New Mars Forums

GW, A while back here, we looked into the possibility of building some kind of vertical launch assist.  This would accelerate a rocket to ~Mach 1, vertically, over a vertical distance of a few km.  The idea was to eliminate the propellant mass needed to reach Mach 1 from the launch pad, when propulsive efficiency is low.  The concept appeared to show promiss.  The most practical option appeared to be a steam cannon, which would accelerate a rocket sitting atop a sabot.  The cannon would be about 3km long and would be located within a deep pit, with the rocket exiting the barrel a few hundred metres above ground level.

This concept was aimed specifically at reducing the required mass ratio for an SSTO to reach orbit.  Do you have any methodology for determining how effective it would be?

On Titan, large volumes of warm air could be enclosed by tent like structures.  There will be no differential pressure across the tent.  It only needs to withstand buoyant forces and wind loads.  Buoyant forces are relatively weak under Titan gravity.  And windspeed is low at the surface.  So the tents can be slender structures.  You don't need to heat and expand the entire atmosphere.  Just the bits you want people to live in.  Kind of like this:

The same would be true for a rogue planet.  A relatively cold atmosphere with a desirable atmospheric pressure is as much as we need.  We can paraterraform beneath it.  For much smaller bodies, a liquid ocean is something we could use instead of a thick atmosphere.  Polymer enclosed bubbles of air would provide low-g living space.  They would be ballasted to maintain a depth where pressure is appropriate for human habitation.  On a body with 1% Earth gravity, a 1bar pressure will exist at a 1km depth.  Kind of like this:

Pluto and Eris would be candidates for creating thick atmospheres by injecting additional heat.  The water world aquaforming idea, with submerged floating cities, could be applied to hundreds of thousands of TNOs and Oort cloud bodies.  Basically, any body greater than about 50km in diameter coukd be turned into a water world.  But atmospheric terraforming would only be possible for relatively large bodies.  Pluto is close to the minimum size at which that is possible.

In intersteller space, where temperatures can drop as low as 4K, it might be possible for smaller bodies like Sedna to hold onto a cold nitrogen atmosphere.  The atmosphere would be warmer at the bottom than the top, because we are heating it at the bottom.  As relatively warm nitrogen rises into the atmosphere it would cool by radiation and then condense into solid nitrogen snow.  This would then fall into the denser and warmer lower atmosphere where it would sublime back into gas.  In this way, atmospheric escape can be kept in check for small bodies.  It only really works if the upper atmosphere of the body can be kept cold.  Much the same thing happens on Enceladus.  Most of the water vapour expelled from cracks in the surface fall back onto the surface as snow.

We could potentially harvest the solar wind or interstellar medium using magnetic fields.  About 90% of the particles within this medium are protons.  But the balance will be deuterons, helium nuclei and about 1% heavier ions.  The p + p fusion reaction occurs too slowly to be useful because it relies on electro-weak interactions which convert a proton into a neutron.  But protons will fuse with deuterons, yielding He-3 nuclei.  Deuterons will fuse with each other to yield tritium and He-4.  If we can master deuterium based fusion then neutron economy becomes far less important because we no longer rely directly upon tritium.  Outer solar system bodies tend to be dominated by water ice, which makes up roughly half the mass of bodies like Pluto.  We can expect deuterium to be present within this water ice as HDO.

According to this reference, about 1 in every 2000 hydrogen atoms in comet 67P is deuterium.
https://iopscience.iop.org/article/10.3 … 357/abacc3

That would mean that every kg of cometary water contains 0.1g of deuterium.  Fusion of 1kg of deuterium will yield some 571,182,758MJ of energy.  So each kg of comet water contains 57,118MJ of potential energy.  Of course the products of D-D fusion are also potential fuels themselves.  But the fusion of all deuterium in a 100km diameter cometary body will yield 379 billion GW-years by my reckoning.  That is about 100GW of continuous power for about the remaining lifetime of the sun.

Nations that develop an aptitude for manufacturing always do well.  Japan and Germany both achieved high levels of wealth and that wealth was well distributed because manufacturing pays good wages to people that aren't necessarily the brightest.  Both nations have declined of late due to demographic ageing and poor choices when it comes to energy policy.  But their dominance in high quality manufacturing has cushioned their decline.  Even if a more distributed manufacturing system reduces aggregate wealth, it would still have benefits of improving wealth distribution.

A country with a well paid middle and working class, would be a better and more dignified country, even if its billionaires were a little poorer.  But I'm really not sure that such a society would be any poorer.  If there are plenty of well paid jobs for middle and working class people, then taxes can be lower.  It is taxes on wages and personal expenditures that fund government.  Billionaires can hide their money.  But a wealthy middle and working class is also less likely to need government handouts.  So in addition to paying more tax, they are less dependant.  That sounds like a net positive to me.  If the bulk of population are wealthier, they will also support a wealthier economy when they spend that wealth.  The more concentrated wealth is, the less economuc prosperity it generates.  A billionaire only needs at most a few cars.  But a thousand millionaires will buy at least a thousand cars.

Here is something else to think about.  In order to be at the cutting edge of technology in aerospace, a country must have an aerospace industry.  The same is true of steel, cars and electronics.  You cannot be at the forefront of technological competance if you don't make anything.  Concentrated manufacturing makes a few people very rich.  But it leaves almost everyone else worse off.

But there is one caveat that must be understood.  A wealthy society depends upon cheap energy.  Consolidation of industry is realky away of attempting to mitigate expensive energy by pushing scale economues to their limits.  It only half works.  Whilst enormous producers may reduce the price of goods, they also pay fewer people good wages.  Britain has pushed this trick to its limits.  Average wages are low and a majority of people recieve some money from the state.  Living standards are maintained because supermarkets explout tgeur huge buying power to drive down prices.  So everyone is poor, but everything is cheap.  At least that was how it worked until COVID.

The UK economy falls into recession.
https://youtu.be/aTFRu7l979Q

According to the UK media, it was unexpected.  Which leads me to wonder, who in the world was surprised by this?

Heavy water moderated reactors have found a home in countries with limited uranium enrichment capability.  The problems are: (1) Heavy water is energy intensive and expensive to produce; (2) The slowing down length in D20 is somewhat greater than in H2O.  This makes the core bulkier, with greater distance between fuel assembles.  That increases capital cost.  The consensus within the industry is that using enriched uranium in a lightwater reactor is a better solution overall.  But heavy water reactors have been shown to work.

Renewables aren't renewable.
https://www.mackinac.org/blog/2025/rene … -renewable

Another study, this time by the University of Texas, reaffirms what we already knew.  The embodied energy and natural resources needed to extract a kWh of energy from the sun or wind is extremely high.  This is due to unchangeable characteristics, specifically, low power density.  Powering an industrial civilisation using renewable energy is a bit like trying to body build on a diet of boiled cabbage.  The thermodynamics are not favourable.

I built a small wind turbine out of aluminium and scrap wood.  This was a purely mechanical device designed to tumble stones.  Very few moving parts.  All the same, the amount of time and energy I needed to invest in building it is impressive.  And it still isn't finished.  It will need to operate for at least a few years to save enough electric power to recover the cost of building it.

I am sick of Britain.  The place is a corrupt hellhole, run by thugs who punish people just for being alive.  They honestly don't know what to do next.
https://youtu.be/2NVwL6iz6js

Trial by jury is set to be abandoned.
https://youtu.be/YIWa58tox9A

The only dream worth having now is the dream of getting out.  I would rather live in Sweden and pay 60% tax than pretend to live in Airstrip 1.  In the UK, there is no such thing as property.  There is no freedom.  There is no future.  This place is an open air prison camp.  More people pour into it every day.  It feels more and more like a pressure cooker.

Fascinating.  Robots have come a long way in a short time.  Though I note that the Boston Dynamics robots do not seem to have found much of a market outside of military applications.  I would suspect that ITAR regulations stand in the way of commercialisation.  The world's military powers are locked into an arms race for drone technology and no one wants to relinquish control over something that might be of use to an adversary.  Rather like nuclear technology before it, robotics is too tightly controlled to allow effective commercialisation.

I remember GW writing about carbon fibre composites about a year ago.  These materials are immensely strong, but are easily damaged.  Worse still, when damaged, the fault is often unrevealed.  Unlike metal tanks, there is no steady progression of crack growth culminating in failure.  CFRPs fail suddenly and without warning.  Quality control and careful handling is therefore essential.  It sounds to me like morale is deteriorating and people are getting careless.

Colonising plutoids.
https://www.researchgate.net/publicatio … the_galaxy

This is interesting.
https://skyandtelescope.org/astronomy-n … 032520166/

In the past, Pluto's atmospheric pressure may have been up to 28KPa.  The temperature of Pluto is close to the nitrogen triple point.  This means that a small increase in temperature results in a disproportionate increase in atmospheric pressure, as nitrogen sublimes.

If humans introduce atmospheric nanoparticles, the resultant global warming effect should be sufficient to trigger the sublimation of solid nitrogen on Pluto's surface.  Once pressure is sufficiently high, areas of land can be made habitable by erecting tents filled with breathable air.  The air within can be heated from ~70K to 250K, using nuclear waste heat.  There is no difference in pressure between the inside and outside of the tent.  But outside, the nitrogen atmosphere would be far colder and denser than the air within.  So the tent must withstand bouyant forces.  But these are fairly minimal.  On the order of 50Pa.  So a simple polyethylene sheet drapped over a thin metal frame, shouod be sufficient.

Whilst Pluto is unlikely to be turned into an analogue of Earth, it may turn out to be one of the easiest objects to make habitable for humans.  It doesn't need a biosphere, just an atmosphere that we can built non-pressurised enclosures under.  The same may be true of Triton, Eris and Titan.