I suspect we’ll set foot on Mercury if our society doesn’t collapse. As for the really long run I expect our descendents/inheritors won’t be human, so they may well not even have feet to set down on any planets they reach.
An FTL drive is likely literally impossible. A generation ship is well within the laws of physics.
There’s no need for the machines to be especially durable; they just need to take along everything they need to build their own machinery to replace anything that breaks. And I’m not sure why it would matter if their society changes.
Societies have lived essentially isolated on islands for thousands of years; humans are perfectly capable of functioning like that. In fact I think that the unlikely part of the generation-ship colony vessel idea isn’t the ship; it’s that the people on it would be interested in leaving their ship once they got wherever they’d been sent. I’d expect them to be more inclined to build more ships or space stations rather than colonize anything as alien as a planet would be to them by then.
Rather than colonization vessels, I think a more likely realization of generation ships would be as permanently inhabited nomadic towns or cities. They wouldn’t be interested in colonizing planets; they are the colony. They’d likely be more interested in asteroids and comets than in planets, barring any with life.
We’d need a better way of getting there than we have now. Mercury is hard as hell to get to. It took Mercury MESSENGER seven years to achieve an orbit around Mercury. And that was just delivering a little probe.
Well, that’s another part of it, if it does get done, what can precict if who gets it done will be readily identifiable as “us”. Whoever does may have as much in common with “us” civilizationally as we do with the cave painters at Altamira. If it doesn’t take so long that biological evolution into other-than-“us” happens.
Ah, yes. The human inclination that has got to explain how come people ended up in places like Yakutia…
Unless there’s some sort of FTL drive invented, I think it’s going to be Mars and Jovian and Saturnian moons.
And yeah, we need a permanent manned station on the Moon. If for no other reason, to make mistakes there (a 3 day flight away from the Earth) than on Mars (a 6 month flight away from Earth, if one leaves Mars in it’s most advantageous position).
My understanding is the briefest Martian manned mission is going to take 2 years. 6 months travel time each way, and 12 months for it to come around to the most favorable position for a Mars to Earth return trip. Am I wrong with this? How much volume are they going to need for 2 years worth of MREs, water, and disposables for a a crew of 4?
A crew of 4? Four people is too small to do it properly. You need one person to get hurt at the inevitable alien site, two people to drag him back to the ship, one of whom doesn’t make it…another to die mysteriously, one more to die discovering the alien threat has returned with them, and then at least three more to die as tension slowly builds. That leaves the hero/heroine (who originally survived dragging the injured person back to the ship) and his/her opposite-sex buddy to make a last stand and agonize about the danger of returning to Earth with the possibly still-existing alien threat.
I figure nine people, minimum. Of course one of those turns out to be an android, so that’s either eight or nine, depending on where we are politically on the self-aware machines civil rights movement.
In this context, I count as “us” all our descendants, even if considerably removed, culturally or physiologically. They might even seem more removed to us-today than we to the cave painters (who in the big picture are most certainly “us,” not Martians or dolphins)
What would be the political impetus for landing people on a Saturn moon? It would be as costly as a Mars mission for far less perceived public support.
I think we’d have to be much further into space exploration than we are now to consider it. After landing on Mars to because it’s there, after prospecting the asteroids, with no other goals to achieve we’ll need another Grail to pursue. But right now the cost is unthinkable.
A computer than lasts a thousand years is no more or less subject to the laws of physics as an FTL drive.
It matters if that society forgets how to operate the ship!
We are talking about a trip lasting hundreds or thousands of years ago. A couple thousand years ago the Roman Empire ruled the world. Hoe much change has society experienced since then? Now imagine that society stuck in a bottle the whole time.
Yeah! And they haven’t had to operate and maintain devices more complex than a dugout canoe!
I supposed if you’re going to do that, you don’t need to send them out of the solar system. Or even off Earth for that matter.
We won’t need to put people on generation ships – just cryogenically frozen genetic material. We send out thousands of relatively small, automated ships, stocked with the genetic material of humans and all the other useful and necessary earth life forms. When these ships find a suitable planet, they seed it with life – start with bacteria and single-celled life forms, then plants and insects, fish and sea-life in the seas, and eventually complex animal life. This might take hundreds of years or more – but that’s okay. Eventually we’ll have a planet ready for human life, and the robots will incubate our frozen genetic material into the first new generation of humans, who will undoubtedly be equipped with all kinds of interesting psychoses from being raised by robots.
But what I’m really looking forward to (not that I’ll be alive to see it even with my youth), will be real pictures/videos of the surfaces of the planets.
I want to see the methane oceans of Venus, it rain diamonds on Jupiter, etc. etc.
I think that by the time we are considering travelling beyond the solar system, humanity will have progressed to being a collection of artificial intelligences, instead of meatbags. AIs can be made a lot more durable and are effectively immortal, so sending some on thousand-year journeys becomes a lot more viable.
NASA has no plans to construct a crewed facility on the lunar surface, and in fact their future in-space crewed exploration plans are focused on developing the technology and infrastructure to support the Asteroid Redirect Mission.
Any problem that would compromise the crew of a lunar outpost would likely be no more recoverable than a Martian one, at least with the existing infrastructure. Given current propulsion technology, it is only possible to launch a mission to the moon (within a reasonable timeframe) for a window of a few days out of every month on average. So being able to launch a rescue mission on demand is not a practical option.
There are a number of other problems with operating a lunar base, chief among them is the electrostatically attractive lunar dust. See NASA/TM—2005-213610/REV1 The Effects of Lunar Dust on EVA Systems During the Apollo Missions, James Gaier, April 2007. Landing and operating on, say, Mars or Titan, will be substantially different than the conditions and entry mode on the Moon. And going to the Moon doesn’t really develop the necessary technologies for interplanetary transportation or sustainable orbital habitation. In fact, what the Apollo program aptly demonstrated was that what we call destination oriented programs have grave difficulty in extending beyond their initial goals. Even before the Apollo XI reached the Moon and the Eagle had landed at Mare Tranquillitatis the Apollo program was being slashed, and none of the proposals for successor programs–not even the low cost Apollo Applications Program using hardware that was already fabricated–had any real traction.
Although a so-called “generation ship” may not violate physical laws in the same way that superluminal transit does, there are a large number of reasons why the concept isn’t remotely feasible with extant or foreseeable technology. Setting aside issues with propulsion, reliability of systems, ability to maintain order within a closed society and maintain the necessary skill base to sustain such a long term effort (on the order of thousands of years to the nearest systems which could realistically harbor planets vaguely suited to human life), the energy requirements, hazard from intercepting even the smallest amount of solid debris at interstellar speeds, et cetera, there is the basic problem of thermodynamics; that is, that your “ark” is going to have to produce enough power to sustain the society within (as well as power required for propulsion), the waste of which will have to be radiated out to space. In our terrestrial ambient environment this is almost never a concern except in very localized circumstances (e.g. inside of a heat engine or power plant) because the ambient environment provides both an enormous heat sink and a great means of conducting heat (convection by the air or water). In space however, the only means to rid a body of excess heat energy is via radiation to the 2.7 K microwave background, which even for a perfect blackbody can only be done at a given rate per amount of outward facing aspect relative to the temperature difference. Even a small vessel, producing power continuously over a long duration would require a huge radiator surface to maintain an equilibrium temperature within human tolerances. A ship with a population numbering in the thousands would have to be the size of a moon.
Grey also makes a good point upthread, to wit: “…why you’d want to sit yourself at the bottom of a massive gravity well.” Any permanent manned presence in space is predicated on being able to not just sustain itself but produce necessary resources. (I’m avoiding the “must make a profit” statement as it assumes fiscal viability in a capital-based market economy, but we can expect any human civilization that is established in the solar system will be sustained by some kind of trade in material resources or manufacturing of finished goods in addition to any service labor and scientific research.) Unless interface propulsion technology is advanced to the point that it is vastly more reliable and trivial in cost compared to existing (e.g. chemical) rockets, it just isn’t going to be practical to transfer material resources from the surface of a planet or moon into space. Yes, we can hypothesize railgun and other electromagnetic propulsion systems which will deliver materials into interplanetary space at pennies per kilogram, but only if we ignore the practical limitations imposed by thermodynamics and material science.
So it makes more sense to use resources that are already in space, e.g. small asteroids. Of course, this will require new procedures and technologies to manipulate and process materials in freefall, but there are a number of advantages that can be leveraged using centrifugal separation versus using terrestrial gravity.
There is also the opportunity to recreate terrestrial environments to a high degree in orbital habitats in space, e.g. Earth-like simulated gravity, atmospheric pressure, temperature variations, et cetera. I’ve [POST=14049658]written[/POST] [POST=9514841]elsewhere[/POST] regarding terrestrial-like environments that could be produced using minimally processed materials found in space (water ice, silicates). Compared to the best case possible environment that could be produced even presuming that planetary-scale terraforming (which requires a presumption of technomagical technology) to Mars or Venus it would be both more Earth-like and more defensible against any natural hazard (meteorite, solar radiation event, et cetera). So, even from a “want to create Earth-like conditions” perspective, it probably makes more sense to expand into manufactured habitats than establish outposts on celestial bodies that do not have and cannot be made to resemble terrestrial conditions.
As far as finding terrestrial-like planets around other stars, the odds of finding a truly habitable planet is highly improbable. Even a planet of mass, diameter, and distance from a G-class star is vanishingly unlikely. If we want Earth-like environments, finding occurring elsewhere naturally is probably an unreasonable expectation. Of course, we may ultimately modify our own form to something that no longer requires a terrestrial environment, and so such considerations (as well as the above about maintaining a terrestrial environment during interstellar transit) may no longer apply. But the vision of the future that is presented in conventional science fiction as much a fantasy as Narnia or Middle Earth.
Mercury sounds like a pretty ridiculous idea. You might be able to explore the (extremely cold) dark side for a short while, but you still have to plow through the intense solar radiation just to get there. Even a few thousand kilometers out is beyond the reach of the shade of the planet, and you have to face that furnace blast twice, for quite a while. For what? I find it difficult to imagine that we would learn much of interest that could not be discovered by an automated probe.
The 13-year-old in me says: This sucks. Sucks, sucks, sucks.
So, we’re doomed to know more and more about places that none of us can ever experience firsthand. I guess it’s not THAT different from any individual human only knowing about 99% of the world vicariously – even the best-traveled among us has read about or seen pictures or film of many, many more places than they have visited, and I’m not even counting all the places we’ve never seen at all (heck, I’ve never visited nor seen pictures of the crawl space in my own house, nor set foot in more than five of my nearest 20 neighbors’ houses.)
But this feels different. Surely the technology for vicariously “experiencing” a place will also advance – a GoPro video played through a helmet playback system is just the start – but still, it’s not the same, and no vicarious setup can overcome the comlink delays imposed by space-time.
And of course I’m just talking about experiencing a place – basically what the Apollo missions did. I haven’t touched on all the other activities true colonists would engage in.
It sucks being a meatbag. In a way, despite the impressive adaptability of our species, we’re as hyper-adapted to a restricted set of environmental conditions as the Northern Spotted Owl. I guess I should be happy that I could hope to visit Antarctica in my lifetime, something no Spotted Owl could pull off.
Ref the snippet above, why? The “per-month” part implies it’s related to the Moon’s position in its orbit. Is it simply a matter of the Moon’s orbital inclination and we can’t move far enough North / South from the plane of the Earth’s equatorial plane to catch it no matter where it is, so instead we need to wait and then time the launch to intercept the Moon as it passes a node?
And are we that short of total delta V, such that it’s impossible, or merely much more expensive? Said another way, what’s our delta V shortfall for a launch-anytime-on-demand vehicle: 2%, 20%, or 200%?
Obviously we lack the practical and logistical ability to prepare and maintain a complex vehicle like that in constant readiness for immediate launch indefinitely. I’m setting that issue aside.
Earth’s moon (informally, Luna, although it has never been assigned a proper name) is highly inclined relative to the Earth (roughly 18 to 29 degrees to the Earth’s equator) although it might be more appropriate to say that the Earth is rakishly tilted and the Moon simply hasn’t come into line. This translates into a not inconsequential difference in required impulse (or as it is colloquially known, “delta-v”) depending on at what point the intercept occurs. The Moon also has a not insignificant eccentricity which isn’t of great consequence but with a marginal spacecraft can make enough of a difference to further reduce available insertion windows. I don’t have hard numbers for the amount of impulse per mass of spacecraft required because it depends on the trade between duration of the lunar journey, distance to the moon at the time of the insertion, et cetera but a totally off the cuff SWAG is that it would add somewhere on the order of 50% more required impulse. This may not sound like much, but realize that every kilogram of propellant boosted up to the trans-lunar injection point is a kilogram of payload (e.g. spacecraft, astronauts, supplies, and instrumentation) that is lost. If we had extra mass budget to burn–literally, in this case–it wouldn’t be such an issue, but given the marginal performance of even the best space launch rocket boosters it just isn’t feasible to mount a rescue mission at any given point.
Practically speaking, before we can maintain any kind of significant extraterrestrial presence, we’ll need to build a space-based and predominately self-sustaining space transportation infrastructure. That means not carrying everything we need from surface to orbit, but rather building a collection of individual elements which can operate most efficiently for their intended tasks, e.g. space tugs for orbital maneuvering, an interplanetary shuttlecraft to go to the Moon, Lagrange points, a single stage Lunar lander/ascent module that doesn’t require leaving 80% of itself behind on the Lunar surface, et cetera. Sine qua non of all of this is the ability to extract, process, and use space resources, especially water/ice, silicates, precious and structural metals, and rare earth elements. Once space habitation can be made a going proposition, exploring and, if we were so inclined, colonizing other bodies is merely an exercise of logistics and risk management using mature technology.
But exploring the way we currently plan to explore–desperate, single, flags-and-footprints efforts to send a tiny crew of typically non-scientists for glory and a t-shirt–is not a productive or sustainable means of exploration. Just as we did not return to the Moon after a handful of missions “proved” that we could best the Soviets at the game they had been previously winning, a single mission to Mars at a cost of hundreds of billions (US$200B is a low end estimate; realistic costs for a crewed mission of six people with a reasonable expectation of success is on close order of US$500B) is simply not repeatable, even if we assume that the cost of a follow on mission using the same technology will be a third of the cost. Until we have such an infrastructure, the most viable and economic–not to mention low risk–means of exploration and developing the means to exploit space resources is to do so with the crew operating remotely, i.e. using robotic probes and landers.