farmerben

Actually we probably need an antenna on the dark side of the moon just to scan the radio bands that are full of human signals. Our own signals bounced off the moon may be much louder than the signals we are looking for. Beyond a hundred light years or it would be difficult to detect a civilization exactly like ourselves. And we stopped building >500kW radio transmitters for civilian use several decades ago.

It is challenging to keep liquid oxygen in space, you have to keep it chilled. Hydrogen peroxide decomposes on its own. Dinitrogen Tetroxide also seems subject to spontaneous breakdown, though I would like to know more details. Many cryogenic fuels have the same difficulties as liquid oxygen. Kerosene will probably last forever in a steel tank, but it probably needs to be warm to work. Hydrazine might be more stable than the oxidizers, but I'm not sure. What about solid fuel might be stable in space. I wonder if it is feasible to make solid rockets on the Moon or Mars? Mars exploration requires storability of 2 years minimum. It would be nice to have much more.

https://en.wikipedia.org/wiki/Footfall

Not necessarily. Omni-directional radio falls off in intensity at 1/r^2 and stars and large magnetospheres pollute the radio with noise. If a civilization wanted to send messages hundreds of light years they would be more likely to use a modulated laser than an omnidirectional radio. Now that more people are streaming content online and through phones the strength of signal is low.

I like an idea from Neal Stephanson's "Seven Eves", the cheap spacesuit is just the arms and a coffin like solid box for the rest of the human body.

I didn't find ISP information for C-stoff and T-stoff. There is a lot of water on those, but the storability advantage could be huge. What temperatures do they freeze or separate I wonder? I was considering the possibility of water pipes on Mars. You might need bulk water from the poles or Valles Marineras but the pipes would freeze with ordinary liquid water. When we get to the point of wanting to move tons of ice thousands of kilometers on Mars, surface transport starts to look good again. A railway with regenerative braking could bring its diggings down to pay for the energy of the lighter load of ice going up. Cog driven systems are perfect at low speeds. On the other hand two rail system can simply be your hot AC transmission line in the form of a rail. At least for now nobody is worried about safe crossings. If you can build poles to support overhead cables, then you can build railway sleepers. Probably easier since stone and even ice can make rail sleepers, but not poles.

you could patent that

Because of the low air density on Mars the lifting performance is approximately 200 times worse than airships on Earth. It has to be huge just to lift it's own envelope. And then you're at the mercy of the wind.

oops

Or maybe carbon monoxide and oxygen, as you can make that anywhere.

This might be a simple question: What are the alternating sunlight and darkness periods on the surface of Deimos? It is tidally locked to Mars with an orbital period of 7.5 hours. If you were standing on the outward (non Mars facing side) does this mean you would have "day" 7.5 hours long, followed by 7.5 hours darkness? On the Mars facing side you have a significant fraction of the sky taken up by the planet that throws Deimos into eclipse every "day". What portion of the day would be eclipse? How big is Mars as viewed from Diemos?

It seems to me that the ideal place to prospect for valuable mineral ores on Mars are the large volcanoes, including Olympus Mons. These high altitude sites might be ideal for other purposes as well, including slightly lower cost to obit. However the lowland such as the north pole ice cap is worth stationing for fuel, water, and air. So we have the need for transport between these regions. What would be the ideal vehicle? What sorts of road or track surfaces might be worth it to build on Mars. An electric wheeled rover that can handle off-road terrain is probably first. What comes next?

Other than the sonic boom breaking nearby windows I don't see what's so bad about going through air. A train is the most streamlined vehicle there is by default. Good skirting between and under the cars would help even more. I recall the Air force missile testing going up to Mach 7 on rails. On the moon or Mars we have a blank slate, without any of the height or width constraints on our terrestrial networks. You could go as big as you want.

Magnetic dust is your basic iron ore resource. You can collect magnetite easily and sinter it using microwaves into a solid I think you need wheeled vehicles for most new applications. Rail only makes sense when you know you need the same route thousands of times, i propose it being more useful than conveyor belts. A battery powered loco, and inert rail, would get the job done on a 20 km route. But you still need separate power cables for your mining equipment. The question is what do you use for rail sleepers... styrofoam... regolith coblestones?

The towers full of windows, at the top of the thread, are a bad idea. The radiation from even normal sunlight is three times higher than on Earth overall radiation is much higher. We will want viewing cupolas and observatories, but when not in use we will live underground with shielding.

You could scale down a standard railroad by at least 6 times and still have satisfactory performance. A steel railway built to the standards we have on Earth could handle insane mass. Still that is a possibility. It could turn out to that we get plentiful black sand magnetite just by passing a magnet over the dust.

Ideally you use lunar resources to create space mirrors and other infrastructure. The sodium cooled kilo power reactor is a no-brainer to start with.

My idea is 100m long plastic silage bags that fit inside small spacecraft. Unroll and inflate them on the moon. Then spray on an epoxy and hardener, this could be done from inside the tube, if vacuum epoxy doesn't exist. Afterwards it can be burred in dust. This idea minimizes launch mass and volume. A long horizontal tube has advantages over a dome, especially for this project where you have a sunny site and a sunless site connected. We eventually want transport over a 20km route. A narrow guage railway with aluminum rails might be the best solution. Cars of about 10 ton (mass) loaded capacity on aluminum wheels. I'm thinking of rails about 1 cm wide 10 cm tall, one is ground and one is 15,000 volts. The high voltage rail would be supported on glass insulators. That solves power transmission at the same time. The transition through airlocks presents a new engineering challenge, but it should be easy given the strength of rails. To connect the sections of tubes would require different types of couplings. At the two terminal ends a 6 or 8 sided connector dome with more branching 100 m sections would be great.

Hypergolics work good. That's what was mainly used on the Apollo lander.

Your mission: collide mystery goo into the surface of the moon at the maximum possible speed. Our scientists are interested in the results. You can use the F3 menu to check maximum speed reached even if it varies slightly from the indicated surface speed the moment before impact. My record so far is 18,495 m/s. My strategy was to launch with the moon directly overhead and not turn. A score of 20,000 m/s wins.

A Mars colony devoted to self-sufficiency is not going to grow very fast. Maybe the goal should be to expand habitable/vegetated area. Or to increase construction materials like glass and aluminum. Those are related goals anyway. Haul vitamins and microchips from Earth. The survival of an interplanetary transport system should be high priority. The motive of having insurance if Earth is destroyed, is not the most reasonable.

The idea that a city on Mars can be self sufficient is pretty far fetched. It might be better to shoot for Earth dependent O-Neil cylinders first. And also foundries on asteroids and the moon. An outpost on Mars would be a good thing. I just don't think self sufficiency is practical with our current technology.

Nah its aluminum and silicon. Much better for a Kardashev II civilization. In the long run we want to surround our star in computronium.

fun! i did it on the third design. don't have a video though

http://benoit.carry.free.fr/publication/refereed/2012-PSS-73-Carry.pdf There are several outliers in this data. Even the uncertainty in the data is problematic. One thing I noticed is they measured Psyche to be 3.3 g/cm3 ( +/- 1.1). That seems low. Soon we will have better data.