Hannu2

They save significant amount of money and time by using the same basic engine everywhere they can. They tried to develop much bigger engine. However, full staged combustion cycle has certain optimum size, which is not as large as they hoped. It is more advantageous to use large number of "small" engines.

So far it has not been a great motive. But now it begin to be very clear that environmental destruction has very high pricetag. Costs are usually not immediate and directly visible but modern science begin to understand mechanisms and most governments take environment things very seriously and are willing to pay huge amounts of money to develop new cleaner society. That is flawed logic. My logic can be used and will be used if someone actually invents perpetual motion. I did not say it is very fair to laugh those statements. They was very well justified based on information available at those times. As well as conservation of energy is for us. Development of science and technology was just unforeseeable then. Colonization or space industry is not possible for our generation but it begin to be somewhat foreseeable future. We know that there are almost unlimited resources available and our rocket technology is rapidly developing. Also awareness of severe consequences of reckless pollution and destroying nature is rapidly increasing and there is will to spend money to avoid it among people and governments, even among some businessmen. Utilization of space for mining and refining is very straightforward solution under those conditions even it will be very expensive to begin. It does not need any new science or natural phenomena, like perpetual motion machine. It is just politics, economy and engineering.

Everything you dump in atmosphere in the Gobi desert spread rapidly everywhere. You have to also mine everything which does not happen to be abundant in the desert from some other places on Earth with higher environmental value. Actually, I can not really say that desert nature has less value than some other areas with higher biodiversity. There are certainly many special species specialized to desert environments in all deserts on Earth. I do not believe that we will see space mining or industry. Except maybe some early experiments. But on the other hand, it is difficult to think that after couple of hundreds of years significant part of industrial production is not in space stations. It would need some catastrophic breakdown of development to prevent next logical step.

One thing is that as far as we know yet. We know that there is many more that 5 computers in the World and there is also very strong evidence that heavier than air aircrafts have flown. But nothing can prove that there will never be perpetual motion machine. We just do not know such natural laws yet. As far as I know, expanding universe has not time translation symmetry and therefore conservation of energy. Maybe some technomagic level civilization could utilize it. Almost certainly it never happens anywhere in the Universum, but it is impossible to prove impossible thing to be impossible (in nature, it may be possible in logical systems, like mathematics). But there is nothing against known natural laws in colonization of Solar system. It is only economy and engineering depending on political will. It does not produce profit in any reasonable schedule but it could be done as ideological project with our current scientific knowledge. Most of monumental projects in human history are ideological. Probably building and maintaining slowly (but exponentially) growing Mars colony few millennia would cost smaller percentage of US's, EU's or China's gross product than building of famous pyramids costed ancient Egyptians.

You are in prestigious gang with this statement. You must have heard for example: “heavier-than-air flying machines are impossible” from lord Kelvin in 1895 or "I think there is a world market for maybe five computers." from Thomas Watson, president of IBM, 1943 But if you are famous in your real life after couple of hundreds of years people will laugh to your statement. You are correct that those thing are not directly foreseeable at current tech level. And if you think our lifetime you are clearly right. But in longer periods there is no real obstacles. It is extremely expensive project to move mining and manufacturing industry to space but it can lead to almost infinite growth. There are many orders of magnitude more raw materials in space and no need to care pollution or other environmental aspects. Space will not be safe and comfort workplace for humans but there are always people who are willing to take risks if you pay well and there is probably not much need for human work. On the other hand, huge rotating space stations with gravity enough to keep people health may give orders on magnitude more living room for mankind. It would be interesting to se what happens to Earth at long run, when significant part of humans live in space or on other celestial bodies. Will it be exclusive natural paradise for rich people and average people live in space stations around the solar system? Or will rich people live in luxury space stations, average people in huge middle class stations and poor people on old fashioned Earth with all nasty natural problems? Will the Earth be some kind of natural preservation zone where lives some extreme conservative people in relatively primitive conditions? This is only apparent but not real fact. We can not use all land and resources because environment problems will be much more expensive than profits. We have already probably exceeded long term sustainable level of land using for our industrial and agriculture needs. Environmental problems and expensive countermeasures are already severe restriction for economic growth on Earth and will increase every decade in future.

It can be ideological objective in very far future. But it is hard to imagine as motivation for begin interplanetary living. It takes probably hundreds of years before colony could be enough self sufficient to work as backup and could not help in any case now living people. Probably curiosity is more important motivation at beginning phase. It is also very difficult to believe so extreme conditions that it would be easier to survive in space than anywhere on Earth.

Why not? Barge is probably so cheap that if there is reasonable possibility of hitting it it is worth trying. Especially if passive barge can be used. I do not know is it reasonable idea but if they decide to skip fabricating new SN17 does that license allow SN15 to fly again as SN17?

OK. I misunderstood your opinion. Sorry. As far as I know (based on my solid state physics courses) hydrogen is absorbed in regular palladium lattice and do not need defects. Wikipedia says that there can be 0.7 atoms of hydrogen per palladium atom at normal pressure. But you are right, impurities diffuse usually to suitable lattice defects in normal materials and small concentrations. Palladium's ability to absorb hydrogen in its lattice is exceptional. It may be that density of hydrogen atoms is highest near suitable defects in palladium and cold fusion theory is somehow based on it.

I disagree. Coulomb barrier for fusion between deuterium nuclei is about 400 keV. Chemical bonding energies of lattice defects are single or tens of eV per atom. There is a difference of at least 4 orders of magnitude. Also, distance of nuclei needed for probable fusion is extremely small compared to distances of nuclei in lattices. There is also no credible experimental evidence of cold fusion in palladium crystal (as far as I know). Also nuclei distances and energies in predicted metallic lattice is several orders of magnitude less than needed for fusion.

Fully mechanical robot is interesting idea. But the article did not tell anything about mechanical sensor technology. It is quite futile idea to make a rover which just run aimlessly until hits an obstacle. Sensors have to be electronic. Maybe some simple things, like temperature sensor and basic data processing would be possible mechanically but I can not imagine mechanical solution to analyze samples, see environment and react to it or receive commands from Earth.

Of course situations may vary. It is the reason why NASA wants to have more than one company capable of their operations. Final results will be clear in future when both ships have retired and replaced by newer ships. But so far Dragon has been clearly cheaper (If I remember correctly Boeing has been given much more money) and more productive.

Return to launch site needs delta-v but I think possibility of rapid reuse is more important than optimizing mass of single launch. It takes days to bring rocket from sea to launchpad and gives more restrictions if there is bad weather on sea.

Why not? That exploding ship try to achieve new landing maneuver which can make far larger and cheaper ships possible. But first capsules was flown to orbit and back in 1960. There is nothing really new in Boeing's capsule. Dragon makes everything Starliner do but is much cheaper to operate. Certainly it do. But it is also certain that Starliner achieves never any milestones in manned or unmanned operation. It is second best tool for routine work, selected in addition to best tool because redundancy and political issues. Starship at least intends to achieve new things in both categories. In addition to fanboys also NASA officers seem to trust company. I agree that fans are sometimes quite annoying. Especially those who takes aspirational schecules too seriously. But SpaceX's ability to take risks and develop new things seem to be exceptional. It is clear that Boeing can not compete with fancy ideas as publicly traded company which owners demand profit but it is sad that Blue Origin seems to fall behind. It's owner has enough money to do whatever crazy things and he could compete with Musk. SpaceX's de facto monopoly will be bad thing for space business in longer period.

If I remember correctly this project began before routinely reuse of rocket boosters. It is clear that rapid and cheap reuse has destroyed most markets of these plane rockets. It may be practical to use standard 747 for some small rocket launches with special need of inclination but I can not believe that building and maintaining this kind of very special planes will be productive business.

Probably you could get very short drive immediately after you turn electronics on. But practically all electronics on Earth is very dependent of air cooling. Power electronics of the car would overheat very soon in Martian conditions. No only large FETs which control main current for motor but also processor boards before you begin to actually drive. Those tiny components need also air to absorb heat.

This does not sound reasonable. There is 86400 seconds in a day. That would need launch every 86 seconds. Even powered flight is much longer. Also 100 times per day is not credible. It takes about 500 seconds from pad to pad and it is clearly impossible to refill booster and install new Starship and make all safety checks and countdown in 6 minutes. Practically one launch per day would be incredible pace.

No. Any known spacecraft comparable to Starship in any way? No. Any significant advances in manned spaceflight in last 40 years? Very little. Sometimes you must invent new things if you want to go further. Physics is the same but technology is much more developed. Abilities to simulate things, plan optimal structures, new materials and fabrication methods etc. Many severe restrictions in 60s are simple problems now. But this is the thing we will very probably see in relatively short future. I think this summer is too aspirational schedule but in next summer we may see how cylindrical Starship handles hypersonic reentry. If I remember correctly there was debate like this before first Falcon 9 landings. Some prediction from 60's was that rocket engine can not work if you try to brake at supersonic speed. I do not know was it theoretical prediction or based on some tests with actual engines.

I am sure they have simulated whole reentry thoroughly. Empty Starship has relatively low mass/area -ratio, which probably gives more possibilities than compact capsule with high mass per area.

Probably it do not. But in any case that kind of problem must be analyzed carefully to make clear is there any risk in continuing old way or changing procedures. If there are risks in both ways probably they postpone manned flight and send few satellites to make sure that change works properly.

It is not a binary thing is person dead or alive. You can think execution in guillotine, which cut head very rapidly. What do you think is actually time of. Usually death is defined as stopping of EEG activity but brain cells stay alive couple of minutes without blood circulation. But of course the blade cause irreversible fatal injury in less than a second. I guess that explosive evaporation of water at 5800 K ambient temperature would cause some kind of shock wave, which would proceed at about 1.5 km/s, which is speed of sound in water. Such a shockwave would clearly reach any point of human body and destroy all biological activities in less than a millisecond (1/1000 s). If you mean a microsecond (1/1000000 s), shock wave would have proceeded just few millimeters and biological processes deep in the body would be unaffected.

They can not travel to same direction. Otherwise at least one of them should be on hyperbolic orbit, i.e. not bound on Earth. They must have quite large inclination difference, I would say at least tens of degrees without calculations.

What is the difference in this case? Methane and liquid oxygen are common chemicals in industry and they are used in enormous quantities in many processes. Spacex's tank farms are small and trivial compared to for example those of LNG ship terminals or oil refineries. As far as I know they must obey the same industrial standards set by laws. I do not see any good reason why very standard off the shelf liquefied gas tanks would not work for SpaceX. It is strange decision to build own tank, but maybe they developed something in welding process and decided to make a tank instead of dummy test rings. If their welding quality is enough for rocket it certainly fulfills all standards needed for storage tank. It is not straightforward to just weld a tank and store thousands of cubic meters dangerous liquid in it. Probably even bureaucracy needed to get permission to use tank for storing dangerous chemicals is quite time consuming and expensive. I am not sure if aerospace certificates is accepted for industrial storage use (I hope USA has easier bureaucracy but in EU country I would not even ask). If you buy a tank from experienced company they have all needed certificates already.

That rocket seem to have some kind of transparent nose. Maybe there is an elite compartment with maximum view and crazy high ticket prices. Those tourists must be brave if the rocket hits the tube at couple of hundreds meters per second.

I wonder it too. Otherwise they put so much effort to videos and all kind of PR work but video system of ship is from cheap store. I am quite sure that installing a proper video link would not cost too much compared to total PR expenses. But they certainly have too much small things to do and too little workers as all companies nowadays. Videos work, everyone see does it success or crash, and they prefer other problems.

I can not understand all that patriotic ideology, which is so important for americans. I am pragmatic and appreciate space operators based on what they have done. Not based on who owns them, who pays them or what they say they will do in future. I have to say that I do not have much trust on Artemis yet. There has not been any significant things or funding decisions yet. I think SLS is just political industrial subsidize mechanism, not real space program with severe objectives. I would not be surprised if US government announced that Artemis has been cancelled and they begin a new manned Mars-program instead. There is no real will to make manned space operations or compete with other countires in USA or anywhere else. All current projects are slow small budget low priority tinkering instead of competing superpower's displays of power (like Apollo was).