnes. Changing the speed of such a large object would take a lot of force! The easiest way to change an asteroid’s speed would be to send a rocket to crash into it, but this might break the asteroid into pieces. Instead, astronauts could send a really big spacecraft out to get close to the asteroid. The gravity of the spacecraft would tug the asteroid slightly in another direction. However, this is not an easy solution. The spacecraft would require an enormous amount of fuel.

Another way around this problem is to use laser bees, which are sunlight-powered lasers. They would surround the asteroid and zap its surface. This would cause the surface of the asteroid to begin to vaporize. Large pieces of material called ejecta would be thrown from the surface of the asteroid. The ejecta would have momentum. This method could indeed change the asteroid’s speed.

Multiple Laser Bee method
Artist’s interpretation of the Multiple Laser Bee method (Source: NASA).

Scientists estimate that dangerously large meteorites only hit the surface of the Earth every several thousand years. Still, it’s possible that one may hit Earth within our lifetime. That’s why scientists are always trying to find new ways to detect and deflect dangerous asteroids, and keep us safe! 

Starting Points

Connecting and Relating
  • Would you know the difference between a shooting star and an asteroid? Have you ever made a wish on a shooting star? 
  • Have you ever worried about an asteroid hitting the Earth? Why or why not?
  • Are you aware of any asteroid impact craters in your region of Canada? If so, where is it and what evidence is present?
Connecting and Relating
  • Would you know the difference between a shooting star and an asteroid? Have you ever made a wish on a shooting star? 
  • Have you ever worried about an asteroid hitting the Earth? Why or why not?
  • Are you aware of any asteroid impact craters in your region of Canada? If so, where is it and what evidence is present?
Relating Science and Technology to Society and the Environment
  • What would be the social and environmental consequences of a large asteroid impact on Earth?
  • There can be a lot of money, time and resources put into looking for asteroids. Do you think this is a good use of resources, given that the chance of a large asteroid impact might only happen once every 1 000 years? Why/why not?
  • In what ways are science and technology combined to develop plans to change the speed/direction of an asteroid that might impact the Earth?
  • Should all world governments play a role in detecting and paying the cost of developing technology for deflecting asteroids that might impact the Earth? Why/why not?
Relating Science and Technology to Society and the Environment
  • What would be the social and environmental consequences of a large asteroid impact on Earth?
  • There can be a lot of money, time and resources put into looking for asteroids. Do you think this is a good use of resources, given that the chance of a large asteroid impact might only happen once every 1 000 years? Why/why not?
  • In what ways are science and technology combined to develop plans to change the speed/direction of an asteroid that might impact the Earth?
  • Should all world governments play a role in detecting and paying the cost of developing technology for deflecting asteroids that might impact the Earth? Why/why not?
Exploring Concepts
  • Which areas on Earth have impact craters? 
  • What causes asteroids to be of different sizes? Explain.
  • Why would scientists try to change the velocity of an asteroid to deflect it rather than trying to hit and destroy it?
  • What do you think is the best method to stop an asteroid hitting Earth? Explain.
Exploring Concepts
  • Which areas on Earth have impact craters? 
  • What causes asteroids to be of different sizes? Explain.
  • Why would scientists try to change the velocity of an asteroid to deflect it rather than trying to hit and destroy it?
  • What do you think is the best method to stop an asteroid hitting Earth? Explain.
Media Literacy
  • Does the media place too much emphasis on asteroid impacts by creating movies like Armageddon (1998)? Explain.
  • Do you think movies about asteroids take advantage of people’s fears of potential asteroid impacts? Why/why not?
Media Literacy
  • Does the media place too much emphasis on asteroid impacts by creating movies like Armageddon (1998)? Explain.
  • Do you think movies about asteroids take advantage of people’s fears of potential asteroid impacts? Why/why not?
Teaching Suggestions
  • This video and article can be used to support teaching and learning of Space Science and Space related to the topic of asteroids. Concepts introduced include asteroids, meteorites, meteors, atmosphere, deflect, speed, force, ejecta and momentum.
  • While watching the video, teachers could have students use the Read-View-Listen learning strategy to help students obtain and summarize information presented in different ways (text, images, audio) in the video.
  • After viewing the video and reading the article, teachers could have students conduct a Think-Discuss-Decide learning strategy to consider and answer the STSE question, “Should society spend the time, money and resources to continuously look for asteroids?” Download ready-to-use reproducibles for the Think-Discuss-Decide learning strategy for this article in [Google doc] and [PDF] formats.
  • To extend learning about this topic, teachers could have students work through the case study Killer Asteroids and the associated case resources.
Teaching Suggestions
  • This video and article can be used to support teaching and learning of Space Science and Space related to the topic of asteroids. Concepts introduced include asteroids, meteorites, meteors, atmosphere, deflect, speed, force, ejecta and momentum.
  • While watching the video, teachers could have students use the Read-View-Listen learning strategy to help students obtain and summarize information presented in different ways (text, images, audio) in the video.
  • After viewing the video and reading the article, teachers could have students conduct a Think-Discuss-Decide learning strategy to consider and answer the STSE question, “Should society spend the time, money and resources to continuously look for asteroids?” Download ready-to-use reproducibles for the Think-Discuss-Decide learning strategy for this article in [Google doc] and [PDF] formats.
  • To extend learning about this topic, teachers could have students work through the case study Killer Asteroids and the associated case resources.
Additional Resources
Additional Resources

Learn more

What’s the Difference Between a Comet, Asteroid and Meteor? 

An infographic with a short article by Universe Today, describing the difference between a comet, asteroid, meteoroid, meteor and meteorite.

Deflecting killer asteroids away from Earth: How we could do it (2011)

An article on Space.com that discusses techniques at our disposal to nudge killer asteroids away from Earth.

References

Dunbar, B. (2019, April 22). Planetary defense frequently asked questions. NASA.

Haynes, K. (2018, November 19). How would we save the planet from a killer asteroid? Astronomy.