By Dr. Gary Deel
Faculty Director, School of Business, American Military University
This is the second of two articles examining the existential threat of a major asteroid collision with the Earth. Check out part I here!
Assuming an asteroid is on an imminent collision course with Earth, there are a number of ways we might prevent it. The asteroid could be slowed down, sped up, or by slightly changing its trajectory just enough so that it does not intersect with Earth’s orbit when and where Earth happens to be.
One way to effect such a change in trajectory would be to use nuclear weapons. Detonating a nuclear device in front of, behind, or to the side of the asteroid could be enough to make a trajectory change sufficient to avoid a collision. The size of the device and the proximity of the detonation to the asteroid would be determined by the asteroid’s dynamics and how much force is required to make the necessary adjustments.
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Detonating a Nuclear Device on or in an Asteroid Would Turn a Large Asteroid into Hundreds or Thousands of Smaller Ones
Nuclear weapons could be used to “blow up” an asteroid, as was done in the movie Armageddon. However, detonating such a device on or inside of an approaching asteroid is not advisable because the blast would turn one large asteroid into hundreds or thousands of smaller ones. Better to use the blast wave from a nuclear weapon to push the asteroid out of harm’s way in one piece than to break it apart.
Changing an asteroid’s trajectory could also be accomplished by a kinetic impactor. In other words, rather than detonating a bomb near the asteroid, a projectile could simply ram it at a very high speed, enough to “shove” it in order to either slow it down, speed it up, or move it aside as necessary.
But we wouldn’t necessarily need to crash into the asteroid violently to effect a change in its trajectory. Another option would be to send a spacecraft to gently maneuver the asteroid out of its original trajectory. The spaceship could attach itself to the asteroid and fire its propulsion engines to nudge the asteroid into a safe path of travel. This would have the same effect as the projectile method but without the violent collision.
With Enough Warning, We Could Use Solar Wind to Change the Asteroid’s Trajectory
If we had enough advance notice, we could also accomplish a change in trajectory by using the force of the solar wind. The Sun’s electromagnetic radiation exerts a small but constant pressure on objects that the radiation bounces off. So, if we could cover a large part of the incoming asteroid with foil or coat it with reflective paint, the pressure of solar radiation reflecting off the surface of the asteroid over enough time could be enough to move it out of harm’s way.
Yet another way to propel an asteroid out of a collision path would be to superheat a small point on the surface of the incoming asteroid, either with a laser or with focused sunlight. Over time, the asteroid would begin to spew internal matter from the hole created by the laser or focused sunlight, due to the increased pressure that accompanies the heat. This is no different than steam bursting from a tea kettle when the water begins to boil. Just as the steam could theoretically move the tea kettle on the stove, the material shooting out from the asteroid like a geyser would propel it in the opposite direction.
Using a Gravitational Tug Could Also Move an Asteroid off Its Trajectory
A gravitational tug is another way to move an asteroid off its trajectory. Everything in the universe that has mass also has gravity. Thus, while a spacecraft near an asteroid would feel its gravitational pull, the asteroid would also feel a gravitational pull from the spacecraft.
Depending on the difference in size between the two objects, and given enough time, this gravitational pull could be sufficient to move the asteroid enough so that it is no longer a threat to Earth.
One final idea for avoiding a devastating impact would be to deploy a mass driver. A mass driver is essentially a machine that, when delivered to the surface of an impactor, would hurl large excavated pieces of the asteroid into space in the opposite direction from which we wish to move the asteroid. Newton’s third law of motion states that every action is accompanied by an equal and opposite reaction.
A machine could be designed to throw pieces of an asteroid into space, akin to a baseball pitching machine at a batting cage, but mounted on an asteroid. Such a machine and the asteroid on which it is positioned would both experience a small push with each throw. Over time, these minuscule pushes could be enough to achieve the desired change in trajectory.
The threat from an asteroid impact is real and is not something to be taken lightly. We know from geological records that more impacts in the future are inevitable. NASA’s Near-Earth Objects (NEO) search program is working diligently to identify potential dangers, but there is still much work to be done.
Assuming we can identify the next major threat in time, there are many workable ideas for avoiding an asteroid impact catastrophe. With careful planning and the benefit of advance notice, there is no reason why we shouldn’t be able to avert such an existential crisis when it occurs.
About the Author
Dr. Gary Deel is a Faculty Director with the School of Business at American Military University. He holds a JD in Law and a Ph.D. in Hospitality/Business Management. He teaches human resources and employment law classes for American Military University, the University of Central Florida, Colorado State University and others.