Hannu2

Probably that kind of ocean would be very unstable. It would dry during ice ages or probably geological processes would divide it to smaller lakes. I read somewhere that some scientists estimate that there is comparable amount of water in Earth's mantle. If it is true volcanic processes could change significantly amount of surface water. Or if mantle were dry plate tectonics would be different or even non existent. Actually depth of oceans are very shallow on planetary scale. Average depth of about 3,5 km is nothing compared to radius of 6700 km. If you have normal 30 cm spherical world map it would correspond to 0.15 mm. Deepest point would be 0.4 mm. Earth is not a wet planet, if has just some fine spray of water on it.

https://lhc-machine-outreach.web.cern.ch/lhc-machine-outreach/components/beam-dump.htm This source says that energy of beam (total of all circulating protons) is 350 MJ. It is huge amount of energy released in less than 100 microseconds. It is as much of energy as 90 kg TNT (or dynamite) releases in explosion. I can believe that it evaporates significant amount of anything it hits and if target is not actual beam dump intended to handle it there will be very expensive repairs.

Engineering would be technomagic from current point of view. Solid structures of orbit size are not possible under current natural laws. Separate bending magnet and acceleration satellites would be better option, but such a project would need much more resources than is possible in foreseeable future. Huge accelerators intend to get as much energy per particle as possible. Losses depend on curvature and therefore the larger radius the higher energies are possible. That would give access to new physics at higher energies. On the other hand, antimatter production does not need extreme energies per particle. Producing as much optimally energetic particles as possible is better and I think huge size would not give significant benefits in antimatter production compared to many smaller and simpler facilities.

I also read from somewhere that Voyagers stay recognizable as artificial objects on the order of billion years. Wearing in interstellar space is extremely slow process, but radiation and particles kick atoms off from surface during astronomical times.

I do not know but car's weight is about 1.5 t but Orion and service module have 25 t. Orion is also not intended to last long enough. If they made a flyby it would be as dead piece of space scrap as Musk's car at Martian orbit. In addition to these problems I am sure that they want to have their expensive test craft back to intensive inspection.

Yes, but those things are significant reasons why current space rovers drive 10 miles per year instead of hour. Average or even top speed of 10 mph is totally unrealistic with current technology.

Everything should be understood practically literally. Water, concrete, stone, metals, human flesh etc. common materials which you probably think to be relatively fire safe burn very aggressively in fluorine gas. Only some fluorine compounds which already have strong bonds between fluorine and other elements can resist. Fluorine can be stored in some metal containers because thin solid fluoride layer forms and prevents further contact between fluorine and metal. However, if the layer will be damaged reaction may be so aggressive that new layer can not form and metal begins to burn. Not very nice if it is some part of rocket engine's oxidizer feeding system.

As most chemicals, amount makes them toxic. Also many heavy metals are necessary at ridiculously low amounts, because they are needed in some enzymes, but toxic (and lethal) in larger quantities. Rocket launch would release hundreds of tons of hydrogen fluoride which would flow with wind and be toxic and environmental hazard at distances of tens or hundreds of kilometers. They should evacuate half Florida when they launch a rocket. Price of fluorine itself is not reason why it is not used. Price of safety precautions, handling etc. in all phases is why it can not be used. Now also environmental laws. Firstly you should build a new launch complex to very distant island. Then logistical costs, handling, material and manufacturing. Fluorine is so extremely aggressive that reusability would probably be impossible. Materials which can handle fluorine rich gases at combustion chamber conditions during multiple launches probably do not exist. And after all, it would be possible that launches would have to be stopped because severe sea pollution.

Someone have to get political decision and funds, then plan and build a new telescope before BFR in needed. As we know from history, such project takes about 2 decades. Even it can probably be simpler, because more capable rocket, 1 decade is in any case completely unrealistic optimism in large space telescope project. JWST can probably have several delays and make whole career before successor is ready to begin its work.

I think few cans of paint and a stencil with ULA's logo would do the trick.

I would not trust SpaceX staff's time estimations. Their boss has said himself that they may be a little "aspirational" (or word like that). It probably takes at least a decade before BFR makes first commercial unmanned space flights. Then they need much work and bureaucracy to get crew ratings and much more to get permissions to fly all countries near big cities. I would not say that it happens in foreseeable future.

It is very difficult to see situation in which it would be more economical to fly rocket stage from ship to launch pad than drive ship few hundred kilometers to coast. Maybe there will be fully equipped floating launchpads in very far future, but I am certain that any rocket which is now in planning or prototyping phase will be launched from traditional pads on coast.

It is not interesting is it technically possible if whole country wants it at any costs. It is practically impossible if costs of transport are too high and obviously it is the situation in real life. Therefore road transportation is not an option to be taken into account when they decide where to build factories or how to transport rockets. I am sure that random transport company crews are not allowed to remove signals. Only road owner's (or contracted companies) crew is allowed to make changes. Also only power companies electricians can move power lines. Probably those companies do not have enough crew to make hundreds of such modifications in reasonable time and costs. SpaceX has also intention to increase launch cadence things go even more impossible. Maybe they did not have to count single millions in Shuttle program, but I Musk are going to push paunch costs to single millions per launch, they can not certainly disassemble and reassemble half the country for every rocket.

No, exactly same thing as a one seat plane made of sticks and canvas from 100 years ago. Real differences are in gas bottles. Old ones are metal or composite cylinders with hemispherical heads but new ones are... hmmm... composite cylinders with hemispherical heads and magic touch from SpaceX's main wizard Musk.

I am very positively surprised if that crazy mechanism from scifi movie ever work in real life. If not, engineers should probably take some cheap "keep it simple stupid" -course before next 10 billion project.

Difficult to say, because such a project would need so much totally new technology. Costs would be more important issue than weight (for example methane as fuel of upper stages instead of hydrogen which would give lower costs even launch mass would probably be slightly larger). I think if you assume current safety regulations modern crafts would be more massive in spite of advances in material and information technology. Any Apollo-crafts would not certainly get man rating certificates today, probably even not in Russia or China.

I guess that it was some kind of flying machine (plane or helicopter, not extraterrestrial spaceship). Supernovas (and other rapidly variable stars) are slower phenomena. Supernova's brightness increases days and dimming takes several weeks.

I have not seen, just heard stories, because I was not born then. That was fun time, but then money talked and repurposed bovine waste walked. I could as well boast that I am going to build a plane, I already bought couple of screw drivers and cheap welding machine. It is long way from laminating mold to first commercial mission to orbit and many things can go wrong and ruin schedules or budgets.

I do not care what blabbermouth Musk says. His merits are indisputable but unfortunately he ruin part of his credibility with crazy fantasy stories. Problem is that Mars mission cost hundreds or thousands of billions of dollars. There may be couple of single billionaries who would like to make such trip, but unfortunately their money lacks orders of magnitude and they hit also legal barriers. It needs rich superpower state or huge company to fund Mars mission. No new technology? What the heck? Would you use Sojuz as manned craft? As far as I know it and Chinese craft much like Sojuz are currently only spacecrafts able to carry crews. Dragon and Boeing's craft will be new technology. How about lander? You would take old Apollo LM from museum and polish it? As far as I know no space agencies or companies have any spacecrafts able to land on another bodies currently in production or even severe planning. And launcher? Falcon Heavy is far too small and it is largest currently available. You probably mean that no new science is needed but Mars-mission would need huge amounts of insanely complicated and expensive technology to be planned, built, tested and certified. Practically all components of the mission would have to plan from plain paper. No currently operational spacecraft could be used in any way. I think it is futile to argue this kind of things. Let's just wait until 2030 and see who is right. BFR is much closer to thought experiment than a functional spacecraft. Let alone all crazily overoptimistic cost predictions will be true. No-one knows will it ever fulfill expectations and when. Musk's schedules are nothing more than telltales for kids. It take probably 10 years to get first unmanned launch to orbit, if Musk have and want to put endless billions to development. After that they have to develop reusability and get development costs paid back. It take decades even with optimistic launch cadence. They have to certify it for manned use, get all fuel transfers to work, build and test life support equipment and so on. Musk can not fund it alone, it needs government's money and political decisions. There are infinite unpredictable factors and many of them are very mission critical.

Possibility is not just technical things. Economic and political things are much more important in real world. Manned Mars mission would certainly be technically possible, if most of humankind and especially politicians of richest countries and richest people would want to it at any cost. Both economic and cost of lives. It we had attitude the kings had in period of great expeditions and if we sent missions and crews one after another until one lucky would return, I believe Mars-mission would be done in 20 years. However, reality could not be further from that. Most people are not interested in space missions and think they are wasting of money. Companies can not get profits so rich investors do not spend on space. Politicians are not interested because taxpayers are not. And everyone are also very afraid of losses of life. Lost crew means lost face for politicians, businessmen and state officers. It means losing work and funding. Under current attitude atmosphere great steps in manned space exploration are impossible. There will be infinite plans on bases on Moon or expeditions on Mars, but no one dare to give actual money and begin the project. SpaceX will send commercial satellites and maybe crews to ISS, but Musk's fantasies about Mars will not come true. A culture must be changed, pioneering spirit must arise and we must grow to stand risks before any space fantasies comes true. Such a change takes at least couple of generations. We will not see it.

Size is beautiful. Saturn V is in its own class until there will be larger rocket. As someone mentioned N1 was nice too and gets extra points from Kerbal attitude. It is sad that it did not perform as expected and there was no real final spurt and more rounds in space race.

Practically it is. Boiling point is only couple of degrees higher than for normal hydrogen and heat of vaporization is low. I think that deuterated propellants would not pay back high costs compared to little larger storage of normal propellants. Also, low weight of regular hydrogen is benefit because it gets more velocity at certain temperature. Water ionizes spontaneously to H3O+ and OH- ions. Reaction is dynamic and happens in both directions. In other words water molecules exchange hydrogen atoms continuously as they collide into each other. Therefore most deuterium atoms is moved to DHO molecules and D2O is very rare (if D concentration is low).

It looks like plastic bag or part of cardboard box or some scrap like that. Wind from engines lifts it in air. It seems to be so far that flow speed and temperature are relatively low.

Every superpower states have effective warning systems for ICBM launches. Therefore it is practically impossible to launch secretly rockets to orbit. Every launchpad would get some cruise missiles soon after launch. Such mobility would be quite hard and expensive. Probably it would be more productive to sell honest launch services if you have such resources.

It is quite difficult in space industry because there are practically infinite amount of asteroids and resources in Solar system (compared to current production levels or deposits on Earth) and no realistic means to prevent others to utilize them. Even some corrupted government would give monopoly to prime minister's brother's company there are many other countries which would certainly compete.