Imagine a massive rock the size of a house is hurtling towards Earth – what do you do? Duck and cover? Head to an underground shelter? Call Bruce Willis? Everyday Einstein explains how to survive an asteroid attack.
An asteroid that hit an ocean would create devastating tsunamis, while impact on land or in shallower bodies of water would stir up enough dust and ash into the atmosphere to block sunlight. The ensuing cold, dark, dusty conditions (known as "impact winter") would likely cause mass extinction and may be the reason humans and dinosaurs never got to coexist.
What America Is Doing to Monitor Asteroids
Unfortunately, once an asteroid hits, there is not much you can do other than hope you are not in the wrong place at the wrong time. Luckily, we have the technology to prevent an impact. NASA uses radar, optical, and infrared searches to track near-Earth asteroids that are either larger than 1 kilometer in size or are otherwise on trajectories with high impact likelihoods.
One such asteroid is Apophis, which caused a moment of panic back in 2004 when its measured orbital parameters indicated an impact with Earth in April of 2029. As astronomers continued to monitor the asteroid and honed their models of its orbit, however, they were able to rule out a possibility of an impact in 2029. At that time Apophis will instead travel beneath our communication satellites on its closest passage yet.
Depending on the trajectory of Apophis at that time, astronomers will know whether or not we need to prepare for a direct (although unlikely) impact with Earth on its next orbital pass in 2036.
How Can We Deflect Asteroids?
So what do we do if we find an asteroid on path to hit Earth?
Some suggest the brute force method of blowing the rock up with some kind of bomb. Unfortunately, the size, speed, and trajectories of the resulting pieces would be nearly impossible to control and thus potentially could create a whole new set of problems. However, vaporizing an asteroid into dust may be the best option if time is short.
Another approach would be instead to nudge the asteroid off its path so that it just misses our planet. This nudging, called a gravitational tractor, can be done with rocket boosters attached to the asteroid or by placing an object near the asteroid that can coax the asteroid off course with its gravitational pull.
A third way would be to paint one side of the asteroid and therefore change its "albedo" or how much light its surface reflects. Darker surfaces absorb more light than lighter ones (it's why we are better off wearing white clothes in the summertime rather than black or navy), and the resulting force difference due to the hot versus cold sides can actually affect the asteroid enough to push it off course. This force imbalance is known as the Yarkovsky effect and has been measured for asteroids from the Sun’s incident radiation.
Another important piece of the prevention puzzle is to continue sending space missions to gather information on asteroids so we can better understand their sizes, shapes, and structural and chemical compositions. Knowing a few asteroids in depth allows predictions of similar parameters for asteroids where we don’t have as much information. Such studies also help us to better understand how to deflect any asteroids headed toward Earth, should we find one.
Lucky for all of us, there are scientists, like my friend and colleague Dr. Patrick Taylor, who just attended the Planetary Defense Conference in Rome where scientists, engineers, and disaster-response experts all get together to discuss how to find and characterize asteroids that may be hazardous to Earth, as well as how to take action against any potential threats. Dr. Taylor says:
"The best way to protect the Earth is to find all of the potentially hazardous near-Earth asteroids that can cause catastrophic regional damage. Detailed characterization with optical, infrared, and radar telescopes can then determine if the asteroid poses a risk and guide us in how to react, whether with a deflection mission or through coordinated emergency response prior to and post impact."
Worst comes to worst, we can always call on Bruce Willis and his team.
Until next time, this is Dr. Sabrina Stierwalt with Everyday Einstein’s Quick and Dirty Tips for helping you make sense of science.
I want to give huge thanks to all of you science fans for tuning in each week. As I announced last week, there is a change coming to Everyday Einstein. Starting in May, new episodes will be released on Monday evenings instead of Fridays. I hope this new schedule will give you more time to satisfy your scientific curiosity during the week and maybe free up some weekend time for going outside!
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