farmerben

Calcium is also a major byproduct of refining regolith. What uses are there for calcium? Perhaps in the vacuum of space calcium mirrors would be viable.

canal locks are a lousy analogy

How do you convert a DC voltage into a different DC voltage? I'm thinking about the adapters that plug into a 12V cigarette lighter in a car, and have a 5V output. They don't heat up that much, so I don't think its just a resistor drop.

One of the easiest mining processes to do on the Moon and Mars

How smart is it to stack hydrofoils vertically? My idea is for a proa sailing vessel in which the smaller windward hull foils. But instead of one foil it could be a multitiered foil, like a biplane wing. You would be able to pilot it such that at ideal power only the bottom foil is exposed. But the upper foils allow it to lift even at less than full power. In choppy seas the upper foil will slam in and out of the water but it might be OK.

Imagine for some reason you were completely fossil fuel free but still allowed to use ethanol fuel. Other than the fact they are platinum and you can't easily get them on todays market ,what if fuel cells combined with sterling engines to recover part of the waste heat are better than ethanol only engines. For that matter there are not many pure ethanol engines in cars or planes or anything. A major downside is the hydrophilic aspect of pure ethanol which degrades its ignition potential. But, I think a bit of water pollution is less of a problem in fuel cells. Helium filled sterling engines are more efficient than steam engines as a secondary heat engine. It would be easier to implement on boats and trains before cars and planes. Methanol fuel cells also work extremely well, and methanol is a small percentage waste product of ethanol production. Do you think an ethanol only based fuel cycle is feasible? What types of engines actually work well?

https://news.cornell.edu/stories/2022/02/new-catalysts-steer-hydrogen-fuel-cells-mainstream Cheaper fuel cells, yay!

Methane fuel cells are available as well. They are crazy expensive though. I'm actually designing a catamaran to take the Northwest Passage. I'm looking at the best way to power it and to heat the whole boat. Perhaps fuel cells could be built into the oven. You can cook on the heat generated by fuel cells. Open the oven door and blow a fan across it to heat the whole boat. Of course there are numerous approaches you could take for heat, the priorities are lightweight and fewest number of potential failure points.

What is the weight to energy ratio of hydrogen fuel cells? I googled it but can't find simple off the shelf hydrogen fuel cells with their mass and energy output posted like the ones in KSP.

Is an ocean planet really colonizable? How?

Bezos loves KSP proof in taters video above.

Most of the objects we are interested in have periapsis at the range of Pluto and beyond, namely balls of frozen water and ammonia which will help build an atmosphere on Mars. We should be able to find plenty of Kuiper belt objects with the inclination close to ideal already. 4000-5000 km/s of delta V should be more than adequate. If you had a mass driver you might be better off flinging snowballs at mars thousands of times and letting the main comet go into interstellar space. This would allow you to adjust your aim. And if some of your shots miss by 1000 years it will not be bad for the Martians as small ice chunks will "burn up" in the atmosphere, where a giant comet might not.

The scenario of deflecting a comet so it misses a planet is very different than deflecting one so it hits. You want to do most of the pushing way out in Kuiper belt where velocity is slow. You have to maneuver the comet very precisely. So I think you need to land on the comet and have variable thrusters. Nuking it is not precise enough. The painting strategy might not be precise enough either.

I think you need to use the comet itself as propellant.

What is the best propulsion method to perturb a comet so it will impact Mars?

Part C must be a vacuum filled Beryllium chamber. The other part can be an actively cooled helium sterling cycle engine. The electricity derived could support quite a lot of systems. It's unclear whether the discs will be coated with U235 or some more exotic unobtanium. Americium or Curium might be better. This is because of high energy alpha particles interacting with the beryllium will excite neutrons driving it above criticality. And you want to a fissile material that has a large cross section for both fast and slow neutrons.

I dunno what TRL means. I think the TWR is rather low. But ion thrusters are in the 5000s ISP range, so they are not quite up for interstellar voyaging.

https://en.wikipedia.org/wiki/Fission-fragment_rocket

Would carbon monoxide be the ideal fuel for a Mars direct style ISRU fuel system? It gets and ISP of only 200s. So its half as powerful as methane or kerosene. But you only need 1/9 of the dV to go from surface to orbit. The real question is can you the machinery to make carbon monoxide out of CO2 and separate the oxygen as well be made in a compact lightweight form? You can also blend gaseous fuels (possibly). Wood gas is about half carbon monoxide and half hydrogen.

It's not on my list of major concerns period. You could more than make up for the dose by eating less radioactive potassium, fewer fresh outdoor grown fruits and so on.

For a mission we could do today. Land a stationary probe in the center of the caldera on Pavonis Mons. Equip it with high quality telescopic cameras and radar. You can scan the entire vertical surface looking for caves, and scanning the minerals as best you can from 20 km away. The cliff walls of the caldera are over 150 km in circumference and 5 km high. Dust does not rest on vertical surfaces.

I know somebody else who said the same thing. I liked it even though its very implausible. Maybe I just like the concept of an orbital ring civilization.

I enjoyed the Ender's Game novels as well, including the sequels. But by far my favorite author is Neal Stephanson.

Pavonis Mons is an ideal spot for an agricultural city as well as other things. There is a deep crater to dome over and hold atmosphere. Natural rock will provide radiation shielding for all but a slice of sky. The center of the dome/crater could become agricultural while the habitations are carved into the walls of the crater. The other nice thing about Pavonis Mons is the rim is right on the equator so it an ideal spaceport, or a rail launched mass driver. All the spoil from excavating can be rolled down the slopes of the mountain to create tracks for mass driver/rail/road/electricity transport. The top of the mountain is above the height of many dust storms so cleaning the solar panels is relatively easier than at low elevation. Not sure about water. Water and air might have to be hauled in and continuously recycled. It makes more sense to grow your veggies in containers for water recycling and other reasons. Giant dehumidifiers will be needed to catch the moisture from plants and animals. The basic floor and walls of the crater can be left as bare rock. That is somewhat permeable to air and water. But allows you to be constantly working fresh ground. https://en.wikipedia.org/wiki/Pavonis_Mons