Imagine if an asteroid was on a collision course with Earth. What would we do? How would we even know it was coming? Most importantly, could we stop it? Scientists are working on planetary defense strategies to tackle these questions.
Before we can figure out how to stop an asteroid, we need to understand what it is. Asteroids are rocky leftovers from the early days of our solar system, about 4.6 billion years ago. They can be as small as a few meters or as large as hundreds of kilometers. Even though there are millions of asteroids, their combined mass is less than that of our Moon. Every day, Earth encounters about 300 tons of meteors, which are the shooting stars we see at night.
NASA has identified over a million asteroids, with about 26,000 being near-Earth objects. Of these, more than 2,000 are potentially dangerous, and 158 are over one kilometer in diameter. A giant asteroid hitting Earth could be catastrophic, as history shows us. For example, the Tunguska event in 1908 flattened millions of trees in Siberia with an explosion equivalent to 12 megatons of TNT.
Earth has been hit by asteroids many times. The Chicxulub impact, which happened 66 million years ago, is famous for causing the extinction of the dinosaurs. It was a massive explosion, equivalent to 100 million megatons of TNT, and left a crater over 300 kilometers wide.
Unlike the dinosaurs, we have the technology to detect and possibly deflect asteroids. Governments and space agencies are prioritizing asteroid detection and deflection. NASA and other organizations conduct simulations to prepare for potential impacts. However, current technology cannot stop an asteroid with less than six months’ notice, so early detection is crucial.
To protect Earth, we need to find asteroids long before they pose a threat. Currently, we’ve only detected about one percent of potentially dangerous asteroids. Improving our detection efforts is essential for planetary defense.
Several methods are being considered to deflect asteroids, including kinetic impactors, gravitational tractors, and nuclear blasts. The kinetic impactor technique is the most developed and involves using a spacecraft to collide with an asteroid to change its course.
NASA’s Double Asteroid Redirection Test (DART) is a mission designed to test the kinetic impactor technique. Launched on a Falcon 9 rocket, DART aims to collide with the asteroid Dimorphos in the Didymos system. This mission will help scientists understand if they can alter an asteroid’s orbit, which could be crucial for future planetary defense.
While no large asteroid is expected to hit Earth in the next 100 years, only about 40 percent of potentially dangerous asteroids have been found. Continued efforts in detection and deflection are vital to ensure the safety of our planet.
Using clay or playdough, create a model of an asteroid. Think about its size, shape, and texture. Once your model is complete, research and write a short paragraph about the characteristics of real asteroids and how your model compares to them.
In groups, use a sandbox or a tray filled with flour and cocoa powder to simulate an asteroid impact. Drop a small rock from different heights to see how the impact changes. Record your observations and discuss what factors affect the size and shape of the crater.
Choose a historical asteroid impact event, such as the Tunguska event or the Chicxulub impact. Create a presentation that explains what happened, the effects on Earth, and what scientists have learned from the event. Share your findings with the class.
Imagine you are a scientist tasked with designing a mission to deflect an asteroid. Choose a deflection technique, such as a kinetic impactor or gravitational tractor, and create a plan detailing how it would work. Present your mission plan to the class, explaining why you chose that technique.
Use online resources to track near-Earth objects (NEOs). Choose one NEO and research its size, orbit, and potential threat to Earth. Write a report on your findings and discuss how scientists monitor these objects to keep our planet safe.
**Sanitized Transcript:**
[Music] What would happen if an asteroid were heading towards Earth? What would we do about it? How would we detect it? But most importantly, would we be able to stop it? Planetary defense and mitigation solutions—what are the options on the table if we did detect a threatening asteroid?
There’s a lot of characterization that has to be done before determining the correct strategy to deflect it or minimize the damage. This goes back to something we’ve discussed repeatedly: understanding the nature of the asteroid itself is crucial.
Asteroids are rocky remnants left over from the early formation of our solar system, about 4.6 billion years ago. These objects can range in size from a few meters in diameter to several hundred kilometers across. The total mass of all asteroids combined is less than that of our Moon. Earth encounters about 300 tons of meteors a day, which includes all the shooting stars you see at night.
There are approximately over a million known asteroids to date, according to NASA. About 26,000 are near-Earth objects, and over 2,000 of them are potentially dangerous. Among these, 158 have a diameter of more than one kilometer.
A giant asteroid hitting Earth is not good news for life on the planet. While there’s no need to panic over an imminent threat, scientists have reason to be concerned. The surface of the Moon bears mute testimony to the frequency of asteroid strikes in the solar system.
The June 1908 Tunguska event, where a massive space object exploded over Siberia, released energy equivalent to 12 megatons of TNT and flattened an estimated 80 million trees over an area of 830 square miles. It is the largest impact event on Earth in recorded history, though much larger impacts have occurred in prehistoric times.
According to the Lunar and Planetary Laboratory at the University of Arizona, our planet has suffered up to three million impact craters larger than one kilometer in diameter, with the largest stretching more than 300 kilometers across. The Chicxulub impact event, which occurred slightly more than 66 million years ago, was a 100 million megaton blast that devastated the Gulf of Mexico region. This event is also known as the cataclysm that led to the extinction of the dinosaurs.
Fortunately for us, dinosaurs did not have a space program. If they had, perhaps the outcome would have been different.
Asteroid detection and deflection should be a priority for every government in the world. If we were to discuss asteroid impacts the way we talk about other threats, we would be better prepared. Grants are provided to amateur astronomers who look for and track asteroids.
NASA and other space agencies have conducted simulated exercises of asteroid impacts, revealing that none of Earth’s existing technologies could stop an asteroid from striking within a six-month time frame. This is why the goal is to find any potential impact years to decades in advance, allowing for possible deflection strategies.
Asteroids are interesting for many reasons, including science, resource exploitation, and exploration. However, from a planetary defense perspective, we must first know where they are to defend against any that might be headed toward Earth.
Currently, we have detected only about one percent of the total population of asteroids that could potentially cause serious damage if they were to hit Earth. Therefore, we need to enhance our discovery efforts to protect life on our planet.
The most viable options for asteroid deflection today include kinetic impactors, gravitational tractors, and nuclear blasts. Scientists have also suggested methods like laser ablation and painting asteroids white. Among these, the kinetic impactor technique is currently the most mature, as it is based on existing and affordable spacecraft technology.
NASA’s Double Asteroid Redirection Test (DART) is a planetary defense mission aimed at demonstrating the kinetic impactor technique. It was launched on a Falcon 9 rocket from Vandenberg Air Force Base in California. DART will be the first mission to demonstrate asteroid deflection using this technology.
The target for the DART mission is the Didymos asteroid system, which poses no threat to Earth. In September 2022, the spacecraft will collide with the asteroid Dimorphos at a speed of around 6.6 kilometers per second. This impact aims to see if Dimorphos’s orbit can be altered, potentially decreasing its orbital period around Didymos by about 10 minutes.
While no known asteroid larger than 140 meters has a significant chance of hitting Earth in the next 100 years, only about 40 percent of these asteroids have been found as of November 2021.
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Asteroid – A small rocky body orbiting the sun, mainly found between the orbits of Mars and Jupiter. – Scientists are studying the asteroid belt to understand more about the formation of our solar system.
Earth – The third planet from the sun, which is home to all known life forms. – Earth is the only planet in our solar system that has liquid water on its surface.
Detection – The process of discovering or identifying the presence of something, often using special equipment. – The detection of distant galaxies helps astronomers learn more about the universe’s history.
Deflection – The action of changing the direction of an object, often used in the context of altering the path of an asteroid. – Scientists are researching methods of deflection to prevent potential asteroid impacts with Earth.
NASA – The National Aeronautics and Space Administration, responsible for the United States’ civilian space program and for aeronautics and aerospace research. – NASA launched a new satellite to study the effects of solar radiation on Earth’s climate.
Impact – The action of one object coming forcibly into contact with another, often used to describe collisions in space. – The impact of a large meteorite is believed to have caused the extinction of the dinosaurs.
Technology – The application of scientific knowledge for practical purposes, especially in industry and space exploration. – Advances in technology have allowed astronomers to observe distant planets and stars more clearly.
Solar – Relating to or determined by the sun. – Solar panels are used on spacecraft to convert sunlight into electricity for power.
System – A set of connected things or parts forming a complex whole, in particular. – Our solar system consists of the sun, eight planets, and numerous smaller objects like asteroids and comets.
Threat – A potential danger or risk, often used in the context of space objects that could collide with Earth. – Scientists monitor near-Earth objects to assess any threat they might pose to our planet.
