mindstalk | Entries tagged with space

Some space enthusiams nostalgia: https://www.youtube.com/watch?v=LMbI6sk-62E

Edit: Keith Loftstrom on using power storage loops as a way to bootstrap to launch loops. http://launchloop.com/PowerLoop

Crossposts: https://mindstalk.livejournal.com/546191.html

I wouldn't have recalled that interplanetary radar has been a thing, but it has, and http://arxiv.org/abs/1301.0825 proposes an interstellar radar system for distant imaging. Claims no new technology is needed, just expense. Lots of expense, he estimates $20 trillion. My friend G and I had estimated a cost for Project Longshot -- an interstellar orbiter (unmanned, no return) -- of $400 billion to $4 trillion. OTOH Longshot would take over a century to reach the nearest star system and would need robust automation to match, though the uncertainties there are part of the cost (and the marginal cost of multiple probes could be lower... as low as $40 billion?) Radar could return data within my lifetime, and once built could image many nearby systems.

G likes to account for things in "war units", $400 billion or a trillion, a la the cost of the Iraq war and associated shenanigans. "We could have another war, or we could send a probe to Alpha Centauri." The radar looks expensive even in that light: $1000 per rich country person for 20 years, or $140 per global person. OTOH per capita income is $10,000 globally, so 1.4% of global GDP for 20 years. As science budgets go, very expensive; less than the global defense budget though.

I'm partly intrigued by the idea, partly amazed that there's finally a case where sending probes seems cheaper than remote observation.

This definitely calls for the Void Engineer icon and the sceince! tag.

Crossposts: http://mindstalk.livejournal.com/362937.html

Inspired by a thread on plausible alien invasions.

As I think I've blogged before, in a sense we may be quite close to being technically capable of sending a ship to a nearby star. At the raw physics level, we already have the energy sources. The Newtonian kinetic energy of mass at 0.03 c is comparable to the energy density of fission fuels, and means getting to Alpha Centauri in 140 years. The tricky part is delivering the energy into exhaust of such speeds; thermal engines melt, mass drivers quench, ion drives I'm not sure about, plasma drives ditto, photon drives have too much exhaust 'velocity' to be efficient, fission fragment rockets would be just right but the atoms that want to fission aren't the ones in a good surface position to send fragments out the back.

Still, it's possible that an ion drive, or plasma drive, would in fact work. The extreme case is Project Longshot, where a fission reactor is used to force D-He3 fusion pulses, getting you the energetic plasma needed (and more, it's like a fusion afterburner) while ducking the problem of fusion power reactors being among the hardest things the human race has ever tried to do. (Here, plasma squirting out is a feature, not a bug.) And of course there's always Project Orion, another fission-fusion combination, and maybe one that could use the much cheaper D-D reaction. Or fragments.

Of course, then there's the matter of having something that lasts 95 (Longshot) to 140 (pure fission) years, in hard radiation to boot; this might well be harder than simply making something go fast. Even more so if you want to send live beings.

But... there's a common assumption that if you can send a ship like that, you don't need to invade, you can build space colonies and such. But it's not true. Leaving aside whether people want to live in space colonies, the problems are different. The ship 'just' needs to last over a century; air leaks can be replenished from ice supplies, breakdowns can be compensated for by redundancy, spare parts, and a portable machine shop; people need some combination of a few generations, stasis, or longevity (possibly including partial longevity through partial stasis, or slowdown.) While a colony needs to be more permanently robust, and to contain or have access to a complete industrial ecology.

So invading your neighbors with the desperate hope and need of taking them over, and using their labor and industry, may in fact be easier than a self-contained space colony, and at any rate is a different problem.

Another key note: the sort of "we could expensively build it soon" fission-fusion interstellar ship above does not include ground to orbit capability for Earthlike planets. Moon landers sure, Mars maybe, but for anything we could send, taking capsules down to the surface of an Earth would be a one-way trip. We don't know how to get off again without an army of thousands building the return vehicle.

And of course for any rocket a one-way trip is a lot cheaper than a planned round-trip without guaranteed refueling. And if you need lots of fissionables, refueling may be hard and chancy.

So while the probability of having near neighbors to invade seems very low, and it'd be expensive, there's actually a certain plausibility to would-be conquistadors not much more advanced than us coming and trying to bluff/conquer/trade their way in, without any option to go back home, or even get back off the surface once landed without help. Not very plausible -- but the alternatives, that anyone crossing interstellar distances must be magically more advanced, are not clearly true. You just need fission, you don't need indefinite life support (if you're counting on another ecosystem you've observed with telescopes), you can't necessarily get off the planet, or zip around a solar system arbitrarily.

Crossposts: http://mindstalk.livejournal.com/336043.html

So, there's a couple thoughts about realistic starships. One is that we can't do them and they're centuries of tech away. Another is what we could do them, or probably good with a decade or two of engineering research, but they'd be really expensive. Most people with a clue tend to think the first. But! The second might be more accurate, at least as far as the propulsion goes. The classic one is

http://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion) and variant http://en.wikipedia.org/wiki/Nuclear_pulse_propulsion#Medusa

where you blow up nukes against a pusher plate. Advantage is that it utilizes the one kind of energy productive fusion we can actually do, fusion bombs. Disadvantage is people's nervousness about huge quantities of nuclear bombs, plus since a bomb has a minimum size, the vehicle has to be large. Which can be good if you're really out to send something big, but if you just want a probe, is problematic.

( Mercy cut )

I guess the takeaway lesson is that you need nuclear energies to have even kind of crappy interstellar ships, but we *do* have nuclear energies, and throwing large but reasonable amounts of fission, and maybe explosive fusion, at the problem will suffice for automated probes, such that propulsion may well be the easy bit.

Crossposts: http://mindstalk.livejournal.com/310806.html

One common response in these discussions is "but there are so many assumptions". This annoys me. As I see it, the whole *point* is to make those assumptions explicit and facilitate talking about them. And then people cycle through various objections as if they're refuting the paradox, rather than proposing various solutions.

Semi-formal statement:

Given the fact of a huge and old universe,
and assuming that we are "normal" and thus life, intelligence, and spacefaring industry are common,
and [assuming that such would be detectable
OR assuming that interstellar transport of something that can propagate is possible, with even more detectable results]
then where the hell is everyone?

"Paradox" isn't a particularly good name for it, but it's traditional. But the conclusion of some natural (to many) assumptions is a result at odds with observation, hence sort of "paradox", and discussion. Which of course consists of give and take dispute over various assumptions. "Why do you assume detection is possible?" "Because..." And more assumptions, on *both*, or *all*, sides. It's not clear to me who has to make the strongest assumptions; after all, someone saying travel isn't possible is ruling out *every* combination of propulsion, AI, stasis, mini-tech, longevity, etc., and every form of replication (including bio-heavy ones), while the pro-propagation view just needs one viable way to spread. Life (or replicators) is like water, and the universe prone to leakiness.

Similarly if we posit stealthy civilizations, we ultimately need all of them to be stealthy, in all modalities, including radio deliberate and leaky, thermal emissions, artificial lights, gamma or neutrino emissions, stellar occlusions, probe debris, etc. (Not that we've looked thoroughly at all of these; everything could change tomorrow with some new signal discovery.)

I guess I'm complaining about tone. If you dispute some assumption, you're not proving Fermi was bunk, you're participating in the discussion as intended.

Crossposts: http://mindstalk.livejournal.com/305984.html

Papers on the Fermi Paradox, aka "the universe is huge and old, space is transparent, colonization doesn't seem that hard, where are all the aliens or signs of their existence?"

http://www.kschroeder.com/weblog/the-deepening-paradox/
Karl Schroeder linking to the next paper, and briefly mentioning his own idea of Rewilding, that advanced technology for some reason ends up looking like nature.

http://arxiv.org/PS_cache/arxiv/pdf/...111.6131v1.pdf
13 page PDF by Keith Wiley, "The Fermi Paradox, Self-Replicating Probes, and the Interstellar Transportation Bandwidth", reviewing the potential impact of SRPs and flaws in various arguments against them, including Landis's percolation model, and Sagan's "mutations would be just too dangerous". Percolation stoppage requires unrealistic assumptions, and modern tech shows that we can reduce viable error rates to very low levels. For that matter, the number of replications in our own bodies is at least comparable to that involved in sweeping a galaxy -- he actually cites a much higher number, 10,000 trillion -- without having all that many cancers.

Comments to the blog post include David Brin pointing out that his 1983 review paper on the Great Silence is online:
http://adsabs.harvard.edu/abs/1983QJRAS..24..283B
27 page PDF, oldie but goodie. Modifies the Drake Equation, as does Wiley.

Me, I've long been in the camp of what Brin calls the Uniqueness Hypothesis, allied with the Anthropic Principle. Someone has to be first, and if von Neumann probes can sweep the galaxy easily, then the first can be the last. If we get as far as being able to envision such probes, probably no one else has yet, and we will. Unless we do ourselves in first, but that sort of thing doesn't help the number of aliens be larger than 0 either. As for why we might be first: planets are common, and life might be fast to develop where it can (but see Hanson on hard steps), but *stable* planets might be a lot rarer; we could be unusual in not having had total mass extinctions. Or human level intelligence is rare. Or industrial civilization -- heck, humans were around for maybe 90,000 years without developing agriculture; why?

( Other papers )

( How long? calculations )

Crossposts: http://mindstalk.livejournal.com/305811.html

Voyager 1 120 AU out and still doing science
http://www.rocketpunk-manifesto.com/2011/12/distance-119-au.html
power and fuel to operate to 2020
http://voyager.jpl.nasa.gov/mission/interstellar.html

SAD

Judge gives people a choice of jail or church for a year http://www2.wkrg.com/news/2011/sep/22/serve-time-jailor-church-ar-2450720/ You'll be unsurprised to learn it's Alabama.

Carbon credit land theft http://www.nytimes.com/2011/09/22/world/africa/in-scramble-for-land-oxfam-says-ugandans-were-pushed-out.html

HAPPY

Non-violent first person shooters: http://www.popphoto.com/news/2011/09/warco-first-person-shooter-arms-you-camera-rather-gun
http://www.escapistmagazine.com/articles/view/issues/issue_66/385-My-Hindu-Shooter

I've learned that the 'yucca' root I've eaten in restaurants is cassava, or 'yuca'. I'm horribly disappointed; as a one-time SoCal geologist, I'd seen eating yucca as revenge. http://en.wikipedia.org/wiki/Cassava

Funny used yoga mat ad. http://seattle.livejournal.com/6491700.html

From James, another link about the explosion of space probes and the modern golden age of space exploration. http://babelniche.wordpress.com/2011/08/03/the-robot-population-of-deep-space/

New Goya painting found via X-rays http://www.bbc.co.uk/news/entertainment-arts-15018174

possible ice chemistry of Europa
http://www.jpl.nasa.gov/news/news.cfm?release=2010-319&rn=news.xml&rst=2755

SF book like a Watts-Egan mashup
http://james-nicoll.livejournal.com/2671773.html

Japanese SF authors James Nicoll likes
http://james-nicoll.livejournal.com/2650811.html
especially Issui Ogawa

Milky Way Tube map
http://news.discovery.com/space/milky-way-transit-authority.html

JPL scientists sue NASA over open-ended intrusive background checks.
Caltech rolls over
http://www.airspacemag.com/space-exploration/NASA-v-The-Scientists.html

{the JPL employees asked NASA how exactly the information would be used. In response, NASA released a “suitability matrix,” which lists “sodomy,” “cohabitation,” “attitude” and “loitering” among the potential factors in considering whether JPL researchers should keep their jobs. NASA refuses to rule out that it might use any part of the matrix to evaluate JPL employees.}

Supreme Court arguments tomorrow

I wouldn't be born for another 6 years. But my half-sister was watching the moon landing with my parents, who might or might not have been married by then.

There's cool filk about it all; see here for a couple samples.

I used to be more into space and space colonies and such, but now I have no problem with the thought that sending people to space is currently expensive, dangerous, and nigh-useless. I wouldn't make any predictions about "we don't go back" -- seems likely that if wealth increases, someone will eventually go privately. Colonies are a harder bet but I hope Terragen life has a long, long, future, plenty of time to expand. Especially as AI or robots better built for it all. But for now, I care more about sustainable wealth on Earth, and bringing 5/6 of the world's population into the promised land of electricity and running water, and Americans into universal health care, and such. And doming cities and managing vulcanism and deflectng asteroids and generally being a deep-time Kardashev Type I civilization. And immortality, biological or or cyborged or uploaded. Give us that, and space will take care of itself.

Temperatures here have plunged from 80s to 50s overnight. Hello, autumn? I repeat my call for climate controlled cities; the environment is too important to be left to nature.

Pretending I'm akashiver (entertainment news): Warner's president of production says no more female leads.

Suburban blight

Zombies for Jesus. I don't know how this interacts with "God is a fairy".

Odd Republican sex death. Yes, this is the one with two wetsuits.

I just had this thought: space colonies not being obviously profitable, some people have fantasized about billionaire space fans building them for the hell of it. Others have imagined space hotels slowly expanding. Reading Richard Conniff's Natural History of the Rich I wondered if space mansions might not be a takeoff point. After all, the real question is not "what can colonies do for Earth" or "for humanity" but "for the people living in them."

Well, I guess "for Earth" is relevant for investment purposes. But "for the people" works for buying purposes, and people do buy weird shit.

ADDED: Mules occasionally foal despite normally being sterile due to odd chromosome number. I was alerted to this by a Usenet thread on books by Alan Dean Foster and Robert Heinlein where colonies on other planets lack amenities such as maps, as might be taken by a satellite, or even by a handheld camera from orbit. Time Enough For Love has mules, okay, rifles, okay, and no maps, not okay.