New Mars Forums

GW,

As I have repeatedly pointed out, we don't have that data, and the 3-5RPM limit is entirely vibes based, typically from people who don't know what they're talking about. But we *know* people can tolerate 10RPM for at least half an hour. And getting longer term data is well within our means.

Incidentally, the existence of playground roundabouts does tell us one important thing, which is that children at least aren't badly affected by spending half an hour to an hour each day rotating at 20RPM.

2m radius, 6RPM, force of 0.08g on the outside. Need to angle the floor a bit. But it should be enough space for someone to spend a few days inside. A larger one for weeks to months would be maybe 10m radius with signficantly more angled flooring. But again, it's not exactly a pricey experiment to run.

EDIT: just turned slowly in a circle whilst timing myself. 7RPM. It's tolerable enough.

Also, transient high rotation is enough for excercise. We can use a lower gravity for day to day activities, only the gym needs to be spun up to full g. And we actually do have data that says high rotation is not a problem for such stretches of time.

RTGs using more efficient energy conversion and suitably containable isotopes might achieve power densities comparable to nuclear reactors for certain applications. Strontium titanate puts out about 250W/kg; it doesn't seem unlikely to me that a 1 tonne complete system could achieve 100kWe.

If we get good at nuclear tramsmutation, perhaps we can achieve far higher power densities than that. Even if it's very poorly performing as an energy storage system, the energy to produce it would come cheaply from large solar farms, and provide something far more suitable for use in spaceships.

Keen on antimatter mining too of course. Maybe we'll finally get fusion power... Once we reach Jupiter and can harvest plentiful antimatter to use as the trigger.

Tbf, a lot of the parts that have burned shouldn't have much growing there anyway... it would be terrible and funny and not at all surprising if California just rebuilds exactly the same and regrows everything and ten years later it all burns down again.

I'm unconvinced by claims about  low maximum tolerable RPM. If you spin on the spot, you don't get much dizziness from 10RPM, and that only when you stop. What matters is how close your ears are to the axis of rotation/the coriolis forces they're exposed to. Figure skaters can go far higher than that.

We could investigate this fairly cheaply on Earth. Using training periods, people can acclimatise to 26 RPM.. A centrifuge hab could be built to examine longer term effects, angled to account for earth gravity of course. Though getting up to the highest levels would not be simple, given how much centrifugal acceleration would be involved.

We'd want to spin the crew quarters anyway for convenience, but it doesn't have to be anywhere close to 1g to make plumbing work and dust settle and provide a definite down directiom. Maybe 0.1g. We can achieve that spinning about the long axis... gravity just isn't that big a deal for missions tbh, the only reason the station lacks a centrifuge is that someone with influence is actively opposed to going beyond LEO...

Since we haven't ever gone to Mars, we are going to find out by building stations to do the research. Until then, there isn't the data to use in designs. Our one data point for partial gravity suggests a lot of the issues resolve with Lunar levels. That's in mice, which can't be put on am exercise regimen, so we don't know how well partial gravity + exercise will do. Doing the research is far far cheaper than commiting to a design that is excessive.

Going back to the ring concept, what if it was a cylinder? Enclose a small rubble pile with a spinning cylinder and then deliberately disrupt the pile. Possibly with gas added to help fluidise the rock and dust. With enough centrifugal force (1% g? 5%?) the rock will settle on the ring, and it may be possible to make it settle out by density as well for ease of processing.

This could also be done under thrust, using the thrust of the spacecraft to do it. One can imagine a large frontal funnel which is used to push the asteroid, containing it as it is disrupted. A means to move small rubble piles around.

Starmer has announced that Labour plan to cut immigration. Down from close to a million a year (the "Boriswave"). We'll see how it goes. Seems though that the Anglosphere is finally closing the main doors; Trudeu has announced Canada will be severely curtailed immigration also.

I mean, maybe we'll still be running at 200k a year. Which is still bad, but nowhere near as bad as 900k a year.

There are people working on this -- Terraformer Industries, solar powered methane synthesis.

Personally I think the money is in Dimethyl Ether more, but, we presently have infrastructure for using Methane. Pricey for heating but usable for electricity generation.

I wonder if an amnesty bill could get through Congress with the proviso that anyone who takes advantage of it will be barred from American citizenship - - if they want a pathway to citizenship, they have to leave the country and reenter legally. Provides amnesty whilst still providing some kind of consequence for illegal immigration.

The Op is about drilling (well, partly blasting) through rock. But many places where we would like to tunnel, both on and off earth, involve building tunnels in soil, which requires supports to be built either as we go or before hand. I haven't found anything about the application of microwaves in this case, even though they've been considered as a way to sinter lunar souls to produce infrastructure.

If sufficient heat could be applied in the right location, a temporary structure could be sintered through the soil, which could then be excavated. Most applicable in clay soils, where the temperature requirements are lower and the brick produced AFAIK is stronger, but potentially doable in sand and gravel soils too, such as those found south of the Thames. Heat could be delivered via microwaves, but also direct heating elements - - bricks are fired at a temperature comfortably below the melting point of steel, so steel rods could perhaps be rammed through the soil before running high currents through them to heat the surrounding clay. Sand and gravel would be harder, but even then it might be an option - - perhaps graphite? The heating elements would be sacrificial, so they have to be cheap and disposable. With microwaves, a combination with a tunnelling shield could work. Sinter the tunnel a metre or so ahead, excavate it, move forward, and repeat.

I don't expect the tunnels produced to be used as is, but it would make the installation or construction of a permanent structure far easier.

Re. nuclear waste heat and boreholes, it seems that every option for heating besides direct nuclear (which presumably can be throttled over a year) would benefit from some means of interseasonal storage. If we're relying on reactors for electricity, that heat is being wasted in summer.

What's the waste heat production for Britain's current reactors, 10GW? I know they provide about 5GW of power. If some means of storing that heat was available, would the existing fleet be enough, combined with actually insulated houses?

The boreholes (storage) and network (distribution) concept seems to be pretty agnostic about what the source of heat is. Which is a bonus, because it doesn't become a stranded asset if we decide to pursue a different heat source. The systems in Europe have proven this.

The difficulty of and resource intensity of (fast) interstellar travel, coupled with the sheer abundance of our own solar system, would seem to work against interstellar colonisation for resource reasons. That leaves fringe groups who want to settle it for ideological reasons -- and fringe groups are usually not that well resourced (see the Expanse's Mormons for an exception).

Slowboats and island hopping otoh, that could be different. But also far far slower. A civilisation expanding at 0.01% of the speed of light could settle the entire galaxy in about... 10 billion years.

Settling the solar system, that seems to be something within our technological capabilities. We can still have our space opera future