Hannu2

Self replication is obvious solution to problem of huge area under exploration. It makes exponential growth of exploring ability possible. It makes possible to chart every planet on every star in whole galaxy in geologically or biologically relatively short period. Practical solution would be some kind of robot colony which send smaller mining probes to asteroids and assemble robot factories on suitable orbits. Every solar system has materials and energy needed. All humans's machines are made from few tens of elements by using electric and thermal energy. What is the material you think is so special in our solar system? As far as I know everyone of them (at least which are used in industry) have been detected from space and there is also theoretical base why we can expect to find them everywhere. It is completely impossible with current or foreseeable technology. But there is no known restrictions from known natural laws. It is very much like interstellar traveling, which is many orders of magnitude away but no clear impossibilities are known. I am quite sure that we can build automated self replicating process and test it in asteroid belt before we can transport such system to nearby star system. Probably interstellar crafts will need some kind of intelligent and self repairing robot swarm to maintain them during very long trips. It is easier solution to believe than exotic energy shields against damage or near light speed propulsion at least for me.

I have always Mandelbrot set. My avatar is central part of my flag.

I have heard that you can build own spaceships in stock game too. It is certainly boring to fly spaceships some other person has planned but real fun is to build your own.

Maybe, but political situation was completely different on those days. Apollo was a propaganda project for cold war between superpowers. It had so high share of state's budget that nothing even near is possible in foreseeable future. Unfortunately space exploration is now low cost low interest science project for nerds and budgets compete with tardigrade investigations and ancient languages of disappeared cultures. SLS could fit in Apollo -like situation but several billions per launch ruin all current scientific space projects immediately. If administration of USA does not give crazy level of funding for example manned moon operations no one is able to buy SLS launch, which cost about as much as whole flagship class planetary mission. And I do not see such funding very realistic.

I think the most valuable things would still be metal asteroids. They are rich in rare metals and if they were able to be transported to Earth they would drop prices and availability and give new possibilities to utilize them in better products. Gas planets are made from hydrogen and helium which would be very impractical to transport in industrial quantities. Possibilities would depend on how large those spaceships could be. Building refineries and factories in space would reduce pollution problems on Earth very much and give possibilities to better life for most people.

He is not interested in science for science. Science is a tool for him and actual objectives are to do some monumental operations (and have absurd amount of money and power to make it possible). There is no good scientific reasons for manned space operations now. It is based on ideology. But if Musk and other new space company owners develop powerful and economical rockets and get those programs profitable by launching tens thousands of commercial satellites, also space science will benefit of cheaper launches. It will be possible to have higher performance probes, space telescopes, gravity wave observation satellites etc. scientific stuff for future science funds. Science will never be a reason to develop rockets. SpaceX does not have ability to build planetary probes. It would cost more time and money than developing of rockets. And no organization able to build Mars probes would not have accepted first technical test flight of new rocket model to launch their multi billion probes even flight has been free. Few hundred millions for ULA or Ariane rocket with very reliable launch record is small part of Mars probe's budget.

Fortunately Musk had cheap OBD controller which can clear error codes and turn off warning lights for inspection. Duct tape will fix it permanently before longer flights.

Metastability is only practical thing. Metastable material would be stored in normal tanks and processed with normal tubes and pumps. But energy could be released also from non metastable metallic hydrogen. Bond strength of metallic phase is much less than between atoms in H2 molecule. It takes something to overcome metastable barrier but combining released atoms to molecules give 216 MJ/kg. If you burn H2 with O2 you get only about 10 MJ/kg. Molecular mass of H2 is also much lighter so that it gets much higher velocity at same temperature. Transformation from metallic to molecular phase is chemical reaction which has nothing to do with nuclei. Recombining pure metallic hydrogen to molecules would give ISP of 1700 s but 7000 K temperature would be impossible to handle. Practical solution would be to dilute metallic hydrogen with water (ISP about 500 s) or molecular hydrogen (ISP about 1000 s). Even that would give very significant buff to rocket's payload to intitial mass -ratio. Numbers are based on this reference: https://dash.harvard.edu/bitstream/handle/1/9569212/Silvera_Metallic.pdf

You should take some physics book and learn what metastability really is. You mean stability in your sentence but are still incorrect. Liquid hydrogen is not stable at outer space conditions but will evaporate rapidly at zero ambient pressure. Liquid phase is stable if ambient pressure is larger than vapor pressure at given temperature. There should be planet sized mass of liquid hydrogen free from any star which could keep evaporated gas as an atmosphere to reduce further evaporation. Wikipedia have short article but it is intended to be reference and not school textbook and may not be very clear. https://en.wikipedia.org/wiki/Metastability It may be that there will be some applications for metallic hydrogen. However, it is not very credible that any of them have any relations to rocket propulsion. Metallic hydrogen need so extreme conditions to be manufactured and stored in significant quantities that civilization at such tech have no problem to use fusion or antimatter or whatever many orders of magnitude more energetic exotic phenomena to propel their spaceships. There will not be new materials able to handle it. If it will be useful it must be confined with crazy strong fields. All matters depend on same electromagnetic forces which affects in metallic hydrogen. Electron mediated bonds between atoms. Such bonds can not be infinitely strong. Crude estimates of bond strengths can be calculated even for non existing elements. I have never seen any estimates that there will be very strong bonds between heavy elements (or really stable heavy isotopes, "island of stability" means half life of whole seconds so that physical and chemical properties of predicted elements can be investigated instead of billions of years needed in practical use as structural material). Outer electrons of large atoms are relative loosely bounded and can not make strong bonds. Toughest compounds are those made from light elements, like diamond, boron nitride, aluminium oxide etc. We should find completely new physics, interactions and particles able to form material, to be able to make material structures able to contain metallic hydrogen, fusion reactions etc. scifi stuff. Baryonic elements can not do it. I am not going to hold my breath during waiting. I think you can feel safe to have all gorgeous and overpowered scifi stuff in KSP 2. It is clear that there is no economic market for more realistic nerdy game. Devs do not care our discussions. I hope that there will be tools to mod such scrap out of the game and put real things in. If not, KSP is very good game as long as future operating systems can run it.

I expected that 150 m looks much higher flight in videos. The rocket is huge. Very nice to see progress in development.

It may very well be true. Or at least large majority of comets are relatively close orbits and disturbances, like star flybys, regenerate some sparse far population by throwing some objects to very distant orbits from where they slowly dissipate to outer space. I do not know on what assumptions those estimates of several light years are based on.

I agree. I have tendency to think from very practical point of view and keep difference of unfeasible and impossible as philosophical pedantry. It is in those time scales and decisions which are reasonable in my life. In my opinion that is lazy base on story. Possibility of such species and civilization to survive and develop to astronomical state is just as possible as hydrogen atoms to bond metallic lattice. And as I said, there is also no gaming need for scifi propulsion. KSP propulsion set is very much enough for this kind of game. New things are practically same things with fancy names or ridiculously overpowered and break the idea of realistic space flight simulator.

There has also been many star flybys with much closer distance in lifetime of solar system. It is strange to think that stars can go through Oort cloud without destroying it during billions of years. Maybe decay is so slow that cloud can stay the whole main sequence lifetime of Sun.

All large particle accelerators which create new particles, for example LHC, convert kinetic energy of projectile particles to mass. For example 2 protons with mass of about 1 GeV and kinetic energy of several TeV hit and produce a Higgs boson with mass of 125 GeV (and bunch of other particles too). But I understood that Spacescifi meant conversion from electromagnetic field (photons) to massive particles. As far as I know it has not yet seen in laboratory.

Building and operating cleaning probes will probably be economically profitable after big companies begin to lose satellites. I think Kessler syndrome will not be huge issue anymore at near future launch prices, but nobody will act before it is necessary to keep business running.

It handles rotation around vertical axis by adjusting rpm difference or pitch angle of rotors instead of tail rotor. Coaxial two rotor helicopters have been used in aviation too. Otherwise it has similar swashplate and pitch control as normal helicopter. ------------------------------------------------- Info graphics show that Centaur burn RCS almost continuously during coasting. I guess it is for keeping liquids where they should be. Why it can not use just short ullage burn just before ignition?

Moreover, practical conversion ratio from energy to matter is ridiculously low. Particle accelerators consume tens of MW and produced nanograms in year. I think that if you call that antimatter "waste" as product and that regular hydrogen as waste you increase your company's profits by incredible many orders of magnitude. Otherwise I wonder what is the cost of disposing antimatter waste in municipal recycling plant. For some reason it is not mentioned in their catalog.

You can not achieve it by playing, because it would take insanely long time, but maybe you can use some mod to move your craft so far from sun that orbital velocity is rounded to zero. I think you have to test does such trick work or just call Kraken. All other objects have finite SOI and such trick is impossible.

It is very different to make a game which stay interesting when focus moves from exploration to colonization. At colonization phase automation should take big role. Player plans service routes and take care that there are enough suitable ships to handle transportations. It is interesting to make exploration flight with lery limited resources but very boring to flight easy routine cargo flight with overpowered craft. Musk's talks are 99 % repurposed bovine waste. And it is totally unrealistic assumption that civilization use all resources to space technology. At such level it is better to keep game without background story and just fly from empty planet. I think the most significant disagreement between us is meaning of words. You have researcher's optimistic attitude. Every phenomena which have been shown in lab experiment or observed in nature are almost ready and very realistic tech after "small" developing. I have engineer's pessimistic attitude, in which things are real when they are built and tested. For me technomagic is all necessary devices around reaction which keeps conditions possible for fusion and utilize produced energy to something useful, like thrust or electricity. As an engineer I am the guy who have to plan those practical devices before things happen and I am also the guy who is asked in boss's office when something does not work as intended. I can not see every exotic lab experiment as potentially usable technology in practice. They have to be developed much further before I can handle them as realistic possibilities to build something working and very large majority of ideas die in that process. If I think fusion propulsion, fusion reactions are certainly real and their properties are well known physics. Some of them can be produced also in laboratory, but any such equipment can not do it long periods in real space conditions. Such spaceship is therefore not realistic currently. I can not put a deadline and trust that is is kept even I had superpower's military level funding. If such technology is decided to be developed, there may be dozens of drawbacks before any real application and no one can predict how many decades it take to solve all of them. For example fusion in terrestrial energy production has been 50 years away during my whole lifetime (little bit less that 50 years). Many expensive and some crazy expensive tests have been made, but always when some problem has been solved another has arisen and delayed success. Fusion may or may not be practical energy source on Earth or in space at some day distant future but not now. If it is used in entertainment, authors or devs must invent many things and it will be completely science fiction.

Do you mean speculated real world hydrogen or dev's choice in the game? Latter can be of course whatever. I do not care much such details in this kind of situations. I think there is no need in thrusters more effective that NTR or fission powered ion engines in space exploration game, which models the civilization which makes first probes and manned excursions to bodies in their solar system. It takes probably hundreds or thousands of years development from that point to get those futuristic technomagic engines which makes it possible to colonize the whole system and make regular fast tourist and business traffic between planets. I disagree. In my opinion it does not make idea realistic if some concepts are taken from real science, like fusion or antimatter, but every practical aspect is assumed to be technomagic. It also breaks the story. Why in the heck supercivilization able to build fusion powered machines and product and handle industrial quantities of antimatter has not investigated their whole solar system thousands of years before. It is as credible as astronauts in first manned rocket sent to investigate celestial crystal sphere of Moon would notice that "hey, you do not believe this, our planet is not flat disk but ball".

Yes in principle, but no in practice. I am quite sure there will not be tools to calculate that kind of trajectories and execute maneuvers. At least I may calculate it once by hand, then program help program and use it couple of times and then think it is too tedious, if there will not be Mechjeb like mod which can make such operations automatically. Orions and fusion drives may be somewhat realistic. However, what is purpose of them in planetary flight simulator? Only interesting thing in spaceflights is try to achieve goals with limited resources using optimal trajectories. Otherwise it is very boring to fly easily from sphere to another. Such propulsions could be usable on interstellar operations or business trips, but they are even more boring. They are turn nose to target, hit red button and use extreme timewarp -operations. It is also hard to believe that anyone could ever make interesting content so much that it do not fit in one solar system. And if can, player's lifetime is not enough to find all interesting places. Fusion nuclear reactions are of course well known real things, but you have to accept quite much technomagic in material physics, magnetic confinement tech etc. to get fusion work as propulsion device. Same with Orion, it is very hypothetical concept even though it is based on some physics. As far as I know there is not any applications expect some forms of nuclear bombs. I expect also that current fusion bombs may be little on large side from Orion optimal. I like too more if overpowered magic drive have properties known to belong fusion and is called fusion instead of completely fictive descriptions. But it is not requirement of my entertainment. Reasonable balancing to give realistic like technical challenges is. And unfortunately it seems that KSP2 will not give it at vanilla, at least without personal restrictions. And if there is too much such restrictions, there is no point in tech tree. Thrust under high time acceleration and realistic ion engines would be very nice.

I agree, but I think that economical realism is against us. KSP2 is intended to sell much more than KSP and it has to attract people who is not interesting in science or learning proper ways to fly in space. They want to have practically unlimited dv and fly to target by just heading nose to target and throttling and they want to read that kind of meaningless pseudoscientific jargon to get their immersion to game world. As far as I have understood there will be whole bunch of ridiculous scifi stuff in KSP2. At least I have to see what kind of game it is and can it be modded to be reasonable simulator instead of scifi fantasy full of graphical eye candy. I can stand pseudoscientific jargon but I am sure that most of engines will have ridiculously overpowered performance compared to what is needed with near optimal trajectories. It is not fun for me. I want to use porkchop plots and plan maneuvers with Mechjeb. But I understand that there must be easy way for lazy people to see gorgeous planets. If it is true that just few percents of KSP players ever leave Kerbin's system, aesthetic work would be quite futile otherwise. And what is the most important to devs, sells will suffer.

Geometry of spacetime (i.e. gravity) is affected by stress-energy tensor. It takes momentum (i.e. speed of massive object) into account, but as far as I know, you can not replace mass with just simple mass growth effect but you have to make nasty tensor calculations. In any case reasonable interstellar ships can not cause dramatic effects for bodies around if they do not collide. Getting enough energy to accelerate someting to so extreme velocities than it can disturb nearby celestial objects cause probably more problematic effects to space around and objects there. https://en.wikipedia.org/wiki/Stress–energy_tensor

Tidal force depends on gradient of gravitational acceleration. Sun's tidal force on Earth is about half of Moon's. Other planet's influence is very small and have to be taken into account only in very accurate predictions.

That is about the same order of magnitude I remember. Orbital period (and length of the day) is then about 50 (current) days if I remember correctly. After that system begin to loose energy due to tidal interactions of Sun and other planets and in very very far future Earth and Moon will be combined. However, Sun goes through a transition to red giant and white dwarf and may affect very radically to Earth-Moon system before such things will occur. As far as I know tidal interactions can not lead this. It would need another massive body to kick Moon out of Earth's sphere of influence.