
Roadmap to Alpha Centauri - dnetesn
http://nautil.us/issue/3/in-transit/roadmap-to-alpha-centauri?utm_source=tss&utm_medium=desktop&utm_campaign=linkfrom_feature
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dredmorbius
Read Charlie Stross's "High Frontier Redux". It's simply not that easy (and a.
cent. is the wrong target).

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...](http://www.antipope.org/charlie/blog-
static/2007/06/the_high_frontier_redux.html)

~~~
BrandonMarc
What would the "right" target be?

~~~
dredmorbius
Stross answers that.

My response is "under your feet".

~~~
afafsd
Stross says Gliese 581c on the grounds that it's the closest currently known
vaguely-habitable exoplanet. Most likely there are others closer and we
haven't found them yet.

Probably not Alpha Centauri since it's a binary system.

~~~
dredmorbius
A habitable plainet would require a vaguely Sun-like star. Odds of one hiding
between us and a. Centauri are low. Gleise or a neighbor are best bets, and
near exoolanets are also generally easier to spot.

~~~
afafsd
Not one hiding between us and Alpha Centauri (which is unlikely), but one of
the hundred or so stars between us and Gliese 581.

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.

~~~
dredmorbius
Ease of finding an exoplanet, among other things, increases with proximity.

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.

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idlewords
It's sad that the biggest barrier to space travel remains the inability to
mobilize large amounts of money to fund ambitious projects. We have no
difficulty funding the most nugatory military operations at ten times the cost
of a manned mission to Mars. But peaceful projects, whether on Earth or in
space, run out of political support at a fraction of that price.

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.

~~~
tptacek
Uneducated guess:

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.

~~~
idlewords
I'm not sure what you would _do_ with billions of dollars thrown at cancer. At
least with guns and rockets there's hardware to build. I suspect breast cancer
research, for example, can't usefully absorb more money.

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.

~~~
mikeyouse
>I'm not sure what you would do with billions of dollars thrown at cancer.

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.

~~~
marcosdumay
I doubt all that would take more than a billion or two. For the entire world.
And giving more liberty to researchers will probably lead to savings, not
expenses.

It's both sad and great that we probably can not spend those $500B in cancer
research, yet there is so much to improve.

~~~
XorNot
"Cancer" is also simultaneously a narrow and broad field. Computer technology
improvements has probably done more to advance modern biology and microbiology
then other single advance - but would receive no funding at all under the
banner of cancer research.

Broad funding for scientific research is important.

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chisophugis
The biggest barrier to space travel is our biology. We must create non-
biological humans that can shut off and wait for the entire trip.

~~~
enraged_camel
Or cyrogenics.

It's all starting to come together guys!

~~~
chisophugis
It's about more than just shutting down though. Biological complexity makes it
infeasible to significantly engineer our biological bodies to e.g. make them
smaller to reduce fuel costs, or make backups so that we can easily do
potentially dangerous experiments involving ourselves (also reproducible
experiments).

My prediction: humans will have to be 100% human technology to free ourselves
from the Earth.

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eudox
Missing: Project Valkyrie

[https://en.wikipedia.org/wiki/Project_Valkyrie](https://en.wikipedia.org/wiki/Project_Valkyrie)

[http://www.projectrho.com/public_html/rocket/slowerlight.php](http://www.projectrho.com/public_html/rocket/slowerlight.php)

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kabdib
(not original with me): "The fastest way to travel to the nearest star is to
wait 100 years and _then_ go."

That's kind of depressing. But it's a lo-o-o-ng way to Alpha Centauri . . .

~~~
tunesmith
I've wondered about that, and how the break even point would be calculated.
The soonest date that someone could get to Alpha Centauri wouldn't be on the
same trip for the soonest date someone could leave for Alpha Centauri (and get
there successfully).

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bane
A little closer, I wonder how far we are from making something a little more
mundane like a Babylon 5 spinning habitat, or even a 2001 spinning wheel
station. Are these just a matter of money, or is there some other fundamental
technology challenges to getting those things built?

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.

~~~
afafsd
Depends what you mean by "just a matter of money".

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.

~~~
bane
Well in an age of $19billion chat app acquisitions, $6 trillion ain't what it
used to be. That's only a one time cost of 8% of the Gross World Product.
Spread that over a 20 year construction time-frame and that's $300billion per
year _globally_.

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.

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dghf
If you're going to use a warp drive (or any other means of FTL travel), you'd
better hope that Novikov's self-consistency principle [1] holds, or else be
prepared to deal with the ensuing causality violations [2].

[1] [http://en.wikipedia.org/wiki/Novikov_self-
consistency_princi...](http://en.wikipedia.org/wiki/Novikov_self-
consistency_principle)

[2] [http://www.askamathematician.com/2011/09/q-hyperspace-
warp-d...](http://www.askamathematician.com/2011/09/q-hyperspace-warp-drives-
and-faster-than-light-travel-why-not/)

[Edited to add second link.]

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hcrisp
"(The stars) remind us of the puny distances we men travel; the nearest one,
Alpha Centauri, is four light-years away, far beyond our capability to visit
today or in our lifetime, yet beckoning, mocking us and our dreams." \- Mike
Collins (Apollo 11 astronaut)

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TheSpiceIsLife
"What is more, the ship would be impossible to steer, since control signals,
which are restricted to the speed of light, wouldn’t be fast enough to get
from the ship’s bridge to the propulsion system located on the vessel’s
perimeter."

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.

~~~
CWIZO
Imagine a ship travels at 1.5x the speed of light. Now imagine the signal from
the "steering wheel" travels to the ruder with light speed. You turn the
wheel. Before the ruder gets the signal and turns (and let's ignore human
reaction time) the ship has already traveled however much distance you cover
when traveling at half the speed of light. You would have an enormous lag
basically.

Something like that :) I'm rubbish at physics :)

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alexyes
It is extremely sad that we have not traveled beyond Earth orbit since the end
of the Apollo program in 1972. Space exploration inspired many of us to study
math and CS and fostered innovation. The majority of the most relevant people
in tech in the last 30 years (Bill Gates, Jeff Bezos, etc.) have repeatedly
commented how the Apollo missions were inspiration for the their studies and
careers.

~~~
dredmorbius
Correction: humans haven't travelled beyond _low_ Earth orbit since 1972.

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.

~~~
michael_nielsen
It's a marvellous fact that the Apollo missions achieved escape velocity, or
close enough that they could have done so with small design modifications.

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.

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mrfusion
Why can't Orion take off with conventional rockets and then switch to nuclear
drive once in space? Wouldn't that address the main drawback?

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Vektorweg
Lets hope this doesn't start like Sid Meiers Story ...

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rbanffy
Interesting there is no mention to EmDrive or Q-Trusters.

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qwerta
It was calculated that 2 people would die from exposure every time Orion
spaceship takes of. It is hardly 'nuking the earth' as article suggest.
Millions of people die every year from background exposure.

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kazinator
> _Load your starship with 300,000 nuclear bombs, detonate one every three
> seconds, and ride the blast waves._

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.

~~~
ricardobeat
Although the article doesn't mention it, the original idea, having been worked
on by a host of scientists and not a random person on the internet, does take
that into account:
[http://en.wikipedia.org/wiki/Project_Orion_%28nuclear_propul...](http://en.wikipedia.org/wiki/Project_Orion_%28nuclear_propulsion%29)

