Sunday, November 30, 2014

Space Marvels - galaxies, space-power, "my" asteroid... and comets...

One of the best things I have ever watched: Invest four minutes for the video clip Wanderers! This -- rather than anger and cynicism -- is what being human must be about...or else, why bother?

Oh, also note: almost all of the places depicted here are real. Many of them extrapolated from photos taken already by our robot emissaries. “We” have already been to these wondrous spots. We are already titans!  On our way to unimaginable greatness.

(Though I will keep trying to imagine.)

== As we move ahead... ==

Could life exist in the Kracken Mare Sea on Titan?  I am working on stories… but right now I am simply jazzed by this image… sunlight glinting off one of Titan’s “seas” of liquid… methane? Ethane? Gasoline?  Take a look at the video: NASA's Cassini captures sunlight glinting off Titan's seas.

You are a member of a civilization that does stuff like this!  Stop letting cynics and fear-mongers undermine your confidence in us.

NASA's New Horizons spacecraft comes out of hibernation on December 6 -- in preparation for an encounter with the dwarf planet Pluto. Closest approach will take place in July. 

NASA/JPL have just released a gorgeous new high-resolution image of Europa -- its icy surface crisscrossed by cracks and ridges. Beneath its icy surface, Europa may have more liquid water than Earth. In NASA's video: Europa: Ocean World, astrobiologist Kevin Hand discusses the possibility of life on Europa. Phil Plait’s “Bad astronomy” site offers a cool riff about a possible mission to Europa. 

It is estimated that Europe’s new Gaia probe will have discovered some 20,000 Jupiter mass exoplanets by the time it completes its survey in 2019. Unlike the transit-eclipse system used by the Kepler mission to discover most of the 2000 or so confirmed exoplanets, Gaia will use the astrometric measurement technique, where planets around another star show up as a tiny wobbling motion of the star as the planet orbits around it. Somewhat less likely to discover Earthlike smaller worlds, Gaia will be far less dependent on just happening to find systems whose ecliptics are lined up toward us.  It will also be far better at detecting planets that orbit farther from their star.

Here’s a fascinating astronomy blog that takes on some big topics. This particular posting tells of Antarctic lichens that seem to have adapted well to  Mars-like conditions.... amazing in its tentative implications.

== New Insights into Galaxies ==

Scientists believe a mysteriously bright object in a galaxy 90 million light-years away could be a rogue black hole evicted during the merger of two galaxies.

A really thought provoking paper suggests that of the estimated 100 billion galaxies in the observable universe, only one in 10 can support complex life like that on Earth. The reason, most other galaxies are either smaller or lower in “metalicity” and therefore have many more Gamma Ray Burst events that can destroy the ozone layers of life-worlds for thousands of parsecs in all directions, conceivably knocking down all but the most primitive, ocean dwelling organisms, making galaxies resemble the image Isaac Asimov portrayed in his novels, one with scads of biospheres, owned only by single cell life forms.

Short gamma ray bursts last less than a second or two; they most likely occur when
 two neutron stars or black holes spiral into each other. Long gamma ray bursts come from supernovae.

Tsvi Piran, a theoretical astrophysicist at the Hebrew University of Jerusalem, and 
Raul Jimenez, a theoretical astrophysicist at the University of Barcelona in Spain, 
explore that apocalyptic scenario in a paper in press at Physical Review Letters.

Compared with the Milky Way, most galaxies are small and low in metallicity. As a
 result, 90% of them should have too many long gamma ray bursts to sustain life, 
they argue. What’s more, for about 5 billion years after the big bang, all galaxies were
 like that, so long gamma ray bursts would have made life impossible anywhere. And inward of 10,000 light years from the center, our galaxy is still dangerous.

Researchers sending up NASA’s Cosmic Infrared Background Experiment on short duration rockets  have discovered something remarkable in the universe's diffuse background light: As many as half of the stars in the universe may have been stripped from their home galaxies and flung into space. Studying the extragalactic background light, Caltech astronomers  say there's just as much background starlight coming from these dim rogue stars as is coming from all of those giant galaxies.

== Reaching toward the sun ==

 A probe will be sent to visit the Sun.  I am interested - of course - in any human effort to … er… sun-dive.  Only there is an interesting design twist here.  Solar Orbiter will have a titanium foil heat shield on the outside painted black, with a hint of charred animal bone.

A very interesting exploration by Keith Henson of the economics and practical aspects of   lifting to GEO a solar power satellite system whose first use would be to laser heat the exhaust of Skylon lifters taking yet more solar power systems to GEO.  A bootstrap method that could (in theory) soon result in vast amounts of clean energy coming to us from the sun... via our collectors in space.

Some portions of this method have received preliminary seed grants from us at NASA NIAC. But many other sources will have to solve many puzzles along the way. It's good to have folks pushing this... while others push to make it unnecessary by vastly improving solar here on Earth.

== Comets and Asteroids ==

Given the results that have come in from the Rosetta Mission's rendezvous with a comet, I thought I'd offer you all a glimpse at my 1981 doctoral dissertation! It dealt with what happens when an icy mix of volatiles and grains gets heated from above. Naturally, some volatiles (e.g. water) sublimate and leave at high molecular velocities -- that get higher as the comet approaches the sun. Large dust grains may stay put but smaller ones get entrained into the escaping stream and become part of the Dust Tail. (Comets have two tails.)  

This means a mantle or coating layer of larger grains starts to build.  This will eventually be thick enough to shield the virgin material, slowing down the rate of sublimation.  Like a thermos coating. But the comet is heading sunward so the grains get hotter and a wave of heat penetrates inward, causing a delayed but large pulse of sublimation which will, here and there across the surface, cause an explosive blow off of the covering mantle, resulting in a surge of heavier grains in the dust tail and venting off pressure from an area.  Some of the heavier grains then rain down elsewhere on the comet surface, causing some areas to build such big layers that they choke off, semi permanently.  When this happens everywhere, the comet goes dormant and begins to resemble an asteroid.

Note that the one visited by Rosetta -- 67P/Churyumov–Gerasimenko -- is not a virgin but has gone through a number of perihelion brushes with the sun, so it's been baked a fair bit. Oh, if only the harpoon anchors had worked to dig the Philae lander onto a good vantage point! I fear that the little lander may not get enough sunlight to do much more science.  And even if it does, those gases shooting out of the mantle layer will likely blow the poor thing into space, before any of the real action starts.  At which point we'll still have the main Rosetta Orbiter...

... for which I am grateful! It's always nice to see your graduate work confirmed, At least superficially, it looks like I shoulda stayed in comet studies.  I was on a roll! Could have evaded the sci fi rat race....

== More personal news from outer space! ==

My own asteroid had its closest approach to Earth on November 18. Asteroid 5748 Davebrin passed within 1.256 AU for a summer that's actually pretty balmy and close.  So close that humanity might someday include it in efforts to access the fantastic riches out there.  May it be disassembled and turned into wonderful things! I just have two wishes. 

First, to share in the action! Hey, I got a claim.

Second? To go out there in person and kiss my...

...oh, never mind. ;-) May you ALL get your own space rocks.  

And each live for fifty more of its orbits.


Joanna Drzewieniecki said...

Thanks for your unflinching optimism and bringing fascinating science to my facebook full of political scientists and human rights activists. Love that you have a comet named after you. May it never meet an obstacle in its way!
I await your next story.
Best, Joanna (in Peru)

Tacitus2 said...

Wanderers indeed a thing of beauty. Darned Vimeo format sure loads sluggishly at least on my system.

The antarctic lichen link is an interesting thing to contemplate. Our biology is advancing so much faster than our warp drive research (I think!). It looks as if it would be possible to launch some spores and start terraforming. Just make them produce oxygen, something we can burn for heat, like cellulose, and something edible. I have in mind making them generate Hostess Twinkies, covers both the cellulose and the food.

Pretty much Manna as originally described, a fine powder in the harsh desert.

Oh, I get that we would need to make sure first that we were not wiping out indigenous exobiology, but the concept of a Mars Terraforming project that could be started in my lifetime is seductive...


Alex Tolley said...

If only 1:10 galaxies could ever have supported complex life, this is almost good news - it implies the "great filter" is behind us, not in front.

Lichens surviving in mars simulator. Nice to know that early speculations about lichen-like life on Mars were not so far off base. The experiment implies that lichen could be used as part of the approach to "green" Mars, should we wish to do so. If wild lichen can survive, this suggests interesting possibilities for engineered lichens. Is it the alga, the fungus or both that adapted?

Life on Titan. I would give very long odds of life on Titan. However as we discover more about the moon, it seems possible that life could survive in the "warm" icy layers below the surface, perhaps metabolizing hydrocarbons. Again, perhaps no native life, but possible to introduce engineered terrestrial microbes.

Alex Tolley said...

@Tacitus2 - I use DownloadHelper to download such video links and then view them off-line (VLC is my preferred viewer). It also means I can ensure I keep a copy of such excellent work in case the link breaks in the future.

Tony Fisk said...

I don't think it's enough to invalidate the conclusion, but there would be a slight bias, in our observation of galaxies a billion light years ago, toward seeing smaller, younger systems with lower metallicity.

If life on Titan could arise in an undersea ocean, how long would it take to leech out onto a surface somewhat less hostile than Europa's (whose cracked surface has a suspiciously mottled sheen of red)?

David Brin said...

working on a story. the wax beings on surface Titan have long been at war with the water-lava monsters from below. Humans land... beings whose blood flows with molten water! They assume we'll side with our "cousins."

"What... with THEM? More boring under-ice water creatures? We find em everywhere. Europa, Enceledus, Callisto, Ceres, Ganymede and a dozen more. But you wax guys are INTERESTING!"

Duncan Cairncross said...

Hi David

To go back to the previous thread on solar power

The panels are now $1/watt ($0.5 if you get them direct from China)

The inverters are still too expensive - a 5Kw inverter costs $5000
The "inverter" in my car is 75Kw and cost me $600
I know they are not the same but the solar inverter is still massively overpriced

Three years ago I paid $400/Kwhour
So a 20Kwhour battery which would be enough for going off grid would be $8,000

I am waiting for that nice Mr Musk to get his Gigabattery factory working so the prices come down

This whole area is changing really fast
Inside a couple of years it will be a total no brainer to have solar PV on your house

Paul451 said...

If half the stars in the universe were ejected from their galaxies, and 90% of galaxies are inhospitable to complex life (and the other 10% inhospitable during their first few billion years, and still hostile in parts), the majority of complex-life bearing planets will therefore exist outside of galaxies.

Paul Shen-Brown said...

Paul 451, if half the stars capable of supporting life are outside the galaxies, then we may have many situations akin to the planet Krikkit in Douglas Adams' Hitchhiker's Guide to the Galaxy. However, there may be some sort of bias in terms of what type of stars get ejected from galaxies, so not all types might be represented. If it is mostly little K and M dwarfs that get ejected, these hold a possibility for life. But if it turns out to be the enormous Type O and B stars, these are highly unlikely to harbor complex life. Just a thought ...

Jumper said...

Lichen grows slowly, doubtless more so on Mars. So the caribou herd would be small, confined and the robot lichen-gatherers' many.

Robert said...

Well. It seems the winds may be turning... A growing number of elder Republican statesmen are saying climate change is real. When you consider Reagan is the "grand old man" of the GOP and one that all but the most vehement consider the best Republican President around (the most vehement consider him and all other Republican Presidents RINOs), for Reagan's former Secretary of State to be going green is rather important.

The article even points out the recent cop-out, "I'm not a scientist," is actually a good sign in that it means they're backing away from claiming authority on the issue and may thus reverse course in the next few years.


A new material has been developed that could reflect infrared heat back into space... and adjust IR radiation into a wavelength that is not absorbed by the atmosphere. Dr. Brin has in the past talked about low-lying fruit including painting roofs white. This could go a step further as the material reduces cooling costs for buildings in warm environments while having heat "beamed" into space in a form that isn't easily absorbed by the atmosphere.

Of course, the problem lies with how effective this material is on a larger scale - they've not yet coated a roof with this thin film material. Nor does the article comment on how effective it is in environmental situations - how does acid rain affect it, for instance. Still, even if it is only viable in a "dinner plate" size, that could be used for a new type of shingle that could be placed on roofs to reduce heat absorption.


Finally, scientists have been researching methods of turning human waste material into rocket fuel. I will admit some amusement at how they claim the water is not fit for human consumption, seeing that current filtration systems can easily remove particulate matter, and some next-generation filters can even reduce water to a level very close to distilled, but that water could still be used for more than just oxygen generation in any event - long term habitation of the Moon or other environments would require growing food after all, and potable water can be used in that regard.

Rob H.

P.S. - That short movie with Carl Sagan speaking in the background? That sort of thing is needed. Yes, "Interstellar" is inspirational and "Gravity" might help remind people of the hazards of space and the human elements... but it is movies like "Wanderers" show how space can be fun. Seriously. Diving through the atmosphere of Titan? Walking across Europa and watching Jupiter above you? These things make people go "wow! I want to do that!" It makes ME want to go into space and enjoy myself up there, and I'm lazy! ;)

Recently my friend finished up writing the first draft of a book reviewing short horror films. There is a lot of that stuff out there. "Wanderers" makes me wonder: how much short science fiction is out there? Perhaps that's a genre my friend should look into next, once he gets his first e-book published. :)

Rob H.

Daniel Duffy said...

Not just only 1:10 galaxies capable of supporting life, but only a small fraction of our own galaxy as well (and only recently capable of doing so):

SteveO said...

Metallicity plays into an explanation I have been kicking around about the Great Silence...

Our sun might be of the first generation to actually have enough "metals" (in the astrophysical sense) to support life. We haven't heard anyone else because we (and all the others) are on about the same timeframe. Nearby life can't have been expanding for billions of years as posited in the Fermi Paradox - maybe a few millions or less...

On Titan's inhabitants...both my girls and I have been playing a game for years when we pretend to be aliens from Titan (or sometimes alien archeologists from the future). When we are Titans we are horrified at the lava raining down from the sky on Earth. Only slightly less horrifying are the nearly molten heated flecks of lava called "snow."

How could life as we know it even exist!?!?!

SteveO said...

Ha, didn't see Daniel's comment until just after I posted. Great minds....

Cosmist said...

Wow, Wanderers is a stunning video. It has that feeling of cosmic awe that you get from 2001, Apollo, Cosmos, or Arthur Clarke's best work. This is the kind of vision of a cosmic civilization we need right now, because the retrograde forces of religion, tribalism and general pessimism are immense, and there is a dire need for something potent to counteract them. How can visions of an "Islamic State" or a new feudalism compete with humans walking on Mars, the asteroids and the moons of Saturn? The question is, how can we get there? Or will our simulations get so good that we won't feel the need to try?

Duncan Cairncross said...

I still say the gamma ray bursters are being over egged as mass extinction creators

If a burst zaps everything on one hemisphere and changes a lot of high atmosphere chemicals to mop-up ozone
Then it would have little effect on the other hemisphere for a long time - weeks or months or longer
The fact that the earth has a long lasting ozone "hole" over the south pole shows that mixing at those altitudes is very slow

During which time the ozone depleting chemicals would be being depleted themselves by the continual creation of ozone

A much closer burst would be more serious but a burst giving 1/10,000 of the energy of the dinosaur killer would be nasty but not cause a mass extinction event

Paul451 said...

Re: Metallicity and the Great Filter¹

Even if Earth is part of the first generation of star systems to be able to form terrestrial planets, there's a lot of stars. Reduce the number of sufficiently "metallic" stars by 90%, that's still 20 billion. Reduce the number of Earth-like planets around those stars, and stars too short lived, etc, by another 90% and that's still 2 billion suitable stars. Reduce it by another 90% to avoid GRBs, and that's still 200 million stars.

And there's a lot of time. Judging by birds, some of the advanced dinosaurs were at the pre-sentient threshold before the big-kablooie. Without the big-kablooie, or at least without quite as big a kablooie, there was an extra 65 million years for them to take the path the primates later took. That 65m years is a long time to develop a space faring civilisation. And variation in planetary formation could easily gain hundreds of millions of years, even if it took 5-8 billion years to reach this point.

In other words, there still has to be another filter (or many filters) to reduce the numbers from millions or hundreds of millions more years and hundreds of millions of life-bearing planets down to "only now" and "only one".

¹ Latest in my new children's series.

Robert said...

Duncan, the reason the hole in the Northern and Southern poles (and yes, there has been a hole in the northern pole, though it has only appeared a couple of times and vanishes within half a year) is due to wind patterns. Antarctica is surrounded by oceans and the winds follow the currents. This has resulted in a concentration of ozone-destroying gases at the pole and intensified it as a result.

Now let us look at a GRB that wipes out 70% of the ozone in one hemisphere and generates oxides that break down ozone. Prevailing winds will spread that damage and the ozone-destroying agents across the globe within a week. An example of this can be found when Chernobyl blew. The radiation reached western Europe because of prevailing winds which dragged it across Asia, through North America, and across the Atlantic. (Yes, some regions of Europe received it earlier due to weather patterns and the like. But regions such as Spain and France wouldn't have been affected by those weather patterns, only the global ones.)

So you have a GRB that initially wipes out much of the ozone in one hemisphere and within a week has spread across the globe. Remaining ozone will be diffused and destroyed in turn.

Now let's say the best-case scenario happens and only the Northern or Southern hemisphere is hit. In that case, the ozone hole would take longer to spread and ultimately would have less of an impact - but that also depends on land masses and how they disrupt wind patterns. If there is a mountain chain akin to the Himalayas that pushes weather past the equator, then you will have mixing of the ozone-destroying agents at a more rapid rate.

GRBs are dangerous not because the planet is hit by radiation that kills everything under it. It is dangerous because of the ozone-destroying gases it can generate in the upper atmosphere which persist for a long period of time. And should it happen during a period just prior to heightened solar activity? Then the impact could be intensified.

Trust me. The scientists who talk about GRBs know what they are talking about.

Rob H.

Duncan Cairncross said...

Hi Robert
Those were the low altitude winds - not at all sure about the high altitude winds

High UV levels are not a good idea
Some species would suffer yes
Some would go extinct
But most species??

I would expect shorter lifespans - but not immediate death
That would take care of any megafauna with their tight survival limits but most animals would survive and adapt
Especially those that were nocturnal or lived in bush

If you have ever tried to actually kill anything by using UV
(for sterilization) you would find that its not some magic bullet - its only effective on microscopic creatures in a very clean environment - any particles of dirt for them to hide behind and they survive

Certainly no good at all at killing mice or cockroaches

I would expect shorter lives and a higher death rate - but not extinction

I am certain that the scientists writing those papers know what they are talking about re- astrophysics and probably chemistry

Less sure about the actual effects down on the ground - life is tenacious

Paul451 said...

UV impairs photosynthesis, and plants can't hide from unfiltered UV behind a few specks of dirt.

Since some wavelengths of UV penetrate the surface layers of the ocean, plankton and particularly phytoplankton numbers may plummet for many decades after a long-GRB. The rest of food chain will quickly collapse.

And remember, our modern micro-organisms may be descended from the survivors of a previous GRB hit or two.

Wait, hang on...

No oxygen, no ozone layer. So the first 1.5 billion years Earth's micro-organisms originated and evolved with unfiltered higher UV levels. That protective cellular chemistry wouldn't vanish immediately after ozone layer formed. And any subsequent GRBs would simply restore the UV-tolerant life to the fore.

Hmmm, you might be right. It could screw us now, but is not likely to interfere with early life. And if GRBs are a regular occurrence for planets in the early galaxy or nearer the core, life on those worlds would never lose its UV tolerance, regardless of its complexity.

They'd actually be less vulnerable to long-duration GRBs than we are. Unless there's something to close GRBs beyond the ozone eating.

[Turing: "Mrs. Blazer".]

Robert said...

Now think that to the next logical step.

What are some mechanisms organisms use to tolerate higher radiation levels? Additional methods of ensuring genetic mutations are eliminated, perhaps?

Now consider this: what happens when you eliminate genetic mutations?

Rob H.

Tony Fisk said...

Paul451 said
"Judging by birds, some of the advanced dinosaurs were at the pre-sentient threshold before the big-kablooie."

I think it would set a few heads scratching if some chipped flints were ever discovered at the K-T boundary. When did Wernecke's structure develop in birds, anyway?

Re: batteries. Anyone mentioned fuel cells recently? It has just been reported that graphene can be made permeable to hydrogen ions (but not *atoms*).
Much hype ensues, of course, but there are definite possibilities here.

Tony Fisk said...

David said:
"You are a member of a civilization that does stuff like this! Stop letting cynics and fear-mongers undermine your confidence in us."

On that theme, folk may like to look at an recent interesting talk by Lawrence Lessig on underlying issues of US democracy today (if you can reclaim it)

Paul Shen-Brown said...

I would like to say a quick thank you to Tony Fisk for finding that Wanderers video for us. Inspiration! Many centuries ago, when I was a bushy-tailed college student, I painted a picture on the same theme. It was a silhouette of a man's and woman's face, lips only millimeters apart, with a backdrop of Jupiter and its many moons. I titled it "Why Settle for Kisses Under the Silvery Moon?" We can use more things like this to inspire people to think beyond our celestial cradle.

On UV and ozone depletion, correct me if I am wrong, but I seem to recall that water is an excellent shield against UV. If so, Terrestrials would be in for some major problems, but our Aquatic friends might not have such a problem. Here's a scenario in which the finned might inherit the Earth (or should it be the mackerel, since it starts with /m/?) The chemistry of the atmosphere does affect the chemistry of the oceans, so I could be wrong, here.

Alex Tolley said...

OT. Complexities of Carbon Lowering - Iron fertilization might be less efficient at storing carbon in the deep ocean than previously reported.

I agree with those that suggest that GRBs will not have a huge impact on aquatic life. Enough phytoplankton live deep enough to protect them from any UV that results from a stripped ozone layer. Other organisms like deep living macro algae will also survive, maintaining the lowest trophic levels of the marine ecosystem. We also cannot rule out evolution grinding along on organisms selected for UV resistance, much as it must have before the oxidation of the atmosphere. Organisms that live protected underground will also be fine, although terrestrial plants will be in trouble, but perhaps not all of them. Earth has survived some huge extinction events, but not one of them blasted us back to pre-multicellular life. Life is very tenacious.

David Brin said...

Drive traffic to my piece on "Libertarian aspects of SETI"... !

Jumper said...
This comment has been removed by the author.
Jumper said...

Paul 451, I found your proposition about life being more common in ejected stars quite profound. Now I am wondering about the "filter." All I can find so far is old:

SteveO said...


There may be other filters for intelligent life, yes. Consider placement within the galaxy. Too close to the center it might be too crowded for planets to form or there might be occasional bursts from the galactic center.

Other filters might include any number of ones we have heard hypothesized. Given billions of years, at least one would have spread across the whole galaxy, but given a few millions, the other filters come into effect.

(Statement of belief...) I tend to think that life is probably fairly common, but intelligent life is not, though there are others out there somewhere. Intelligence seems so...unnecessary...for life (a.k.a. organic pattern propagation and evolution).

The primary probabilistic constraint has to be the one of deep time - given such massive timeframes as the length of the universe, you pretty much can't find enough filters to stop some crazy civilization from spreading everywhere in one form or another. If we reduce the possible time horizon down to where other filters come to bear, we can end up matching our model to our (extremely limited) observations.

The metallicity observation does a good job of naturally doing that.

Jumper said...

I meant a hypothetical filter that only unsuitable stars are ejected from galaxies, meaning even if they were now free from radiation catastrophes, they would not harbor life. I suspect small stars would get ejected more than large ones, but tend to think F, G (!), K could escape. These that did harbor intelligent life would be remote and give up on interstellar travel, perhaps. A shame.

Paul Smith said...

Great video clip! Now where do we get The high ISP rockets to make it come true? We've almost exhausted the possibilities of chemical propulsion. The 1950's Orion project would do just fine but any sane person would be a little worried (hundreds of A bombs in one location). Gets you a call from homeland security. Ion propulsion looks nice but 1 newton thrust from a megawatt input power isn't going to cut it. Any ideas?

Tim H. said...

PZ Myers didn't much care for "Wanderers"
For reasons that make a kind of Luddite sense, but if we get that sort of tech it implies a handle on many Terrestrial problems, as long as rent-seekers don't manage to twist it into new chains....

Tony Fisk said...

Myers raises some relevant points about Earth vs. the rest of the Solar System, but I think he's reading too much into the message of 'Wanderers' by referring to Sagan's words as the philosophy of the locust. Nobody's suggesting humanity en masse moves to Mars or Titan because elevators and flappy bird imitations!

Alex Tolley said...
This comment has been removed by the author.
Alex Tolley said...

P Z Myers is being somewhat curmudgeonly. You can sum up his view as "The needs of the many outweigh the needs of the few, or the one". I see no reason for binary thinking. The few can colonize or vacation on Titan if they want, preferably with their own resources. I don't expect people will emigrate from Earth, en masse. It makes no sense. But if access to space becomes cheap, and spaceflight easy, I see no reason why a mass market for space flight shouldn't develop, much like cheap vacation travel here on Earth. Climbing a glacier on Europa is not intrinsically different than climbing Everest, and that now needs years of advance booking to get a slot. Give it a decade or two, and tourists will be deep diving to the ocean trenches. Most of us will accept ROV trips, simulations and even Rekall type memory transplants.

Of course the kicker may be that it isn't human meat that gets to do these things in the solar system, but machine bodies with mind uploads. Renta-a-body on Titan, upload your mind for the trip, then transfer the new memories to your body (if you still have a flesh one) and wake up. Relatively cheap. No months or years of dangerous spaceflight. No enviro-suits needed. If you have an accident and die, don't transfer those memories to the original.

David Brin said...