dawg wrote: ↑Sat Nov 13, 2021 9:37 pm
Wibbs, from my ( engineers ) point of view, resolving the issues is the thrill of it.
Oh most certainly.
Present talk is to tanker fuel to leo ( and maybe the moon ) and set up a refueling station
Nextgen motors run off (liquid) O2 & CH4
Assumption that this can be produced from water, CO2 and sunlight ( i.e. fuel plant on Mars )
Well let's look at Mars. Yes there's a load of CO2 and a fair bit of water but they're either locked in the poles in ice form or
extremely difuse in what passes for the atmosphere. OK the average human takes around 20,000 breaths per day and on breathing out there's a fair bit of CO2. Comparing the air density of Earth to Mars against that Mars would be a minute or two of breathing out. The Martian atmosphere is crazily thin. The sunlight is also half the strength of the levels hitting the Earth. So you have a few serious practical engineering problems. You first have to collect the CO2 which will use lots of energy and not a little time. Then you have to process it into a form usuable by the engines and get it into storage. More energy. Solar is going to need at least double the size of the equivalent on earth and you have to keep the panels clear of the ever present Martian dust. Pulling CO2 out of Earth's much more amenable atmosphere and storing it using solar energy would be a longwinded affair and take a fair bit of time and that's without all the other hazards of Mars involved and you have all the materials you need to hand. Splitting water into O2 and H is bloody energy intensive too. It looks easy if you stick two wires from a car battery into water and get bubbles, but on an industrial scale it's really not. That's one problem with using hydrogen to replace fossil fuel engines. Ah sure we're surrounded by water we can split that. Nope. Most of the hydrogen produced today uses a different method, ironically using fossil fuels as the base ingredients and it's pretty dirty. You pretty much may as well use the fossil fuels.
Then you have the problems of living there. That flic the Martian had the stranded astronaut using Martian "soil" to produce spuds. Nope. Martian soil is full of stuff like chlorates that's very toxic to plants and any that will grow in it would need brought in nutrients and would concentrate those toxins in their roots, leaves and fruit, so it would be toxic to eat too. Then you add in the lack of light for photosynthesis. In teh same flic you had his living quarters battered by a Martian storm. The reality is you would barely register hurricane force Martian winds on the hairs of your arm.
The business of the earths atmosphere & gravity ( i.e. energy needed to get out and energy given off on reentry ) doesnt crop up with moon or Mars to the same extent. Once the big stuff has been powered out of earth gravity, perhaps they should stay up there with little yokes going down to earth ? ( dont think thats in anyones plan at present - and why would it ? clearly a second best approach )
When they were looking into Apollo in the early days one notion was to build a space station vehicle assembly type affair in near earth orbit. They gave up on that plan because a) at that stage they'd only made suborbital flights b) it would be scarily expensive and c) no way could they do it within the decade. The fact the Saturn V went from initial ideas to flight in six years was incredible enough. So they went for the much "cheaper" and dirtier big feckin rocket with two small craft, where one would leave and go down to the surface and back again(a hairy notion in of itself). The One giant feck off rocket landing directly on the Moon a la the Tintin pic above was dismissed early on as the thing would have been huge and the ladder to the surface a long way down and would have been about as stable as a one legged stool. And they had no idea how solid the moon's surface was at that point. Some reckoned the surface was made of extremely fine dust going down hundreds of metres and any craft would just sink down into it, or the engines would blow a huge crater and sink into that. Until Apollo 11 actually touched down they still weren't sure. Hence the landing gear didn't compress fully and Neil had to jump the last metre or so from the ladder to the pad. It turns out the moon's surface is covered in fine dust, but for most of it not very deep, a few inches to a few feet. You can see that with the film of the Apollo landings, some kick up a load of dust, some bugger all. Even planting the US flag was a problem as the pole would only go down a couple of inches on some missions. Armstrong was very conscious of it falling over on international TV and when they took off from the surface it did blow down.
Earth orbit is easy and we'll get ever better at that alright, but going beyond Earth to the Moon or Mars or beyond is of a serious magnitude more of a leap. As for interstellar travel... Well, unless we figure a way to bend spacetime it's essentially unfeasible, even with imaginary future propulsion systems. Even if you could get near the speed of light, the energy required is
staggeringly vast. Then you'd have to have some sort of deflector ahead of you because at even half those speeds a grain of rice hitting you would be like a small nuclear explosion. And there's a lot bigger stuff out there. Stuff that at those speeds would be hard to spot and harder to steer around. Beyond Pluto there is a huge area called the Oort cloud far from the light of the sun, beyond that feck knows. There could be lots of dark planet sized objects just hanging out beyond the gravitational influence of stars.
Travelling to another star system is kinda like attempting to fly a paper plane across the Atlantic. It would be
technically feasible and we could imagine how we might do it, but it would take a very long time and you might get across once in every thousand attempts and what would be the point of trying? Until we confirm an Eart like planet we could colonise and even then. It's likely there isn't one in our nieghbourhood so add on more decades of travel.
The other problem is that you wouldn't want to be the first to try. Chances are in your many decades of flight new tech could come along on Earth and newer faster missions would follow and pass you out on the way and they'd have no way to meet up and move you to their ship. And whatever trip you took would be a one way one.
Rejoice in the awareness of feeling stupid, for that’s how you end up learning new things. If you’re not aware you’re stupid, you probably are.
