Perhaps the biggest obstacle to colonizing the galaxy is the huge distances between stars. The nearest star to Earth is Proxima Centauri, 4.2 light years distant. Traveling in a normal spaceship at what is currently a realistic speed of 50,000 km/hr, it would take about 91,000 years to get there. This makes the trip patently ridiculous without resorting to assuming we will achieve radical advances in spacecraft speed technology. As for proponents of suspended animation who foresee freezing (or whatever) people for 91,000 years and thawing them out afterwards, good luck! You’ll need it. Oh yeah – and once you get there, we have no evidence yet that there are any planetary bodies orbiting Proxima Centauri on which to land. So is there any way to save the concept of interstellar colonization? Perhaps.
Although stars are far apart in our neighborhood of the Milky Way, rogue, or nomad planets might be much closer. In fact, there may be 100,000 times as many such nomads floating around in space as there are stars. We just haven’t seen them. After all, nomad planets don’t shine like stars so they are hard to detect. Recent advances, however, give hope that they are out there waiting to be found by the thousands as detection technologies improve. Nomadic planets have two particularly neat characteristics. One is that, unlike a star, it is possible to land on many of them. Some are gas giants, and thus lack surfaces to land on, but even those may have landable moons. Another is that, because there are so many of them, the nearest ones are a lot closer (hence easier to get to) than the nearest stars. How close?
There are 9 stars within 10 light years of Earth. Therefore there may be 900,000 nomad planets within 10 light years. That suggests 900 nomads within 1 light year (since a sphere of space 1 light year in radius has 1/1000th the volume of a sphere 10 light years in radius, just like a cube of space 1 light year on a side has 1/1000th the volume of one 10 light years on a side. By the same reasoning, the nearest nomad planet is likely to be just over 1/10 of a light year away, a lot closer than Proxima Centauri. How long would it take to get there?
The likely distance in astronomical units (one AU is the distance from the Earth to the Sun) is about 6,600 AU, or just under a trillion miles. At a speed achievable with today’s spacecraft of 50,000 km/hr, it would take about 2,200 years to get there. This is bad, though not as bad as the 91,000 years to get to Proxima Centauri, and at least there would likely be a place to land. If we can just get travel speeds up by a factor of 100, it would be a 22-year trip. It would be easier to hopscotch through the galaxy, colonizing nomad planets about 6,600 AU apart, than it would be to jump from star to star, since stars are so much farther apart.
A major problem, of course, is that since these nomads are so far from any star, their surfaces are exceedingly cold. What is needed is drilling technology that would enable “mining” heat from under the surfaces of these interstellar nomads. Heat can be used to generate electricity and other forms of energy needed to manufacture nutrients and otherwise sustain human life, however dreary living underground and eating artificial food might be (soylent gray, anyone?) . Such drilling technology is clearly within our grasp on Earth, although exporting it to another planet just as clearly requires some advances.
Colonizing nomad planets is not likely to occur in our lifetimes, though the important first step of finding them is. That may be just as much fun (or more) than eking out a life on one of them. So what are we waiting for?
Reference
“In fact, there may be 100,000 times as many such nomads floating around in space as there are stars, but we just don’t know about them.” L. E. Strigari, M. Barnabe, P. J. Marshall, and R. D. Blandford, Nomads of the Galaxy, draft paper, available at arXiv, 1201.2687v1, 2012.
Leaving the idea that the universe is mostly void opens up a world of possibilities. What if there is not only rocks out there that we haven’t seen but exotic sources of energy smaller than we have cared looking for yet.
Come to Hilton Head Island, South Carolina, Thurs, 15 March, 4pm EDT to see in the Kepler Space Institute and National Space Society Convention William Mook presenting from Christ Church via Kim Perlt’s Virtual Orbiting Space Settlement for simulated images and ideas on this subject. The website has full details on the Convention.
Interstellar travel is certainly daunting today, but those who are interested in it should look up Project Icarus, which is doing engineering feasibility studies for a spaceship that can travel unmanned to the nearest star system in less than 100 years. Worth a look.
I certainly am open to study and search for the nomads, but they seem way out there as far as manned settlements. For the foreseeable future (<100 years), we need to focus on the Moon, Mars, the asteroids and some of the outer moons, in that order.
Interstellar travel does, indeed, seem to be off the agenda for now, due to the lack of suitably rapid transport. However, there are fleeting signs of new physics theory that might allow faster travel, i.e. the “Heim-Droscher” Theory, which was taken seriously enough for an article in New Scientist, a short while back. Personally, I would want to forget about interstellar transport until there are proven New Earths to go to, and put as much effort as possible into techniques for teasing out the visual and spectroscopic signatures of Earth-sized exo-planets, from the glare of their suns. Once there is somewhere interesting to go, but unreachable, people will start bending their minds towards how to get there, with an intensity and enthusiasm that is, understandably, lacking at the moment. Who knows what determined research will turn up?
I’m looking forward to the possibility of detecting oxygen in far-off planets’ atmospheres. If we can do that, we have detected life, because there is no way to get a lot of oxygen into an atmosphere except with life more-or-less as we know it.
I agree with Haym’s comment above that we shouldn’t skip our solar system before going to the stars. We need more energy and resources than one planet can provide (since Earth is also supporting our huge population) before we will be able to do truly great things in space. It’s easier for us to cross Earth’s oceans today than it was for the ancient Polynesians because our industry is so much more powerful than theirs was. They couldn’t have imagined building an ocean liner, or even just mining and refining and transporting the metals needed for it. Conquering the resources of Earth to support industry has made ocean crossings easy. One day, with the billion-fold greater industry that the solar system will support compared to Earth’s comparatively miniscule industry, and with advances in technology that we cannot anticipate, we may find that crossing between the stars has become easy, too.
“This makes the trip patently ridiculous without resorting to assuming we will achieve radical advances in spacecraft speed technology. As for proponents of suspended animation who foresee freezing (or whatever) people for 91,000 years and thawing them out afterwards, good luck!”
I have to disagree with your generalizations Daniel. A combination of atomic bomb propulsion and suspended animation can get human beings to other stars in time frames of several decades or a few centuries. We actually could build star ships propelled by nuclear devices right now. A revivable freezing procedure is not that far away.
I suggest you recalculate numbers for about a quarter the speed of light and consider epsilon eridani space colonies as a possible outer limit.
Patently ridiculous and good luck are more appropriate for proposals like faster than light propulsion and statements concerning our “huge population.”
We have formidable resources on this planet that could launch starships within a few decades if we had to– and if we could freeze people.
—-
Response: Yes, if we can get to a quarter of the speed of light, that would be a game changer in terms of interstellar travel. Also, it is true that freezing people and reviving them later is theoretically plausible in a way that faster-than-light travel is probably not. However, a workable technology is a ways off. Not to discourage someone from trying to get it to work, of course!
Minor disagreement but Voyager (34 year old technology) can reach Proxima Centauri in 73,000 years. Advanced ion propulsion could get us there in about 42,000 years. But it doesn’t matter, it’s still too long.
I’m not too worried about a target planet. The rate of discovery is so quick nowadays, by the time we launch a true interstellar mission I think that we’ll have a specific nearby rocky exoplanet, exomoon, or yes, even nomad planet in mind. Just look at how far we’ve come in discovering exoplanets just the last 10 years.
I think that the rationale for the nomad-planets-as-stepping-stones approach is not well thought out. There is the Faster-Later issue. If it takes 100 years (or whatever) to reach such a nomad planet, how much faster will our technology be by that time. I’m guessing that, at that rate (1.000 years to Alpha Centauri) we’ll have beamed propulsion and hibernation which will get us to Alpha Centauri faster than 1,000 years.
However, there is a very important LifeBoat reason for attempting such a mission. Fermi’s Paradox suggests that other intelligent civilizations may not exist (since there is no evidence for them). Although there are several good potential explanations for this apparent paradox, one of the worrisome explanations (which is getting more plausible by the day) is that intelligent civilizations always kill themselves thanks to their own self-replicating technology (probably by accident). If the only way that an intelligent civilization could survive such an relatively unforseen event was to excape their entire solar system alive, then interstellar travel becomes the very high hurdle that no intelligent civilization overcame before they destroyed themselves. If this is the case, then our challenge is to actually achieve a “manned” interstellar mission before our own existential event occurs, or…we make it far enough away (1 light-year?) to survive whatever the event is.
I actually believe that there is such a plan which could be implemented using near-term technology. It could be used for either a true interstellar mission (all the way to Alpha Centauri) or to one of these nomad planets. Just Google: “The EGR Mission” to see that plan.
Folks, do check out “EGR mission” if so inclined.
However, in order to plausibly make claims about the capabilities of future technology, it helps to have a trend to extrapolate. Then, the big question is what “Moore’s Law” curve for space travel could be identified, and what does it predict about timing of future space-faring technologies? If someone has found such a curve, I’d sure like to find out.
> we shouldn’t skip our solar system before going to the stars.
These two goals are not in conflict. The one leads to the other. Most scenarios of beamed propulsion require in-space infrastructure. Probably, this means lunar infrastructure. But, to permanently open up the solar system, we will probably also need lunar infrastructure. Likewise, early beamed propulsion from the Moon would be most helpful in shipping things around the solar system. Gary would likewise point out that the Moon is a safer platform from which to launch nuke-based missions within the solar system as well as to another star system.
> We have formidable resources on this planet that could launch starships within a few decades if we had to…
But herein lies the rub. We probably won’t know that “we had to” until it was too late. Most realistic scenarios in which 100.0% of humanity is killed don’t involve a slowly developing crisis that gives us enough time to put the world’s economy on a “war footing”. Rather, they will happen in much too short a time frame to allow us to do anything useful.
Thanks for the topic — and agreed with Mr Church’s comment that attaining a quarter the speed of light would be a game changer in terms of interstellar travel. I’d consider nomadic planets, interstellar rock and such as a hazard more than anything else.
If you get up to those speeds, you are not slowing down for anything — and in so any sizeable object — sparsely distributed as they are — a collison with such uncharted objects could prematurely terminate any such mission. Also the slow-down and re-launch after landing on such could restrict the speeds one aspires to for such a mission.
Mr Benaroya is correct though — this is not relevant for the forseeable future — nor does it need to be — as a civilisation we would need to learn how to sustain colonies elsewhere in our solar system first, and as Mr Hunt points out — this is something we should consider sooner rather than later. Most existential risks considered here don’t give much lead time from when they start to manifest. The whole CERN/LHC debate was a classic example.
“But herein lies the rub. We probably won’t know that “we had to” until it was too late. ”
Agreed.
An understanding of cosmology and evolution seems to recommend space exploration and perhaps migration, to most of those involved with some variant of the space program. Unfortunately, the usually argued case seems to be to gain a slightly longer survival of intelligent life; this seems recurrently non-persuasive to the larger population and policy makers. Paradoxically, a greater and even less readily achievable goal may be more persuasive to a species that understands and seems to like to contemplate infinities. Is there an underlying, unstated argument that life might, through its adaptability and potential for exponential growth, influence and change the course of cosmology?