Wednesday, February 21, 2018

Science fiction short story - That Final Moment

I wrote this in 2016 and finally decided to publish it on this blog. It was my first written foray into the mechanics of deep space industrialization. 

by Casey Handmer

"I am Sita." She could write a monologue of thoughts, organized by each activity at the moment of ideation. Identity and thresholds seemed to go together. She ran the flow check necessary to use the Mars surface airlock safely. Open valves to dump lock atmosphere into the air processor. Close valves. Check pressure on both gauges. Check the spacesuit was, in fact, not pajamas. Well sealed. Comms, temperatures, smell, pressure holding. Ears didn't pop--always a good sign.
She reached for the external door locking wheel and put her weight behind the mechanism. It ran smoothly enough. With practiced motion the door unlocked, opened inwards. A tiny puff of dust, cut by slanting rays of faded sun. She stepped through the narrow portal, like a submarine bulkhead door. Like a birth canal, no wider than it had to be, at least for people. Their machines birthed through a different door.
Vivid memories of her former life on submarines surfaced and just as suddenly faded into the depths. Between this outpost and those underwater islands of humanity, there was something fundamentally insular about society. Sita was here, now. She stretched towards the open sky for now there was no roof over her head. A few light steps over the trampled ground and, with intake of breath, a staring at, an acknowledgment of the horizon. If a problem is spherical, it is hard to see all of it at once.
    Sita's problem was Mars. The outpost behind her looked no more worn than it actually was. Sita had accepted the mission with eagerness. Go to Mars, live there until something breaks beyond repair, then bail out. If you could. Sita had not flown with the exploration missions. She had waited on Earth and then flown with the outpost. She herself had explained it many times. "How do you solve the problem of machines eventually breaking more frequently than they can be fixed?" On Earth, all machines would eventually be retired, but on Mars, the very air was produced by a machine.
Therefore, an outpost on a dusty plain where humans lived indefinitely, with resupplies of parts and sometimes crew, every other year. Sita and a few others lived in this experiment. Or the experiment lived in them, since the blood and toil that kept the concern operational was the sheer dexterity of human ingenuity, their own capacity for biological regeneration, far better than any machine, and occasionally a liberal dose of the will to not-die-that-day.
    And, she mused, a gigantic nuclear reactor. Every machine, every light, every pump, every vehicle, every robot--they all needed power, and their nuclear reactors provided it. She could see a heat shimmer beyond a nearby hill where they operated and quietly irradiated the surrounding area. Heaven help them if it ever broke down!
    She scuffed the ground. How many years ago had they trenched the ground here, laid the power cables deep enough that frost creep and spring blow and wheels couldn't damage them? That tractor had been trouble from the start. Like every other machine, they could and did completely disassemble it with basic tools they had in their inflatable workshop. But, like nearly everything else they had back then, it had broken too frequently to be worth repairing.
Sita had dragged it out to the boneyard of orphaned machinery, a place of sculptures, metaphorical monuments to industrial ambition and too much clever complexity. There, with dozens of other unloved machines left by parents too busy to keep them alive, they waited only for oblivion. Which was worse? Gradually harvested for scrap, whittled away to nothing, and yet pieces living on as parts of other, more valued equipment? Or forever neglected, until sun and sand and aeons abraded the paint, wore away the shell, the chassis, and scattered every molecule in a wide, flat, glittery sand dune that ever so gradually slunk downwind from the outpost in shame?
    Of course, Sita reflected, being recycled in some sense only delayed the inevitable for obsolete machinery. And indeed, explorers had passed, their bodies unretrieved, sometimes. Caught out at night, perhaps, and frozen to death. Or fallen and breached their suit. Or broken bones. Or poisoned by bad air. Or burned. So many abrupt paths to the end.
    Sita had found one once. Kind eyes in his frozen, perfectly preserved face stared up through his wind abraded helmet, right into the void. Right into Sita's own black eyes. His peaceful expression reflected none of the ambition that must have driven him to Mars, to die out here alone. Her suit's profile, a hemispherical head with burning flashlight eyes, reflected in the glass of the deceased. The yet living and the dead superimposed in imago, like one hand covering the other. They placed him in the burial ground, opposite the boneyard and obscured beneath the crumbled surface.
    Sita never found the other bodies. In her mind, they gradually transmuted from cogito ergo sum insularity to landscape. Wouldn't they all eventually find themselves blasted to smithereens by the passage of time, condemned to wander the northern latitudes by seasonal winds? Perhaps, given the risk of explosive decompression, that was why thoughts of identity and more importantly its willful continuation pervaded during airlock operation.
    Sita's mind and eyes wandered the landscape as she stared into the horizon. Their outpost was spread out over a large area, a perfect island of solitude within a world that was, for now at least, empty. Positioned in a broad valley between distant ranges, their faded peaks in the distance. A tiny speck, a blemish, precarious in a nonsense landscape that told a garbled saga of dust and ice and wind and countless ancient impacts.
    Her booted heel scratched at the ground as she turned to take in the view. She felt the sun's weak warmth through her pressurized carapace, her inner reptile took a second breath. In the distance, beyond the greenhouse, beyond the burial ground, she spied their return vehicle. The rocket sat there, inert, waiting to take them back to Earth. It had waited a decade. Four times, Earth had swung across the sky, daring them to cease their foolishness and fly home. Four times, they had duly performed the procedures to wake the sleeping behemoth and prepare it, just in case. Four times, Earth had passed out of range, its pale blue dot fading amongst the rest of the stars, and their loyal rocket had been put back to sleep. Sita wondered if the rocket could tell that Earth was no longer really home. That morning, something had changed. Everything had changed.
    Sita felt she could have been happier. Against the odds, that same morning her mission had been deemed successful, by the squints up on the big world. Her team had proven the design methodology that could keep them alive indefinitely. Now, humans could come. Humans would come. First by the dozens, then the hundreds, then the thousands. An unstoppable rain of humanity from the sky. And her maintenance protocols would keep them alive, most of them, while they built their mines and refineries and foundries and factories and farms and cities, until humans could live on Mars without continuous resupply voyages from Earth.
    Industrial autarky. Involuntary industrial autarky, necessitated by the hundred million miles of space between the nearest money and her. At least until someone made a warp drive or something. Then people would come by the million. Sita felt numb at the prospect. For a decade, just her and a handful of others under the Martian sky. Long rover traverses, endless testing, breaking, and repairing. Blue dawns to red days to blue dusks to black nights. Nothing but a planet and a mind, her mind, in it. Building Field Camp 18 in the next valley, confirming the aquifer. Building out a farm, growing food. A lifetime of learning and building and fixing and learning all over again.
They had one hundred days left. A message from the pale blue dot, confirming launch after thundering launch sending cargo and passengers to Mars. One hundred more days of relative solitude, before the new Martian hordes landed at the field camp aquifer, unfurled a gigantic tent over the barren plain and made the frozen desert bloom. There would be so many new faces. What does a face even look like? From the outside?
    Sita didn't have to wait around to find out. There were still tasks to complete, systems to check, failures to diagnose, procedures to document. And Sita still had one hundred days of solitude to tread the rocks beneath her feet. Some were dark, scattered, their faces faceted and scored by wind. Some were rounded, perhaps some ancient alluvial disaggregate. And beneath them all, more rocks. Rocks on rocks, all the way down, enough rocks to hold a person to the planet's surface with a gentle, forgiving force. Sita could jump right over a rover in the three-eighths gravity. Not such a good idea, she thought as she eyed the dozens of patches holding her pressure suit together. It would be thought exceptionally bad form to leave the ranks of the living just before things got really interesting.
    Sita stared beyond the return vehicle, right out along the almost featureless plain until the horizon's pastel browns and reds smeared ground right into sky. The horizon on this tiny world was never that far away. She could walk over it before lunch, find the outpost completely out of view. She could even make it back without running out of air, probably. Her helmet's glass fogged slightly with each breath. It was never warm outside. She checked her gas and power levels, then sat down on what had once been a voice command mainframe interface, its little silicon brain zapped by a cosmic ray. It had been a slow death, rambling ceaselessly in idiomatic Esperanto while Sita attempted repair before it, too, succumbed. Now it was a bench outside the airlock.
    Sita leaned back and looked up towards the zenith, where the sky is always white. Why does the universe contain introspection? Why so little? Why at all? Her eyes looked through a few inches of air, a millimeter of polycarbonate visor, the pitifully thin Martian atmosphere, and then infinite space, where the very first photons were stretched beyond the limits of human eyes. If you look far enough in any direction the view is deepest red.
    Metal robot oblivion dust is probably more glittery than the scoured remains of dead Martian explorers. Sita wondered how glittery she'd end up. If she lived long enough for the new city to get its biosphere up and running she'd request they recycle her remains. Nitrogenase and tyrosine are hard enough to come by without dumping them onto the frozen, ultraviolet blasted surface. But how was being eaten by worms any different from her recycling parts of broken machines? Were not humans machines themselves? Thinking, feeling, self-repairing and optionally self-replicating machines, but machines nonetheless?
    Sita could cut off her oxygen supply with trivial ease. She could purge her suit's fuel right into the dirt. There would always be new ways to die a pointless death on Mars. But nothing could stop the new ships bringing new people to their new world. Sita's mission had shown that humans could live on more than one planet. Her identity was now part of the tapestry of human destiny. Something to mull over.
    Sita stared at the sky and remembered the site as it was before they had built the outpost. She liked its design, a central hab connected to a variety of satellite structures by cylindrical tunnels. Against the odds, a tiny patch of human-habitable volume in an unlikely corner of the universe. Her project, her refuge, her home, her triumph. As much as she empathized with her ragtag family of machines, only flesh and blood could rebraid itself into humanity's raging torrent. More than her physical constituents would survive her passing. The contribution of her life's labor to the pool of human achievement might even someday enable her to find meaning despite the inevitability of both death and self pity.
Sita once more looked into the distance, where together they would all build their new city. In her mind's eye she saw their arrival on Mars. They would come, just as the previous cargo resupply missions had come. One by one the ships streaked across the sky. They came as a bright dot, then an expanding fireball, each brighter than the sun. Then the crack and jolt of the sonic boom, the roar of engines felt through her feet. The sun careened off the panels of each ship as they hovered, descending suspended on point-like engine glows and fat columns of dark, rushing smoke. And when the last of the ships had landed, their engines cooling but their effervescent contents not yet disgorged, Sita alone would savor that final moment of silence.

Thursday, February 8, 2018

Falcon Heavy and the era of post-scarcity heavy lift launch

Yesterday (February 6 2018), SpaceX successfully launched the Falcon Heavy rocket. 

This rocket, first publicly announced in 2011, had been a dream for so long I almost could not believe it was only a week away. Then a day. Then an hour. At the moment of lift off, 30 colleagues and I were crammed in a tiny conference room around a laptop with tinny speakers. Several of us had worked on this particular vehicle over its protracted development. You could hear a pin drop. 

And then the 27 Merlin engines roared to life. It flew to space. It staged successfully. It landed two boosters on the ground, and narrowly missed the hat trick. The upper stage flew a whimsical payload of space suit, star man, and Tesla Roadster around the world (and over Australia) once before firing for a third and last time over its home in LA, boosting it away from Earth toward the orbit of Mars. It will orbit in empty space for many thousands of years.

Image: SpaceX YouTube. 

What does this mean? SpaceX does hype well, and millions of people tuned in to watch the launch. People reacted to this concatenation of the impossible in many different ways. I felt a profound catharsis, a joy, a renewed faith in humanity.

As usual, media got a handful of details wrong. This is not the first car ever launched - but it is the first production electric car ever launched! The French mounted (but didn't launch) a Renault once upon the Diamant BP4 rocket, NASA launched 3 electric rovers to the moon in the early 1970s, the Soviets landed two nuclear powered robotic rovers (Lunakhod) on the moon, the Chinese one solar powered rover (Yutu), and of course NASA has also dropped a total of four electric robotic rovers on Mars (Sojourner, Spirit, Opportunity, and Curiosity). 

Second, the Falcon Heavy has been described as the most powerful rocket since blah. As far as I know, it is the most powerful liquid fueled American rocket since the Saturn V. Other rockets with greater thrust include the Soviet N1 rocket, which experienced four catastrophic launch failures in the 1970s, the Soviet Energia rocket, which launched twice in the 1980s, and the space shuttle, which derived most of its thrust from solid rocket boosters rather than liquid engines.

It also has the largest payload to orbit of any American rocket since the Saturn V. Technically the shuttle had more mass in orbit, but a lot of that was shuttle, and its total payload was, at 25T, comparable to other modern rockets. Officially, Falcon Heavy can deliver 64T to LEO in expendable mode. 

Usually, though, Falcon Heavy will be used in reusable mode. In this configuration, it can launch a similar payload to a single stick Falcon 9 expendable launch, or around 25T. Provided that recovery is usually successful and turnaround on the ground quick and cheapish, this mode for medium lift launch is extremely competitive. 

SpaceX, enjoying a high profile, has an unusually high concentration of public pundits, commentators, and self-appointed experts who are always ready and eager to deliver a verdict on a mission or design choice. Let me add to their chorus and say that launch is really hard, and getting it right the first time is just extraordinary. It is impossible to overstate the magnitude of this technical achievement, particularly given that it was privately funded and relatively quickly developed. It is always easier to critique than to build, and I was somewhat dismayed by the usual twitter outrage over everything from the carbon footprint of the rocket to the colour of the car. 

People, SpaceX *deliberately* chose to be provocative. Why? Because they're competing in an industry against incumbent heavyweights who, instead of using their launches to sell electric cars or liberate the launch market, lobby for protectionist policy and sell weapons to third world despots. If you think humanity has a future, that future involves space, and it has to be done somehow.

So, of course there was Elon's red Tesla sports car driven by a mannequin in a space suit with cameras on every angle, a bunch of memes scattered around, and a tiny hot wheels Tesla with a tiny space suit on the dash. I wouldn't be that surprised if this particular car was retrieved in flight and plonked in a museum before I die of old age, or internet outrage.

This launch and its excitement was important. It showed the two generations born since Apollo that space was cool again, space is relate-able, and space is exciting. NASA does space very well, but NASA is beholden to a bizarre incentive and funding structure, and as a result must be extremely risk averse in both mission execution and PR. NASA and SpaceX have formed a productive partnership in part because, for cents on the dollar, NASA has been able to outsource a lot of development and branding risk to SpaceX. 

As a serious space nerd, I was born in the late 80s, an era of shrinking ambition and fading glory. As I learned more about the practice and prospects of space travel, I grew more and more despondent. There was every chance I would live and die without seeing the next big step. This launch was not that step, but it foreshadows it. I can now live with hope. Hope to see, and perhaps to participate in, this really exciting adventure. Maybe Australia will even get a space program?

The single most overwhelming fact about Falcon Heavy is its size. During the shuttle era, there was a belief put into practice that space activity could be modularized and large stations assembled in orbit. That belief has been tested now for 30 years. It is possible, but it seems that, unless there is no other way, assembling stuff on Earth, where one can breathe, is preferable. I am currently working on a book chapter dealing with ideal division of labor by environmental hostility, but the bottom line is that:

"There isn't a problem in space that can't be most effectively solved by building an even bigger rocket on Earth."

My generation of space nerds has spent decades working out how to design ambitious missions with small, bite-sized launches. Falcon Heavy is big enough that it significantly raises the bar for harebrained space activity design. And SpaceX is deep in development of the BFR, a rocket so mind-numbingly huge that it can launch perhaps six times as much as Falcon Heavy. Instead of spending a decade playing space lego in LEO, a rocket like this can launch an entire neighbourhood in fifteen minutes. 

The final point I want to make goes back to the cost efficiency and reusability of Falcon Heavy. Falcon Heavy is really just a special center core that is compatible with any two normal Falcon 9 boosters that happen to be lying around. Provided that SpaceX has perhaps half a dozen Falcon Heavy cores, plus steady upper stage production, it can perform essentially on-demand heavy lift launch. SpaceX has already successfully recovered 21 Falcon 9 boosters - more than half the total they've ever flown. 

We are on the cusp of a paradigm shift in launch. Today, launch is so expensive and missions so difficult and dangerous that program management necessarily has to function in an incredibly risk averse way. In the early 1960s, the US launched dozens of Ranger and Surveyor spacecraft at the moon in preparation for Apollo. What is the difference? In the 1960s there was an essentially unlimited supply of ICBMs that could be used to launch experimental, iterative, minimalist designs. 

Today, a single space robot carries the hopes, dreams, and careers of hundreds of engineers, scientists, and technicians. But there's essentially no reason why previously flown systems, such as the Curiosity Rover, can't be mass produced and one with custom instruments sent to Mars for every university on Earth. It is my fervent hope that Falcon Heavy symbolizes the return of launch supply abundance and post-scarcity robotic space exploration. One Falcon Heavy launch could easily fly six Curiosity-style rovers or literally thousands of solar powered drones to Mars. We're going to need to upgrade the Deep Space Network!

I would like to see NASA, ESA, JAXA, or any other funded agency sign a contract with SpaceX today that guarantees a Falcon Heavy launch to every planetary exploration target on every launch window - a steady campaign of about one launch per year per planet. With a steady pipeline of launches guaranteed, the race will be on to fill each one up with a variety of complimentary and innovative payloads. Let's do this!

Image: Wikipedia.

Sunday, February 4, 2018

Rocket launches!

This post is the first in a series describing a number of recent projects that I've recently completed! This one is to do with rockets.

Some time in 2015 I was reading some space exploration history and came across this photo on Wikipedia.

It depicts the Redstone and Atlas rockets launched with humans on board as part of Project Mercury - the first six flights to space by US astronauts - at their moment of lift off. At this moment, the rocket is supported entirely by hot expanding gases at its base and is pushing hard to escape the Earth. Of course no crewed flight has ever completely escaped Earth's gravity (yet) but getting to orbit is just staggeringly difficult and amazing.

Here's another photo in a similar vein.

These are the launches in Project Gemini, ten crewed launches by Titan II to Low Earth Orbit to test technologies for the Moon landing. Each flight tested a variety of things, such as space walks, docking, control, orbital rendezvous, and the systems that made them possible. 

The following Apollo program used two types of rocket, the Saturn IB and Saturn V. The Saturn V was the most powerful rocket ever launched, and here's a photo of every flight.

The first two flights, and the last flight, didn't have people on board. But Apollo 8-17 took three humans each into space. Six of these flights (11, 12, 14, 15, 16, 17) landed two people on the moon, a total of twelve humans who have ever walked on another rock. As of February 2018, seven of these have died of old age, leaving just five alive. Given the time it takes to develop space exploration programs, there's a good chance that even if China, Russia, the US, or any other country began development in earnest tomorrow, all twelve Apollo moon walkers would be gone before anyone else landed there. Food for thought.

After Skylab was launched on the last Saturn V flight, the three remaining vehicles were parked in various museums or fields and the US space program turned to the space shuttle. Over about 30 years, the five shuttles launched nearly 800 people into space on 134 separate successful launches. One more launch was not successful, and one re-entry was also not successful. The shuttle was retired in 2011, and since then no astronauts have launched to space from US soil. 

Hopefully this won't be a permanent state of affairs. Several entities, including NASA, Boeing, SpaceX, Blue Origin, and Virgin Galactic are developing human rated space vehicles which are due to fly in the next few years.

Still, I was captivated by the minuscule number of rocket launches that have *ever* launched people to space, so I decided to make a version of the images above that included every single launch. 

This process began with identifying every launch and a photo online and collating them in a gigantic spreadsheet. While I was at it I wanted to collect metadata - the who, when, where, why, and how, and combine this somehow. And since I was being ambitious, I have a separate spreadsheet for Soviet/Russian and Chinese launches of humans into space. In total, a meager 321 flights to date. Fact checking and proof reading all the metadata took FOREVER. But one really cool side effect was being able to make a world map with all the landing sites, colour-coded by program.

This is what the metadata formatting looks like in the final version. If you find any errors, be sure to let me know!

I quickly realized that photos at the moment of launch and the same perspective, while being in some cases difficult to find, are also very similar and thus monotonous. So I found a variety of photos of launch that captured some of the power and diversity of the experience. In 2011 I personally witnessed the last launch of the space shuttle in Florida, and it is really something else, even from 10 miles away.

After two years of neglect and then a few months of work, I'm pleased to report that the US launch poster is complete, and indeed hanging on the wall behind me! Moreover the metadata poster is also done. The full size images are available on my website, but this is what they look like!

And the version with all the metadata. 

As an important note, Challenger's final flight is not included in this list as it did not make it above 100km, the boundary of space, before catastrophe struck. By this criteria, other failed missions including Columbia's last flight, Soyuz 1, Soyuz 11 are included as they reached space before suffering fatal accidents during landing. Finally, Soyuz 18a, which suffered a staging fault but reached an apogee of 192km before (barely non fatally) crashing to Earth, would also be included. Early X-15 flights which went above 50 miles (80km) but not 100km, are excluded.

I would love to make a Russian version or even a combined version, but unfortunately publicly available photos of Russian launches are often of very poor quality, or even missing entirely. If anyone can find me a photo of Vostok 3, Vostok 5, Soyuz 12, Soyuz 18a, Soyuz 22, Soyuz 23, Soyuz 34, or Soyuz T-14, that would be amazing. Russia is still regularly flying people to space, so the poster would probably have to have a few blank spaces towards the end!

In the meantime, I literally cannot wait for a new US human space launch so I have to update and fix the poster. I'm glad to have finished it off and I hope you enjoy looking at it as much as I enjoyed making it. 

Saturday, October 28, 2017

Principles of Mars urban planning (first pass)

Autarky Complete and indefinite self sufficiency, or breakout capability to reach such with trivial effort.

Regular readers will know that I occasionally discuss aspects of Mars settlement. This blog is inspired by some slides presented by SpaceX at IAC2017, which showed a SimCity base growing on Mars. Since Mars cities won't look like this, what will they look like?


The first city on Mars is oriented toward rapidly developing autarky, to minimize exposure to the period of time when the base is dependent on shipments from Earth. This differs a lot from a mostly static Antarctic station outpost, and thus determines a lot about how the city must be planned. No one knows for sure how many people are needed for autarky, but is likely at least a million and will thus require decades of blistering growth. The primary role of fixed infrastructure on Mars then, besides keeping death out, is enabling growth.

In Estimating Mars Settlement Rates, I attempt to estimate growth rates using ship construction and utilization estimates, combined with a population/self sufficiency relation. The Earth Mars launch window occurs every 2.2 years, and initial population growth targets are a factor of 4 per window, later dropping to a factor of 2 depending on ship production, capacity, and reuse.

No city in history has needed or managed to sustain growth this fast. On Mars, the primary task is building more city for impending arrivals, and the primary constraint is labor availability. To maximize production efficiency, construction will need to use mechanization, automation, and wherever possible, a shirtsleeves environment.

All this is fairly obvious. Can we now draw a map? Not really. I don't know what a self sustaining Mars city looks like and I probably will not live long enough to find out. Indeed, attempting to learn from experience that doesn't yet exist is a pointless endeavor. But I will wave my hands a bit about the first decade of growth.

In addition to enabling its own maximal growth, the Mars city will perform every other kind of function from life support, transport, recycling, and entertainment to privacy, education, mining, manufacturing, communication, and emergency management. Some of these functions will be distributed, others more centralized. To maximize the utility of limited living space, for instance, compact apartment geometries can be imported from Earth, while landing and launch operations, and other especially hazardous activities, will have to be separated from more vulnerable or less defensible areas. Practically speaking, all functions span a continuum from local to centralized. Somewhere in the middle of this continuum is a point of mandatory separation, and it is here around which individual pressure vessels, habs, vaults, arcades, tunnels, small domes, and vehicles will be divided from each other.

All of the more local functions (health, education, libraries, sport, food, recreation, spirituality, music, common space, food distribution, non-transformative recycling, life support, temperature control, atmospheric processing, grid stabilization, communications, data storage, residential, non-hazardous industrial live-work spaces, etc) are ideally collocated. Since these all take place in a climate controlled pressure vessel, each pod is self-contained and resilient enough to withstand substantial extrinsic challenges, while nominally meshing and sharing capacity with adjacent systems. Vacuum ops are required only for initial construction and exterior maintenance. Everything else is done in shirtsleeves at minimal marginal labor cost.

Opinions vary on ideal structure design and material, and methods will no doubt continue to evolve drastically during deployment. My personal preference is for hangar-like structures. A cylindrical roof spreads pressure, requires no internal support, can be shielded with dirt, and unlike spherical domes, has simple curvature and decouples ideal volume from geotechnical concerns in the foundation. With few or no windows, the interior could be somewhere between a modern submarine or a Vegas casino - both structures quite comfortable despite uninhabitable exterior environments. I envision structures ranging in size from Quonset huts to Hangar One at Moffett field and larger.

Arched structures of various scales (lrtb). Quonset huts, Project Iceworm, South Pole logistics archways, some building in Hawthorne, Hangar One, Atlantic City Convention Hall.

They may be connected by sealable bulkhead doors, while the roof can support solar panels or farms, especially the equatorward face of east-west oriented pods. They also have good volume to material/labor ratios. Building materials can range from curved prefab panels to locally produced concrete or brick. Brick vaults may be assembled robotically without formwork using a variety of techniques. Brick and concrete structures are compressional so need preloading before pressurization with several meters of dirt. Numerous other materials and methods are possible, including inflatables.

A growing Mars base, then, could be a densely packed crosscutting network of arched pods, with outskirts being built out at ever more ambitious scale. Manufacturing, chemical work and other non residential activities can be confined to dedicated pods, which can be repurposed (loft conversion!) over time as demand shifts.

Primary demand for water, (nuclear or solar) power, fuel synthesis and storage is associated with launch, so it makes sense to collocate much of this capacity outside the city. Pads with retractable hoses and robot arms can handle ship surface operations at each pad. If the city outgrows the spaceport, construction of new pads and pipes is much less labor intensive than demolishing and/or rebuilding pressurized pods. Spaceports will ideally be located 5-10km north and/or south of the city to keep east-west approach/departure paths clear. On Mars this is well over the horizon!

While it may be possible to house a million people under a square km of high rise roofs, and contain industrial processes under 10sqkm, farming on Mars, while not an immediate priority, will eventually require the bulk of covered land, perhaps 100sqkm. It makes sense to operate at the same pressure as the base, rovers, and suits (perhaps 340mbar) but with enriched CO2 for plant growth, and every other trick worked out by decades of dedicated research that hasn't happened yet! The primary difference between farming and habitation structures is that farms need transparent roofs, though ideally still with a layer of water, ice, or glass to mitigate radiation. I like the idea of transparent inflatables sealed to the ground at the periphery and anchored with cables at regular intervals to spread the pressure load into the ground. There's no reason why residential pods couldn't be interspersed between greenhouses. These structures, similar in concept to an air mattress, would look a bit like this.

One final consideration is scaling and congestion. Pod bulkhead doors are natural choke points. While clever neighbourhood designs will keep the base walkable for most activities (food, hygiene, schooling, training, recreation), movement of large equipment or lots of people may require progressively larger thoroughfares. This is a great problem to have, since that many people on Mars implies many other problems have already been solved! I think use of tunnel boring machines for subgrade roads and repurposing of legacy structures will prevent problematic congestion.

This is my first pass at Mars urban planning. I have no doubt overlooked many details and obvious issues. I'm interested in developing sensible system design axioms from which any given city plan can be more-or-less trivially derived. I don't know of much other work done with such an aggressive focus on growth, and I'm curious to get a better understanding.

Thursday, October 26, 2017

Visit to Ohio and Australia

Last week, C and I had back-to-back weddings and excitement. 

It started late Friday evening. We found our way to a conspicuously ultra-baseline economy flight, settled in behind an actual dog, and took the red eye direct to Columbus, Ohio. There, we met C's mother's new cat and celebrated the delightful marriage of E and G, whose subsequent honeymoon was, we hear, rather exciting!

I ate a belated birthday cake and then we flew back west once more, passing over spectacular canyon scenery, various faults, a Hyperloop prototype, and the Ivanpah solar thermal plant on the California-Nevada border. Back in LA the sky was a bruised colour from numerous fires, and we found our way to a lounge in the international terminal. 

Later that evening, we boarded a flight to Sydney. I read a few books, watched the latest Pirates of the Caribbean film, and tried to understand system properties of urban planning in space. On the ground, we were unexpectedly collected at the airport by my parents B&A, and whisked off to our rental apartment. We had planned relatively little for the first few days so that essential tasks like finding suits could be taken care of. I squeezed myself into a sharp blue number, while finding time for a few hikes, avocado toasts, and admiring the luxury cat home my parents transformed their flat into.

All too soon it was time to dress up and help my brother M into a matrimonial state. The wedding went off without a hitch. Or rather, only one hitch! We had readings from Song of Solomon and sang Jerusalem, and I didn't burst into flames. Then out to the harbour foreshore for photos, then the golf club for a fabulous dinner reception. Once again I was required to engage in some gentle brotherly ribbing as I gave a mercifully short speech welcoming my new favourite sister (sorry A) into the family.

C and my wedding in August was conducted on a remote island, so it was fortuitous that M was able to assemble the entire family in one place for C and my convenience so soon after. I enjoyed catching up with all the rellies, recharging my accent, and doing some sneaky research into my family's more mysterious origins on the continent. This will be the subject of a future blog post!

Well, we breathed a huge sigh of relief, borrowed dad's car, and set off on a road trip to see a bit more of Australia than we had on prior trips. Australian roads are good but the speed limits are horribly low and the drive thus extremely boring. We did see a good variety of wildlife though. 

First stop was the NSW central coast, where we gatecrashed my grandmother's choir rehearsal, investigated the giant pelicans, went for a hike, and attempted to avoid being dive bombed by seagulls while rowing around the bay. C and I cooked a huge dinner for my grandparents which was well received. One of the parts were potato latkes, which seem to me to be a lot of work to get out something which is basically a baked potato. 

After a couple of days we set out once more, traveling via Norah Head Lighthouse, where we got the best Australian accent lesson ever, to Buttai, a remote corner of the Hunter Valley where my great grandfather used to "go off the leash" with his brothers in semi retirement, reliving their incredibly poverty stricken childhood. Sooner or later the entire area will be strip mined, so good to check it out while I have the chance. 

We continued up the road, turning off on the Bylong Valley Way, a picturesque route through the Wollemi National Park, and also soon to be strip mined. At the town, we enjoyed a quick snack in the general store and explored a nearby graveyard. Almost all the graves dated from around Australia's regional grazing boom (1870-1930) but there were two fresh graves from 2015 in which a 97 year old couple had been (post mortem) interred.

Nearly there. We arrived in the late afternoon at my aunt G's farm outside Rylstone, finding noone but a lot of dogs and a half-cooked dinner. Perfect for exploration, so we found the new house site, the folly (a whimsical shed to contain us) and, eventually, living humans. 

There was much excitement in town because it was the start of the semi-annual international chainsaw large scale wood sculpture symposium. Later, we met a local who was involved in making a horror film documentary, so all things considered it was an ideal time to spend a few days sleeping in an isolated shed with no electricity, running water, phone service, or much but trees and kangaroos around. 

We enjoyed meeting the sculptors and seeing the incredible art being installed everywhere. We found a lot of large spiders, not all of them still alive. The biggest by far was Mr Tiny, a 4" wide huntsman spider who kept a few eyes on us while we took a shower. Later he refused to stand still so we took him outside. 

Overnight it began to rain, so the next day we suited up and went for a quiet walk down the main ridge of the property. This part of the world has some incredible "beehive" sedimentary rock formations. I have long had a secret ambition to hollow one of them out and build a cozy house inside. Once, I stayed in hollow rocks in central Turkey. It might be easier to build the house and then clad it in rock-like material. Getting useful windows that are invisible from outside would also require some finesse. 

All too soon it was time to head back to the city. We drove south and east via the Three Sisters near Katoomba, then spent a few hours at my old school talking to students about careers in STEM fields. That evening we gathered a few friends and gatecrashed my sister's house for an amazing dinner of purple risotto and music. The following day we relaxed with family, hung out with my old neighbours whose house is full of Antarctic art, and then flew back to the US. About an hour after taking off I looked out the window and saw Lord Howe Island cruising by! It's also a pretty cool place to visit, some time.

Recently it has seemed as though I make it to Australia about once a year. It's odd to see evidence of how much time has passed, but I'm sure the experience is similar for Australian residents who rarely see me! I have a few more years before my grey hairs become overwhelmingly obvious, I think.

Sunday, October 1, 2017

SpaceX update at IAC 2017

Late last Thursday evening I enjoyed watching Elon Musk deliver his second update on SpaceX's plans for Mars, or Making Humans Multiplanetary. If you haven't seen it, watching this video will make the rest of this blog much less confusing. I've written a bit about Mars over the years, and I'm always excited to hear what SpaceX has been up to.

A year ago, I wrote a blog about the plan as then presented, and I'm thrilled to see its evolution and write a bit about my new thoughts. I'm going to split this blog into three parts. The first will deal with the major development - money. The second will discuss the mission profile. The last will deal with Mars urban planning.


In 2016, it wasn't immediately obvious how to pay to develop the Mars rocket let alone run the program. A couple of months ago, I wrote a blog on this topic. And I'm thrilled that not only did I not guess what SpaceX was planning (though I was closish), what they have proposed is a better idea than anything I wrote about there.

SpaceX plans to retire the Falcon and build only BFRs for every mission it can think of. It will redirect all its engineering know how to building the new system, and thus finally find a method to freeze design of the Falcon 9 at Block 5 without further meddling! Why is Falcon a dead end? It is not fully reusable.

SpaceX can build and sell the Falcon 9 for about $65m for a single expendable launch. While their recovery of the first stage can help their business both by decreasing their fixed costs by a factor of perhaps three and increasing the number of boosters available, they can do a lot more. Even if they could refly the first stage hundreds of times with marginal cost per launch, the fixed cost of the expendable second stage, which must be near $10m, means that they can't revolutionize launch completely.

Here comes the realization. At $65m a launch they're already crushing the competition. With the landing of the booster SpaceX lacks credible competition for at least a decade. They could lower their launch cost to maybe $20m a launch and nourish the microsatellite market, but the overall demand for launches is likely to remain fairly static in terms of mass to orbit. This is because thousands of cube sats don't weigh much compared to the really big communications and military satellites.

Enter the BFR. The BFR might cost $500m to build. But if SpaceX charges $65m a launch - the same as it is doing today - and the BFR is entirely reusable, then it can recoup that cost within the first year of launches and then some. The BFR only has to fly about 10 times to close the business case, and there's no reason it couldn't eventually fly hundreds of times. Given that the cost of fuel is somewhere around a million dollars per launch, SpaceX has a huge advantage, because customers have no ability to force the price down against other competition who already charges between four and ten times as much as SpaceX.

The BFR is hugely over specced for any launch currently manifested. With a nominal capacity of 150T to LEO and perhaps 40T to GTO, there isn't a satellite it can't launch. Hell, it could probably launch any existing satellite into the sun. Well, not quite - it turns out that's really difficult. Does it matter that there's no real demand for 150T to LEO launches? Does it matter that the BFR will thus fly 5% full for most launches? Not if those launches are profitable. The airline industry's costs are about 13% for fuel, so a single BFR launch may cost as much as $5m, but SpaceX won't have many of the airlines fixed costs, like hiring pilots. So while the BFR's capacity could enable huge space telescopes or probes to Saturn or gigantic space stations, it can also fly mostly empty, or perhaps carry SpaceX's own cargo (such as fuel or internet satellites) with its excess capacity.

Here's another way to think about it. Given the current cost of launch is 100x the fuel cost, a fully reusable rocket could be 100x too big and still make economic sense. Why 150T, then? SpaceX wants these rockets to be big, for moving stuff to Mars. But really large rockets are harder to build and transport. Elon tweeted that the BFR was sized to fit through a door in an assembly facility. The door size constraint also set the size of the Saturn V.

Since last year's presentation, the performance of the Raptor engine has deteriorated slightly, which probably reflects its development path. It's worth pointing out that while a heavier BFR with a less exquisite Raptor might not be very useful for flying back from Mars, it is still capable of flying there, and more than capable of launching stuff into orbit around the Earth. Big dumb rockets suffer a design constraint which is that small changes in structural efficiency have big (and bad) effects on overall system performance. A good illustration of this is the evolution of the Falcon 9 rocket. When it first flew, it could only just loft 9.5T into orbit. Today, it is rated at 22.8T, even though the underlying plan remains the same. What changed? The engines got a bit better, and the rocket got a bit lighter. Imagine if the Mars ship, designed to lift 228T to Mars, turned out for the first few years to only lift 95T? The mission would be over. Elon briefly addressed this in the talk, when explaining a benefit of on-orbit refilling of fuel and oxidizer. Even if the booster turns out to suck, the spaceship can still be fully fueled in orbit, retiring that developmental risk.

What about the possible use case for high speed transport on Earth? Very roughly, the numbers check out here too. Oxygen and methane cost about $200/tonne, and each rocket needs about 4000T of fuel. So taking the airline numbers again, each flight could cost $5m. If each rocket can carry 150T of payload, that's about 1500 passengers, so the per head cost might come to $3000, which is comparable to current long haul costs. Interestingly, over shorter distances, the spaceship alone (without the booster) could make a flight. So this seems to address current usage patterns and cost structures, though is much more marginal than the launch business. Finally, although Elon would no doubt love a launch pad near every city, they are noisy places and town planners generally did not provision for the 4-6 mile exclusion zone they require. My eyebrows remain raised!

So what are we to make of the other efforts to bring about industrial capture of disruptable industries? Even though SpaceX's plan is to capture the launch market with a fully reusable rocket ("shuttle done right") it has a few other plays in internet satellites (Starlink) and tunnel boring (The Boring Company). I think these efforts are developing technology which is important for the Mars project and may eventually become huge sources of revenue themselves.

Mission Profile

Elon Musk provided a few updates on the mission profile. As an example, the spaceship has enough ΔV to fly to the Moon and back without lunar refueling if refilled in an elliptical Earth orbit. This would take about three times as many tanker flights, first to fill up a tanker completely in LEO, then fly that to an elliptical orbit several times to refill the spaceship. A Mars ship launched like this could also take much more cargo to Mars, though its Mars entry would be proportionately more difficult.

I have heard some discussion about distribution of the engines and their uses. It is important to remember that the rocket is ten times heavier when fueled up, and the bigger engine bells work much better in space. Therefore, while one Raptor engine is adequate to land a nearly empty spaceship, all 31 on the first stage are needed to lift the whole stack off the Earth. Similarly, a fully fueled ship lifting off from Mars needs four high efficiency vacuum engines, while two sea level engines are adequate for landing.

I was fascinated to see the section on the Mars entry profile, as I wrote a somewhat less sophisticated model to study this problem some time ago. Landing on Mars is very difficult for all kinds of reasons, but attentive watchers may have noticed that the spaceship enters the atmosphere upside down. Why is that? It turns out that entering the Mars atmosphere at 8500m/s, as SpaceX plans to do, is easily fast enough to skip off and escape the planet entirely. The spaceship is a lifting body and uses its lift not to fight gravity, but to help gravity pull the vehicle closer to the ground as it tries to skip off the atmosphere. In my model I computed that the spaceship would have to fly below about 40km to be able to beat centrifugal force. In this way, the entering vehicle curves around the planet. When its speed drops below Mars orbital velocity (~3700m/s) then it gradually rolls to a nose up attitude, where its lift continues to dissipate speed until, falling straight down it lights the engine and performs a flawless landing on the surface. The 2017 spaceship has really pointy legs, so I hope they pick a really hard flat surface to land on.

The LEO refilling concept has also been simplified. Rather than two spaceships flying close along side like mating whales, they now back up to each other. A small thruster creates enough force for fuel to drain from the tanker to the ship. Alternatively, if the parking orbit is low enough, residual atmospheric drag could provide some ullage force.

Although this was not explained, I presume that the landing pads build on Mars have hatches beneath which coiled hoses can be lifted to the spaceship for autonomous refueling. For this and related reasons, I think the spaceship might need a robot arm. Similarly, while a crane on the ship can lower cargo to the surface, an established Mars base would have to have mobile gantries that can be rolled alongside like siege machinery to facilitate rapid unloading and loading of cargo.  

Mars urban planning
Finally, Elon had a couple of slides on how the Mars base would grow. I like the images. I like all space-related concept art. has some of the best!

But these images are very Sim City. Will a Mars base actually look like that? What will a Mars base look like? Why? I talked a bit about Hab design principles in my Mars book. But Mars urban design is not an established field, and I think Elon was trolling us with this design. Indeed, I think SpaceX's main goal at present is to systematically derisk a human Mars mission to entice NASA and Congress to bite. Designing Mars bases is a few steps ahead. Moreover, SpaceX would like other titans of industry to join in and collaborate on these issues.

In particular, all those glass domes are just 200m from the landing pad! How far from the landing pads does the city have to be? What are its primary functions? What are its design principles? All these questions are good topics for a future blog. But clearly balancing primary needs for transport, power, water, fuel, and above all growth, are non-trivial!

I can't wait to see what comes out over the next year. This, the settling of another planet, remains the single most challenging, exciting, and worthy problem for all of humanity. I firmly believe that if my generation doesn't achieve this, the eventual extinction of humanity is all but certain. For more in this vein, check out these epic Wait But Why posts.

Tuesday, September 19, 2017

Estimating Mars settlement rates


How to get to an industrially self-sustaining Mars settlement in the minimum time?

Previously I've approached the broader problem in a book ( and several blogs, focused on a transport roadmap ( and potential sources of money
( In this blog I'll attempt to integrate previous knowledge and make projections about time frames and costs.

Edit: Now all the data is available (csv) so you can slice and dice it.

In the previous post, I used the following graph to explain the relationship between population and self-sufficiency under a variety of scenarios, including constant and linearly increasing cargo capacity. It turned out that the final result did not much depend on how many rockets were available when, but the timescale certainly does. In this blog, I will build on the SpaceX exploration architecture. The most fundamental bottleneck is the rate of rocket construction and launch, so we will explore how construction rate affects the population and self-sufficiency timeline.

This graph shows a schematic relationship between population (horizontal axis) and mass self-sufficiency (vertical axis) under a cargo-constrained Mars settlement scenario. The settlement begins at the bottom left and scales towards the top right, where at some population likely exceeding a million people they are sufficiently industrially diverse that they no longer depend on crucial technology to be shipped from Earth.

Before I dig into actual numbers, I'm going to state my assumptions. For better or for worse, a lot of space-exploration themed writing, technical or otherwise, does not hew to the best possible standards for rigor. Here, I'm not going to delve into religious disputes about asteroid mining, lunar fuel stops or any other peripheral concept that's not related to the core bottlenecks.

There are two primary phases of the settlement timeline. The first, corresponding to the region of the red line below the purple cusp in the diagram above, marks the phase where scaling population within the limits of cargo shipments is a growing challenge. Loosely speaking, this challenge peaks with the successful instantiation of ore mining and refining for every industrially relevant metal and chemical - requiring interaction with the raw, unfriendly Mars environment. This phase is also the phase most directly applicable to current technology and projections.

Assuming the first phase proceeds more or less as planned and everyone doesn't die, the second phase marks the rush from the cusp to full industrial independence. By this point in the program, at least decades after initial landings, technology at every point of the exercise will have evolved to the point where predictions are difficult to make in 2017. Specifically, I expect that the forcing function of extreme Mars labor scarcity will result in drastic improvements in rockets, automation, manufacturing, and so on. It is possible, even likely, that this flowering of technology will reduce the minimum viable technology population more rapidly than ever-expanding immigration increases it.

That is, at the point of the cusp perhaps 20 years after initial landings, best estimates may still place the minimum viable population at 10 million, at least 30 years away even if the population doubles each launch window. At that cusp, net immigration could be in the tens of thousands per window but will have to increase to 100x that, something I think it rather unlikely.

Instead, rapid improvements in extraction and manufacturing technologies will reduce the minimum viable population to less than a million and perhaps less than the tens of thousands. As this trend continues, it will be possible to launch entire self-sufficient cities in one go, and perhaps a few decades later Mars will have thousands of self-sufficient towns, even though the total population may never reach the 10 million originally required.

It is important to emphasize that self-sufficiency is represented in reality as more capability than practice, since trade will always help increase overall economic efficiency.

I will sketch a picture of phase two, but first I will provide some numbers. Afterall, if the first self-sustaining settlement doesn't get built, there'll be no way for the ones that come after.

Phase One

As I explain in my book, the hard part is getting rockets from Mars to Earth, and to a lesser extent, from Earth to Mars. Here, I'll explain the constraints on total shipping capacity, then build a model that creates a plausible shipping capacity roadmap.

A spaceship has a number of important properties.

Cargo capacity to the Martian surface. Based on the IAC2016 talk and subsequent tweets, initial SpaceX Mars ships will have a cargo capacity of around 300T to the Martian surface. Second generation ships may increase this to around 1000T, but further increases are limited by a variety of physical constraints including the thinness of Mars' atmosphere.

Whether it can be reused and rate of reuse. The Mars ship is composed of a space ship, a tanker, and a booster. Initial boosters and tankers will be flown 6-30 times to refill the spaceship. The first spaceship will fly to Mars, spend nearly 2 years on the surface making propellant, then fly back to Earth. While the first few spaceships will be put near the Smithsonian, later spaceships will be able to fly to Mars every launch window after the emplacement of a fuel/ox plant and storage by the launch zone. Much later, improvements in engines could permit two flights to Mars per launch window. Over this time, the total number of Mars flights a spaceship can perform before retirement will also gradually increase.

Rate of construction. These spaceships are super complicated and difficult to make. Initial spaceships could easily take multiple years to build. Over time, the construction time will decrease and a single line can make more of them per launch window, increasing the total number of spaceships. Additional parallel lines can be built, perhaps by other space agencies using related technology, which also increases the total number of spaceships.

So how many spaceships are there per year?
To answer this question I built a Mathematica model that takes as inputs a function for the construction rate of various types, and outputs all sorts of information about total flights and total mass. This model can be downloaded from my github at But here are the key results.

This table contains a summary of all the different types and versions of spacecraft used in the model.
This is a reconstruction of build rate (per window) from the global manifest data. We see here that as Version 1 reaches rate Version 2 is in the early production phase, on a roughly 8 year design cycle. After 2042, Version 2 production dominates investment and an additional line is added.

This graph shows how spaceship production and reuse increase the payload to Mars year over year. From 2042, Version 2 lifts the total throughput by nearly an order of magnitude.

This graph shows the cumulative cargo transported to Mars, reaching the crucial million tonne mark in about 2052. Given that mass transport begins in 2027, this process takes only 25 years to achieve.

I had a couple of surprises when seeing the results of this model.

First, total payload capacity increases very quickly. The period of time for which an initial settlement is constrained by quasi-constant cargo capacity is basically non-existent. This actually makes sense heuristically, in that it's easier to build lots of spaceships on Earth than it is to build a complete industry in space. It has a positive consequence too, which is that if the general relation between population and mass independence is maintained, the overall population can be scaled up even more quickly than before.

The second surprise was that there is genuine utility to building a Version 2 spaceship with 3x the capacity - as it compresses the timescale to reach a million tonnes of cargo by 15 years.

So how quickly does the population scale?
This is another difficult question to answer, but assuming a population-industry trajectory like the red curve given in the first graph above, the total mass each sequential settler has to bring with them can be predicted and a population-mass relation extracted.
This graph shows the total mass payload per person, assuming that the first 10 people, landing in 2027, consume the 900T of payload then available, and that the residual payload is 500kg, enough for a person and the food they have to eat on the journey.
This graph shows how the cumulative mass shipped scales with population. The population reaches a million people as the cumulative mass hits 620,000 tonnes.

This graph shows how population grows as a function of time. Here, the population exceeds a million in the 2050 launch window, 23 years after first landing.
This graph shows the window over window fractional population increase. The population grows very rapidly in the first decade to around 10,000 people. This reflects the easy gains of rapidly increasing shipping capacity and gas/water processing for plastics and propellant. 10,000 people is enough to begin mining and processing of metal ores to complete the set of available Martian feedstocks for the development of advanced industry.

Window over window gains drop below 2 from 2045 as all available space in Mars ships is consumed with passengers. If further explosive growth is needed, more ships and more flights are needed to transport people.

What does it cost?
In the previous section we eliminated mass to discover the population-time relations. Here, we reslice the data to discover the mass per passenger on a launch window basis.
This graph shows that by 2033, cargo mass per passenger has fallen to about a tonne, putting a ticket within reach of a middle class family. Someone arriving in this launch window could be the 10,000th person on Mars, and will mark the transition from program-selected specialists to self-selected professionals.

In 2035, a Version 1 spaceship can carry about 300 passengers, each with a tonne of cargo. By 2044, a Version 2 spaceship can carry about 2000 passengers, each with 500kg of cargo.

Let's adopt some ballpark numbers. A version 1.5 spaceship+tanker+booster may be constructed for a price comparable to a modern composite passenger jet, say $500m. Each refit costs $100m (of which a tiny fraction is propellant), for a total lifetime cost over 16 reuse cycles of $2b, or $125m per flight. If this is split evenly in time and between 300 passengers in 2035, the per ticket cost is around $420,000. A version 2.5 spaceship+tanker+booster will cost $500m to build, $50m to refit, and fly 30 times. Split evenly, the per-ticket cost in 2044 is $33,000, for a $65m/flight total cost.

Unfortunately it is difficult to be more precise than this, due to multiple cascading uncertainties. By the onset of "general admission" tickets in 2035, many billions will have already been spent on development and construction of spaceships which may not recover their construction costs in regular service for decades.

That said, I can attempt to estimate development and construction costs. Design rate and cost for both spaceships is $500m and 20/window, which works out to around $4.5b/year. This starts at the beginning of the program, even if the production rate doesn't reach design rate until 8 years later. Thus construction costs alone reach $4.5b/year in 2022 and $9b/year in 2032.

Reuse costs are initially low due to low numbers of reused spaceships, but eventually dominate overall program costs. By this point, however, ticket revenue will effectively offset this cost, and eventually fund the construction of new ships and entire program.

The primary financial outlay, then, occurs between 2018 and 2040, and may total $132b at an average of $6b/year.
This graph shows how the number of ships built and launched varies over time. If refit costs are 20% building costs, then building costs dominate until about 2040, by which time general admission revenue can begin to cover much of the program's operating costs.

Model Limitations
This model is generated from rocket building history alone. It doesn't take into account any other aspect of the universe, including human mortality, accident rates, or the possibility of mission failure. While guessing numbers and adding them to the model is technically easy, I judge that it would greatly increase uncertainty (fudge factor) while not adding much insight. Model complexity is only useful up to a point.

Phase Two

Earlier, I defined phase one as the era of cargo constraint, and phase two as the era of accelerating returns. As we've seen above phase two has a different kind of restraint, namely an immigration capacity restraint. By 2045, the critical path for growth is how many people can fit on a Version 2 spaceship, although under nominal predictions a million people are reached only 5 years later, by 2050.

Here, I will wrap up by listing technology concepts that could lift this constraint and permit further high rates of growth into the future.
  • Higher construction rate of Version 2. Constraints on construction and launch rate are so low that many thousands of ships could be launched every window. Construction rates could climb into the hundreds per year in a single factory. Ticket revenue could fund this, if a positive margin on launch business was maintained.
  • Faster ships that can launch multiple times in longer launch windows. This requires better engines and better mass ratios, but eventually there could be cargo and people arriving year round.
  • Entry of other companies and agencies into the bargain. Could achieve 10x, possibly 100x on rate.

On the flip side, I think it's likely that the minimum viable population requirement will shrink to the point that even small outposts will have the ability to reach full autarky.

Project Timeline

Mars 2020 - Aquifer search probes land, Version 0 ships performing atmospheric tests on Earth.

Mars 2026 - First 10 crew arrive, 3 ships on surface. They scale propellant plant, assemble a lot of base for new arrivals.

Mars 2030 - Middle of explosive growth phase, base population grows to near 1000. Pilots for all primary industries established.

Mars 2035 - First private and 10,000th settler arrives. Mars spaceport hosts dozens of Version 1 ships and the Version 2 prototype, looming over the rest.

Mars 2043 - Ticket prices fall below $100k and the population exceeds 100k. All secondary industries at least in pilot phase. "Mission accomplished"

Mars 2050 - Population on Mars exceeds a million. Dozens of outposts formed.

Mars 2060 - A web of towns and cities all over Mars, with the first base and by far the largest forming a sort of hub.