Nibb31

The difference is that there was demand, even before those inventions, for fast transportation. People needed cars and planes (and horses and ships) because there were places that they wanted or needed to go to. There were people at those destinations that they needed to meet up with, places that they wanted to visit, customers to sell stuff to, business to be made... Space is not comparable, because it isn't an actual destination for anything worthwhile. You aren't going to space to go conduct business meetings or to visit relatives, neither is there a market to sell stuff to people. So it is never going to be a mainstream destination for mass transport.

Because centrifuges aren't a good solution at all. They introduce vibrations, rotational torque that needs to be countered, and structural stress. They are also big, heavy, expensive, and because they need many moving parts with motors, seals, lubricants, etc... they also introduce failure modes that could be catastrophic. They are simply not practical for manned spaceflight at this stage. Most of the negative effects of microgravity can be countered by medication and exercice, which is where most of the progress has been made over the last decades.

It would be so much easier to smuggle a bomb on a cargo ship in a 20-foot container and blow it up before it's inspected by customs.

You're right, the collision was a low-velocity bump with a Progress. Depending on the home, most MMOD punctures would cause a slow decompression, which would be spotted immediately and would allow ample time to take either repair measures, shut off the failed module or to proceed with an evacuation. The most dangerous incident would be a rapid decompression on Unity, Zvezda, or Zarya, with crewmembers on board the USOS. This would basically cut off their evacuation route. Still, they would close off the decompressed modules. The crew would still have enough time to figure out a contigency strategy. They could attempt a repair or EVA from the US airlock to the Russian segment.

Gas giants are planets. Tellurian planets are planets. Pluto, Eris, Ceres, etc... are not planets, they are dwarf planets.

The SSME is now called RS-25. The existing ones have been refurbished to remove the regenerative cooling nozzles and other reusability features. Then they will be thrown away on the SLS. If there are more than 3 SLS launches, Aerojet Rocketdyne will have to build new ones. They are pretty efficient engines. I'm not sure what you would achieve by improving their efficiency. As with most aspects of engineering, the laws of diminishing returns apply here. A poorly optimized designed only requires a small effort to make a spectacular improvement. A highly optimized designed (like the RS-25) requires a huge effort for litte improvement. Effort is money, so it's not worth it.

No. To propell, they would need to repel something.

No, there was no ranking between Mission Specialists. The numbers are assigned to the seat positions in the flight deck, not ranking. Originally, NASA astronauts were all top-level test pilots with huge egos, so when it came to giving callsigns to the seats on Gemini, they refused to have a "pilot" and "co-pilot" position, because the term "co-pilot" is typically used for rookie pilots. So NASA had to go with the Commander (CDR) and Pilot (PLT) callsigns. When Apollo arrived, they needed a new callsign for the third crew member, who had to be a pilot. NASA wanted to use Commander, Senior Pilot, and Pilot. Again, the Astronaut refused, which is why they used Commander (CDR), CM Pilot (CMP), and LM Pilot (LMP), even though many of the Apollo missions didn't carry a LM. On Skylab, the LM Pilot callsign was replaced by the term Science Pilot (SPT). And on ASTP, the third astronaut was Docking Module Pilot (DMP) although there was no "piloting" involved in the docking module. With the STS program, NASA kept the the Commander (CDR) and Pilot (PLT) call signs, but because you couldn't reasonably have 6 or 7 "pilots", all the other crew members became either Mission Specialists (MS1-5) or Payload Specialists (PS1-2). Mission specialists were typically NASA astronauts, whereas Payload Specialists were non-NASA crew members (civilians, foreign nationals, scientists, industry employees, etc...). The Payload Specialist position was eliminated after Columbia.

There is a 1:1 mockup of Ariane V at a theme park near where I live. You can get up close and personal with it, and it really isn't that big. The Vulcain engine bell is about as tall as a person.

It doesn't matter if there are volunteers that consider themselves expendable. There is a difference between people volunteering to go on a suicide mission and the government or a corporation sending people on a suicide mission. One can be considered heroism (or stupidity). The other would be unethical and criminal. It's a political non-starter. - - - Updated - - - What difference does it make? These are highly automated vehicles. They can fly unmanned if necessary. NASA crew rotations don't need a cab driver to take them to the ISS and back.

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Compromises!

Better, cheaper, sooner. Pick two.

No it isn't, and you keep on repeating this fallacy. The amount of launches per year depends on the demand for launches. Demand is only remotely related to launch cost. If you cut the cost of launches by two, you would not multiply the number of customers by the same amount. In fact, SpaceX has cut launch prices by nearly 50% yet we haven't seen demand for launches increase twofold. The launch market is already saturated. There is a surplus of offer, with high competition and increasingly low margins. To increase the demand for launches, you are going to need to find new customers, and this is where the challenge lies. Again, your launch cost is proportional to how much time you spend on operating the entire launch service, not just building the rocket. You keep on repeating that the biggest factor in launching rockets is building the rocket hardware. Well, it isn't.

Hyperbole would make it the most powerful rocket in the Universe !

Which is irrelevant if you have enough engine pods and launch rates are. Even if you have 24 launches per year, with a fleet of 6 vehicles you can take 3 months to refurbish/restack them, which is more than enough. If you need a higher flight rate, it's easier to simply grow your fleet than to redesign the system for faster turnaround. Fast turnaround is only important if you reach insanely high launch rates and each vehicle is super expensive. I agree with that increasing staging events means increasing failure modes, but it's can be cheaper to have 3 people refurbish a rocket in 10 weeks than to have 30 people refurbish it in 1 week. It all depends on the flight rates, and the launch market is simply not big enough to sustain fast turnaround. May I remind you that none of those other techs have yet been proven technically or economically. Sure, this is a stop-gap preventive study from ULA just in case they do need to start reusing hardware, but until the launch market sees a serious mutation in terms of payloads and launch rates, they are playing it safe, which is what their stockholders want them to do. And the only company in the World with vision is SpaceX... blah blah blah...

Actually, the one-day approach is much harder on the astronauts. They have to basically do the same amount of work in 1 day as they would normally do in 3 days. From pre-launch activities to docking, that's a very long and stressful day.

The difference in latency between teleoperating a Moon rover from EML-2 and from Earth is negligeable and not really worth the cost of setting up a manned EML-2 outpost for that purpose. Teleoperation a robot on the surface from Mars or Venus orbit is something that might be considered, but even then, robots are more and more autonomous so latency is becoming less of a problem. The sheer cost of sending a manned mission to Mars orbit, the limited duration, and the risk involved to the crew, outweigh any enhanced capabilities that you might get from reducing teleoperation latency.

The best reason to upgrade to 10 is to get rid of the abomination that was Windows 8. It basically reverts to Windows 7, but without the Aero bloat and the outdated "shine" look, and much better performance. For those who stuck with Windows 7 to avoid the 8 fiasco, you can safely upgrade to 10 and enjoy a much leaner and faster OS.

The fanboyism is annoying, whether its for SpaceX, Apple, Ford or your favorite washing powder. These are corporations, not football teams.

Not everywhere in Europe. In France, Germany, Spain, Belgium, Switzerland(the places I've driven), it's Green > Yellow > Red > Green.

It may not have any logic to you, who are interested in space flight. For politicians, it makes perfect sense. Funding a big rocket has more prestige than painting rocks. Maybe a few thousand, not 20000. And SpaceX doesn't have synergies with military projects. Nobody votes on space policy. The more informed voters look at education, security, employment, but most people just vote on their party habits or on one-line statements and tweets. No it isn't. NASA doesn't build stuff. The main contractors for SLS are Boeing, Aerojet, and ATK. Orion is Lockheed Martin. That's a misinformed and exaggerative statement. So I guess NASA is constituted of 18000 idiots and the smart guys all work at SpaceX, right? NASA doesn't set its goals. Its policy is decided by the President and Congress. If NASA's manned spaceflight program lacks focus, it's because politicians can't anticipate beyond the next election cycle. As long as the money for space exploration comes from the taxpayers, space policies are going to change every 5 years.

Two were planned from the start to be fitted to the two PMAs.

But they are still developing a whole new upper stage.

Elon Musk says a lot of things. It doesn't mean that we have to take everything he tweets at face value. SLS is funded by the US Congress. Congress isn't interest in BEO exploration. Thet are interested in subsidized the aerospace industry to keep a national competitive advantage and to maintain jobs in their district. As such, the longer it takes SLS to be developed, the more money is spent, the better it is. It is meeting requirements beautifully. In a perfect world for them, SLS is cancelled as soon as development is complete, and they can replace it with something else. Congress is not interested in replacing SLS with a hypothetical heavy launcher from SpaceX. That would mean massive layoffs at Boeing, Lockheed Martin, and ATK. It would also mean that they would be giving money to a privately-owned company owned by an eccentric billionaire rather to the major actors of miltaro-industrial complex. Hundreds of unemployed engineers and technicians looking for aerospace jobs in their districts, and an aerospace industry that becomes less competitive on the international market and that loses synergies with the defense industry. Nobody wins. I'm not saying this is how it should be or that this is a great system, but it's just the hard reality of how things actually work.