By Lexor Adams and Nicholas Haberling

In Part 1: Escape From Earth we examined the current state of space exploration and several factors influencing the future. In this series we intend to examine the factors influencing a space economy. We mentioned humanity being a multi-planetary civilization as a prerequisite for a space economy, as seen in science fiction. This makes sense because otherwise trade is bound to a single planet...once there’s trading between planets...voila: space economy . That being said, most sci-fi films, books, and movies, with varying levels of realness, attempt to have some explanation for interplanetary travel beyond teleportation (except maybe Stargate...still a great show). These explanations typically center on a few key technologies that explain why the future humanity is capable of interstellar travel in a way we aren’t currently able.

In Part 1 we discussed how space exploration is a function of both the perceived benefits and available technology (which determines the cost). We also discussed how as the perceived benefits increase, more research money and time is devoted to new technologies, which lowers the cost even further. Most of the key technologies used in science fiction to explain the interstellar travel is conceivably possible in the future if enough research goes into it. Neither of us are physics majors; but, based on the reading we’ve done, the technologies mentioned below are conceivably possible according to the laws of physics.

There is one fundamental problem in interstellar travel--humans limited life span. The time it takes to cover the vast distances of space pose a serious problem to human’s comparatively short lives. Just making it to Mars, the closest planet in our solar system, would take approximately 7 months for a manned mission with our current technology. And that’s only one way. Of course, extending beyond Mars: the distance, and thus time, increases significantly. Humanity has two ways of addressing this problem (and these are also the two ways science fiction explains : covering the distance quicker or aging slower during the journey. This means humanity has to have a way to survive the long journey. This is assuming people won’t find multi-generational starships as a suitable form of space travel or simply send unmanned spacecraft filled with human embryos to distant worlds for colonization. It’s likely scenarios that require distances to be traversed in generations would eliminate any sort of economic activity between star systems. Why trade with your distant cousins who are a 200 years away as the probe flies when you can just mine asteroids in your own system?

The first is a problem of propulsion. While current rockets have advanced leaps and bounds (case in point Space X’s reusable rockets landing upright on their own), they still simply can’t handle the distance with as much speed as is necessary. This is where more advanced propulsion comes in. Current research into photon propulsion may seem outlandish; but, some estimates suggest a light spacecraft (in the realm of several hundred pounds) could make the journey to Mars in only three days (see Philip Lubin of UCSB’s research DEEP-IN for more on this). Photon propulsion (which relies on lasers accelerating spacecraft...yeah, that’s real life not science fiction) could allow speeds nearing the speed of light. There’s an interesting side effect to going this fast. The theory of relativity predicts an effect called time dilation. In stupid simple terms this is a conclusion that objects moving experience time differently. This effect has been observed repeatedly in a number of experiments involving atomic clocks at altitudes. The important part for science fiction, and potentially future space travel, is the faster you go, the more this effect increases. When going near (or over) the speed of light, time dilation would increase to the point those on board a space ship would experience time much slower than those on various planets, in effect delaying their aging while they were travelling vast distances at such a fast speed. (From the Nick corner: The Forever War is a fun book that looks at this. Do we really want to return to an Earth that is a few thousand years older from when we left it?)

New forms of propulsion solve the problem of distance and time, both directly by covering the distances faster and indirectly in the form of time slowing for humans onboard such a space expedition. But, science fiction has one other hypothetical technology trick up its sleeve to solve the time problem. This technology is essentially human hibernation, often called cryo-sleep. Games such as Halo and movies like Alien all rely on this technology to explain humans ability to not require as much sustenance and not age during space travel. Most explanations of this technology involve the human entering some sort of chamber that puts their bodies in a hibernation like state, typically utilizing extreme cold to slow down the body’s processes. While this is firmly in the science fiction realm, there are some facts that suggest this could be feasible at some point. Cold is actually good for humans in cardiac arrest. Victims who drown in cold water can be resuscitated much beyond the typical resuscitation period for those whose hearts stop on land. The cold slows down body processes and holds off brain damage. There is also some research suggesting therapeutic cooling provides better outcomes in cardiac arrest (even in cases where the patient hasn't started out cold). This may not seem important; but, it's essentially proof that cold slows body processes significantly and blunts the effects of a lack of oxygen. In theory, if there were a way to freeze a human without causing cell damage (the real kicker at this point), they could be unfrozen and everything resume without fail. Another example of current medical use of extreme chilling is cryo-therapy (many elite athletes visit hyper chilling centers that utilize extreme cooling for muscle therapy). These are both obviously a long ways from intentionally chilling and introducing a mix of chemicals to put someone to indefinite sleep and suspend their body processes for months or years. The underlying physiology suggests it’s not outside the realm of possibility though. Cryo-sleep definitely falls in the “more distant future” category along with Faster Than Light travel; but, in the future, these could be key technologies underpinning longer distance space travel.

Altogether, solving the time problem is critical for creating a truly interstellar species. Being able to go between Earth and Mars is great; but, hardly creates a space economy. Surviving a multi-year journey between planets asleep, with the equivalent of a biological month or so passing, makes for good science fiction, but a very slow moving economy. The true underpinning of any science fiction style space economy is extremely rapid interstellar transportation cutting the travel time between planets to days or weeks. We can dream.