Hannu2

Those numbers are typically quite optimistic. Probably they can also manufacture few new ones during end of the year. As far as I know they have relatively fast production line.

You encounter first problem very soon. I recommend to make some studies at moderate speeds before actual experiments at "orbital speed + huge aerodynamic losses" velocity range. Oxygen is strongly paramagnetic and therefore air is paramagnetic. All nice magnetic contraptions built to handle diamagnetic fluid, like water, do not work.

I am actually amazed how one company can have 8 working rocket stages simultaneously and half of them are used and to be used again. If someone had predicted this decade ago I would have thought he is crazy and maybe need medical help. Actually I think Musk is crazy but in very creative and positive way and does not need doctor but billions of funding for his crazy ideas. SpaceX has made impossible to obvious in a decade, even all those manned Mars things are not realistic.

It is not so simple. You have to take viscosity and heat capacity of ambient gas into account. You should use Navier and Stokes equations to solve flow field and show that it can transport enough energy at reasonable temperature. What a good starting point to plan a base to extreme hostile planet. Would you like to be first inhabitant in base built using your guesses? :-) What? External heat exchanger is fro cooling. It gives heat to ambient air, which warm up and begin to flow. You have to obey fridge manufacturer's instructions when you build your kitchen. If there is not enough room for air flow fridge overheats and its efficiency and lifetime decrease. It is exactly same problem in Venus. You must make sure that you generate enough gas flow to transport excess heat away without overheating exchanger. You can not guess based on fridges or other familiar applications on Earth. Venus atmosphere is so dense that practical intuition based on air do not work. Terraforming seems clearly impossible for now. Many unexpected developing steps must happen before it is possible and even then it is not clear is it profitable to anyone able to do it. As I said, I think that humans do not need planets at that technical level terraforming will be possible, if it ever be. This is true. But how realistic is building of that scale in Venus? What kind of technology is needed to transport of fabricate materials and build such huge buildings? And if we assume such a technomagic, what is reason to build on such impractical environment? Things may be impossible also if no-one with enough resources to make them has any reason or will to do it.

They are ablative materials. They evaporate and absorb heat during couple of minutes of atmospheric entry. If I remember correctly, entry burns several centimeters of ablative stuff. Any plastic can not handle high temperatures continuously. You must use carbides, ceramics, stone or glass wool etc. if you want long lived thermal insulator. Probably chemical composition of Venus's atmosphere restricts materials. I have no idea how for example gaseous sulfuric acid affects to normal insulator materials. I know and use it to cool electronics. But it has limited ability. I would not trust that 150 K temperature difference induce enough mass flow at conditions on Venus. How cooling tower work in high density atmosphere and how to build such massive buildings on extreme hostile environment? Nothing in real world can't be proved impossible. Even if something is against known natural laws there is always possibility that we find new physical phenomena or known natural laws change for some reason (there are speculations on some odd phase transitions of space or quantum fields, which can change natural laws, but I am not familiar with such extreme physics). In my opinion it is much more interesting what is practically possible or impossible in foreseeable future and realistic resources. Manned operations on Venus is certainly impossible with these rules. But I read somewhere that industry investigates gallium nitride electronics, which can operate at much higher temperatures than silicon. They may be able to operate at Venus temperatures at some day (it is investigated to get smaller and cheaper power electronics, not for Venus operations).

Good luck in plastic building on Venus. I would use some low density ceramic insulator. Are you sure? It is not trivial problem what kind of flow 900 K gas causes on Venus and is it enough to transport all heat away. Or how much power you need to produce such flow artificially. I meant exactly this kind of questions. Usually in science fiction and overoptimistic techtalk this kind of questions are omitted. Complex things are just assumed to be done "somehow". But I think that if there is not answers operation is impossible for now. It may be possible in future, if it is investigated and solutions are found, but before that it is unsure and I can not say it is possible. You probably think that what is not proved to be impossible (i.e. against known natural laws), is possible by default and can be done.

Humans ask always do we really need or want or can afford it. And unfortunately, but not surprisingly, those who have money and those who think cool space adventures are needed are completely different groups. I wrote about time when operations on Venus are possibly considered severely and not just in small talk on net forums. It must be hundreds or thousands of years in future.

What are practical amounts of powers and coolant flows?. Efficiency of electric production is very poor in those temperatures. You have to get rid of tens of megawatts excess heat for every produced megawatt. Do you know for example what kind of winds there are? Othervise you heat gas around your powerplant which decreases efficiency and power output and, on the other hand, increases power intake of building cooling. You are in positive feedback loop, which ends to destruction. Even in cold Finland they have to occasionally decrease the power of nuclear powerplants if we have exceptionally warm weather because they have strict limits how much they are allowed to heat sea water around them. In Earth it is easy to replace them with other means, but in Venus the situation is not so nice if there is no winds and air begins to warm around the base.

Actually those are much more terrible as they sound, if I think development of production or scientific devices. There is not any applications for tech in those conditions on Earth. There may be sensors, rotor blades, tubings, valves, tanks etc. but not complex machines or electronics working there. Your "can" means we do not know exact natural laws against it. From my point of view as an engineer it is science fiction. "Can" means that I know how to do or where to order components or can find it out in reasonable time and budget. If my boss ask something operating on Venus, I have to say that it is impossible. He is not interested natural laws and philosophy but when it is ready to work and how much it will cost. Those are questions in which no one can answer. And in my opinion those must be include in word "can". And my personal feeling is that at the time they can be answered there is no reason to do so. Humans are adapted (with genetic engineering) to zero gravity and live in huge space stations. There is no reasons to live on planets, except maybe some kind of scientific research and primitive cultures on Earth. Asteroids give all resources and space stations have room for billions of humans. All such is probably easy tasks compared to living on Venus or terraforming it. It must be much more practical to change human biology suitable to space than space suitable for current humans.

If it was 1 s at full (or high) thrust, they probably investigated ignition process. Start up process of rocket engine takes several seconds and may cause some special requirements for something.

Yes, you certaily need a pusher plate. As KAK already told, planets are very much like liquid droplets. Their structural strength is negligible compared to their mass and internal forces. You can no bolt technomagical superengine to bedrock and give thrust. Energy is another issue. If you want to make some major rearrangement of planets in Solar system you need tens of km/s dv. Kinetic energy is comparable to gravitational binding energy of planetary sized bodies. For example binding energy of Earth is about 2E32 J. It corresponds to velocity of 8.2 km/s. If you think for example saving earth when the Sun becomes a red giant, you need more. It is known that energy efficiency of rockets are very poor, and the higher ISP the poorer efficiency. Even we can assume unlimited energy source (which is not trivial in such enormous energy levels), we must also have technology which radiate loss energy to space instead of vaporizing the transported planet. For example bomb type solutions use very large part of energy to heat pusher plate. They would certainly not work even pusher would be larger than Earth. I think you have to assume violation of conservation laws in any case or accept that operation takes hundreds of millions of years.

Need is not driving force in space. To be honest, we do not need anything but telecommunication and some surveillance satellites on LEO (to live normal live and run normal business). All manned operations and astronomic research are "nice to have" things, which get small public funding from wealthy countries. I think that in USA space research funding is less than a percent in federal budget and in all other countries much less or nothing. Economic or environmental benefits of other celestial bodies (for example asteroid mining) are behind huge economic and developing processes and any state government or large capital owners do not see reasonable profit possibilities in reasonable time scale in such operations. Musk may have some ideology, behind his business but he is also clever and greedy businessman. I think all that manned Mars hype is a vision but not important reason behind his investments. Global satellite network is. It may pay all investments in SpaceX back and give very good profit in his lifetime, if everything goes well. Manned Mars operations will take decades, probably couple of generations and need economic resources and political will of superpower state. Even richest individuals can not fund such an effort, even they can operate about an order of magnitude lower costs than public space administrations. There is no real need of superrockets. No funded plans base on them, for obvious reasons, because there are no such rockets and development schedules are known to be extremely overoptimistic and unrealistic. And it is difficult to get funds for superrockets, because no-one can say clear use for them. But I am sure that if such rockets will be available, for example BFR or New Glenn, satellite industry will soon learn to get benefits from their increased capacity. Also public projects will benefit if mass limits are significantly higher and cost per kg lower. It is the same thing in all transport logistics. Bigger units are always economically better. The whole development of ships, airplanes, trains and trucks have been increasing sizes and loads. Every generation have been bigger than predecessors and cost of transport (per ton and kilometer) have fall down even unit cost of behemoth class devices have increased. It is also economically possible to obey more strict safety regulations and environmental protection measures in single massive and expensive unit than distribute them to many smaller units. I do not see any reason to expect that space transport will differ from general rule.

In any case general attitude must change before humans can get new significant manned achievements. We have to learn to accept that crew losses are inevitable in such extreme conditions. Pioneering work near frontiers of known world will never be safe. Before that cultural change manned activity will be boring investigation of tardigrades on LEO and endless talk of pompous "future plans" without any kind of realism. Astronaut's attitude is not a problem. There is certainly more willing individuals for heroic but dangerous work than ever can be employed. But attitudes of politicians and funders is real problem, and that is based on opinions of average people.

Some times ago there was discussion that important reason for methane development was lower sooting in combustion (compared to kerosine, supercold superflammable hydrogen is in any case too impractical for safe rapid reuse). Soot causes problems or at least need for extra cleaning between uses in kerosine engines, like Merlin. I did not remember was it in turbopumps, it does not sound reasonable that soot accumulates in actual chamber.

It is certainly possible, if you have couple of billions extra money for development and building and not intention to get it ever back as profit. But I would not ask funding for such project from anyone else. I can not believe that you can compete with SpaceX's or Blue Origin's coming big rockets in any part of performance or economy. As far as I understood the most important reason to choose methane as a fuel is better reusing properties. It will be essential in economic competition of next generation rockets. It seem also that optimal engine size for effective staged combustion is smaller than F1 was. 5 huge engines is probably worse than large number of smaller ones. Etc. Saturn V was very specific solution under conditions of limited time and unlimited budget and therefore many basic design choices was not suitable for modern requirements of economy and reusability. Of course you can build modern rocket about the same size and call it Saturn VI for nostalgic reasons, but technical solutions will be very different.

Gimbal can compensate torque if the thrust vector points to the center of gravity. But it causes lateral force, which makes killing of lateral velocity impossible, if the rocket is not tilted so that working engine is under center of gravity. Landing will be asymmetric and cause excessive load to lander legs. Probably they can save the rocket in emergency situation, but it is hard to believe that they could use asymmetric landing as normal operation and reuse the rocket after that.

Not in foreseeable future. Power is not the only problem, power must be also focused to ionize and accelerate ions. Antimatter can contain huge amount of energy but it is far from trivial to convert gamma radiation produced in annihilation to any usable form. Current devices can not handle mass flow and/or acceleration voltages needed for 1g acceleration. It depends on efficiency of energy conversions. We do not have any reference tech which makes conversion from antimatter to anything reasonable or good practical ideas how to do it. Theoretical considerations of antimatter rockets typically assume perfect conversion ratio without mentioning how to do it in practice or is it even possible under known natural laws. In scifi story you have to invent some magic tech in any case, if you operate with antimatter, so you have freedom to choose what fits to your story. In my opinion you should use more time to create interesting story and not so much to thinking issues with realism. Antimatter and interstellar transport are topics from which we do not have any real understanding what can be done and how. It is clear that it is totally impossible with our tech level and its predictable successors and it is also not possible to predict what will be possible in distant future. Typical predictions (for example in fictive literature) are extrapolations from recent development but true development have tendency to saturate until some unpredictable black swan incident happens and gives new possibilities and steers development to new direction. https://en.wikipedia.org/wiki/Black_swan_theory

Maybe you can assume more developed civilization and species too with antimatter rockets. Current competitive capitalism with time scale of single years or even quarters will never produce that high civilization needed to utilize whole solar system. If we do not manage to develop better administration we will compete each other to extinction on this planet. That is always a personal opinion. Nature or science does not answer that kind of questions. Probably always will be individuals who think that it is somehow wrong to change world any more than necessary for primitive living and other extreme who think that development and expansion is a duty for intelligent species. Majority want benefits but not NIMBY -effects. No. Mass of rings is negligible compared to Saturnian system. At least some astronomers think that ring system is naturally short lived thing in astronomical timescale (100 million years). You have to use imagination in any case. Net made from superstrong unobtainium strings is certainly one option. But it is difficult to predict what is the most effective method with scifi tech level. It is more easy to imagine antimatter rocket engine and calculate its performance than extreme development stages of mundane technology. If you want more futuristic story you can for example use micro or nanorobots for cutting pieces from asteroid, sorting them based on mineral concentration and transport them to melting chamber.

If I understood correctly, you have to achieve trajectory which goes closer than 100 km of massive body. It means practically dwarf planets, because you probably do not want to enter into atmosphere at relativistic speed. Actually you have to assume scifi technology to handle very dilute interstellar gas. Such predictions and targeting accuracy is as impossible as your drive. You have to invent some cool scifidevices which can handle it. All real spacecrafts measure their positions relative to targets and make several course corrections during the trip. Even in solar system when you have very good predictions of target position. Even if you target to star itself it needs impossible aiming. And you need also some nice unrealsitic tech to stop the ship at 100 km altitude over photosphere and accelerate several hundreds of kilometers per sec to normal trajectory without overheating.

I did not say so. Reason is obvious. I compared hydrogen to methane and kerosine with liquid oxygen. Hydrogen is extremely cold (even compared to oxygen and methane) and causes hydrogen embrittlement which gives very strict restrictions to materials. Hydrogen is light which needs large tanks. It is exceptionally flammable (compared to normal fuels, of course exotic stuff like hypergolics or fluorine are even worse). Hydrogen flows through metals and other materials which makes storage and transportation bureaucratic and expensive. Etc. I do not believe that hydrogen will ever be significant fuel in any large scale applications.

Because hydrogen is so impractical and dangerous too. It is good choice for upper stage of expendable rocket, but it seems that SpaceX and Blue Origin will use safer and simpler methane in their big reusable rockets. I have understood that it is main reason why it is investigated for propellant. It is not actually safe but not as dangerous for workers and environment than hydrazine compounds. It has other good properties too but I do not know why it is not used. Is there some unsolved problems or is space industry just so conservative that nothing changes if it is not absolutely necessary.

Space tech was very special and classified military tech at 50s and 60s when they considered fluorine and other exotic and dangerous chemicals as a fuel. But now space tech is civil industry and have to obey strict environmental and human safety regulations. Which are going to develop to more strict direction on next decades. Space companies have tendency to move to safer, cheaper and more common chemicals from all exotic and expensive stuff. I think the trend of next decades is to replace hydrogen and hydrazine derivatives with safer stuff instead of search the last digits of ISP with unobtainium fuel. Cheap reusing and next generation of private companies' huge rockets will make safety and reliability issues even more important and take away the advantage of dangerous superfuels.

I think the risk is acceptable if another option is to land on enemy territory with parachute.

Maybe in version 1.251170.0.

I just noticed that background sky seems to be real. There is Orion, Taurus, etc. familiar constellations clearly visible. Is it stock or does Outer Planets mod change it? When they did change it?