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Starship could be used to launch large infrared telescopes. These would have enough resolution to identify near Earth asteroids down to a few metres across.
https://www.nextbigfuture.com/2025/10/a … -2035.html
This is interesting because asteroids in the size range of a few to several tens of metres are the easiest to mine. We can enclose the entire asteroid in a bag and use grabber shovels to pull material off the surface. Useful metals can be seperated out and silicate wastes can be used as reaction mass to bring the useful materials back to high Earth orbit.
Some asteroids have orbits that require very little energy to reach beyond that needed for Earth escape. These are the ones we want to begin with. Large IR telescopes are a valuable tool for identifying these most promissing mining candidates.
Quite a lot to read through here, so I will comment again when I've had chance to read it all. Gas turbine blades have always been made from high temperature nickel alloys. Since the 90s, they have been grown as single crystals with mineral rods embedded to provide cooling channels by dissolving the rods in weak acid after casting. So I'm not sure why the reference suggests that using nickel alloys is impractical or expensive. It is standard aerospace practice. Take any COTS GT and you find nickel alloy components. For non-moving parts, steels can still be used at 700°C. Strength will be reduced substantially and corrosion in hot CO2 will be more of a problem. But is can be done. There are specialist oxide dispersion strengthened mechanical alloys that were specifically developed for operation in this temperature range.
Trump is trying to rebuild the US domestic manufacturing base, as it existed in the 1970s. The problem is that we live in a very different world today to the one he would have known as a young man. The demographics of the workforce are different. The workforce has gotten older throughout the world, but especially in Western countries. Energy is more expensive.
To a great extent, globalisation was an attempt at keeping production costs down by relocating manufacturing to places where energy was cheaper, the workforce was younger and environmental regulations were weak or absent. But there is more to globalisation than just that. Many products cross national borders multiple times before they are finished. Different parts of the manufacturing process require labour at different price points and skill levels. It isn't as simple as saying that a car is made in Mexico or Japan. In the modern manufacturing system individual components may cross national borders multiple times for specific manufacturing processes that just happen to be most efficient in a particular place.
Tariffs risk disrupting trade arrangements that took many years and a lot of dollars to set up. They also ignore the reality of how products are produced in the modern world. Tariffs are a tax on consumers not producers. The additional revenue that the US government is receiving is coming directly from the US consumer, who is now paying higher prices. This is a direct source of inflation that erodes consumer purchasing power. This is on top of the post-COVID inflation that had already eaten into wages. So consumer spending is going to be squeezed on both sides.
I will be back in Holland week after next. Not somewhere I thought I would be going back to so soon, but it is where my son wants to go for holiday. We are planning on visiting different places this time. We are staying in Haarlem and will be getting the train to Utrecht, Delft and Den Hague. I will take pictures as last time and post them here.
I have always found the Holland to be quite inspiring. It is a place where about half of the land is reclaimed from the sea and much of the remainder was boggy marshland before humans terraformed it. The sea is held back by a system of soil dikes. Behind the dikes, water drains into ditches, and is pumped to sea level by pumps, originally wind driven. This seems quite analogous to what we plan to do on Mars. In that case, land will be recovered from vacuum by constructing a roof structure and covering with soil to counterbalance internal pressure. The resulting habitable land will be relatively expensive. Under the roof, the challenge will be to develop towns that are comfortable to live in despite high population density. The urban architecture of pre-industrial Europe gives us solid examples of how to do that.
Lest we forget No More Kings...
Agreed. The present king (Charles) is an utterly pointless person. He really does nothing for the planet except consume oxygen. So long as some are more equal than others, it is difficult to build a proper democracy.
That said, the North American rebellion was more a proxy war by the French against Britain. It had nothing to do with American freedom, though that did come later.
Much depends I think on how we construct space suits. If we go with an MCP design, then you have an elastomer fabric covering skin. Other, tougher garments can be worn over this. As Robert noted, Mars dust grains are more rounded than lunar equivelent. So I don't see that we need anything special compared to Earth based clothing. On the moon, the situation is quite different. That dust will destroy most fabrics quickly. CNT or BNNT would appear to be necessary there. Sharper dust will also be more toxic to the lungs if tracked back into the hab.
I have a GoreTex coat that is about 10 years old now and has seen heavy use. It is still in good condition and is still reasonably waterproof. That is a necessity in the northern parts of Britain. The surface is easy to wipe down as it is relatively impermeable. So it shoukdn't be difficult to keep clean on Mars. The moon is a different case entirely. It was noted that the original Apollo space suits were destroyed by a few days expusure to lunar dust. I hate to think what it is going to do to astronaut lungs long term. Will it be as bad as asbestos?
This topic has sat idle for a while. It covers both power distribution and transportation through pipelines, though the initial intent was power distribution.
TH raised a good idea in the use of ice in pipes as a low friction medium that vehicles can slide along. A smooth surface could support high speeds. It can be renewed by melting the top inch of ice periodically and allowing it to refreeze. Microwaves would do that very effectively. Or maybe some kind of radiant heater. Propulsion could be provided by driving wheels pushing against the sides of the pipe.
Steel has a 0.04 static friction coefficient and a 0.01 dynamic friction coefficient against ice.
https://www.engineersedge.com/coeffient … iction.htm
This means that every tonne of mass transported would require some 37N of driving force. Given that Q = F × D, that amounts to 37KJ/tonne-km. The sled and drive car will have mass as well. As an initial rough estimate, lets say 50KJ/tonne-km. That is about the same energy cost as rail (on Mars) but without the cost of the rails. We would only need about one inch of ice. The tunnels would need to be sealed and covered with regolith to prevent sublimation. But provided the atmosphere within is maintained at high humidity, they would not need to be pressurised.
Gerard O'Neill's Island 1 was intended to present an appealling image of a space habitat so that people could become emotionally invested in the project. But if our goal is to set up space manufacturing capabilities and the purpose of the space habitat is to house the workforce, we do not need to begin with such large habitats. They are things that we can build up to over time. Starship is designed to house up to 100 passengers in a habitable volume of 1000m2 for at least 6 months. That is a 10m3 volume for each passenger.
If we used Starship as a guideline for the required habitable volume of a minimal space habitat, then a workforce of 1000 people would require 10,000m3 of habitable volume. That is a sphere some 26.7m in diameter. We can be more generous without the space habitat becoming unrealistically huge. Lets assume 10x the Starship volume per worker. That is 100m3 each, or 100,000m3 in total. That is equivelent to a spherical habitat some 57.6m in diameter. Say 60m.
Let us assume that such a habitat rotates to produce artificial gravity. Human beings can endure about 3 rotations per minute before inner ear problems start to become problematic. There is some evidence that humans can adapt to higher rates over time. But lets assume for the time being that 3 rev/min is what we will design to. That is 0.314rad/s. Centripetal acceleration can be calculated as:
A = w^2 × r.
Solving for r = 30m, gives a centrifugal gravity of 2.96m/s2 at the outer edge of the sphere, or 0.3g exactly. This is slightly less than Martian gravity. The closer one gets to the centre of the station, the shorter the radiys of rotation and the lower the centripetal acceleration. Lunar levels of gravity (1.635m/s2) would be experienced some 16.58m radius from the centre. This means that about 60% of the internal volume of the sphere would have gravity greater than lunar. Habitation areas will be concentrated around these outer sections.
The total volume of a 60m diameter spheres is 113,097m3, or 113.1m3 each. Some of this volume will need to be apportioned to life support functions. Food will be produced using a mixture of hydroponics, algaeculture and extracted chloroplasts. Using acetate salts, food can be produced in very compact volumes without sunlight. Gone is the need for the extensive agricultural areas that O'Neill anticipated in the 1970s.
Such a habitat would not have any wide open spaces. But there is sufficient volume for every crew member to have their own small bedroom, equipped with a personal ensuite. A cubic room with dimensions 2.4m aside, would have internal volume 13.8m3. If every crew member had such a room, they would collectively account for 12.2% of internal habitation volume. There would be canteens within such a habitat, as well as lounges, gym and cinema. There could even be small green spaces beneath artificial lighting.
How much would such a habitat weigh? This is difficult to estimate. For Island 1, mass was dominated by cosmic ray shielding. This amounted to 5000kg of silicate slag per square metre of hull area. For a sphere 60m in diameter, this equates to a total shielding mass of 56,500 tonnes. This is only 1.44% of the 3.9 million tonnes of shielding that would have been required by Island 1. As our habitat will be constructed for the workforce of a lunar ore processing facility, it is reasonable to assume that this mass will be derived from lunar materials. We could either use the first 56,500 tonnes of lunar ore as shielding or just work without shielding until we have 56,500 tonnes of silicate wastes from the ore refining itself. Much will depend on the mass that can be provided by an initial lunar mining operation.
I am going to call this 60m, 1000 person habitat concept, Island 0.1. Back in the 1970s, O'Neill had assumed that the colonists in Island 1 would be working families, with children attending school in the habitat, with both parents working. This seems less realistic for an early habitat supporting space manufacturing, though it isn't impossible. I think it more likely that individual workers would sign up for a 2 year contract, which would include transport to and from the habitat, food and accomodation, in addition to wages. The habitat would be attached to the ore processing and manufacturing areas. These would mostly be low or zero gravity. Operations would either be automated or controlled remotely from within the habitat. Only maintenance that cannot be carried out robotically, would require humans to leave the safety of the shielded habitat. This allows exposure to cosmic rays to be minimised by limiting exposure time. So the majority of the space factories will not require cosmic ray shielding.
Isaac Arthur has released his latest video on space based data centres.
https://youtu.be/iLNrYwx0th0
The neat thing about this is that it obviates the need for transmission of power from an SPS to the ground. Power is used where it is generated. This is a product that can realistically be sold to Earth based customers for profit. There is huge and growing demand for it. The downsides are transmission delay - 0.1s to a satellite in GEO. Such a satellite would also probably need a manned presence.
I am presently looking into buying a computer with enough capacity to handle fire modelling CFD applications. The cost is likely to be $5000 - $10,000. The problem is that for a 3-Dimensional geometry, especially structures, the number of cells increases very quickly, which eats up a lot of memory. To run a simulation in a reasonable amount of time, a high end Intel Xeon W-series processor is needed. A minimum of 1TB of free memory space per simulation and preferably, 64 cores to be able to run the simulation in hours rather than days. It gets expensive very quickly. But it is such a significant advantage to me as an engineer, that I am minded to take the hit and make the investment.
I read the Space.com article. The thing that really put the boot in Gerard O'Neill's concepts, was the failure of the space shuttle project to deliver a low cost, reusable launch service. Maybe Starship will ultimately do what the Space Shuttle couldn't.
There were other problems, such as failure to develop a reliable mass driver that could lift the required megatonnes of ores into high Earth orbit from the lunar surface. This failure had more to do with the mass driver being something of a bespoke application for lunar mining. There weren't really any other commercial drivers for it. It was too bulky to be useful to the military. For research of high velocity impacts on Earth, the light gas gun is a lot more compact. The real benefits of the mass driver are very specific to offworld mining applications, where propellant is not available in large quantities.
Although O'Neill's vision was not achieved during his lifetime, events are unfolding in a way that brings it closer to reality. The Artemis programme and the commitment to developing a lunar base. The development of Starship with its promiss of rapid reusability. Whilst O'Neill's colonies have always generated excitement, the reality is that the mass budget of these space stations, makes them impractical in the near term. We need to be focusing more on the problems of lunar mining and space manufacturing of products that we can sell to customers on Earth. We will need a workforce in space. But their initial accomodations will be a lot smaller than Island 1 and will likely be attached to factory complex that they are working within. As the scale of operations expands alongside revenues, at some point Islands 1, 2 & 3 will become affordable. How long that will take is anyones guess.
Wave power and tidal power are two different things. Both are worthy of consideration. But they need to be discussed seperately. The energy available from tidal power at a particular site is a function of tidal range.
https://www.researchgate.net/figure/Ran … _334235446
The higher the tidal range, the greater the potential energy available to exploit. Tidal range will determine both the volume of water flowing and the difference in head height between high and low tides. So the energy available per metre of coastline will be proportional to 0.5 x R^2, where R is the height difference between high and low tide. The energy available at a particular site will depend upon regional tidal range but is also influenced by local geography, which can funnel the tide.
There are other factors that may come into play when considering the site for a tidal power project. Environmental considerations have halted development in the UK, despite the UK having the worlds best resource. Tidal lagoons may provide side benefits, such as storm protection of the coast, protection from erosion and marine aquaculture in the lagoon itself. These other benefits may encourage development in places where the resource is otherwise marginal. The longevity of lagoons once created, makes the concept attractive as a longterm investment.
In places where coastal development is impractical, tidal stream power generation is possible as well. These draw energy from tidal water flow, rather like underwater wind turbines. But like wind turbines, the power output is proportional to the cube of flowrate. When this is factored in, the tidal stream resource tends to be quite limited. For example, the straights of Gibraltar experience tidal flow as Atlantic water flows in and out of the Mediteranean. The average power is a few hundred MW. This is not nothing. But compared to the electricity needs of a large nation (a few to several hundred GW) it is a small resource.
TH, this may be of interest.
https://en.wikipedia.org/wiki/Woodbridge_Tide_Mill
There were quite a few tidemills in Britain during the 19th century. But as with windmills and watermills, the steam engine put them out of business. With coal in decline and electricity increasingly expensive and unreliable, it may be time for a comeback of these old technologies. With hydraulic power transmission, a modern mechanical tidemill would be far more efficient. But as I have learned from my own wind power project, simplicity has value in itself. If systems are simple enough that they can be built by a cratsman with modest skills and simple materials, they are accessible to people who are prepared to commit their time and don't necessarily have a lot of cash to spare.
Spacenut, that is an interesting concept. It would appear to allow hydropower generation without too much disruption to the river. It would also be cheap and relatively easy to set up. For repairs it could be hauled up onto a slipway, allowing people to work on it outside of the water. Another advantage is that this device is simple and cheap enough to be built locally by craftsmen. It doesn't need to be a commercial product. That may be important in the years ahead, as supply chains come undone.
I have occasionally wondered about the potential for a small asteroid mining vehicle. This would target NEAs <10m in diameter. Such bodies would be completely disassembled. Useful metals and volatiles would be extracted. The remaining slag would be a mixture of iron, magnesia and aluminosilicates. These could be used as propellant by heating them into plasma with radio frequency heating. Small vehicles equipped with solar electric propulsion working on this principle, could ship the valuable materials back to high Earth orbit. The same propulsion tech would then be used to shift the orbit of the asteroid mining vessel to intercept the next NEA.
We have examined how we would mine such objects in previous work. One method would be to surround the body with a rotating ring. The ring would carry a set of arms equipped with enclosing shovels. These would grab chunks of surface material and drop it down chutes also mounted on the ring. The whole arrangement would be enclosed in a thin polymer bag to prevent loose material from escaping and contaminating the local space. The chutes would empty into ore processing. How we seperate recovered materials into useful elements needs more consideration.
The kite sail concept looks very promissing. This is something that can save fuel when the wind speed and wind direction is sufficient and be wound in and packed away when not needed. And it doesn't eat into hull volume and cargo space. Definitely something that deserves wider application.
Liquid air could be deployed as part of a hybrid propulsion system. The waste heat produced by the diesel engines is high quality heat at a temperature of up to 500°C. It would allow for efficient energy recovery from the liquid air. But on the plus side, the ship still functions on diesel if liquid air isn't available. So again, this is something that can save fuel over the lifetime of the ship. In the medium term, we don't necessarily need to phase out diesel altogether. If we can use it more efficiently then we extend the lifetime of the resource base. But things that add a lot of additional hardware cost only make sense if diesel is physically unavailable.
The low energy density of liquid air would appear to be less of a problem for inland or coastal freight transport. Maybe rail could make use of this tech as well.
The low efficiency of an atmospheric pressure steam engine (5-15%) makes the concept unsuitable for most power applications. But as part of a combined heat and power system, in which the rejected heat has practical use, the economics of the system look better.
It has been a while since anything was posted in this topic. But I found this today, which is interesting.
https://www.sciencedirect.com/science/a … 8112007082
The atmospheric steam engine uses heat at temperature <100°C, to raise steam in a boiler under vacuum. The condenser has a temperature of 30°C and a pressure of 4KPa. The low temperature difference between hot a cold side, mean that this heat engine is relatively inefficient. At 100°C boiler temperature, theortical efficiency is 25%. This drops to 10% for a boiler temperature of 69°C. Real efficiency in a practical device would be lower than this, perhaps 6-15% in a steady flow turbine system. This has led to relatively little interest in the atmospheric steam engine.
However, this concept deserves further study. Whilst it is relatively inefficient and bulky, it is easy to build. All of the pressures involved are beneath atmospheric. This means no expensive pressure vessels are required, as forces act inwards. Concrete shells capable of resisting implosion forces are easy to cast insitu. As the differential pressures are low, components are not under a great deal of stress. It should be possible to make use of low alloy steels, polymers or even wood for moving parts.
The low efficiency is also less of a problem if the abundant waste heat at 30°C can be used. This is where district heating becomes attractive. We could use water in this temperature range to heat houses and other buildings. Or we could store this heat with the ground during summer and extract it as input heat for a district heat pump for winter heating. A solar thermal powerplant built in the UK would generate some electrical power during the summer. The waste heat it produces could be stored in boreholes ready to supply district heating systems during winter.
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Additional: The addition of a small biomass fuelled boiler would increase the capacity factor of the powerplant. Solar power would preheat the water entering the boiler, with the boiler then heating the water to a consistent 100°C. Using solar power in this way, allows us to stretch the benefits of a limited fuel supply.
A while back, someone proposed building a rotating statite. This would gradually accumulate rotational energy that could then be used to launch payloads.
I wondered about building such a device in the asteroid belt. A while back we discussed mining ice from Ceres and then firing ice packages onto an orbit that intersects the orbit of Mars. As the ice packets explode in the upper atmosphere, they would saturate the Martian ionosphere with water vapour. This would have a global warming effect. Additionally, solar UV would break down the water vapour into hydrogen and oxygen. The hydrogen would escape and the oxygen would accumulate within the atmosphere.
It would take many centuries to build a breathable atmosphere in this way. We would need something like 700,000km3 of ice to do it. But patience is essential for terraforming. To do the job in 700 years, we could need to deliver 32,000 tonnes of ice every second. That means either a very big statite or more likely, lots of smaller ones.
Void, that is interesting. It is worth remembering that most of the mass of a space habitat will be cosmic ray shielding. Ice can be used for this purpose. It doesn't need to rotate. The metal shell of an Island 1 colony was estimated to mass around 100KT. But the shielding would mass at least 3MT. The mass of the air within it is also not trivial.
Using KBOs as starships makes no sense. These bodies have huge mass and the energy needed to dV them by any practical amount is just enormous. The only caveat is if we find a rogue object that is already travelling in the direction we want to go at a respectable speed. That is possible.
Isaac Arthur is without a doubt, one of the greatest futurists of our time.
Void spent some time researching the use of water ice as a building material. The colder ice gets, the stronger it becomes. On icy moons and dwarf planets, ice could serve as a structural material for buildings and dugouts. Insulation would be needed to prevent heat from habitable spaces from draining into ice walls. For free space habitats, cosmic ray shielding dominates the total mass budget. Ice is one of the most efficient shielding materials that we know.
Turns out Makemake has an atmosphere, albeit a very thin one.
https://www.space.com/astronomy/dwarf-p … scientists
This is surprising, because methane is a light gas and a world as small as this should not be able to hold it. The very low temperature this far from the sun no doubt reduces the vapour pressure of methane. So escape is a slow process.
Interesting topic. As the study notes, there are a number of ways to power a tug. Liquid air is promissing, as the water surroundingbthe tug can provide a heat source. Stored thermal energy in a phase change material could work as well. In the case of liquid air, the heat pump producing the air could dump heat into a district heating system. Liquid air has the advantage of being storable in underground tanks. A well designed system could avoid the need for cryogenic pumps by allowing liquid air to be distributed by gravity. Seperating the air into LN2, LOX and noble gases, would allow other revenue streams. Air liquefaction also allows CO2 capture from the air.
Bennu is technically easier to reach than the surface of Mars, or indeed, the moon. Its mass of 70 million tonnes, is sufficient for 20 Island One habitats and several hundred 10GWe solar power satellites. It is known to contain water, carbon, nitrogen and phosphorus, in concentrations much greater than we are likely to find anywhere on the moon. Whilst Mars is scientifically more interesting, Bennu offers better near term commercial prospects. The two goals are not mutually exclusive of course. But if I were in Musk's position, I would probably prioritise near earth asteroud settlement and mining, for the simple reason that they are more likely to offer a return on investment in a reasonable window of time. For space settlement to be sustainable, it needs to pay. The biggest hurdle that space colonisation faces is developing a business case for it.
This calculator provides the Jean's escape parameter for an atmosphere around a body of known radius, mass and temperature.
https://agentcalc.com/jeans-escape-parameter-calculator
If the parameter is less than 3, gases escape rapidly. If the value is greater than 10, an atmosphere can have a long lifetime by human standards.
I have been reading about superheavy gases, specifically sulphur hexaflouride. This gas is extremely dense ~6kg/m3 at room temperature. This makes the gas ground-hugging. It remains trapped in a tank with open air above it, because its high density limits the rate of mixing. It occurs to me that sulphur hexaflouride introduced onto a small rogue planet like Pluto, would tend to result in a strong thermal inversion within the atmosphere. The SF6 close to the ground could be much warmer than nitrogen above it, because gaseous nitrogen remains less dense than SF6 is at room temperature, even when the nitrogen is close to its boiling point. Any SF6 diffusing into the cold nitrogen layer, would rapidly freeze and fall back into the SF6 gas layer as snow. Any nitrogen entering the SF6 layer, would absorb heat, making it less dense and causing it to rise back about the SF6. The two layerswill therefore remain seperate, even if the lower SF6 layer is much warmer than the N2 above it.
Provided that colonists are able to provide an artificial heat source, and are able to locate sufficient flourine (a big if), ground conditions could remain warm, even with a cryogenic atmosphere above the SF6. The SF6 functions as a kind of blanket.