Roadmap to Alpha Centauri
nautil.us
nautil.us
And no, it's not a simple matter after budget priorities either. Physics, bitch.
http://www.antipope.org/charlie/blog-static/2007/06/the_high...
My response is "under your feet".
Probably not Alpha Centauri since it's a binary system.
Closer exoplanets aren't necessarily easier to spot, we've spotted those around Gliese 581 because they have a nice short period of a few days.
A close and attentive reader of my original comment might possibly note that my argument wasn't for Gliese but against a. centauri. The salient point being that you'll need to schedule and budget for markedly more than 4.6 light years.
And thus a long slow boat to the stars starts off as simple resource extraction. Sure, long term we might only be looking for gas giants as a ready supply of fuel vs planets to live on but there are other paths to the stars than a one shot moon landing style.
While that is clearly possible, it remains an endeavor for which all but the very closest targets (Moon, Mars, Venus) remain years away. I don't know that anything other than very cursory human travel will be possible. No targets are particularly hospitable (Venus especially not, Mars barely), the total land area available in the _entire_ solar system is pretty modest (as usual, xkcd has a visualization: https://xkcd.com/1389/), and the benefits of travel are relatively modest.
My prediction is that we'll likely see more robotic missions, might land humans on Mars (and will likely return them to Earth), but long-duration settlements are relatively low-probability. Perhaps on the Moon. Possibly Mars. Beyond that, doubtful. And they'll likely be little more than research outposts -- I don't think space will prove commercially viable other than for communications (largely Earth-orbiting satellites) and information (again: largely weather forecasting, sensing, GPS, and imaging, mostly aimed at Earth).
As to the bennifits on the long term, aka 100,000+ years. It's less a question of economics but possibility. Can we have an independent space based economy and there is plenty of energy and raw materials so justifying no is difficult.
Our understanding of geology now suggests that a great deal of the heavy and rare elements in the Earth's crust were deposited during the late heavy bombardment -- after the Earth's crust had formed (and hence, after the heavy stuff had sunk toward the Earth's mantel and core), but before there was a lot of life. Which means that a large chunk of the asteroid belt is actually scattered across Earth.
Modulo plate tectonics, previous mining, and other activities.
There are arguments that, e.g., pretty much anything you could want to get is obtainable from seawater, modulo energy (and a significant filtration system).
That said, yes, there are some rare minerals which are useful that might be present in high concentrations in specific asteroids, possibly tracing their own origins to very specific conditions of supernovae explosions which both created those specific atoms and grouped them together.
But moving even a few hundred kg of matter, let alone thousands of kg or tons, is a hugely different proposition. That's a lot of energy to expend, and complexity to support.
It's a lot more fun to focus on the technology because the technical obstacles to space flight are potentially tractable. The human obstacles seem to resist any solution.
The sad thing is, it's the same phenomenon that gave us all the growth and awesome technology we enjoy today that prevents us from ambitious space missions. Progress of technology is in a tight feeback loop with the economic system, and from the point of view of the latter, space exploration is a big no-no.
Military spending may or may not be justified, but if the whole world cut all military spending, it's not like space travel would get dibs on that money.
Space travel has to justify its existence on its on terms. Right now I'm pretty happy with NASA's science based program. The Mars rover strikes me as a great way to get a lot of science for the money, and learn a lot about operating autonomous robots in space.
Military spending hits a sweet spot of being a tried-and-true generator of middle-class jobs, responding to a perceived urgent national need, and also functioning as a sort of insurance policy, in the sense that we're often paying for something not to happen, making it hard to assess value.
A space program doesn't necessarily hit any of these notes. It requires specialized talent, responds to no immediate need, and, perhaps perversely, because you can measure the success of a space program, it's too easy to foresee things going wrong.
I think you could make a similar case for why we don't plow $500bn into curing cancer, which is a manifestly better idea (even just from an actuarial perspective) than spending 10x more than the rest of the word on defense.
I think you're overlooking an emotional component to military service. For a lot of people it ties into issues of heritage, national and personal identity. For many Americans it's synonymous with the idea of national service.
If our grandfathers' Space Corps had stood strong and unbending in the face of the Martian landing pods, we would likely not have any trouble getting the cool missions funded now.
Giving every cancer research on earth the freedom to actually research instead of preparing grant submissions would probably be enough to substantially decrease the amount of time before significant strides are made. Especially if the money would pay for research assistants, statisticians, and quants to parse the data being collected. Outfitting labs with the latest in high throughput robotics, microfluidics, sequencers, etc. would amplify their efforts.
It's both sad and great that we probably can not spend those $500B in cancer research, yet there is so much to improve.
Broad funding for scientific research is important.
One of the literally marvelous phenomena of the twentieth century is how good people were at pretending that this wasn't happening. It's not just nostalgia: People ignored the militarization of space in real time. Werner von Braun was able to literally drop ICBMs on people's heads, then move to the USA and continue developing ICBMs, all the while maintaining, and apparently sincerely believing, that the ICBMs were not the real story, that the real story was the impending colonization of space. And everyone went along with that, except during Tom Lehrer concerts, when they permitted themselves a little chuckle at the irony of it all.
(I blame World War II. I don't think it's possible for young folks like me to really understand how apocalyptic World War II was. The aspects of the 1960s that scare me witless, like the Cuban Missile Crisis, felt normal to people who had lived through World War II.)
Unfortunately, though, the USA wasn't actually paying von Braun for moon rocks, they were paying for ICBMs. And I don't think it's a coincidence that, once the ICBMs were finished, the money started drying up. Space research is stalled for the same reason that the US military still flies B-52s, designed in the late 1940s: Flight is a solvable problem, and it was solved. ICBMs ended up being overengineered: We have amazing ICBMs, with lightweight warheads, that remain perfectly capable of accomplishing their core mission of destroying all the major cities of the world. That research is finished, and our major concern today is the delicate political task of destroying our remaining ICBMs and never building any more.
In the absence of a military motive, there's a lot less money for space. [2] The good news is that the money isn't quite zero, and our amazing advances in robotics stretch it a lot farther.
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[1] I've heard that it's the worst job in the Air Force and the personnel involved are absolutely miserable: Spending all day maintaining their doomsday weapons, never able to act, praying that they never have to act, knowing that nobody may be alive to admire them if they ever do act, constantly wondering what decision they'll make when the button gets pressed. Drinking, presumably. Watch the first few minutes of WarGames: Those soldiers are based on real people, and their reactions are based on real drills. They're the unsung heroes of the last fifty years. If they don't do their work with care, we might all die, and nobody wants to think about them.
[2] To be precise: There is still plenty of military motive to launch things into space, and plenty of money too. But we now know that the strategic purpose of space is to hold lightweight satellites that watch stuff on the ground, and those satellites are increasingly small and disposable. In the early 1960s we didn't yet know that we wouldn't have much use for gigantic launch vehicles the size of the Saturn V, and we didn't know how microcircuitry was going to happen.
It's a marketing problem, not an engineering one.
In short, I think the problem is that the evident state of engineering makes the venture look somewhat unlikely to succeed. So no matter how awesome your marketing makes the cause sound, it has to be marked down in the final equation in proportion to the likelihood that it is just an expensive way to die.
Space doesn't get money because space doesn't get votes. Military accounts for a large portion of the science of similar hardware because its development and deployment can be spread around and people can relate to it easier.
Still giving the every day person a choice, go to the moon, protect us from the bogeyman, build schools, or free prescription drugs, I know pretty much the order it will go in.
I've seen arguments from the end of the 80s (sci.space.tech, Henry Spencer et al) that if the launch costs went down, the costs of building hardware would go down. From that, there should be elastic demands when e.g. universities can send their own probes. They also discussed how to do it (Big dumb booster etc).
The point was, not that much more money would be needed for this (just check the really expensive launcher being developed by NASA now!).
To lower launch costs is the key and it might be rocket science but, well, not rocket science. The reason this haven't happened until Space X seems to be mainly NASA's need to protect the shuttle (which was really, really expensive) and oligopolies in the launch business for military contracts.
So maybe not the military, but the military contractors are involved.
It's all starting to come together guys!
My prediction: humans will have to be 100% human technology to free ourselves from the Earth.
That's kind of depressing. But it's a lo-o-o-ng way to Alpha Centauri . . .
I bet future Asteroid miners wouldn't mind a cheap place (relative to going down then up a planetary gravity well) to R&R between digs.
The point is, living in zero-g is destructive to humans. Living in even 1/3 g makes a lot of things a lot better ... and a space station with a zero-g part as well as a small-g part would have the best of both worlds.
If you could enslave the entire population of Earth to work full-time on the project for a couple of decades or so then, yeah, you could do it easily. In a world of free will and competing priorities I don't think it'll be possible until we reduce our cost-to-orbit. Certainly there are no big technological show-stoppers though.
As a vague guesstimate, I've read 1km proposed as a minimum viable radius for one of these things. So you'll need a rim about 6km long. The International Space Station is about 100m long, so if you staple sixty of those end-to-end you'd have a minimum-viable 1g station, at a cost of about six trillion bucks. But of course it would basically just be a thin tube, not much living space.
As for asteroid miners: I can't possibly imagine that this is the sort of thing that we're ever going to send humans rather than robots to do.
Something of that scale could reasonably be covered if the U.S., Europe and China/Korea/Japan all agree to Iraq War level spending each for that time period.
[1] http://en.wikipedia.org/wiki/Novikov_self-consistency_princi...
[2] http://www.askamathematician.com/2011/09/q-hyperspace-warp-d...
[Edited to add second link.]
Would someone mind elaborating on what the author is saying here. I would have supposed the warp field would surround the entire craft. If this weren't the case the ship would be torn apart, no? Everything I think about warp drive is so coloured by Star Trek I observe myself having difficulty imagining it could be any other way.
Something like that :) I'm rubbish at physics :)
No human has ever travelled beyond Earth orbit. I believe the Apollo missions may have achieved Earth escape velocity, though their destination was Lunar orbit, which remains within Earth's.
The calculation is fun:
The kinetic energy required to escape Earth's orbit entirely is: G M / R, where G is Newton's constant, M is the mass of the Earth, and R is the radius of the Earth.
The kinetic energy required to get to the Moon is: G M / R - G M / r, where r is the distance to the moon.
To compute the ratio of the second quantity to the first, note that the GM factors cancel. So the ratio is:
(1/R-1/r) / (1/R) = 1 - R / r
The distance to the moon is about 60 times the radius of the Earth. So:
Kinetic energy required to get to moon / Kinetic energy required to escape Earth's orbit entirely = 1 - 1/60 ~ 98 %.
In other words, the Apollo missions had at least 98% the kinetic energy required to escape Earth orbit's entirely.
What truly boggles the mind is that the US at the time was a country of housewives, racial segregation and prosecutions of gays and bisexuals. Yet, or perhaps because of that, they decided that the way forward was to build a moon ship. It says a lot about society at the time.
Ooops! I cannot find the words "stop", "brake", "decelerate", or "slow down" in the article. I guess it is to be understood that you carry 300,000 more nuclear bombs with you and blast them in front so that you don't blow right by Alpha Centauri when you reach it.