Tuesday, February 08, 2022

25 Theses on Starship, Space Tourism, and Human Futures Beyond Earth.

In this guest editorial, my 40 year pal Joe Carroll... who is "Mr. Tether" for saving that now-useful space technology, back in the '80s... puts forward twenty-five provocative 'theses' or assertions about spaceflight across the next generation or so. 

Joe takes into account what's been announced so far, especially about Elon Musk's SpaceX 'Starship program,' offering some points that may need to be solved... or at least resolved based on sound arguments.

You are all welcome to initiate discussion in comments, below!


Theses on Starship, Tourism, and Human Futures Beyond Earth 


It is useful to periodically reconsider our prospects and options for living beyond Earth. The theses listed below are intended to stimulate more serious discussion of some currently popular scenarios. These are assertions. Some may be disproved, but most are way-under-considered.

Use the comments below to get the discussion rolling, then restart by consensus elsewhere. 

Regarding SpaceX Starship

S1. Starship’s main business will be delivering payload from Earth to LEO (& back), not beyond.

S2. Starship may cut LEO $/kg by 100 binary (i.e., only 4-fold), but still revolutionize use of space.

S3. Once launch prices drop ~4-fold, most customers will focus on launch vibration & reliability. 

S4. The STS orbiter cost more per kg than its main engines. That may also be true for Starship. 

S5. Simple “Startankers” can cost & weigh ~1/3 less & deliver >1/4 more payload than full Starships. 

S6. Most useful early LEO propellant transfers will be from one Startanker to a Falcon stage 2.

S7. Later transfers will be to lighter (inflatable?) stages, with lower T/W than Falcon or Starship.  

S8. It is better to find local use for most hardware far from LEO than to return it for later reflight. 

S9. Any military point-to-point payloads will land on their own, with Starship landing elsewhere.


Tourism and Commercial Space Travel 

T1. Early “point-to-point” travel needs a transfer hub in LEO, to grow markets for direct routes. 

T2. A LEO hub is also a great meeting site, and a hub for orbital tourism & settlement testing. 

T3. For science/health - + for space novices - a LEO hub can rotate-emulate Moon & Mars gravity. 

T4. A  “2001 wheel” won't minimize spin-queasiness. Best is a long, slow-spinning dumbbell.

T5. Outboard capture & de-orbit by tether allow transfers in gravity, and can boost payload ~10%.

T6. Most tourists will want access to 0g, but prefer partial gravity for most of their time in orbit. 

T7. Easy elevator access to a range of gravity levels may be a key attraction for tourists & retirees.


Human Futures Beyond Earth

H1. It is harder to live in the best place off Earth than the worst place on Earth (except volcanoes).

H2. The best way to start “mining the sky” is to recycle & reuse most mass now discarded by ISS. 

H3. Growing food in LEO can get us closer to living off Earth than putting people on Mars can. 

H4. The US needed Apollo, in a hurry. We don’t need footprints on the Moon or Mars in a hurry. 

H5. After decades of refining 0g health countermeasures, human health still goes downhill in 0g.

H6. Around our sun, Earth is the only livable ~1g body. All others have 3/8g, ~1/6g, or <0.09g.

H7. We know nothing about sustained human health between 0g & 1g (Apollo stayed 1-3 days).

H8. We can find the effects of 1/6g & 3/8g far safer & cheaper in LEO than on the Moon or Mars.

H9. The only place we can settle off Earth without meters of shielding is LEO inclinations <15o.


Joe Carroll     January 8, 2022     


Alfred Differ said...

S1. Measured by direct revenue, I agree. I think indirect revenue will eclipse that. Think about how Falcon 9 enables StarLink. No falcons, no StarLink revenue because the technical risk reduces willingness of investors to create the constellation. Starship is likely to enable other projects that eclipse it, so if we measure things that way I'd say it's main business will be delivering payload to the cis-lunar volume. [Not Mars]

S2, S4, S5, S7. No doubt.

S3. I don't know, but only because I think we don't know who the actual customers will be. People haven't imagined what they can do up there. They imagine what governments and academia can do, but their OWN interests are still fuzzy.

S6. There are some engineering limits on the upper stage right now regarding lifespan of the batteries, but they'll work this out. When they do I completely agree. There are going to be a number of Merlin vacuum engines in high orbits.

S8. Except for hardware designed to transit the upper atmosphere, I agree.

S9. Military customers already know this as does any company doing business with them. No brainer.


T1. We'd be fools not to build more than one transfer hub in LEO inclined in different orbits. A hub completely changes the "launch window" calculation on the arriving end by providing a number of weather flexible options.

T2, T3, T4. Yup.

T5. No one should debate this with the expert. The physics is clear. It is 'merely' a matter of economics as to when this happens.

T6, T7. Likely. Very likely if they want to go home again without health issues.


H1. Most people have no idea how nice Mother Earth is.

H2. I'd extend this to other discarded mass between LEO and GEO. ISS mass is simply cheaper to get since it's already got.

H3, H5, H6, H7, H8. These are all related. We are ignorant of many things, so we need a low cost way to learn quickly in the field.

H4. Yup.

H9. This is only part of the problem. It is a critical part, but the long pole in the tent will be the fact that all methods for financing activity will still be on the ground for quite some time. The markets are on Mother Earth. No where else. Successful settlements REQUIRE market access.

LEO is real close to Mother Earth and ALSO happens to be easier to defend from radiation.

lurker below said...

S3. Once launch prices drop ~4-fold, most customers will focus on launch vibration & reliability.
Scheduling. Convenience. Although, SpaceX may be the only one with the 4x price drop, with other entrants struggling to match current F9 prices. Not that SpaceX hurries to drop prices absent competitition.
S6. Most useful early LEO propellant transfers will be from one Startanker to a Falcon stage 2.
Eh. Starship is set up to carry methalox. I'm not convinced it will be worth diversifying to RP-1. Might be easier to do a single Rvac stage.
T1. Early “point-to-point” travel needs a transfer hub in LEO, to grow markets for direct routes.
Early point-to-point is point-to point. Orbital dynamics makes a LEO hub a slow way to get around and around. The nice thing is that once orbital, you don't need to worry as much about overflights, which is a hard thing about launching P2P.
H8. We can find the effects of 1/6g & 3/8g far safer & cheaper in LEO than on the Moon or Mars.
Maybe, but we won't find out more about the Moon and Mars that way. And the Moon and Mars have meters of shielding

lurker below said...

H2. The best way to start “mining the sky” is to recycle & reuse most mass now discarded by ISS.
I think the MEV Mission Extension Vehicle architecture allowing extending the life of existing assets is promising and, uh, extensible. ISS proper is on its way out. Time to plan for successors. Although I did enjoy "Red Star, Winter Orbit" So,
1. Extend the life of existing assets.
2. Design new assets for servicing. It would be better to add propellant, new gyros, and new solar panels than to bolt on a MEV, but mostly if the asset is designed for servicing.
3. ISRU rules. This includes station waste recycling, LOX made from local stuff, piling shielding on larger bodies. Quite the continuum.

Alan Brooks said...

Wouldn’t it be transhuman futures beyond Earth?

Mitchell Wyle said...

S8 is obviously true in the long term because the materials can be used for building other things without incurring the expense of transporting the mass to LEO; but I challenge the need for spent second stage Falcon-9 rockets in the short term before solar smelters & construction systems are established. Excellent post, David! Keep them coming.

duncan cairncross said...

S1 - yes that is what its designed to do - if a spaceship does not need to take off and land on earth it can be designed lighter and more efficiently

S9 - a Starship with legs should be able to land almost anywhere - which may be what the military needs even if it is then "wasted" and cannot take off again

T1 - T7 --- Yes

Beyond Earth
Low gravity may well be a long term health hazard - the best place to be will be somewhere with access to raw materials (mass)
Deimos with a 20 km/HOUR escape velocity would be idea - you have your spinning (dumbbell) habitats nearby with a solar powered "thrower" on Deimos
Zero G for huge solar panels - effectively unlimited materials from Deimos - for building stuff - reaction mass - radiation shielding
The heaviest part of your "fuel" is the oxygen - and almost everything that you can find in space is an oxide of some sort or other

duncan cairncross said...

On a different note

The Age-Crime Curve

“The prevalence of offending tends to increase from late childhood, peak in the teenage years (from 15 to 19) and then decline in the early 20s. This bell-shaped age trend, called the age-crime curve, is universal in Western populations …

However, specific versions of the curve vary in significant ways. The curve for violence tends to peak later than that for property crimes. … The curve is higher and wider for young males (especially minorities) growing up in the most disadvantaged neighborhoods.” (National Institute of Justice, 2014)

The criminology consensus on this subject is no longer supported by arrest rates reported by the Office of Juvenile Justice and Delinquency Prevention (OJJDP). The following OJJDP graphs of violent crime and property crime arrest rates by age show that the age-crime curve has collapsed.

The graphs show that the massive spike from ages 15 - 25 has just evaporated!!
Instead todays youth is about the same from 15 to 40


Lead poisoning!!!

Tim H. said...

If "Star tanker" has no reentry tiles, it reopens the possibilities closed when STS was built with tiles rather than inconel, necessitating foam covered external tankage*. Providing one with life support and habitable spaces might be excessively interesting, but much of the required mass will already be in orbit. One could imagine two or more converted tankers tethered on cables, spinning to give the occupants a break from free fall**.
*The foam would've eventually degraded and flaked off, creating a visibility nightmare.
**We really should've sprung for the rotating module for ISS, it would've answered questions that need answering.

scidata said...

I know you Americans are big on the 'jinx' phobia, so I'll just say this. Webb is some kind of machine, wow. All instruments up (including the big antenna) and photon capture is working throughout. Truly, cosmology is a dish best served cold.

Re: Tethering (great post, sir)
In most systems, the really interesting stuff starts to happen when you apply/consider constraints. For example, individual planets are fun, but a gravitationally-bound solar system is much meatier. For you spaceflight physics wonks, The Tethers in Space Handbook (1997) is available here:

Incidentally, the myriad copies of so much deep knowledge is why tyrants have little hope of yoking civilization again. It's like the end of the movie LUCY when they ask, "Where are you?" and she replies by phone text, "Everywhere". The recent spate of book banning and curricula limiting by state legislatures is sad yet laughable. If even a single copy is found buried in the rubble, the light is rekindled and tyranny falls. That's why some of them are postponing autocracy in favour of idiocracy, funding the Age of Gullibility for pennies.

I'm just an old-timey FORTHer, with a head full of Laplace, Verne, and Asimov. The concept of 'Tethered Forth'* is one of my touchstones** (others being evolutionary computing, bootstrapping, syntonicity, and computational psychohistory). This was leading-edge in the halcyon days of ACM SIGFORTH, just before Zuckerberg et al ushered in the gossip/eye-candy/conspiracy-theory idiocracy.

Imagine losing $29B in one day. Live by the sword...
It's much better to tether oneself to a good, resilient, immortal idea. The enlightenment is secured not just by a million credentialled elites, but also by a billion curious tinkerers. Not even nazis can stem that tide.

* usually two computers, which together form a single Forth system. This has the advantage of factoring out the machine- and human- sides to their appropriate platforms.

** yes, I realize I'm slightly mis-using that word, but nobody else ever uses it anyway. I luxuriate in CB's absence of lingo police.

Miles Mutka said...

T2-T7: I agree, the wheel design will not work, since people moving around will redistribute the weight and move the barycenter away from the axis. But that is also true for all the designs where the whole orbiter rotates, especially one with elevators. The most realistic thing is still smaller centrifuges inside the orbiter, like we have now. When the orbiters get bigger, so can the centrifuges attached to them.

H6, H9: You forgot the nearest planet. Floating in the clouds of Venus is a comfortable 0.85g, plus steady pressure and temperature, as much atmospheric protection as on Earth. Livable, but not easy to develop. And not aesthetically natural to human senses.

David Brin said...

Venus, Neptune and Uranus all have roughly Earth surface gravity, but those surfaces are completely uninhabitable.

The longer the tethered dumb bell, the less coriolis effects and the more tolerant the system is, of variations like elevator movements. And the easier it becomes to dock.

S9 Duncan, a dedicated lander is VASTLY less expensive than a throw away starship, especially if it is okay to use parachutes.

S6 good point re Mathalox vs RP-1

scidata said...

I worry about the cable(s) in long dumbbells. It'd be cool to try making some dumbbells out of spinning molten rock, like tektites do. There's plenty of rock and energy in space.

duncan cairncross said...

S9 Duncan, a dedicated lander is VASTLY less expensive than a throw away starship, especially if it is okay to use parachutes.


The "Starship" is being developed as a cheap machine to be made in large numbers

A "Dedicated Lander" may need slightly less performance - but it will probably end up costing MORE

DP said...

About point to point rocket travel.... I remember a joke about ballistic commercial passenger transport: for half the flight the onboard bathrooms can't be reached and for the other half they aren't working.

DP said...

As for living long term on bodies with low g, that may be perfect for seniors. As someone who is starting to experience the aches, pains and stiffness that comes with getting older I am willing to try a retirement community on the Moon with a bunch of other geezers.

It may even be life extending.

David Brin said...

Duncan Starship will land on its tail (and perhaps not even that, if they CATCH it) in order to maximize refurbishment for many rapid uses. A DoD point to point cargo capsulle can use cheap parachutes and then returned to Spacex later, at liesure.


SpaceX to lose as many as 40 Starlink satellites due to space storm! https://www.cnbc.com/2022/02/09/spacex-losing-starlink-satellites-due-to-geomagnetic-space-storm.html

DP said...

With all this talk of terraforming Mars or Venus, the Moon looks a whole lot easier and faster to terraform so we can walk around in shirtsleeves with a breathable atmosphere (which granted would required continuous replenishment).


David Brin said...

DD I assume you mean under domes. No amount of air that you generate on the moon will stay more than a day/

Paradoctor said...

I say that most spaceflight, for the indefinite future, will be done by robots. They don't need air, water, food, meter-thick radiation shields, artificial gravity, and they can be sent one-way. In low earth orbit they can be used for telepresence; and maybe on the Moon as well, if the 3-second round-trip lightspeed delay doesn't give you goggle sickness. Further out they'll be on their own, and will need AI. Telepresence and AI are useful on Earth, but spacesuits are not; so the spin-offs pay better for robots, as well as them being much cheaper.

Humans could eventually follow them out there, but only after the robots have dug underground habitats, and fetched enough comet water to fill up those meters of radiation shielding on the manned ships. (Made from asteroid metal. Lifting from Earth costs too much, even with Orion.) Once on the Moon or Mars, the humans will mostly huddle underground, safe from radiation and micrometeorites, and do real-time telepresence. Gloves, goggles, and a telepresence robot make the best spacesuit. For one thing, through the robot you can see spectroscopically, and in UV, IR, X-rays and radar. Also, your robot's waldo can have micrometer precision. Much more immersive than a face-plate and thick air-stiffened gloves, and safer too.

If FTL is ever possible (despite the time-travel that FTL + Lorentz transforms imply, and the consequent paradoxes) then I say forget about the Enterprise; just connect your robot to an ansible, and you can do realtime telepresence across the solar system and beyond.

Most space exploration will be more like surfing the Web than like driving a car.

duncan cairncross said...

Hi Dr Brin
Parachutes are a good way to break things!
And the tail landing is mostly a matter of software - SpaceX intends building hundreds or thousands of the things
All the "Army Version" would need is some landing legs - and the Mars and moon versions would need the legs anyway (stronger legs for the Army!)

Whatever they use will need to land - if it lands by parachute its knackerred!

David Brin said...

Paradoc, in KILN PEOPLE, humans 'go' to Mars etc as imprinted clay golems, explore, then self decapitate the head to return to Earth for download.

DC the disadvantage of parachutes to the military is not ruggedizing. Esp if the final landing is with retros. No, it is the time the cargo spend hanging there like a sitting duck.

Paradoctor said...

About using a meter of water to shield from cosmic rays: this reminds me of Cordwainer Smith's "Scanners Live In Vain", where an inventor figured out that coating the ships with a shell full of molluscs shielded those within from the Pain of Space. The obsoleted Scanners took exception to this.

gerold said...

DD and DB: for my lunar residential neighborhood I'm thinking lava tubes look good. Shielding is free, and plastering the walls airtight provides large interior volumes at minimum cost.

1/6 g might be a non-starter for health reasons of course. That would bring property values way down.

Der Oger said...

Possibly T3/T4: Just wondered: If you can create the artificial gravity of Earth, you can also exceed it and create higher gs. Either as a method to build up muscles or as a defensive tactic to pin down intruders or other troublemakers.

Also, lower g may be beneficial for geriatric inhabitants to reduce the effects of falls and pressure ulcera/decubiti. Maybe since the head receives more blood, it might counter cerebral ischemia somewhat. Yet I doubt it is worth the trouble of the negative side effects like muscle atrophy and blood pressure problems.

DP said...

According to an article by Geoffrey Landis (http://www.geoffreylandis.com/moonair.html), oxygen and nitrogen are removed from the Moon within about 100 days, due to the combined effects of sunlight and the solar wind.

However, if the atmosphere is thick enough, then this effect would no longer occur. In this case, the gases would last for thousands of years.

Long before that is would of course become too thin to breath, so for practical purposes a terraformed Lunar atmosphere would last several centuries. Hence the need for constant replenishment.

So you are right, domes and/or world house (para-terraforming) would be needed to permanently retain a Lunar atmosphere - a structural engineering task made easier by the Moon's low gravity. So the blue atmosphere and seas of Luna along with its forests and grasslands would be overlaid by something resembling a geodesic dome.

IOW, the Moon would be transformed into a giant disco ball from the 70s.


P.S. Want to go surfing on the Moon? Those waves would be 6x higher than the the most wicked curls off Waikiki. Instead of parasailing, you could strap on actual wings and fly.


Jon S. said...

Miles, you're making the word "livable" do a lot of heavy lifting there. Those clouds you'd like to float in around Venus are made of sulfuric acid.

Duncan, amusing as the "problem" with in-flight bathrooms on ballistic transit sounds, realistically you'd best go before takeoff anyway. You do NOT want to experience multiple Gs on a full bladder!

Paradoctor said...

More xkcd snarkery:
Defense against aliens via critical thinking!

David Brin said...

gerold looking at lava tubes is a top priority at NASA's Innovative & Advanced Concepts program - (NIAC)

der oger higher g could be a way to kep belter spies out of your control room.

DD In my story “The Logs” the crystalline forests of Luna are roamed by herds of elepents (NOT misspelled). But there’s still almost no air.

paradoc that xkcd channels my ancient story "Those Eyes."

Paradoctor said...

"Those Eyes" are why I thought of you when I saw that xkcd.
"Vamoose! This guy will probe us!"

Paradoctor said...

G.D. Nordley recommends wrapping a superconducting cable around the Moon and Mars, to give those orbs an artificial magnetosphere, which will stop the solar wind and thus extend atmosphere retention.

David Brin said...

Paradoc. Any civ that could think of wrapping such a cable could roof over dozens of craters, a vastly more secure prospect. Once they've done that, I recommend this:

Lift the Earth! an entertaining video- https://www.youtube.com/watch?v=Ai8x-ZqjXPc. - and the numbers behind the idea: http://davidbrin.blogspot.com/2014/11/lets-lift-earth.html

scidata said...

SpaceX has demonstrated full Starship + SuperHeavy stacking without a crane (all tower grabs). Looks like only the FAA can block the road to the planets now.

Larry Hart said...


Defense against aliens via critical thinking!

The same applies to human invisibility.

"When I eat a can of beans, do the beans turn invisible too?"

David Brin said...

"When I eat a can of beans, do the beans turn invisible too?"

Depends whether the invisibility is wrap-around/warp-around. Or else pass-all-light straight through anything that's me.

Miles Mutka said...

Airborne settlement on Venus is counterintuitive, and most of the "studies" have been by imaginative enthusiasts. I spent some time on the topic a few years ago, collected also what sources I could find in this post: https://unfinishedwisdom.wordpress.com/2018/03/04/adrift-in-middle-cloud-layer-notes-on-the-airborne-colonization-of-venus/
The most immediate health hazard inside Venus' atmosphere is the main ingredient, CO2, not sulphuric acid, which is only parts per million on average. But the CO2 content makes floating easier, since it turns normal Earth air into a lifting gas.

As for the Moon, adding some centrifugation to lunar gravity for health purposes is a lot less technically challenging than building a centrifugal rotating orbiter that can dock while rotating. The most spartan solution is just riding a bicycle along the inside of a cylinder. Here another blog post of mine: https://unfinishedwisdom.wordpress.com/2019/07/20/centrifugal-force-and-gravity-on-the-moon/

gerold said...

DB: lift the earth alternative

I've always liked the idea of orbiting sun screens that can decrease insolation levels at the surface. On a bulk level it could limit global warming, but maybe also for fine control to steer rain as needed.

Seems a lot simpler and lower energy than lifting the earth.

David Brin said...

gerold, the benefit ends when those screens fail. My system, when it fails, all previous benefits are retained.

Robert said...

"When I eat a can of beans, do the beans turn invisible too?"

In at least one early SF story I read decades ago* the answer was "yes, but gradually". the Invisible Man (and it was a man) had the choice of being hungry or looking like a blob of partly-digested food hovering in midair…

*So can't recall author or title

Larry Hart said...

Dr Brin:

Seems a lot simpler and lower energy than lifting the earth.

Lifting the earth would play havoc with calendars and religious holidays. The evangelicals and Muslims will never let it happen.

gerold said...

DB: the possibility of failure for any of these planet-wide systems is a major consideration. I'm not sure what the failure modes are for a space elevator or EM tether, but if one of those cables comes down it's going to leave a mark.

Suppose we make our screens out of a light weight PV film; to make it big enough for effective insolation blockage we might need something like a million kg of material plus a deployment mechanism (furl/unfurl system?) which is not an insubstantial launch weight but not impossible either. It might be difficult (impossible?) to make PV film last in the harsh environment of space, but if they did it would provide plenty of power for controls etc.

To me it seems the failure modes for a sun screen are less catastrophic than for an earth lift.

Paradoctor said...

Prospecting the solar system can be done in decades, so it's in the time-horizon of corporations. Colonizing Venus's atmosphere with self-sustaining balloon cities would take centuries, the time-horizon of nations. Terraforming Mars would take millennia, which is in the time-horizon of religions. Lifting the Earth would take much longer. Your moon-tether can be abandoned for a long time, but be rediscovered and reconstructed by later species; a trans-species handoff.

If axions are real, then we might be able to build axion engines, which generate thrust and expel axions, which don't interact with hadron-lepton matter. Engines propelled by other dark-matter particles would do. You could bolt some big ones to the ground.

scidata said...

If we're talking about centuries or millennia, I'd go for interstellar exploration over solar system engineering, especially if ansible-robot surveys were possible. The Dutch didn't start building dykes until about 1300. Beach-combing is easier, more fun, more adventuresome, and more serendipitous.

Alfred Differ said...

Prospecting the solar system will occur on many time scales, but it's not about the time-horizons of corporations. It is a fundamental economics issue.

Mineral X found at Asteroid Y becomes Ore X if someone with the means to bring it to market Z can do so at a profit.

At the moment Z is Earth, but it could be anywhere later. In market lingo, it is where the futures contracts get resolved. Deliver so much X to Z at price P on date D.

There are celestial mechanics games one can play to deliver X on D at a variety of costs C. Hohmann transfers minimize energy costs but have high transit times and small launch windows limiting possible D's.

Your company establishes claims on Y and funds projects through risk capital at compounding interest rate R. Whether you make money on a project is at matter of possible NPV's (net present value) assigned to leaves on a branching probability tree covering the most likely events of the project. The weighted sum of them becomes your expected (X)NPV.

Do you plan to make a profit? If XNPV is negative, you likely won't and investors won't take your call. If it is mildly positive, they'll look at the rate of return relative to other projects they could fund possibly at smaller risk and with shorter time horizons.

This is all typical investment risk stuff. What dominates risk calculations for solar system prospecting, though, is the risk that the market will find a viable substitution X* for X before D. That means the price of X* influences the price of X and must be accounted for in the probability branchs. Over many years, the probability of a market finding an attractive X* becomes damn near certain if the price of X is high enough to make XNPV strongly positive. That's what markets DO. Prices of things are signals telling people what needs attention. GO FORTH AND FIND X*!

Time-horizons for corporations reflect the market reality in which they are embedded. If they think in terms of quarters or fiscal years, it is because others like them do. There's not much to be done about this behavior unless the stimuli are artificially imposed, thus possibly removable.

We already know how colonizing ANYWHERE works economically. Colonies trade with distant markets, but they create local markets aggregating the transport function. The work of turning a colony market into a big market takes a while, but establishing it is a snap if people are present. We just do it. It's what humans do.

Alfred Differ said...

Our host is thinking VERY long terms when it comes to lifting Earth. No matter what tech you imagine could shield us from Sol's fits and seizures, it will fail over very long horizons. Remember, he's thinking of extending Earth's modern biosphere tolerating C3 and C4 photosynthesis for WAY past the time that's going to die.

With that in mind, there are really only two choice. Move the Earth or peel mass off Sol.

All the shield ideas are TWODA notions. Yes. Let's build them too. Don't pretend they are anti-fragile, though. They will fail some day, so the other tech has to be built.

This all involves unobtanium at the moment. Don't worry, though. As long as it doesn't demand fantasium, we'll get there some day.

Remember what humans do as we learn. Especially humans in this civilization. Everything except class 5 potentially gets cracked down a level someday. (Maybe class 5, but don't hold your breath.)

1. cotsium
2. special-ordium
3. not-yetium
4. unobtanium
5. fantasium

matthew said...

Alfred, what is "cotsium?" I certainly got a lol from the other four categories, but I'm missing the connection to the first one.

(I know asking to explain a joke is non-funny, but I just cannot figure out what you meant here)

scidata said...

First JWST image (HD84406 in Ursa Major)

- one star in 18 mirrors :)

TheMadLibrarian said...

Daniel, don't forget the classic Heinlein story, "The Menace from Earth"!

scidata said...

Re: cotsium (assumed COTSium)
Collapse-niks focus on an even lower level: scrapium.

Larry Hart said...


Alfred, what is "cotsium?"

I thought he meant "coSTium". As in "Can't do it because it costs too much".

Tony Fisk said...

Scidata beat me with the JWST update. Image acquired in all 18 segments is the key point. Getting those 18 images together is next step. Then getting them to play nice at the nanometer scale is next.
A couple of months of configuring still to go, but progress so far suggests this forward planning thing has its uses.
Thoughts on theses:
S1: think of the space station assemblies...
T4: I get the thinking re. dumbbells, but a large enough wheel would achieve the same thing (and if you quibble at size, see S1)
H7: dumbbells with extensible tethers would allow differing g environments (Liftport was aiming for something more grandiose, but their approach could be applied here.)

Paradoctor said...

Got some gotsium?

Der Oger said...

Related: Who pays for cleaning up that mess up there if space travel/payload becomes cheap enough to produce space wreckage faster than today? Shouldn't satellite and space station owners be taxed? And if so, by whom?

Alfred Differ said...

Cotsium is one of these. Take your pick.

Commercial Off The Shelf (a retail version)
Commodity Often Transferred/Sold (generally non-consumables and things used like money)

I like scrapium, but I'll point out that the stuff collapse-niks find interesting exists in a post-holocaust world where markets have failed.

If you think you can get scrapium for nothing now, it's probably because no one has figured out how to sell it to you at a profit. For example, seashells on the seashore are scrapium until someone 'improves' them. They nicely show the distinction between mineral and ore. Fragmented mollusk shells are common near me. Gulls turn live critters with intact shells into those fragments. I haven't figured out how to 'improve' those fragments enough to make it worth my time that could be invested elsewhere for a better return. No profit = no market.

Alfred Differ said...

I wrote a blog entry many years ago that covers the five classes of marketable 'stuff' as I see it. I've changed the spellings of the terms a bit... especially the last one. The definitions still largely hold, though.


I wrote it for a group of cynics in the space frontier community who honestly felt that one project with which I was affiliated was dealing with fantasy ideas. NOT physically possible. One of them used the term 'unobtainium' and that got me thinking about why they saw it that way.

I wound up dividing 'obtainium' a few times in order to make my point to them which was that my team was dealing with notyetium. They were welcome (in my NOT so humble opinion) to argue the investment risk was prohibitive, but bumping the 'stuff' up a class put them in a debate about what is physically possible with a physicist*. They were welcome to challenge me on that level, but they'd best come well armed.

Nothing came of it all. Using my categories, they amended their statement and argued we were dealing class five. We wound up agreeing to disagree.

* It certainly can be done. None of us has a lock on this stuff. Some of us have spectacular skills in the lab or with equations and spectacularly bad intuitions about basic stuff. Simultaneously.

As a teacher, I was always interested in what my students were intuiting. Many problem solving failures can be traced to intuition glitches.

Unknown said...

"The Menace from Earth" was cute, but I remember that Heinlein weaseled a glowing mention of the Dean Drive into the plot. That was going to be a thing back then, and too bad it didn't - we'd have an interplanetary civilization by now and be working on interstellar probes.

Back in this universe, where reactionless thrust isn't a thing, Mr. Carroll seems to have an accurate view of the future of space. In terms of human habitation, the sea floor is much more forgiving place than space - and I haven't seen any indication that droves of us are colonizing even the better-lit continental shelves, which probably have significant mineral deposits within easy reach.


matthew said...

Thanks for the definition, Alfred.

David Brin said...