Ascent was flawless - 33 booster engines and 6 ship engines all the way up to the suborbital trajectory - and at staging the booster completed its flip and burn manoeuvre well with all 33 engines successfully relighting, although SpaceX reported that it ended early. It is not clear yet why this happened, but it caused the booster to fall short of the landing area and may have been connected to late failures.

The splashdown in the Gulf of Mexico became a crash landing when the booster failed to relight enough engines for the landing burn and impacted the ocean hard. At one point 9 of 13 were shown to be firing on the on screen telemetry, but some shut off. I’ve used the public telemetry to roughly estimate the speed on impact:

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It feels unlikely, down here in the drizzle & mud, but humanity’s destiny is in the stars.

By hook or by crook or by twisted fantasy, we owe it to ourselves to take the leap into the big black. It looks impossible for now, but what choice do we have? We’ve conquered the new world, we’ve mapped the dark continents, cured agues and created silicon intelligence, so what else is there? Let’s take to the frontier once more, lest we lapse into solipsism and digital dreams.

And what to do when we get there? We’ll build and breed, of course, but to do both requires energy. Energy to heat & light ourselves, bring oxygen, render distant soils, grow crops and bring forth metal. Energy is life.

But whether Mars, the moon or some distant spinning tube in the heavens, we need a way to turn effort into ergs, and one that doesn’t turn off at night. If there’s a night.

This means a nuclear reactor, but one specially adapted to the dry fridge of Mars or the moon. There can be no cooling towers, no rivers, minimal concrete and no staff of thousands. How do we do it?

Let’s design a reactor for the skies and bring the power of the atom to Mars!

1: Squaring the circle.

We need energy for everything, but for most things space-based we make do with solar panels, or at least radio-thermal generators, so why not stick with these? We know how to use them after all. Why take a fling with fission?

Well there are a couple of reasons. For one, there’s the obvious factor that the sun sinks below the horizon every night, but that’s obvious. The second point is that if you want to do anything serious on Mars like, say, build things or support a small research colony of actual living, breathing people, you’re going to need a whole lot more power than we currently supply to any space mission, anywhere.

To take a rough comparison, let’s look at the friendly face of the Perseverance rover, which after four and a half years is still bumbling around the red planet and is currently exploring something called the Jezero Crater. No, me neither.

Now, the steadfast, stubborn little rover (I say ‘little’; it’s actually the size and weight of a small car!) needs a reliable power supply. Unlike most space-based explorers, this persistent voyager uses the power of the atom, with a supply of Plutonium 238 slowly decaying its way down to nothing inside the machine. This releases 110 Watts and a decent bit of heat to keep the probe all snuggly warm in the harshness of the Martian night, which is enough to do real science, explore the surface, take samples and do fun things like deploy a teeny-tiny helicopter over the dry-frozen desert of another world. In other words, plenty of power for what it needs.

But not enough for what we need! For those who remember the era of the Tungsten incandescent light bulb (that’s pre-smartphone era, Gen Z readers), 110 Watts is the size of the really big ones that could light up a whole room, and probably made your father cross at the electricity bill back in the day. In other words, it’s enough power for a slow, prowling robo-rover or a big 1980s living room, but wholly insufficient for keeping people alive on the surface of an oxygen-free freezer.

For that kind of thing we need a mission power in the range of 10s to 100s of kiloWatts minimum, thousands of times more than Perserverance and far more than you’d be comfortable generating from a radio-thermal generator working off decay heat.

On a manned mission, which would need to keep people alive for long periods, you’d need that power for creating oxygen, for heating the crew, for generating nitrogen fertilizers, making metal, forming fuel and creating concrete. All things I covered in an article about a year ago that went into a little too much detail on everything you’d need to do just to create concrete on the fourth planet from the sun.

Incautious Optimism

My Martian Hobbit Home

The prospect of colonising another world has struck a flame on our collective imaginations for centuries, and Mars looms large in these ambitions. Yet as rockets grow larger and dreams grow more fanciful, a sordid question remains…

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2 years ago · 13 likes · 3 comments · Incautious Optimism

December 12, 2024

The prospect of colonising another world has struck a flame on our collective imaginations for centuries, and Mars looms large in these ambitions. Yet as rockets grow larger and dreams grow more fanciful, a sordid question remains:

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And that’s a lot of power!

So what about solar panels? Well it’s certainly possible, but our closest heavenly bodies are a bit mean to solar panels. The moon, for example, has a night that lasts a fortnight, which is great if you’re into stargazing. Not so great if you’re trying to live off a giant battery for fourteen days. Mars, meanwhile, has dust storms that last for weeks; not only an abrasive, occluding hazard to solar panels, but also likely to significantly lower a would-be colony’s available power for the duration. Not ideal.

Part of the trouble is the nature of NASA mission design. NASA, as a rule, doesn’t propose missions with a power requirement above what can be reasonably achieved, and development of a new space-based power system usually needs a mission to anchor itself to. This is a fun bureaucratic game of chicken & egg whose only progeny is efficient, but underpowered, spacecraft. Surely we can do better? Well, NASA eventually did.

Enter the Kilopower project!

2: Sodium Simplicity.

The Kilopower project designed a micro-reactor which could sustain a kilowatt of useful electrical power over a minimum of ten years. Now, a kilowatt isn’t very much; it’s about what you need to boil a kettle or run an average English household (or half an average American household).

This may not sound terribly impressive considering that Westinghouse happily commission reactors that generate a Gigawatt of electricity per core, or a million times what the Kilopower does, but you shouldn’t focus on power here, but on design. After all, the reactor is absolutely tiny, can run for well over ten years with barely any maintenance and, most importantly, can be scaled-up as required.

Additionally, Kilopower needed to be appropriate for use in the vacuum of space, on the moon, on an asteroid or on Mars. In all cases that means you lack a number of staples that Earthbound reactors take for granted, namely: Water, atmosphere, gravity, lots of steel & concrete and plenty of regular maintenance and refuelling. Kilopower would need to work without any of these, in a simple, robust and safe package that could be installed on-site by a couple of blokes or a remote rover. Put that all together and suddenly it’s not as easy as it first sounds, is it?

Not as easy, but very, very ingenious.

Firstly, it’s tiny. A core the size of a toilet brush receptacle is joined to a mad twisted stainless steel crown of pipework terminating in a jewellike cluster of cones & pipes at the top. It looks like something a mad alien emperor would wear as a ceremonial headpiece while he casts unbelievers into the sodium lava lake. Possibly while stroking a sort of catlike creature.

The tiny core can remain small because it runs on 93% enriched Uranium 235: This is the proportion of the Uranium that is fissile U235, rather than indolent Uranium 238. U238 makes up the vast, vast majority of uranium on Earth and enrichment is expensive, so how much is 93%? Is that a lot?

93% is really really enriched. A normal pressurised water reactor, the kind we use to keep our lights on, runs on an enrichment level of about 3%-5%. Anything above 20% is considered ‘highly enriched’ and puts you in the territory of military naval reactor cores. 93% is just nuts, a very spicy meatball indeed!

One of the reasons for this unparalleled spiciness is the need to stay small, suitable for space travel. The more enriched the fissile uranium, the smaller the reactor can be. The other reason you might want to use very highly enriched fuel is to make use of the ‘fast neutron spectrum’.

Basically, fission is most likely when a neutron, shooting out of a fissioning uranium nucleus, has just the right energy level. Unfortunately, it starts out hundreds or thousands of times too energetic, and so in a conventional nuclear reactor needs slowing down by collisions with something called a ‘moderator’, typically either water or graphite. This moderation raises the chances of fission and allows modern reactors to work at relatively low enrichment levels.

In a fast neutron reactor, by contrast, you don’t bother moderating but let the neutrons blast around at high speed, and use higher enriched fuel to compensate. This means that you can keep the thing smaller, and also means that high energy neutrons have a small chance of transmuting boring every-day U238 into plutonium 239, which is fissile and a great energy source. In such a way, a fast neutron reactor can make non-fuel (cheap, common U238) into fuel, which is a neat trick, though not one that Kilopower is interested in. Kilopower simply wants to be compact and long-lasting, so highly enriched fuel and a fast neutron spectrum is the way to go! After all, every kilogram costs money when you have to launch it into space.

As a result of this high enrichment, high energy density and the need to avoid moderating water in the core, Kilopower is cooled by liquid sodium: A highly reactive molten metal that becomes liquid at a very manageable 98 Celsius; something that Kilopower will reliably stay well above for the entirety of its operational life, once started.

But first let’s zone in on what’s really unique about this little Reactor That Could: It’s not the high enrichment, it’s not sodium coolant. It’s simplicity.

A normal Earthbound power reactor has banks of pumps, water & steam injection pressurizers, control rod actuation, frequent movement of fuel during refuelling cycles, complex systems of valves, back-up emergency coolant and deluge systems, boron injection… it goes on & on & on. A terrestrial nuclear plant is a triumph of safety-conscious system engineering, but it’s a complicated one, and Kilopower dispensed with all of this. The intention for the system is that you set it up, get it started and just… forget about it, pretty much.

It has a small, solid core with no moving pieces except for the control rod which is designed to be moved on startup and then kept in place, unmonitored, for a decade at a time. The small size & low power means that reactivity effects are dominated by thermal expansion and are extremely stable. Low power designs (less than 100 kiloWatts thermal energy) make thermal management and irradiation damage a non-issue that does not complicate system design. Very low power level designs (less than 10kW thermal) feature such low burnup reactivity that movement of the control rod becomes a ten-year interval. A literal ‘tin’ wedding anniversary, marked out by tweaks to the control rod. There’s a quirky Martian anniversary gift for you! Even at much higher power levels, the stability is such, and burnup so low, that control rod movement would be something you’d only have to do occasionally, every few months or annually. In essence this is a nuclear battery.

In all cases, the reactor is designed to handle worst-case transients such as coolant loss passively without any need for control inputs, further simplifying the system. Truly, this is a zen ideal: Feng Shui engineering, where less is more and the system simplicity brings reliability and safety, all in one. Perfect for missions to space.

Why, Kilopower doesn’t even have any coolant pumps!

That sentence above might give you pause. The more well-informed of you may know that there are terrestrial reactor designs capable of passive cooling, but these rely on convection, or the induced buoyancy cause by density reduction when a volume of fluid is heated in the core. That’s all very well & good on Earth, but Earth has something in abundance that the moon or Mars has very little of, and deep space none at all: Gravity.

How the hell do you cool a core passively without convection and gravity?

Well there’s a way, and it works very well for petite sodium-cooled designs like Kilopower, but to surmise what it is I’ll give you a little clue: Look around you. Find a plant or, better yet, a tree. A tree also lacks pumps, but still needs to get nutrients from the roots all the way up to the leaves, and our little reactor uses something very similar.

It’s capillary action!

3: Of Tree-Trunks and Sterling Engines.

Above the core, projecting like some kind of twisted metal flower, is a radiant expanse of heat pipes. These unassuming stems, almost plantlike, form the primary means of pulling heat from the core, and like a redwood growing majestically in quiet forest, like a grass stem or sunflower rendered in titanium by an atom-obsessed deity, Kilopower pulls sodium and water by capillary action to stay cool!

The heat pipes penetrate the core and surround it peripherally, soaking up heat and vapourising the sodium in the pipes. The pressure of evaporation pushes the vapour along the middle of the pipes to the interface with the Sterling engines, where the falling temperatures condense it into liquid again, albeit still seriously hot. This fluid is then drawn into the inner periphery of the pipe, a narrow wick section that pulls the fluid back to the atomic heart by capillary action: The movement of fluid in tight spaces caused by liquid adhesion to a solid ssurface. Further out, water heat pipes provide the heat sink to the radiators.

OK, so now we have a means to passively move coolant around that doesn’t require pumps or gravity. Hooray! But we still need a way of driving some kind of generator and making electricity, else all this ingenuity will be for nothing. This is achieved by something called a Stirling Engine; a simple and very reliable way of converting thermal gradients into reciprocal motion.

A Stirling engine works by sharing a reservoir of water in between two cylinders, one connected to a heat sink and one to a heat source (in this case, the condenser section of a heat pipe). There are a few ways to construct a Stirling engine, but in all cases the motion is driven by an oscillatory expansion & contraction cycle powered by the heat source.

Firstly, the heat source causes a local expansion that drives the first cylinder outwards, connected to a crankshaft linked to a second cylinder. This motion subsequently causes the second cylinder to open shortly afterwards, matching the increased volume of the shared fluid reservoir as it’s heated. The cooling of the fluid from the heat sink then increases the density of the fluid and shrinks the overall volume, reversing the process and returning the engine to its starting state. As the cylinders move in & out, their exposure to the heat source and heat sink increase & decrease in turn: When the cylinder from the heat source is fully extended there is a maximum net energy flow into the reservoir, and the net expansion drives open the heat sink cylinder, which switches the energy flow outwards and causes a net shrinkage, and so-on and so-forth, over and over.

Here are a couple of animated images that illustrate the concept better than I just tried to!

So we’ve explained how the design uses a stable solid-state core and low-pressure, high-temperature molten sodium. We’ve explained how capillary action can drive a pump-less heat pipe flow and pull energy from the core. We’ve even explained how, with a heat sink, you can then turn this net thermal energy flow into mechanical action that can drive a shaft and so generate electricity.

But what can we use as a heat sink? We have no rivers or cooling towers to play with, after all. The answer once again, is wonderfully simple: Kilopower uses a radiator.

4: The Atomic Mushroom Field

We all know the most distinctive feature of a nuclear power plant: The cooling towers. The fluted, curvaceous steam-chimneys are iconic, nearly ubiquitous and instantly recognizable. There is a reason for this.

Evaporation makes use of a phase change in water to suck vast amounts of thermal energy quickly & efficiency out of a system. The reason this works is that phase changes (between solid and liquid, liquid & gas) demand a lot of energy as they transition from low enthalpy to high enthalpy states. To get an idea of how much energy this is, consider ice in a class of coke, supped on a hot day. Make it a hot day on the beach if you like, sure add some palm trees too, why not?

Anyway, what you will have noticed is that ice added to your fizzy coke takes a surprisingly long time to melt, even on a very hot day where the liquid itself is being heat basted by the sun and your skin is peeling. The reason this works is something called melting enthalpy: Raising a one kilogram block of ice one degree Celsius takes about 2 kiloJoules of energy, or the amount an electric kettle will convert to heat in one or two seconds. However, transitioning it from ice at 0 degrees to water at 0 degrees (melting it) requires a somewhat more impressive 332 kiloJoules. This is why ice is so effective at cooling down your coke, because the enthalpy change of the melting ice sucks up lots and lots of available heat.

And it’s even more extreme with evaporation! The condensation enthalpy of water, which is what’s needed to get water at 100C to turn into steam at 100C at sea level pressures, is an absolutely ridiculous 2,257 kiloJoules per kg! In fact so huge is the enthalpy change required to evaporate water that if you started with water ice at absolute zero (-273 Celsius) and heated it all the way to steam at 100C, the change from liquid water at 100C to steam at 100C would take almost two thirds of all the energy required to get it there from the coldest temperature it’s possible to be.

This is why sweating is good at cooling you, and it’s why evaporation works so well to cool nuclear plants. This is also a very long-winded way to admit that KiloPower has a massive handicap in lacking access to environmental water for cooling.

To make up for this, the KiloPower reactor uses huge radiator fins, which emit heat by radiation into the local environment and therefore can work in thin atmospheres or the vacuum of space. This can be a savage-looking vertical fin or a friendly looking dome shape (you call it), but what’s unmissable is that even with the mini-reactor’s tiny power levels, the radiator dwarfs the reactor system itself.

In fact the design-shaping effect of nuclear radiator systems, where evaporation isn’t an option, can even be seen in a NASA concept for a nuclear-electric Earth-Mars spacecraft. In this nuclear powered albatross, a Brayton cycle fast reactor powers electric thrusters with either Xenon or Argon. This massive interplanetary cargo truck is powered by a hypothetical 1.9 MegaWatt nuclear reactor (a lot larger than KiloPower), and the bizarre thing about it is that the reactor power is limited by the amount of radiator fins that can fit in a single SLS rocket orbital launch stage. An entire spacecraft is literally designed backwards from the heat-sink!

And so it is with KiloPower and other low-maintenance reactor designs. When we finally plug up the courage to bridge the black and land on the Red Planet, or the moon or wherever, radiator fins & domes will probably characterize our first settlements.

Mars, home to the atomic mushroom field!

And so with fuel cycles, cooling, electricity generation and recovery from excursions covered, the only thing left is shielding, and here we will simply borrow from nature! A low power, self-stabilizing reactor doesn’t need complicated shielding systems, and can just be buried in the rock. On our new world, the first trees we will plant will be of the fissionable variety.

But design is one thing, and qualifying is quite another. Until kiloPower came along, every new American advanced reactor design for the previous 40 years had been a failure, with nothing brought to realization. To make our little space-reactor the exception, NASA needed to do some testing. And so commenced a new project: The Kilowatt Reactor Using Stirling TechnologY test project.

KRUSTY for short.

5: Keep It Simple, KRUSTY!

Saying you have a passive, excursion-proof reactor is one thing, but you have to prove it. The KRUSTY project incorporated fully-representative testing of a high power KiloPower reactor configuration and its cooling, heat management, electricity generation and structural systems. How did this work, where previous reactors fell flat?

The daily mantra of the KRUSTY team was something that sounds very simple, but is surprisingly hard for engineers to grasp, and it is: “The best is the enemy of good enough”. The reactor had to be simple, hands-off and do what it needed to do, no more. Far too often the instinct for perfectionism grips the engineer’s soul, and before you know it simplicity has been usurped by the kind of complex, twisted design that gives non-engineers palpitations and engineers the horn: Pipes and ducts like a glassblower’s nightmare, active control systems moving effortlessly from one ideal state to another via valves, motors, sensors, smart control. Thermal and fatigue limits cut to the bone for light weight and efficiency, running a knife-edge of engineered perfectionism.

How exhausting.

Do Not Enhance Performance At The Expense Of Project Success! It should be written in gold letters three feet high.

And one of the benefits of keeping it simple was that the KRUSTY test regime was simple, too. A fully system-representative test rig was created with correct materials at every stage (though with non-fissile “fuel”) so the system could be run up to full thermal power via electrical heating and control excursions simulated on a real system. Neutron absorption could be tested, the damping effect of heating on the neutron reflector assessed, the failure of one or more of the Stirling engines simulated and a loss of coolant scenario run. Because of the simplicity of the design it wasn’t even necessary to run reactivity assessments with control rod actuation, since the tiny, beautiful reactor is entirely passively controlled and only needs the control rod moved to start it.

None of this would have been possible without the guiding principle of design simplicity, and there’s a lesson in this for all of us.

Sometimes the hardest thing to do is take something away.

The core design philosophy of Colin Chapman, founder of the legendary sportscar maker Lotus, was “simplify, and add lightness”. Now anyone who has climbed in or out of a Lotus Elise would probably agree that maybe he could have added a bit more space as well, especially if you’re six foot, but the principle stands. Kilopower could have added more control systems, it could have added a robotic refuelling cycle, remote process monitors, active dousing systems, all kinds of things. It chose not to because, hiding in this empty room was a spirit of pure invention. Invention and a realization: That if you make something pure of form, it doesn’t need to be complicated to work.

And so, for the first time in four decades an advanced reactor was tested in the United States! May it be the first of many.

And may its children take us to the stars.

So it is not out of the question that we stand at another inflection point of history right now. What are the paths we might end up on?

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A previous suborbital mission in February of the Long March 10A variant, which also functioned as an abort test for China’s new manned space capsule, demonstrated part of the recovery process by splashing down in the sea close to the recovery vessel. After this dress rehearsal, they were ready to try for real, and succeeded in catching it on the first attempt.

I have written before about how the lead the US (mainly SpaceX) has over China is down to reusability. You can read a detailed analysis I have done of that here:

This rocket is produced by the state-owned launch company CALT, rather than one of the many private launch companies attempting the same. We should expect to see other Chinese vehicles recover their first stages soon.

The Catch

Despite the inevitable claims that China merely replicates stolen western technology, the recovery mechanism used by the LM-10B is unique. Cables move into position as the rocket approaches so as to capture it regardless of any position error, which is more tolerant than SpaceX’s tower arms.

The cable method also means that the rocket can fly without carrying heavy landing legs which cost Falcon 9 some payload, and also once the rocket is recovered it is in a stable configuration and cannot tip over, which is something that frequently plagued early Falcon 9 landings.

The main disadvantage over the Super Heavy catch method is that this is still a downrange recovery, with the cost and delay that entails. It is also not clear how well it would scale to a larger vehicle. It may well be that, when China scales up to its Starship-sized Long March 9 rocket, they end up with a booster recovery system similar to the tower arms used by SpaceX out of necessity.

Regardless, it could be argued that any recovery method that gets the booster back to you intact is a good one. That is the most important thing, and China achieving it is a significant milestone.

On to the Moon

This reusable rocket is part of the Long March 10 family, which was originally initiated for the Chinese lunar program as a more efficient stopgap before the Starship-scale Long March 9 is available. It comes in four variants:

• LM-10 - a three core all kerosene/liquid oxygen rocket, superficially similar to Falcon Heavy, that is capable of sending around 27 tonnes to the Moon, on par with SLS. All its stages are expendable. This will debut next year.

• LM-10A - a single core variant of the above, with a reusable first stage. This will be used to send the new Mengzhou capsule to the Chinese space station, and is expected to fly later this year.

• LM-10B - Yesterday’s flight, this is similar to the LM-10A but replaces the kerosene/liquid oxygen upper stage with a liquid methane/liquid oxygen upper stage, allowing more payload to LEO. This will be a commercial launch vehicle.

• LM-10C - Still under development, this will replace the first stage with a liquid methane/liquid oxygen variant. Likely it will supersede the LM-10B.

Official sources have stated that the LM-10B can use boosters from the LM-10A, so we can assume they are identical, and the LM-10A booster is a reusable variant of the LM-10 boosters. That means that this launch is contributing to the Chinese manned lunar effort. The LM-10 shares a common upper stage design with the LM-10A, so when that rocket flies later this year all parts of the lunar rocket will have had some testing. Both spacecraft needed for the mission are already being tested as well.

The United States is not standing still though - this week has seen both a static fire for the next Starship test launch, and the beginning of stacking of the SLS for Artemis III. The race is surely on, and from next year onwards we shall see an increasing frequency of launches from both programs.

The Rest of the World

Despite being, seemingly, 10 years behind the US in reusable rocketry, the rest of the world is even further behind. Russia, Europe, Japan and India have all not yet developed any comparable capability, and it will be some time before they do.

No nation can claim to be a 21st century space power without this reusability - the gap in launch capability is too great. The US had this space to itself for a decade, and now the rising power China is joining that club. The strategic implication is hard to avoid: any other nation or bloc that wants to be a part of the space future should act now, or concede space to others.

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This is not mere rhetoric; both because of significant delays on the US side and the innovations of their own program, China is not far behind and can be expected to achieve a landing by 2030.

I thought it would be useful to do a side by side comparison of the two programs - not just in terms of their lunar programs, but as space powers in general. As impressive as China’s progress is, there still exists a significant gap between their mass to orbit and that of SpaceX:

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You can read the original article here:

Here I am going to expand on this model, and address some issues raised by readers. I’m hoping to stimulate some discussion both from those interested in the space side of things, and from those with a background in economics and finance. If you know anybody who might be interested, please considering sharing this article:

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To recap, the original model assumed a wealth distribution of potential colonists, with the wealthiest leading the way, and thus a diminishing rate of kilograms/person of cargo from Earth. The test of colony viability was if this rate could be offset by an increasing mass leverage - i.e. the ratio between kilograms of cargo from Earth and kilograms of useful materials in the colony. I showed that for reasonable wealth distributions, and reasonable advances in in-situ resource extraction and closed cycle life support, it was in principle possible to stay economically self sufficient.

It did, however, require >15% year on year growth in the leverage rate to sustain if you want to stay in the zero exports region - i.e. where you can run the entire colony purely on this model. In reality, most colonies will be able to export something to make this close more easily.

Inflation

Some people noted in the original model I did not account for inflation in the returns. This is a fair point for most products, but recall that the overwhelming expense here (to the point we can basically ignore everything else) is launch costs, and launch costs are not inflating. The cost of launch is dropping and will likely continue to drop over time as new competitors enter the market and volume increases.

On longer timescales, where we want this model to still work, launch costs beyond Earth orbit will decrease through in space infrastructure, such as momentum exchange tethers, in space propellant production, and advances in propulsion. These technical improvements are beyond the scope of this article (although I cover them elsewhere), but suffice to say ignoring inflation is actually a conservative assumption here.

Children

I initially constructed this model to demonstrate a financially viable way of bootstrapping the colony - but the first question a lot of people raised was how the model looks when the colonists start having children.

In a situation where the birth rate matches the death rate, the situation is unchanged over the long period. However, a burgeoning space colony will likely aim to have a high fertility rate (especially if managed by Elon Musk!). So we need to account for the output of the colony fund being diluted by an increasing population.

It turns out that, because even at high TFR the annual growth rate is around 1-2%, this does not shift the model too much. A growth trajectory that is in the no exports region, 20% mass leverage growth per year, still remains there:

If a growth rate is only marginally self-sustaining, then it may make a difference. But the rate at which mass leverage can scale remains the overwhelmingly most important variable for the colonists.

Children require labour to look after them, reducing the workforce available for the main task of increasing the mass leverage. On the other hand, they can start helping out at a younger age than would be normal on Earth. Is changing the cartridge on a CO2 scrubber too hard for a 6 year old?

These dynamics are difficult to fit into this broad model, but in the end it doesn’t matter too much. Generally, people are sensitive to economic conditions when deciding whether or not to have children, and thus will only start having kids once they colony is well established and can support them. It will likely be some time after the initiation of the colony where this happens.

Those Left Behind

Previously I said that the colony fund would have to find some friendly jurisdiction to avoid being overly taxed and seized. This is one approach, but it may also be advantageous to accept some level of tax on the gains of the fund in order to secure the long term support of a state back on Earth.

A colonist travelling to space in this manner would, unusually for an emigrant, leave all of their current assets behind in the country they exit. If the returns on the fund are taxed, it essentially just shifts the curve downwards.

The impact is noticeable, but manageable, for reasonable levels of tax. Obviously if the tax became excessive, it could sink the enterprise. Some politicians may wish to do this on purpose. Others would do it simply out of the sense that there was a pot of money to grab at for their own short term needs.

My own government in the UK has unfortunately gone in this direction; recently some leaked WhatsApp messages from a cabinet minister shed light on the attitude, recounting his experience speaking to other Labour MPs:

Every meeting I have is: ‘Who can we tax in order to pay benefits to others?’

-Pat McFadden, Work and Pensions Secretary

A large fund of people who aren’t on the same planet to complain would be a juicy target for those looking to fund ever expansive claims on the treasury. Indeed, there are rumours that the incoming Prime Minister, Andy Burnham, is being advised to increase capital gains tax to the same level as income tax.

Punitive taxation on a fund of this sort would be shortsighted though. A country that hosted one at reasonable rates would find its domestic space launch well funded, as well as any industries supplying things the colony could not yet manufacture. The alternative would be for those interested in such an enterprise to flee the country, launch from a less extractive tax regime, and leave the treasury with nothing.

The colony and its launching country should not have an adversarial relationship. This is not a formula for abandoning society, but for extending it to the stars in a sustainable manner.

I’ll be continuing to refine it over time; any feedback is welcome and will inform future articles. I am therefore leaving comments open, and encouraging people to share the post.

Space Watch UK appears to be a spin-off of CND, and the general interconnected left wing protest scene. We can see an Extinction Rebellion logo on one of their banners here.

I get the feeling that these protesters have not given serious thought to space matters, and are not especially interested in the topic. To them, its just another facet of militaristic, colonial Western society they object to.

But lets take what they say seriously, and address the points they make.

Nuclear Moon

Space Watch have complained bitterly about some reporting on space nuclear reactors being developed in the UK.

They highlight the example of Kosmos 954, a Soviet satellite with a small reactor on board that suffered an uncontrolled reentry and burned up over Canada. They cite the fact that less than 1% of the nuclear fuel was recovered, which is true. But what they don’t mention is that the clean up ended because it was found that the remaining material was finely dispersed, its radioactivity was rapidly dropping, and it did not pose a danger to humans or the environment.

This was a concerning incident though - the Soviet government paid compensation to Canada, and was rightly criticised for losing control of a space nuclear reactor. Some of the fragments recovered were dangerously radioactive, and had they fallen on a populated area instead of a remote part of Canada, there may have been casualties.

Which brings us to their objections about this particular space reactor project - its for reactors for use on the Moon, and in it there is a statement that the reactor would only be turned on when it reached the surface of the Moon, precluding a Kosmos 954 style accident. Space Watch UK responds to this with this snark:

The scientist who has discovered how to switch radioactivity on and off should be nominated immediately for the Nobel Prize in Physics: such a discovery is an amazing breakthrough which totally rewrites all our previous understanding of the laws of nature.

We discovered how to “switch radioactivity on” back in the 1940s. It is kind of critical for all fission technologies. The point that seems to have been missed here is that a “cold” reactor, i.e. one that has not yet undergone large scale fission, has little radioactivity to it. Once the nuclear chain reaction is started and fission products appear - those are highly radioactive, and the “hot” reactor is now a radiation hazard if that material gets out. This is the elementary physics of nuclear reactors, which someone criticising them should know. And none of it “ rewrites all our previous understanding of the laws of nature”

The group is ignorant of nuclear physics here, and based on that misconception a correct reporting of the matter sounds ridiculous to them, and they mock it performatively for their (presumably equally ignorant) readers. This is an entirely unserious argument, so lets move on and see if they have done better elsewhere.

The Money Argument

In 2023, the group in its first action protested the Virgin Launch attempt from Newquay spaceport, which ultimately failed during the second stage burn. Space Watch UK opposed this flight on the grounds that some of the payloads the rocket carried were military.

Their core objection was that space should not be militarised at all, and that the UK “should be upholding and extoling the virtue of the Outer Space Treaty, signed in 1967, which recognises that space is a ‘global commons’ to be used for peaceful purposes and for the benefit of all countries and humankind” (sic)

First, the militarisation of space is a done deal and can no more be rolled back than the militarisation of the air can be. It is a domain of war, as has been shown decisively in Ukraine, and that genie will not go back in the bottle. Secondly, the group seems not to understand the Outer Space Treaty. It is not, despite the hopes of groups such as this one, some kind of transnational constitution for total peace in space. It does not ban non-nuclear weapons from space, and certainly does not ban unarmed military assets such as reconnaissance satellites or military communications satellites from space.

A second plank of their objection is that they do no want commercial exploitation of space. Again, its a bit late to protest that - 18% of the UK economy relies on space services. Being charitable perhaps they mean as yet unrealised commercial activity like asteroid mining - but a small bunch of cubesats wasn’t ever going to do that.

It is hard to pin down the specifics of why they didn’t like the launch. One protester, though, held up this sign which raised the issue of opportunity costs:

I’m not sure what a “game of Star Wars” is, but the figures involved are ridiculous.

£10.3 million is essentially pocket change for a government like ours. One of the supposed better uses of this money listed is the NHS. That amount of money would run the health service for about 30 minutes. The benefits uprating in the UK this year - as in the automatic increase in existing entitlements to match inflation, not any new social spending - is £18 billion - 1800 times the value listed here, and roughly equivalent to the annual NASA budget. No social service has ever gone unfunded due to a nation spending money on space.

I believe there are several layered misconceptions here - beyond how little space missions cost next to the cost of expansive social spending. There is the idea that UK government services are starved of funding - when the reality is that most of them (notably the NHS) have their real terms budgets increased every year. There is the ‘lump of labour’ fallacy that people who work on rockets can be simply reassigned to do whatever task the protester thinks is more important. There is the notion that nothing beyond basic subsistence can be attempted while ever there is any indication of poverty in society, which if taken seriously would amount to a dismantling of society and the economy - to such an extent that it would make poverty much worse.

It comes across as a cheap shot - because only government spending a particular speaker doesn’t like is portrayed as some kind of theft from the needy in this manner. It is an argument that presumes the thing its trying to persuade you of - that space isn’t worth doing. Unfortunately, despite its logical flaws, this kind of populist argument lands well with those concerned with poverty.

How to Respond

By writing this article, I’ve essentially given exposure to this group while refuting their arguments. Is that a good idea? Maybe, maybe not. As a society we should keep lines of communication open with those with disagree with - recent events in the UK have, I think, shown the dangers of political conversation breaking down. To that end, please consider sharing this article:

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I cannot ever see myself finding common ground with a group like Space Watch UK. Perhaps some people who might otherwise be drawn to them could be persuaded to change their minds though.

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I decided to produce a short introductory guide/reading list for people who haven’t seriously engaged with space, and space colonisation, before. And it is important to understand colonisation, because it figures heavily in the valuation of SpaceX, as is discussed in the S-1 document now available.

This article should not be taken as complete due dilligence and is not investment advice. It is purely for educational purposes.

The Problem of Space Business

A lot of the technical problems of space are either already solved, or known to be solvable without significant new technology. But space has always been expensive, and the trouble has been finding a way to pay for the implementation of the technology.

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A new book New Space Capitalism offers a more positive outlook, takes on the arguments of the doomers, and offers practical suggestions for how to shape the new frontier.

Dr. Rainer Zitelmann is a noted author in the social sciences, which gives him a different perspective than most people in this debate (such as myself) who come from STEM backgrounds and only dabble in sociology, economics and the like where they intersect with our concerns.

His core idea is a simple one - “Only when it is possible to own, buy and sell land on other celestial bodies can humans truly become a multiplanetary species”. I agree with this idea, in fact I find it so obvious on the face of it that it ought not to be necessary to write a book arguing this case - but it is necessary, because there is an entire cottage industry arguing against both private property and space colonisation, often at the same time. This is done under the banner of “ethics” or “planetary protection”, and the book details some of these arguments - such as the notion of the colonisation of uninhabited planets being “western antimineralism” i.e. prejudice against rocks, or that indigenous shamans have some prior claim to the Moon, contrary to both reason and the Outer Space Treaty. In this context, a reaffirmation of property rights, one of the basic foundations of western civilisation, is very useful.

On technical matters, Zitelmann often defers to domain experts like Robert Zubrin, John Logsdon, and Rand Simberg. I spotted a few minor mistakes in this part of the book, but nothing hugely consequential and nothing that undermines the central thesis. A novice coming to discussions of space for the first time with this book would not end up with any significant misconceptions, which is more than can be said for a lot of works in this field.

The main body of the book though regards public policy, and specifically how space exploration became trapped in a quasi-socialist, government-led paradigm after the Apollo programme, and how this is a mistake in the opinion of the author.

The Apollo Anomaly

The success of the Apollo programme is one of the most remarkable events of the 20th century. Not only did a huge government programme come in on time, and only slightly over budget, but it was a project to do something which had never been done before. When President Kennedy set the goal of the Moon, the US had around 15 minutes of spaceflight in total from Alan Shepard’s brief suborbital hop. But they did it, and astonished the world.

This has led to a “Moonshot” mentality from politicians, which Zitelmann illustrates with examples such as Richard Nixon becoming fascinated with desalination technology, and believing he could retask NASA to developing it after Apollo, as if engineers and scientists were interchangeable problem-solving units that can be arbitrarily rearranged and made to produce specific breakthroughs on demand for their political masters.

A more reasonable framing of this idea is provided by Mariana Mazzucato in her book Mission Economy, which attempts to take general lessons from Apollo to argue that big state projects can and should be organised along similar lines to solve big problems, and that indeed the state is the best vehicle for doing so. This notion is one of the largest intellectual targets of the book, and is frequently revisited. Zitelmann’s more liberal view, illustrated with numerous examples, is that in various times and places human ingenuity has flourished in spite of the state rather than because of it.

While it is correct that “Moonshots” are almost universally a failure, and Apollo clearly can’t be generalised to anything the current government wishes would happen, as a glaring example of a successful programme it does deserve some explanation. I have taken a shot at it myself:

There is some acknowledgement of the positive role of the state later in the book, but citing public choice theory Zitelmann ultimately rejects government-led programmes as a way to economically develop space, and prefers the state at best as a mere customer. This part I don’t (yet) agree with - I think, certainly in Europe and probably in the US and China, the private market just isn’t mature enough to stand up on its own. A well-designed government-led space initiative in the right circumstances can work - Apollo proved it - and may be the best way to get to the point where private space interests can take over fully.

Space Property

Where I am in stronger agreement is on what the final goal should be - a solar system of property rights, where the huge investments required to develop space can provide returns to those who take the risks.

This book takes a strong stand on the often-discussed issue of what the Outer Space Treaty (and its misbegotten offspring the Moon Treaty) actually says about private property claims. The final chapter challenges the many people trying to squeeze “space socialism” out of the OST after the failure of the Moon Treaty to enshrine it in international law explicitly.

The case is made well, with examples of how a real, capitalist space economy may work. But I suspect that this might be the start of the debate, not the last word. It is not so easy to separate intellectuals from what Friedrich Hayek called the “fatal conceit” that they are wise enough to centrally plan everything. Why should the vast bounty of space be left in the selfish, anarchic hands of capitalists like Elon Musk and Jeff Bezos, when there are people with Very Good Degrees out there who can perfectly direct resources towards the greatest collective benefit?

Too much media these days consists of people talking to people they already agree with for an hour or more, and having a lovely chat about how everyone who disagrees with them is stupid, crazy and evil. I would recommend that the anti-space crowd read this book as much as the pro-space crowd; and perhaps some of the space socialists mentioned in the book may be willing to challenge Dr. Zitelmann to a public debate.

New Space Capitalism is available to pre-order now

In these reports I’ve been tracking progress in spaceflight, and there has been much to be optimistic about. For several years, Falcon 9 has shown exponential growth at a rate comparable to Moore’s law, accelerating us towards a bright future in space. But true exponential phenomena do not exist in nature, only logistic S-curves. Sustained growth requires stacking those curves to maintain growth rates.

I first noted the signs of Falcon reaching the peak of its own curve two years ago:

That process is well set in now, but the next generation of launch vehicles expected to pick up the baton have stumbled somewhat. Where does that leave the predictions of space colonies?

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The company had been building towards a faster launch cadence, and had just demonstrated first stage reuse. The second stage anomaly from flight three had been addressed fairly rapidly, and things seemed to be going rather well for Blue Origin overall. Until suddenly they weren’t.

The loss of the vehicle and more importantly the ground infrastructure represents a huge setback for Blue Origin, but also has significant impacts on other parts of the US space program. The Artemis and Moonbase programs are now in jeopardy, multiple satellite constellations are going to be delayed, and there will be less redundancy and competition in launch for some time.

The Moon Race

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The rocket cleared the pad noticeably quicker than previous iterations, mainly due to the engines having more thrust. One engine shut down during ascent, but the flight was otherwise nominal up to stage separation. Two anomalies then happened in quick succession.

One engine on the booster seemed to explode during the boost back burn, taking out several others and precluding a complete burn and leading to the booster crashing. This is not necessarily an engine issue - prior failures on boost back have been caused by the motion of propellant in the tanks causing engines to be incorrectly fed. If the high power turbopumps of engines like Raptor ingest a gas bubble, for instance, it can destroy them. We will have to wait for more information from SpaceX to understand the root cause of the problem.

The ship lost one of its vacuum engines early in the burn, and had to complete a longer burn on 5 engines. Notably, it was still able to reach its intended target area accurately enough to be caught on camera by the buoys and drones set up there for the event. The ship made a soft landing, with a visibly intact heat shield, before falling over as expected and exploding.

The engine out precluded doing a relight test on orbit, but the payload - 20 Starlink mass simulators and two active satellites that filmed the outside of the ship - was successfully deployed by a faster, improved “PEZ dispenser”.

Overall, a partial success and a good showing for the first outing of so much new hardware.

The New Version

Starting from the top down, here are the big changes that have been made to the Starship stack.

The ship itself has a redesigned thermal protection system (TPS), most notably the clips which hold the tiles in place. The condition of the heat shield after reentry seems to have vindicated this change, as we are not seeing the tile loss we have seen on previous flights. There is also new hardware added for propellant transfer, which should be demonstrated with this version of Starship, and is essential for achieving its objectives such as the Artemis Moon landings.

The top of the Superheavy booster is notably different. Instead of a disposable hot staging ring there is an integrated structure, and the four grid fins have been replaced by three in a ‘T’ shape. This reduces the weight of the booster, but given how the boost back anomaly seems connected with the hot staging, it may be a focus of fixes in the future. At the base of the booster, shielding around the engines has been stripped back, with the engines themselves redesigned to contain failures.

The raptor engines themselves on both stages are new designs - providing a significant boost to thrust and a small boost to specific impulse. The new engines are also lighter, and have simplified much of the plumbing and moved into inside the engine.

On the ground side, V3 launches from an entirely new pad. Instead of a launch stand over a flat pad, there is now a deeper flame trench to manage the exhaust. The deluge system which dampens the impact with huge quantities of water is also substantially scaled up.

Recent third party photographs have shown the stand holding up well to the launch, with what appears to be only cosmetic damage.

What’s Next

The extent of the changes led to a substantial stand down of the program, and provided that correcting the booster issue on Flight 12 does not require too much of a redesign, the company should be able to get back to more regular flights.

The usual time between previous Starship flights was about 50 days. If that were to be the case for the V3 test campaign, we would expect to see Flight 13 in July, and a total of 5 launches in 2026.

This timeline is probably optimistic for the next launch, but if SpaceX continues to improve there may be acceleration in the latter half of this year. The bear case is continuing anomalies during test flights, or the booster needing a fundamental rework - the bull case is that they reach orbit with Flight 14, recover booster and ship, and reuse a full stack before the end of the year. It’s going to be an important year for the company either way.

Human expansion into space is a continuous process, that is already underway, but society tends not to react to gradual processes, but to landmark events. As the public tends to ignore space news for years until some big event - Artemis II, the first Starship booster catch etc. - they will likely not keep track of continued progress in space habitation until events force them to pay attention.

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And when the first child is born in space, everyone will ask “what does this mean?”

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After last months Ignition event, NASA released a book containing a loose road map for the technologies and capabilities they believe need to be developed by industry in order to realise the vision of a permanent lunar base.

The document follows with NASAs three phase plan for the Moon; and in phase three that includes using the lunar regolith, which is what I’m going to be talking about here. Industry has not had much time yet to respond to the NASA pivot; but many companies have already been working on various schemes for some time, and I’ll discuss those here.

I’m discussing both privately held and publicly traded companies here, and nothing here should be taken as investment advice. The information below is purely for educational purposes.

Glass Domes

I have written about Skyeports before - they have a novel concept to blow glass made from lunar regolith into very large structures. They have been receiving funds from NASA since I last mentioned them to develop this technology, and have produced some demonstrators on Earth with simulated lunar regolith, including a blowing inside a vacuum chamber.

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While only one of these rockets sent a crew to the Moon, the other two will be indirectly involved in the Artemis program - both are due to fly robotic landers to the Moon this year.

I’ve covered the Artemis mission extensively this month so won’t say much more about it here, and focus on commercial matters. The launch industry is in something of a transition at the moment - we are seeing more signs pointing towards the end of Falcon, and new competitors coming along, two of which I’ll highlight today.

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If you know anybody who would still like to catch up with this mission, please share this with them.

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Given the issues that were discovered after the reentry of Artemis I, this mission was delayed substantially and a new reentry trajectory was planned. The decision was taken not to change the heat shield, as this would delay the mission even further. A modified heat shield will fly on Artemis III, and NASA believes Artemis II can still be successful with the older design if it flies a different trajectory.

Before I get on to that, one last update on the trajectory of Integrity as it accelerates towards Earth:

During the mission NASA have been publishing updated ephemris data - the position and velocity of the spacecraft at each point in time - as corrective burns and the lunar gravity have altered it.

These changes are very small, and I chose not to show them on the main trajectory plot and just use the latest one, as the differences would be substantially less than the with of the line. Even zooming in on the entry interface portion at Earth, it looks as if the initial trans-lunar burn was very good.

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