Continuing on in essays about Science Fiction, Momus News wonders: Do reaction engines have a place in Space Opera?
Short answer: No.
What are reaction engines? According to Newton’s Third Law, “For every action, there is an equal and opposite reaction.” A jet or rocket engine propels its craft by ejecting material (often plasma) out the back end at high velocity. This “Action” forces the craft to move in the other direction (forward) as a result of Newton’s Third Law. Take a 777 flight from JFK to Heathrow and you’ve experienced how a jet or even a spacecraft operates.
This is precisely what a reaction engine is. It “reacts” to the “action” of expelling material out of the nozzle in the back. Thing is, to do this, you need boatloads of fuel. In jet aircraft, small planes have a shorter range. Why? They have less space to put all that fuel. Bigger plane means more fuel space, more fuel space, means longer range.
Fate of the Galaxy
Space Opera is all about Big Stuff, the fate of the galaxy and all that. Well, let’s consider how big the galaxy is. It is roughly, 100,000 light years across.. Just to get to the closest star to us (Proxima Centauri), according to universetoday.com/ using reaction engines, it would take “…at a maximum velocity of 56,000 km/h, Deep Space 1 would take over 81,000 years to traverse the 4.24 light years between Earth and Proxima Centauri. To put that time-scale into perspective, that would be over 2,700 human generations.”
That’s just getting to the closest star. Now, it could take less time if the starship propelled itself at one gee acceleration until halfway there then decelerated to arrive at zero velocity at the star. IIRC that would be twenty-four years.
Still too freakin’ long, and way too long for anybody to influence the fate of the galaxy.
So do reaction engines like the giant engines we see in the Star Wars Star Destroyer make any sense at all?
Nope. Those engines are only useful between hyper jumps, and they constitute most of the mass of a star destroyer. So, I want to ask, “Where’s all the damned fuel for those ginormous engines?” That requires a whole lot more space. That would leave about enough room for a life boat aboard the ship! Now before you get all pissy about me stepping on Star Wars, I still love the movies. It’s a fun story if not scientifically logical. Who cares? I enjoy it anyway.
A Science Fiction Tradeoff
In my book, “The Huralon incident” I try to manage a tradeoff between a great adventure story and scientifically plausible drive systems. For that reason, there are no gigantic reaction engines in my book. Instead, I use a drive system straight from my own imagination that uses the current scientific theory of dark matter/dark energy. These are ideas posited by scientists to explain the observable phenomenon of stars accelerating from each other and stars that fail to spin away from galaxies when they should. From that I suggest, “what if dark matter/dark energy were a medium, much like the sea that mariners sailed across in windjammers, that futuristic sailors might use to propel their ships? The dark paddles.”
How does this work, exactly? Well I’m happy to explain, but you gotta buy the book to see how I did that. A cheesy effort to make you buy the book? Well, yeah, but I think you’ll appreciate my genius. That’s my own “humble” opinion, of course.