Friday, June 05, 2015

More Space! Expanding the cosmos

You thought I was done talking about space?  We are currently living through the most exciting time for astronomy and spaceflight and expanding our horizons since the 1970s... cool stuff is happening monthly!  

I don't know which to be more amazed-at. The wonders spilling forth from human competence and cooperative effort... or the astonishing silliness of a people who paid for it all, and cannot turn their head to be cheered by such wonders!

== Universal expansion? Tweeking the biggest question ==
Thirty years ago, it was still an open question whether our universe was “open” or “closed.” If closed, then gravity would eventually overcome the expansion set in motion by the Big Bang, reversing the dispersal of galaxies, commencing infall to a Big Crunch. 

This possible destiny led Tulane University physicist Frank Tipler to author one of the most entertaining, dense and infuriating “popular” science books, THE PHYSICS OF IMMORTALITY — a stunning just-so story about the final era, just before the Final Crunch, when our godlike descendants might collect every photon lingering from earlier eras and study every ray, including those that your body emitted, on a cool night, and thereby they would know enough about you — trillions of years from now — to model-resurrect you into infinite computational realms at the end of time…

Did that just make sense? Sorry. Tipler’s tome is one of the more ornate science fantasy speculations, ever, almost infinitely entertaining! And it would have merited calling Tipler the ‘greatest theologian of the 20th Century.’ That is, if we did seem headed for a Crunch.

(Side note: see the Big Crunch... and its aftermath... portrayed vividly in Poul Anderson's classic novel Tau Zero.  It also feature's in Liu Cixin's The Three Body Problem.)

Ah, but the Big Crunch appears to have been ruled out. Instead, the greatest theologian encomium belongs to another physicist, Freeman Dyson, who appraised how long creatures made of matter might eke out continuation of thought and life amid a Big Dissipation into nothingness that might extend trillions, even quadrillions of years. 

Indeed, that seems to be the direction of things, especially since studies of a particular kind of supernova provided us with a Standard Candle to measure the rate of universal expansion… which we now perceive to be speeding up!  Propelled into acceleration by something theoretical called “dark energy.”

Well, well.  Science oscillates, even as we bracket in, edging closer to true models of reality.  The latest news?  Some University of Arizona astronomers now think those Standard Candles — type 1a supernovas — might come in two types, and one kind might have been more common in the early universe.  If so, the resulting mis-calibration of distances might have had an effect upon those Hubble Expansion factors, causing us to exaggerate the perceived acceleration of the universe….

… a bit.  Maybe. Not enough to reverse the expansion!  Indeed, I am a bit doubtful and would put a burden of proof on those contending that type-1a supernovae were different in the early universe.  Still… how cool to live in such times!  

(Unless that very coolness is a clue?  See my short story “Reality Check.”)

Oh but stay tuned for the next shaker!  That type 1a supernovas might be influenced/altered by... dark matter!

= Another "universal rule" of the cosmos revived? =

The Titius-Bode law was formulated around 1770 and correctly calculated the position of Uranus before it was even discovered. Under this rule-of-thumb, the ratio between the orbital period of the first and second planet is the same as the ratio between the second and the third planet and so on. Now a group of Australians and Danes claim that “We decided to use this method to calculate the potential planetary positions in 151 planetary systems, where the Kepler satellite had found between 3 and 6 planets. In 124 of the planetary systems, the Titius-Bode law fit with the position of the planets as good as or better than our own solar system.”

If this is true, then the T-B law is resurrected from the dead, because I knew of very few  astronomers who gave it credence, deeming it quasi-mystical.  In fact, if these ratios hold up (and I’ll want to see it verified) it would  rank as among the most important discoveries of the Kepler mission or, indeed, planetary science.  Moreover: “Using T-B’s law we tried to predict where there could be more planets further out in the planetary systems.”

Mind you, this flies in the face of a major Kepler discovery, that a vast fraction of planetary systems hug closer to their star that the orbit of Mercury, including massive Jovian gas giants.  Many planetologists hold that this indicates systems that shift orbits considerably, especially in their early epochs. A result that cannot be consistent with the authors’ claims of a powerful Titus-Bode resonance. At least, it’s hard to reconcile.

My, what times.  Oh, but there's more!

== The cosmos is a lonely place ==

A new study indicates that alien super civilizations are absent from 100,000 nearby galaxies: Lee Billings — now astro-editor at Scientific American — explores the implications of a recent search for Kardashev level-3 civilizations. An important part of possibility space! (So to speak.) And also quoting me. Here’s the salon version: The universe is a lonely place.

And see the original paper. Griffith, White, Maldonado et. al  sampled 10,000+ galaxies for the kind of infrared excess that might indicate Kardashev Type III civilization, which might tap all of the energy output of a galaxy. None of their sampled galaxies showed signs that a vastly powerful society is utilizing more than 85% of their stellar output and re-emitting the energy as waste heat. 

If you think about it, that is both a big result and not surprising. If there are no Kardashev Type III civs, that still leaves it possible for perhaps many type K 2.5 societies… that have surrounded "only" a billion of their galaxy's hundred billion stars with Dyson spheres (as I kind of depict in Heaven's Reach.) This paper leaves that Partial-Kardashev level still quite possible.

“If Hart’s reasoning is sound, then we should expect that, unless intelligent, spacefaring life is unique to Earth in the local universe, other galaxies should have galaxy-spanning supercivilizations, and a search for K3’s may be fruitful. If there is a flaw in it, then intelligent, spacefaring life may be endemic to the Milky Way in the form of many K2’s, in which case a search within the Milky Way would be more likely to succeed. It is prudent, therefore,
to pursue both routes.”

Hm... we've only just begun exploring the possibilities.  This result is -- as I said -- both huge... and unsurprising.  And the plethora of remaining possibilities....

== Messaging the cosmos ==

Regarding "Messaging ExtraTerrestrial Intelligences,"  Doug Vakoch – in a short paper for the Astrobiology Science Conference in Chicago -- has added another pro-METI argument:  "Economic Exchange:  An alternative rationale for  conducting an Active SETI project calls into question  the assumption that ETI is altruistically transmitting  signals for our benefit, without requiring anything of us  in advance. However, perhaps interstellar communication is a sort of economic  exchange, in which civilizations share valuable information with one another in a  multigenerational form of reciprocal altruism [3 ] . We  see examples of reciprocal altruism in a variety of species on Earth, and such behavior can be modeled with  game theory, for example, with the Tit for Tat scenario.  But in every case of reciprocal altruism, one party needs to take the initiative ; someone needs to make the  first gesture of generosity."
How utterly bizarre! 
By raising my own argument -- that quid-pro-quo is more common in nature than altruism -- he drops out the most important implication! That our culture/music/art/ and other products of human creativity are our trade goods, of great value. His own assertion makes his ally, Seth Shostak -- who wants to beam "the whole internet" into space -- a would-be traitor to humanity, for aiming to impoverish our kids, by giving away all our trade goods, for free!
In any event quid-pro-quo is NOT the same thing as "reciprocal altruism." The later is more rare and requires extensive reasons for trust, that will not be present at the beginning.
Here's the crux for my friend Doug, "someone needs to make the first gesture of generosity" begs the question of why he assumes the party who has the least information or situational awareness has to be the initiator!  Carl Sagan said that the elder races should "do the heavy lifting."  Nothing about that sage advice has changed.

Mind you, the list of talks and topics at the Chicago Astrobiology Science Conference (coming in June) is simply stunning in its breadth and depth and sheer numbers of researchers engaged in a field that was once a small, side niche topic.  Attend if you can!

== Traveling the cosmos? ==

And...  Okay, SMBC does it again!  Only he left out a major clue to this being a simulation.  A Speed Limit that prevents the test subjects from going and inspecting the crude “stars” and “planets” out there!   Of course, to see this concept explored in much more depth, see “Stones of Significance.”  

Spaceward Ho! Brian McConnell and Alexander Tolley lay down their argument for “spacecoach” interplanetary ships that usewater for life, for shielding and as propellant.  

Roger Shawyer, the British scientist who invented the highly controversial electromagnetic space propulsion technology called EmDrive, claims that NASA Johnson Space Center’s Eagleworks lab has verified his propellant-free, microwave-based propulsion system in hard vacuum.  

As for the em-drive, I am intrigued, of course.  As you know, I am on the board of external advisers for NASA's Innovative and Advanced Concepts group (NIAC), and I have an open mind.  I have, for example, never believed there was an inherent conflict with conservation of momentum.

On the other hand, look at the quality of journalism in the linked article and indeed, the articles to which it links.  If this is true, we won't be getting anything definitive from such sources. It'll take a little while. 

As for talk of increasing power by FIVE orders of magnitude? Well, that'd certainly nail it!  Moreover, the key thing is that Shawyer seems to be getting all the funding -- and competition -- that he needs.  Given that, I am happy to sit back and wait. 

Can the Earth be conscious?  A question I explored from several angles, in my novel, EARTH.  This essay ponders it seriously. "So, even without asking if planets are literally alive, we still can ask meaningful questions about life and planets "co-evolving." We can see it makes real scientific sense to understand life as more than just some green scruff forming on a planet's surface. Thus, even if biospheres don't control planets, they can still play huge roles in how those planets change in time."  And... "This is a particularly important point to consider as we enter the so-called Anthropocene, an era when humans become the dominant force on the Earth's systems."


Recent one-dimensional (globally averaged) climate model calculations by Goldblatt etal. (2013) suggest that increased atmospheric COcould conceivably trigger a runaway greenhouse on present Earth if COcon- centrations were approximately 100 times higher than they are today. The new prediction runs contrary to previous calculations by Kasting and Ackerman (1986), which indicated that COincreases could not trigger a runaway, even at Venus-like COconcentrations.  Prof. James Kasting and his former student Ramses Ramirez suggest that such a runaway to Venus-like conditions is unlikely in the near term.  But all members of this community agree that we should still be far more prudent about the climate. 

And finally... Re: climate change and the GOP, this comic says it all... 

Seriously.  Morons.  Waging outright war on science and every other field of human sagacity.  If you are conservative or libertarian, this rises above all other considerations.  If you are even remotely thinking of voting for the obscenity that has taken over the Republican Party, then you are at very best an utter fool.   This is not "left versus  right."

It is normal (with bits of foolishness and corruption... versus stark jibbering insane.

Moreover, deep down, you know it.


raito said...

Going completely off topic here:

On the bullying front, it looks like everyone is right!

Dr. Brin is right that it's decreased.

And everyone else is right that there's still too much of it.

22%? More than 1 in 5? (about what I observe informally)

DVGill said...

I have been following the EM drive stories with great interest. This article

does a good job of summary and clarification of the so-called null test results experimenters observed when they removed the "slots" that the inventor of the Cannae drive variant claimed were critical to its functioning.

A second article by Benjamin Solomon appeared recently in Huffington Post:

Solomon claims that understanding the experimental results requires a new physics involving subspace, which perked up my Trekker ears. I wonder if Dr. Brin could inform us if the work of Mr. Solomon can be taken seriously, since the mathematics are beyond me.

TCB said...

Re: the 'spacecoach' idea, I pitched the same basic idea in a letter published in the August 2006 issue of Discover Magazine. (Their paper is from 2010). My term was 'honeypot ant' spacecraft, because it resembles the abdomen of one of these insects. Here's a copypaste of that letter:

M.G. Lord’s June cover article [“Impossible
Journey?”] lists a way to shield space crews from
cosmic rays– surround them with five feet of
water– but Earth water isn’t practical. I
informally submitted a better source to the NASA
Institute for Advanced Concepts this past
February. Briefly: solar-powered robotic bases on
Ceres dig out water ice. Mass drivers launch it
slowly but cheaply to other parts of the Solar
system. Arriving near Earth, this ice can supply
water, tritium, hydrogen, oxygen, etc. One use:
what I call ‘honeypot ant’ spaceships. The ship
is basically a very big balloon made of carbon
nanofiber, spun for gravity, with water inside,
and air inside that. Crew live in the central air
bubble. Water is simultaneously shielding, fuel,
and hydroponics/life support; most of the ship’s
mass is Cerean water; Earth supplies the crew,
the ship’s skin, engines, etc. Ceres’ surface
gravity is about 1/36th Earth gravity, and it’s
just close enough for the Sun to power the
machinery. Cerean water may unlock the Solar

[Tom Buckner]

The magazine changed the spelling to 'Cererian', which is apparently the preferred word.

The idea here, which is probably not much different from theirs (being rather obvious and all!) is that the outer envelope need be only a tiny amount of the total mass, if it's strong enough. Since the craft is spinning for gravity, the water is held against the envelope while the air is in the center, even if there were no other internal structure. For more shielding, just build bigger and keep taking on water. Size is good, anyway, from a life-support standpoint, because larger ecosystems tend to be more stable. Make it big enough and it just about runs itself.

In most respects this is merely an O'Neill colony reimagined as using water instead of rock shielding.

TCB said...

Actually, I also pitched it here in 2010...

Alex Tolley said...

@TCB - If you have a URL for your article I would like to read it, should it be useful as a reference for future articles. Brian and I wrote our JBIS article in 2009 and it was published in early 2010. We are having a technical monograph published by Springer this year. You can find details here. Brian just did his talk at the ISDC and his slides are available at the spacecoach site.

TCB said...

Alex, I never did a more detailed write-up. Just that letter to Discover, so what you see above is all you'll find anywhere... I figured this was one of those ideas that was bound to occur to somebody with more engineering expertise (I have NONE! Pure layman, but I like to watch the trends), and the necessary materials are still in development. Specifically, I'd wager that the best material for the outer envelope is a fairly simple balloon of graphene or a composite thereof, and massive graphene manufacture is on the cusp of real viability as in this article:

Room-temperature fabrication, large sheets, cheaper all the time... just what the doctor ordered.

The way I picture spacecraft of this type is that you could essentially send a bare minimum of mass to Ceres: some robotic mining or drilling gear to get at the water is an essential; solar panels for power is another essential; but once this extraction infrastructure is in place, the spacecraft themselves could start as little more than engines strapped to vast empty bladders, to be filled at Ceres and then moved if desired to other locations such L5 in the Earth/Moon system, depending on what's convenient (in terms of time from Earth to the unfinished craft, and in terms of getting people and equipment there cheaply).

As a shabby but visually helpful example, consider the Red Bull Stratos balloon which Felix Baumgartner used for his record-setting parachute jump a couple of years ago.

From the Wired article:

"The balloon stands 55 stories tall and weighs 3,708 pounds out of the box. It was constructed from strips of polyethelene that would cover 40 acres if laid out over a field. The balloon will measure 334 feet tall and 424 feet in diameter when Baumgartner reaches peak altitude."

Now, I don't know if you could enclose a comparable volume of water and air at one atmosphere in a graphene-composite envelope and have it retain its integrity in hard vacuum, all while having a tare weight of a mere couple of tons... but the idea doesn't seem totally crazy to me (especially if you build a double envelope with the outer layer of water frozen after filling! We can expect the outer layer to freeze anyway, due to heat loss to space, I suspect.) So, whatever the empty shell weighs, it's likely well within what we could manage to lift even today, and have it gain 99+% of its mass out at Ceres. No people or expensive gear on board at all until it's back here close by Earth.

If the concept is any good, ships a lot larger than that are technically trivial, at least structurally, later on.

Your calculator seems to assume launching the water from Earth to LEO. I think this is precisely the part that Ceres renders unnecessary; doubly so if you can also mine propellant there. You trade the great difficulty of keeping human crew alive on that outward trip, for the different but potentially lesser difficulty of sending out robotic mining gear sufficient to fill the early, comparatively small spacecraft. A drilling/pumping/ice melting rig sufficient to fill up a large office building needn't be very massive, it just takes longer to fill. This fill time is not such a dire concern if there are no people trying to stay alive at Ceres during this early phase. If this proves successful, expanding Cererian operations and spacecraft are synergetic, and sending humans there becomes much easier once you've got this system running.


TCB said...

Additional thoughts:

Yes, the delta-v from Earth to Ceres is why it's a very challenging destination. But:

You have all that water under what is described as a 'thin, dusty outer crust.' How thin, nobody seems to say. However, digging or drilling under 1/36th Earth gravity is probably not a great challenge, and one might get the job started by using an impactor, steering some other small rock into Ceres and then setting up operations in the crater.

Number one on the shopping list at this point is solar panels and lots of them. You need that energy to

1. Melt that ice from its local temperature of minus 40 (C or F, take your pick).

2. Pump much of it into the spacecraft envelope.

3. Pump some of it into a separate apparatus, electrolyze it into hydrogen and water, and store these separately as propellant.

Whatever the delta-v is, that's for the engineers to worry about: what matters is that solar panels will (just) work on Ceres; the asteroid belt is about as far as you can go and still say that. Get the infrastructure in place and working, and you have a supply of water, mass, and fuel that will not run out anytime soon.

TCB said...

I've now read the Spacecoach blog article: Yes, basically you've covered nearly every base with this design! The only point I don't agree with is, I think it really could be easier to start with an unmanned Ceres water mine and thus do an end-run on the launch weight of Earth water. Not saying I'm sure about this, but rather that it's worth comparative study, and that it lets you start with bigger ships by bringing most of the mass from a somewhat slower but ultimately cheaper source. It was the vast water supply on Ceres, plus the trivial energy cost of getting it out of that worlds shallow gravity well, which led me to the inflatable ship idea, whereas the Spacecoach plans apparently started with the ship concept and then proceeded to consider Ceres as a destination.

Anyway, thanks for your work, it's great stuff and on the right track!

Daniel Duffy said...

To colonize space we need the equivalent of tobacco.

Until the cultivation of tobacco, the Virginia colony was a money loser. The investors back in London had to get some return on their investment in Jamestown if America was ever to become a viable going concern. The cultivation of tobacco showed that New World colonies could be profitable, making America possible.

So what would be the space equivalent of tobacco?

Daniel Duffy said...

Screw planets.

The near term future of manned colonization of space is the asteroid belt. Instead of Mars, we should colonize Ceres in order to establish a logistical base for asteroid prospecting and mining. Ceres has no significant gravity well to overcome and lots of water for life and fuel.

Instead of Star Fleet starting human colonies on the surfaces of planets, we'll have the Weyland-Yutani Corporation contracting out the space equivalent of oil rig and crab fishing work - extremely dirty and dangerous work with a high death rate.

So forget about the bright, shiny and clean Enterprise, our future in space is the dirty, gritty and dangerous Nostromo (face huggers optional).

Tony Fisk said...

DB: Mind you, this flies in the face of a major Kepler discovery, that a vast fraction of planetary systems hug closer to their star that the orbit of Mercury, including massive Jovian gas giants. Many planetologists hold that this indicates systems that shift orbits considerably, especially in their early epochs. A result that cannot be consistent with the authors’ claims of a powerful Titus-Bode resonance. At least, it’s hard to reconcile.

A few unsubstantiated thoughts and speculations:

My understanding of early planetary formation is that the large masses of proto-planets are slowed down by the material in the disc, and so fall inward toward the primary. This ceases when the primary ignites and blows the dust away. Without looking at any papers on the topic (I presume there are a few) I would imagine that smaller primaries would take longer to go stellar, which would mean the planets would have fallen in further. Since smaller stars are far more common, this would explain the preponderance of hot Jupiters (other than Kepler's method of detection being biased toward large, close planets with a higher chance of occultation)

As to the T-B law, I had imagined that it would come down to resonance forcing between Jupiter and its pipsqueak siblings. If there *were* such a binding, it may well be maintained as the Jupiter of the system drifted inward, dragging the others with it, and would increase in strength as distances reduced.

Hmm! Does T-B hold for moons of Saturn? (The realm of the Titan) I might look into that.

As for the Jihad between the Churches of Tipler Crunch and Dyson Bang, they do seem to keep oscillating toward the critical line. It would be ironic if Hoyle's Shrine of the Steady State were to be rebuilt.

Looking at models of matter distribution across the Cosmos, I am struck by the patterning of strands and voids. I've seen this pattern before, in the foam of a breaking wave, or bubbles in a simmering saucepan. Could there be some series of 'upwellings' that pushes matter aside?

TCB said...

On the Tipler subject, I read Physics of Immortality in the 1990's, a couple of years after its 1994 publication. I found it intriguing in many ways, and who doesn't like the sound of being resurrected by benevolent machines for an infinite picnic? Alas, in 1998 Alan Guth's inflationary theory gained enough evidence to knock Tipler's easeful fantasia into a cocked hat. Oh well.

Nevertheless, despite the destruction of his central theme, Tipler's book is not without value. He offers hundreds of pages of philosophically eye-opening observations on the possibility of mathematical reality as reality, on existence as information, on the logical possibility that this really has all happened before and there are copies of us, and so on. From his book I first encountered such ideas as the Bekenstein bound and Kolmogorov complexity. Much of my current thinking is rooted in what I read there, so that when (a few years later) I encountered thinkers such as Nick Bostrom and Max Tegmark, I was easily able to see that they knew what they were talking about, and that their 'wilder' ideas were actually likely to be true.

So, yes to Frank Tipler, and his flawed but still valuable gift. For all that it promised and couldn't deliver, yet I am grateful.

Paul SB said...

Tony, your comment here gave me a (rather trivial) idea.

"As for the Jihad between the Churches of Tipler Crunch and Dyson Bang, they do seem to keep oscillating toward the critical line. It would be ironic if Hoyle's Shrine of the Steady State were to be rebuilt."

The other thing Fred Hoyle was famous for was his brick-thick bible of card games. Maybe for a summer project I'll try to make a card game in which players try to balance forces within their own universes to create a steady state. Come to think of it, that would probably require a lot more knowledge of physics than I could research in a summer that is crowded with other objectives. :{ This is what comes of typing before thinking...

Alex Tolley said...

-@Daniel Duffy To colonize space we need the equivalent of tobacco.

Although it doesn't require colonization, monetary metals like gold will work. That is what the Spanish wanted. After Jamestown there was demand for furs and pelts, like beaver.

So I would rephrase your question as
"What is valuable on earth that can be found or made in space?"

At this moment nothing. Extra-terrestrial experiences are a possibility, which drives space tourism. (Tourism was unknown in the 1600's).
The answer a decade or two ago was platinum group metals. This is still somewhat true today, although less and less so as the primary growth use as a catalyst is becoming less important due to better use of materials.
The fusion advocates want He3 from the moon, but this is totally unproven.
The 1880's idea that zero g would allow manufacture of hard to grow crystals did not pan out.

IMO, IF space tourism takes off at all, then the most valuable material in space will be plain water. If it is cheaper to mine it in space, rather than haul it up from Earth, this will be a driver of a robust extractive industry. Colonization, not so much.

So we are left with the only remaining driver that I can think of, the desire to establish a home away from everyone else. Whether for religion, politics or some other idea, that may be the only reason to go. If so, it had better be fairly inexpensive to migrate and stay alive at the destination.

Alex Tolley said...

@Daniel Duffy : "Instead of Star Fleet starting human colonies on the surfaces of planets, we'll have the Weyland-Yutani Corporation contracting out the space equivalent of oil rig and crab fishing work - extremely dirty and dangerous work with a high death rate."

Yes and no. The oil rig analogy fits well, if we are living as late as the early 21st century. But in space, machines will do the bulk of the work. I can see that people may need to be nearby to offer near real-time brains to help, so maybe they will live in gritty habs. But no "Outland" style working with drills at the rock face in a space suit. Embodied AI will also reduce the demand for "on-site" human intelligence.

Economics will increasingly favor machines over humans. A Ceres water mine will likely be almost totally automated should it be needed.

Alex Tolley said...

In the longer term Brian and I think that Ceres will be the Saudi Arabia of the inner solar system. However, in the short term, the aim is to get a working demonstration spacecoach. This means as much off-the-shelf components as possible, to reduce R&D delays. Therefore it is easier to just throw water to LEO with the cheapest dumb launcher available, most likely a SpaceX F9R or F9H.
For the hull, a modified Bigelow inflatable hab seems the best choice. The water can be stored in bags attached to the inside of the hull, rather than between the hull walls as we would prefer. Artificial gravity would be dropped for the initial tests. (To create artificial gravity that is tolerable, you need a large radius to rotate around, so the water cannot be stored where the g's are high due to the generated forces. Better to keep the water at the rotation axis as far as possible and have the crew stay there as much as possible. Alternatively, have a carousel rotating inside a stationary hull, like the Discovery in "2001: A Space Odyssey". But in that case, Coriolis forces would be uncomfortable and the astronauts would need to move as little as possible and certainly not jog around the carousel as Frank Poole does in the classic sequence.

Lot's of design ideas for people to consider to make this a viable approach. My sense is that the engines are the most uncertain component, but I could be wrong.

Tacitus2 said...

I enjoyed this posting, although I had actually read about several of these recent thoughts on "right leaning" sites already.
I do wish you could simply have a post on science without the egregious ending. Seriously, does calling people morons or at best an utter fool really help persuade anyone?
Its your site, do as you will but the quality of discourse is not what I would consider top notch.

David Brin said...

Tony F… nice planet-formation theory.

TCB wow… I deem Tipler’s book to be up there with Das Kapital as among the greatest of all sci fi tales that sure seemed plausible at the time. In any event, wow on you for reading that thing! I may not have the biggest blogmunity… but it sure is one of the smartest.

And overall politest. I am still bemused and puzzled by the almost complete absence of trolls here, for more than a decade. I truly would of thought my personality would attract them. Not that I’m complaining!

Tacitus, my wife this morning offered me the very same chide. I will try. OTOH it is important to make clear to the mad right that liberals (not leftists) are getting fed up. The right’s expectation is they can do or say anything, hurl any calumny and commit any treason, and then get liberals to back off any heated response by accusing them of discourtesy. It has stopped working with me. And watch. It will stop with more and more people.

Tacitus2 said...

I am unaccustomed to such high level support.

Daniel Duffy said...


The only thing I can think of that "is valuable on earth that can be found or made in space" is energy. And it can all be done with mirrors.

The biggest draw back of solar power satellites (SPS) is the cost of hauling up those huge collectors, arrays, antennae, etc. from Earth's gravity well. But what if we mined asteroids for the materials needed to make the huge lenses and mirrors described here:

"Large lensing structures may not be something of the far future. There was a 2007 NASA NIAC study for making large bubbles in space. Devon Crowe of PSI corporation made a study for making large space structures from bubbles that are made rigid using metals or UV curing. A single bubble can be 1 meter in earth gravity, 100 kilometer in low earth orbit or 1000 kilometers in deep space. Foams made of many bubbles could be far larger in size. The size of a 1000 kilometer bubble is nearly the size of Charon, the moon of Pluto. Charon is 1200 kilometers in diameter. Saturn's moon Tethys is 1050-1080 kilometers in diameter Ceres the largest object in the asteroid belt is 970 kilometers in diameter. A single tesselation foam (like in the picture) of 1000 kilometer bubbles would be about the size of Earth's moon. A Penrose tesselation like the one in the picture of 1000 kilometer bubbles would be in between the size of Neptune or Saturn. A Tesselation foam of 100 kilometer bubbles in earth orbit could form an object the size our existing moon or larger."

Once these mirrors are in place near Earth orbit they can concentrate sunlight on orbiting Stirling engines of PVC arrays that beam down microwave energy to Earth. This could supply a near infinite amount of energy at a fraction of the cost of typical SPS proposals.

As the article goes on to say, these mirrors could be use for "brute force" terraforming of even icy worlds beyond Jupiter or provide the energy needed to propel a laser sail starship. Used as reflectors, they could cool down Venus or even Mercury. With large enough foam mirrors and lenses cheaply made in zero gravity and we make the jump to a Kardeshev I civilization.

Water from Ceres and mirrors made from other asteroids and the Solar System is ours.

Alex Tolley said...

@Daniel - SPS is definitely a good solution for energy needs. I read "The case for Space Solar Power" by Mankins which makes a very good case that this is more affordable than we think. I see it as first being used for high cost power in space, rather than Earth, but clearly the future is with some form of SPS as the potential to expand our energy needs is so scalable and vast.
I also think that beamed power for spacecraft, whether electric or sail would be a good way to explore the solar system (as well as deflect asteroids), the power for which is best generated in space.

But to get back to your original question, what if Europeans didn't like tobacco? The equivalent for SPS is what if we abandon our drive to explore space, removing the need to start SPS development, leaving a large scale, SPS power future stillborn?

Laurent Weppe said...

* "The right’s expectation is they can do or say anything, hurl any calumny and commit any treason, and then get liberals to back off any heated response by accusing them of discourtesy."

The problem isn't being discourteous. The problem is that by hurling accusations that the other side is moronic, it becomes increasingly tempting to join the Plato/Shang Yang/Ayn Rand/Leo Strauss/Bill Maher school of thought and to proclaim "The rubes are moronic bidepal cattle to be beaten into submission and/or manipulated through pretty "noble" lies by the Philosopher Kings", which is the perfect way to rationalize supporting the reemergence of parasitic feudal rule by the "Brights"' spoiled children.

sgs said...

What's the next step for a civilization that has enclosed its star with a Dyson sphere? As it needs more and more energy, it can lower the temperature of its external radiation, down to just above the 3K of the cosmic background radiation. This would be effectively impossible to detect at galactic distances. All you'd be able to detect would be its gravity. Dark matter anybody?

And how about the next stage? "Zero point" energy is effectively unlimited and not connected to a star. But it's that energy that holds space itself together. Use too much of it and space becomes less "elastic" and it expands faster. Sounds like dark energy.

It's a cute hypothesis, but I don't have the foggiest idea how one would test or falsify it.

David Brin said...

sgs.... try reading Heaven's Reach. It's got ALL of that! And much more.

Daniel Duffy said...


If half of all stars are now in the space between galaxies, and if the space between stars is full of brown dwarfs and rogue planets...

.... is the problem of missing matter solved?

TCB said...

@ Alex Tolley - You write:

>(To create artificial gravity that is tolerable, you need a large radius to rotate around, so the water cannot be stored where the g's are high due to the generated forces. Better to keep the water at the rotation axis as far as possible and have the crew stay there as much as possible. Alternatively, have a carousel rotating inside a stationary hull, like the Discovery in "2001: A Space Odyssey". But in that case, Coriolis forces would be uncomfortable and the astronauts would need to move as little as possible and certainly not jog around the carousel as Frank Poole does in the classic sequence.

Holy frijoles, I see your point. My original notion may founder on that (depending, very much, on material strenght and scale). I recall that in The High Frontier (which, back in the day, I tried in vain to get everyone to read! but I digress), Gerard K. O'Neill wrote that a spun habitat needed to be at least 500 meters for Coriolis forces to be manageable for inhabitants. (The exact figure might have been more or less, but that's the ballpark). So, let's be extravagant and assume that the spun habitat is indeed 500m across the central air section and the water surrounding that is, say, ten meters more. The total cross section of that hypothetical habitat is 520 meters, and if we have Earth-normal gravity at the water surface, it must be greater at the outermost point (i.e. where the water is deepest). Gravity/water pressure must grow at a much faster rate than it does on Earth, so the depth/thickness of water definitely will have limits to be determined by the strength of the envelope. Fifty meters of water might be nice, but perhaps no material we can ever make will hold it.

Still, there are workarounds that might pan out. Examples: smaller spun pods at the end of tethers; spinning the habitat at less than 1 Earth gravity; stronger materials than are now available. I've continued thinking in terms of large-scale graphene fabric being available not so far in the future; it takes years to get even middling-sized space missions off the board and into orbit, while materials technology surges at an indecent rate. Good surprises may lie ahead on that front.

But, bottom line, you've convinced me. Ceres will probably need to wait a little.

@David Brin - Thanks, you're kind. But you know what? Good hosts attract good guests, eh?

Alex Tolley said...

@TCM - you may recall that the Stanford Torus design for a colony ended up around 2 km in diameter to get rid of most coriolis forces. The regolith shielding was then left non-rotating outside the spinning torus.

Having craft at the end of tethers has often been advocated to generate artificial g forces, but so far never done. There are all sorts of safety issues in the event of a tether break. If one does have a craft at the end of a tether, perhaps the safest approach is to have the craft "sit" on a some sort of plate or container with is attached to the tethers to handle the loads. Adding mass with water can be done, but it should be obvious what that means on the tether loading.

IFAIK. Nasa has done almost anything to avoid designing vehicles with artificial g, and tried mitigation instead with various approaches. So they end up with all sorts of expensive devices that are designed to work in zero g, rather than generate the forces and use more off the shelf appliances and tools instead.

Carbon nanotube might well be the best material to create the tethers for spacecraft spinning around a CoG. However other materials are available that should work.

BTW, graphene fabric is looking like a very good material for desalination of seawater. It reduces energy requirement making it more economic. California could well do with more such water recycling and desalination plants. Given the huge amount of the state's water used in ag, we need to find a good way to reduce ag demand and effectively recycle ag water we do use. We certainly have a lot of free sunshine to power this recycling.

Alex Tolley said...

Final thought on tethers and artificial g. If tethers are given a current, they will move in Earth's magnetic field. This can increase or decrease orbital velocity and thereby raise or lower an orbit. This effect was used in DB's story "Tank farm Dynamo". But suppose that the current is fed into the middle of a tether and flows to each end instead. This will create a torque around the center of mass, spinning the tether. For a spacecraft that is 2 modules connected by a tether, this would allow a slow spin up without using fuel. The craft could therefore be given artificial gravity simply by supplying power. And of course, could generate electrical energy by being allowed to spin down.

Not just for crewed ships, but this spinning could be used for tethers to launch payloads, using solar energy to maintain spin and orbital altitude. Jupiter;s magnetic field might make this a good place to launch payloads to earth, assuming there is something valuable to launch.

TCB said...

I DEFINITELY did not know the regolith shielding on the Stanford torus was separate and non-rotating. I throw myself on the mercy of the court as it's been 25 years since I read O'Neill. Leaving all that mass non-rotating reduces, by a huge amount I'm sure, the centrifugal stress on the whole structure.

Incidentally, as of 1976 O'Neill estimated the cost of a space colony of that type in the range of 80 or 100 billion dollars, which seemed like an, ahem, astronomical sum...

But nowadays? Even accounting for inflation, it seems to me we could pay for a Stanford torus or similar just by resisting the urge to start any new wars...

David Brin said...

ELEVATED level of conversation here! ;-) (get it?)

My pal Joe Carroll has been working on exactly that, tethered rotating stations that emulate three levels of artificial or partial g.

Paul451 said...

Alex Tolley,
"But in that case, Coriolis forces would be uncomfortable and the astronauts would need to move as little as possible and certainly not jog around the carousel as Frank Poole does in the classic sequence."

Pete Conrad on Skylab.

Fear of coriolis has been exaggerated. More recent work suggests humans can tolerate up to 10RPM in comfort. Pete there was doing about 6RPM without noticing, while doing somersaults. (And "moving as little as possible" is why early coriolis experiments showed issues, the trick is to move as much as possible while adapting.) O'Neill was being deliberately conservative, but his assumption of 1RPM has become some kind of sacred tenet amongst space geeks.

And it's important because at a given centripetal acceleration, radius varies with the square of rotational period. So doubling the RPM will quarter the required radius, ten RPM means one percent of the radius as a 1RPM structure.

(For example, at 1RPM a structure needs to be 1.8km across. At 10RPM, just 18m. That's within the diameter of Bigelow's largest inflatable module. It's the difference between something from SF that no-one would consider, and something we can do today. Hell, you can achieve a full G at 8RPM by sticking two Bigelow's BA-330 together with a central docking node like Unity/Harmony. No tether required, just the simple length of the hard docked modules themselves. With space for floors at partial gravity levels for experiments. Or even a single BA-330, plus the central docking node, if you use the spent second stage as a counter-weight. A 20m tether between the modules and the spent stage and you can get it down to 4RPM at half a G.)

Paul451 said...

Looks like Lightsail is borked again.

(Solar sails really are cursed. I call aliens. This is clearly the forbidden technology which violates the terms of our quarantine.)

Alex Tolley said...

@Paukl451 " More recent work suggests humans can tolerate up to 10RPM in comfort. "

Conrad spinning in Skylab doesn't tell us much. The low rpm rate tolerable was based on Earth simulations for ordinary test subjects. Test pilots can tolerate 10 g's for short periods of time, but I couldn't. That is why the space shuttle only generated maximum 3 g's. There is also a difference in tolerating the coriolis forces and being able to comfortably work in such an environment. But humans are adaptable, and we do tend to to assume the worst (like heart bursting in zero-g before Gagarin's flight proved that wrong).

It would be good if it turns out that humans can adapt to faster rotations in space, but there is little evidence to support it, apart from some Earth simulations.

You might like these blog postings that discuss the issue and also talk about the aforementioned Joe Carroll proposed experiment. (We really should do the experiment).

This link to a book suggests that you may be correct about the conservative estimate for comfortable RPM tolerance:

Here is a paper that shows adaptation to fast RPM. But note the experiment still needs to be done in space.

Alex Tolley said...

Looks like Lightsail is deploying sail - the boom motors are working. Let's hope the sail deploys on this orbit.

Alex Tolley said...

Jason Davis' latest blog post on LightSail-1.
Looks like we will know if the deployment was successful by Monday morning. There should be pictures too.

No word on the issue of tumbling, but it cannot be too serious if telemetry is working.

Paul SB said...

Daniel suggested:
If half of all stars are now in the space between galaxies, and if the space between stars is full of brown dwarfs and rogue planets...

.... is the problem of missing matter solved?

How about black dwarves? (Is it /dwarfs/ or /dwarves/? I've seen both...) I always wondered, given how nearly undetectable these things are, if a plethora of these could explain a lot of the missing matter. Another physics question: wouldn't gravitational sorting affect the structures of galaxies, sorting the various types of stellar remnants into layers, much like the three types of asteroids in the main belt?

And for a completely different question, has anyone caught "Tomorrowland?"

Robert said...

Here's an amusing bit from the New York Times concerning Greenpeace. While the organization has done some pretty idiotic things in the past... this newest one? I have to tip my hat to them for a rather innovative (and high-tech!) method of getting their message across:

Activists have had a hard time sending their message to the G-7 leaders, who are tucked away in a secluded Alpine valley guarded by thousands of police.

So Greenpeace decided Monday to project its demands onto a nearby mountain.

The environmental group used green lasers to beam the words "G-7: Go for 100 percent renewables" onto the side of the Zugspitze, Germany's highest peak.

Greenpeace climate policy chief Martin Kaiser said he hopes German Chancellor Angela Merkel will manage to convince climate holdouts such as Japan's Shinzo Abe to drastically cut down on carbon emissions in the coming decades.

Rob H.

David Brin said...

Cool green laser bit!


Alex Tolley said...

Image of the Greenpeace laser projection: