mikegarrison

Of course, when homo sapiens emerged from the other (now gone) hominids is not 100% clear.

Mostly people hunted deer and rabbits, not mammoth. Anyway, studies of hunter-gatherer cultures have tended to show that hunting -- which brings in a large amount of quick-to-spoil meat and tends to be kind of random -- usually results in the meat being shared. It kind of works like a meat food bank, except that instead of storing the meat in a freezer, they store the meat in the memories of the other hunters, who then later share their own good fortune. Hunting camps still work like this today. It's quite common when you go hunting that if someone in your party gets an animal, everyone stops hunting and helps haul the meat back to camp. And then everyone splits the meat equally. But gathering -- which tends to simply be a matter of putting in the work to get a fixed amount of results -- tends to not be shared, and instead the one who gathers the most gets the most. On Mars, undoubtedly everyone would work together communally, at first, and all eat from the same food supply.

I tend to doubt that many human societies larger than, say, nuclear families have truly not had any concept of personal ownership. People spend time and calories making tools and gathering food, and it is unlikely they would just have no concept that the results of their labor belong to them. A small Mars colony may well start out with most things just being community property, but I would bet that once it got to be enough, people would start claiming their own spaces and possessions.

Selling addictive substances tends to be profitable. Ask Starbucks about that.

AKA the "small fortune" joke. How do you make a small fortune running a winery? Start with a large fortune. (For "running a winery", you can also insert any other notoriously hard-to-profit-from task.)

There is a whole class of companies that do not "exist to make money". These are called "non-profit companies". (Yes, OK, I do know that a non-profit can make a profit. The important part is they do not return any profits to their owners/members/shareholders. But the point is that companies exist for many reasons, and making a profit is not always one of them.)

Jet engines could easily melt their own combustion chamber, if not for the engineering to make sure that doesn't happen. They are not as different as you seem to think. But the typical jet engine combustor is much more complicated than a rocket engine combustor, because it has constraints that a rocket engine combustor doesn't have. Emissions control, for example. There are no emissions rules for rocket engines.

"goal".

You see these ugly gloriously beautiful sketches? I made this in about three minutes in Powerpoint for one of my working papers in ICAO CAEP Working Group 3, and somehow they ended up in the final draft, never getting replaced by something nicer.

https://www.ecfr.gov/current/title-14/chapter-I/subchapter-C/part-38 I worked on this rule for six years almost full-time, and it has finally become part of US code. (It's been law in other places for several years now.)

Turbine engines are usually limited by the combustor, first stage turbine nozzle, and first stage turbine blades. In other words, the hottest part of the engine. All metals lose their durability as they approach their temperature limits. If you keep the temps low enough compared to the temperature resistance of the metal, the hot section can last for an almost indefinite amount of time. But to get more thrust and fuel efficiency, you want that T4 to be as hot as you can stand for it to be. So it's a tradeoff. Usually engines are designed for a certain number of hours on-wing, and then they push the temperatures and pressures up and the cooling airflow down until they hit that target. They could get them to last longer, but it would cost in performance and efficiency. They could get them to have higher performance and efficiency, but they wouldn't last as long.

There is nothing weird about that. The rocket starts with a Vhorizontal = to the horizontal speed on the surface of Kerbin. As it goes up (neglecting air friction), it keep that same Vh. But to stay above the same point it started at, it would actually need a bigger Vh, because the radius above the center of the planet is bigger the higher the rocket goes. So it drifts east, but not as fast as the surface is going east. Thus, relative to the surface, it falls behind by drifting west.

Having done this before, many times, there are many reasons why someone might prepare a proposal like this and not submit it. Number 1 is that your own management, who asked for the proposal in the first place, changes their mind either once they see it or just because time has passed and things have changed.

Yup. Mostly operators want to avoid that, so they burn off fuel. A potentially more difficult problem is if the current fuel load is not within the cg limits for landing. Airplanes can (and do) sometimes fly in cruise with cgs that are not allowed for landing.

No human (or even animal) children have ever been born off Earth, so it's not entirely certain that humans could have children on Mars or in a space station.