Interstellar Space Travel: Why Go and How – Part II
By Dr. Gary Deel, Ph.D., J.D.
Faculty Director, School of Business, American Military University
This is the second article in a three-part series on interstellar space travel. Read Part I.
“Just now, there are a great many matters that are pressing in on us that compete for the money it takes to send people to other worlds. Should we solve those problems first? Or are they a reason for going?” –Carl Sagan
Interstellar space travel holds untold prospects and opportunities, so there are a great many reasons for pursuing such voyages. The first and perhaps most compelling is survival. Right now, there are significant and as yet unresolved threats to the existence of life on Earth. We know that large asteroids have collided with our planet in the past and brought with them the extinction of most complex life.
Despite best efforts by those currently working on this, our space monitoring programs lack the funding, manpower, and sophistication to track all potential space-borne threats, let alone the problem of what we would do if we found one threat that was imminent.
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But let us suppose that we survive the shooting gallery that is our solar system. We know that if nothing else gets us first, in about five billion years our Sun, in its magnificent death throes, will engulf and destroy the Earth and the other inner planets, Mercury and Venus. So, if we are to survive indefinitely, relocation at a certain point is inevitable.
If the Human Species Is Going to Continue to Grow We Must Address the Problem of Resources
Population growth and limited resources are other factors related to survival. If the human species is going to continue to grow, we must eventually address the problem that the resources on and around Earth can support only a limited population. We certainly have not reached the maximum occupancy of our planet yet, but at the current rate of growth, this is something worth considering now.
It could be argued that colonization of other planets within our own solar system would be a prudent first step, and that might be true. However, none of our sister planets has the temperature, atmosphere, and resources suitable to sustain life without significant artificial life support infrastructure. If there are other planets in the galaxy that are Earth-like in terms of atmosphere, climate, water abundance, and other elements conducive to life, they would be far better places to colonize.
A third reason for interstellar travel would be the prospect of economic gain. Admittedly, this is a far-off vision. Once we reach the point where we can travel from one star system to another, it is reasonable to believe that by then we might also have developed the ability to mine and transport resources to Earth from other planets.
The Galaxy Holds a Tremendous Treasure of Materials Necessary for Human Development
The galaxy holds a tremendous treasure of materials necessary for human development, including carbon for fuel, metals for building, and even rare materials like diamond. It has been said that the world’s first trillionaire will be the person who first and best achieves space mining; the mother lodes await us outside our solar system.
A fourth and more existential reason for pursuing interstellar travel lies in the search for extraterrestrial (ET) life. Earth is the only place that we know of so far to harbor life. Yet, one of the most fundamental questions to our existence — one that has likely been asked since humans first evolved into sentient beings — is “are we alone?”
Some might argue that the search for ET could be dangerous. What if we happened upon life that was hostile to us? There is no shortage of sci-fi movies to inspire these worries. However, many experts reject this fear. If a form of life is sufficiently advanced to annihilate us, it is unlikely that we possess anything the aliens would want badly enough to destroy us over. And what if ET were benevolent? Imagine what we could learn, and how such an encounter would revolutionize our understanding of our own existence!
But even if we could muster the public support and funding for interstellar travel, significant obstacles lie in our way. The first and perhaps biggest obstacle is distance. The enormous expanses of space between our own solar system and even our closest neighbors, and our current inability to get there with reasonable speed and efficiency, make any such trips impracticable, especially for manned missions.
The Challenge Is to Develop Propulsion Technology Sufficient to Push Spacecraft up to Incredible Speeds
The challenge, therefore, is to develop propulsion technology sufficient to push spacecraft up to incredible speeds — significant fractions of the speed of light. Right now, various proposals are in the drawing board phase, including ion engines, nuclear-powered propulsion, and other ideas. But actual interstellar test runs with any of these technologies are decades away at best.
Even if we manage a propulsion system that can generate enough force to propel spacecraft to near-light speeds, another problem is fuel management. The laws of physics — specifically those relating to actions and reactions — require that propulsion involve some type of propellant. This means that the fuel needed must either be carried aboard the spacecraft or found along the way. Once a spacecraft reaches the appropriate speed, the near-vacuum of space will mean that only minimal additional force will be needed to maintain the spacecraft’s speed and heading.
However, a vacuum is a double-edged sword: When it’s time to slow the spacecraft upon nearing its destination, there is no resistance to help. In other words, it isn’t as simple as just taking your foot off the accelerator and letting your car coast to a stop. More fuel will likely be needed for stopping power as well.
Some Concepts Plan on Collecting Fuel along the Way
Some concepts plan on collecting fuel along the way. For example, a collector could funnel hydrogen from the surrounding interstellar medium into an engine for burning. However, the physics of some of these models would require that the size of such hydrogen collectors be as large as the Earth itself.
Other models rely on solar sails that use radiation from the stars to “push” a spacecraft forward. However, acceleration and deceleration with these models is a very slow process. In deep space the vast distance to the nearest stars would result in very little available force.
Even if we get past the spacecraft propulsion and fuel problems, there are even odder challenges to be addressed having to do with the very fabric of space-time. In the final part we will discuss these obstacles.
About the Author
Dr. Gary Deel is a Faculty Director with the School of Business at American Public University. He holds a JD in Law and a Ph.D. in Hospitality/Business Management. Gary teaches human resources and employment law classes for American Public University, the University of Central Florida, Colorado State University and others.