So you want to fly to Alpha Centauri…
Fictional Propulsion.
You want to get there, and you want to get there fast. How do you do it?
Well if you're Dale Earnhart Jr., you stomp down on the accelerator. If you're Usain Bolt, you push balls-to-the-wall and run like the wind. If you're Lance Armstrong, you dope up and hope no one notices.
But what if you're a starship captain? Fortunately, you are not real, and so have an advantage over the rest of us. You can engage the warp drive, or the quantum jump engines, or fly through a wormhole and explore the Delta quadrant.
For argument's sake, let's assume you're a real starship captain. That is, you need to obey as many laws of physics as humanly possibly. Basically, this is Hard Science Fiction–think Mark Watney on Mars: even though that dust storm (that extremely rarified 1 percent of Earth's atmosphere dust storm) could have never in a million years blown you off your feet, you still need to obey physics to get back to Earth.
Let's go out on a limb and say that in 500 years we have fusion down pat–as in, it's no longer perpetually 30 years in the future but in actually insta
lled down in engineering on deck 10. Let's inch even farther along that limb and say that we have anti-matter production and containment solved, and know how to derive lots of useful energy from its reaction with normal matter. Deal? Ok, so we've more than inched–we're hanging by a thread off that limb, but these are realistic technical goals within the next few centuries, and they at least let us begin to address the ugly truth: Interstellar space travel is very hard and will require unthinkably enormous amounts of energy.
Let's jump tracks for a moment. What is our goal as a starship captain? Let's keep it simple and easy (and dire): our colony on the third planet of Alpha Centauri just sent out a distress signal. Aliens are attacking, and they desperately need our help. Of course, they actually sent out the distress signal 5 years ago, but the transmission didn't reach us until now because, as we all know, radio waves are a form of light, which travels at the speed of, uh, light. What do we do?
Full speed to Alpha Centauri! Helm, lay in a course! Engage the engines! Full thrust! We will avenge them!
EVENTUALLY!
You see, Alpha Centauri, the closest star system to us, is nearly 5 lightyears away. Let's assume for the moment that our starship can sustain a substantial thrust for an extended period of time. Just for convenience, and because it's nice to have Earth-like gravity on our ship, let's say the thrust is 1 g. Furthermore, assume our ship weighs about 1000 tons, and that we're able to extract ALL of the energy out of our anti-matter reaction and dump it into propulsion. Easy-peasy, right? At this thrust, we'll max out at about 96% of the speed of light halfway through our journey before we flip the ship around and start slowing down in time to not collide with the third planet of Alpha Centauri at relativistic and therefore splat-inducing speeds.
We have a problem.
In this 1000-ton-ship scenario, it takes about 5000 tons of anti-matter to get us there. Did I mention that the 1000 tons of ship has to include fuel? Oops. It does.
Basically, going 1 g at 100% anti-matter fuel conversion, it still takes about 5 times the amount anti-matter than you can store on your ship. Remember–you have to accelerate the fuel too. No free rides!
But let's look on the bright side. Even though our fictional starship didn't actually make it to Alpha Centauri, our non-trip took us only 3.77 years! From our perspective. From the point of view of everyone back on Earth, and the poor besieged souls on the third planet of Alpha Centauri, our non-trip took us 6.66 years. That's because as we approached the speed of light, from our perspective, the distance between Earth and Alpha Centauri shrunk. By as much as 72% at our highest speed. From their perspective, our clocks slowed down. If they could have watched us through our windows with an impossibly powerful telescope, they would have seen us moving in slo-mo aboard our ships.
Ok, so we can't sustain 1 g of acceleration for 3.77 years. How many g's can we sustain, and still be able to store all the fuel required for the trip?
About 15%-18% of a g. That's right, you'll be running around on your ship with the same amount of gravity as on the moon. And you'll have a lot of time to do it–10.5 years. 12 years according to observers.
Let's inch back towards reality. Just an inch. Suppose that our fuel conversion rate is not 100% like we assumed. Let's make it something more within the realm of physics. Like, say, 10% (still generous, if you ask me). Now we're talking about a 34 year trip. 34.5 years for observers because we only (only!) ever got up to about 28% of the speed of light.
You see why riveting, fast-paced interstellar hard science fiction is tricky? And we never even addressed the problem of propellant–you know, the stuff you have to heat up and shoot out the back of your thrusters.
And then there's the single particles of dust that will destroy your ship while traveling at a fraction of the speed of light. And if you're fortunate to not run into a dust particle, then the 1 atom of hydrogen per cubic meter of space will slam into your forward hull so fast that it will soon overheat and melt. And if you can somehow cool off your hull from all the interstellar hydrogen running into it, there's always the background radiation of space itself–the leftover glow of the big bang.
Huh, you say? Isn't that stuff harmless?
Yes, for us it's harmless, traveling very slowly. But speed up in any direction, and those harmless microwaves can blueshift into sunburn inducing ultraviolet waves, or worse, x-rays. But nothing a little lead shielding on your hull can't handle, right?
Uh, better slap on an extra 1000 tons of lead to your 1000 ton spaceship. Which means you'll need more fuel. Which means … crap …you died from old age trying to save the Alpha Centarians, Captain. Sorry.
Just stick to the solar system for your hard SciFi, ok? Think Pluto. Pluto's nice.
For fun, you can try out your own interstellar travel calculations here: https://nathangeffen.webfactional.com/spacetravel/spacetravel.php
Use the calculator to plan your space travel at your own risk. I am not responsible for any accidental time dilation, space contraction, shrinkage (the spaceship kind), old age from excessive space travel, bone density loss, impotence, baldness, and/or death from any misuse of the calculator. Proceed at your own risk.
It’s All About Light
In just three years from now, we will mark the fifty-year anniversary of man’s first setting foot on the moon. Fifty years! It’s gone fast. Too fast. The 70’s and 80’s were full of visionaries projecting that we would have bases on the moon and burgeoning tourism by now. Alas man hasn’t set foot on the moon again since our last Apollo mission in 1972. Eugene Cernan was the last man to walk on the moon and that was almost 44 years ago!
For those of us who grew up on Star Trek and Star Wars, our effort in getting off the planet and into space has been agonizingly slow. Instead, we watch as NASA sends rover after rover to investigate nearby bodies, while mumbling amongst ourselves “how hard can it be?”
But as it turns out, it’s pretty hard. Physics is the most obvious problem, especially for technologies that haven’t been invented yet. And the more we learn about space, the more obstacles we discover. Problems like radiation. Or lack of gravity. Or social isolation. The problems continue to grow based on the most fundamental human traits imaginable. And things we’ve taken for granted for millions of years.
Even with today’s technologies, we only have “ideas” on how to solve some of these problems. And it can be a very long time between initial concepts and working models. Which paints a pretty stark picture. The unfortunate reality is that it may be a very long time before we have a ship capable of going anywhere.
So the question then is…do we even have to? We all know the fastest speed possible (that we know of) is the speed of light. And while we’d love to venture out and see other places and new planets, it all really boils down to just one reason. After all, if you’ve seen one sun, you’ve pretty much seen them all. And I don’t think anyone is all that excited about seeing a planet comprised of nothing but barren rock or clouds of deadly methane.
No, most of us prefer to venture through space with one single, monumental goal in mind. To find life! Any kind of life. Sure, a friendly alien waving back at us, waiting to share their knowledge would be great. But even just seeing plant life on another planet would be incredible. Or knowing that life “exists” beyond our own Earth would change everything. Not just textbooks, but it would validate so much of our beliefs. Even the Drake Equation, as simple and realistic as it is, is little more than scientific “faith”. And knowing that our assumptions and extrapolations were right would fill so many of us with a profound sense of eternal satisfaction.
But we have no ship. And we won’t have one that can help us make these discoveries for a very long time. Most likely after the vast majority of us have long since been laid to rest. Although there is one way.
There is one way that is within our grasp. And it’s possible right now. It doesn’t require huge leaps in technology, or exotic solutions that we can only imagine in diagrams or books. A way that may just be able to answer the question as to whether we’re alone, long before we pass on still clinging to our scientific faith.
I’m talking about planet hunting. The search for distant Earth-like planets, visible to us now thanks to the wonders of light. You see, instead of us having to figure out a way to make the trip, light has already done that for us. And when that light has bounced off a distant planet, it carries with it signatures of the elements that it bounced against.
In other words, by examining the faint rays of this light, even using today’s technology, we can see what molecules are in that planet’s atmosphere. Which means we can determine what caused it. Things like methane and carbon dioxide can be caused by many things, but one thing that is a sure signature of life is oxygen. Oxygen, in large quantities, is unquestionably the result, or byproduct, of a living organism.
This all means that we can potentially answer the biggest question of all, without ever having to leave our planet. At least for now. Because while a plant or forest may not sound interesting, we simply need to remember that those are complex organisms. And to find complex life out there means we will eventually find more complex and potentially intelligent life.
Light is the key. Light doesn’t just provide illumination. It provides information. Like nature’s fiber optic cables, with bits of data that has already traversed the universe, it can help us verify that we are not alone. And that as Frank Drake posited many years ago, there are likely thousands of other civilizations out there.
This is why we all love science fiction. Because deep in our hearts we know we’re right.
And with any luck…simple photons are about to prove it.
Michael C. Grumley lives in Northern California with his wife and two young daughters where he works in the Information Technology field. He's an avid reader, runner and most of all father. He dotes on his girls every chance he gets. His website is https://www.michaelgrumley.com