SeaDog

Well, I wouldn't trust anyone either way on this. There's a good reason why spaceX is private, and one thing is that these things can be kept very secret. And depending on how your internal accounting is done, you can look at it in many ways. For example, it may be that the launch is profitable... But that the difference in launch capacity due to reusability attempt is bought by the development section of the company, which of course spaceX itself pays for, in the end it turns out to be a net loss. But launching the rocket was profitable. So in the end no one knows for sure. I think spaceX needs to make reusability work. I think the rockets at best pay for themselves, but there's substantial infrastructure and development that's still at a loss. For that reason I think any price drop in launch costs will be moderate even when they start doing reusable first stages. SpaceX will put that money into more development. Further, I think space X will need more investors, and they need to really see space x doing revolutionary stuff.

Well, it's much larger than earth. In terms of size, there have been better candidates. Arent they just detecting that there are atmospheres, rather than actually seeing what the atmospheres are made of?

Well, the cool think about chutes is that you can set an airpressure and activate them well before you reach the planet. No further input required. But other than that, yes, what you say makes sense.

It seems to me that the planets already known are already pretty good candidates for earth similarity, judging only by orbits, but they make it sound like this something much better... Is kepler capable of detecting atmosphere content or something like that? Otherwise I guess it's just another planet similar to earth in terms of size and habitable zone.

Actually, I think you're a bit ridiculous. I agree that we can't know for sure that the capsule separated safely from the rocket, but your claim seems to be that it couldn't possibly have done that, the evidence for that is also pretty weak. I think it's at least an interesting speculation, and I don't understand why it's so important to you to prove it wrong, even though you can't at the moment.

Maybe I'm going off topic here, but the only time ingredients are measured in mass here in Sweden is when it is actually more practical. That pretty much only happens when the recipe is aimed at large producers who get their flour in large bags that might compress the flour so that weight is the only accurate measure. Butter is one of the few things you see in terms of mass in regular recipes here, and thats because the packaging shows how much 50 grams etc is.

Why? That's pretty much what it takes to bounce a signal on a LEO satellite, assuming a few ms for the computer to react. In reality, it would usually be more because you go through a few nodes on the ground as well, but still, from the ground to the satellite and back again should be something like 30 ms.

No, the wikipedia link you gave talks about geo stationary. For LEO is actually says latency is no issue. The ship link you're talking about also uses geo stationary satellite. In fact, I think there are good reasons to believe satellites will in the long term offer lower latency than what is usually seen for todays broadband connections.

Thats a strawman i often see when people are disappointed that nuclear power isn't the end all solution to various problems. Nuclear power for everything is a 50's scifi trope and in the case of space travel, there's actually not much indicating that it would be better than solar. Solar has several strong points: While taking up much space, it can probably be made extremely light. It is extremely reliable since you can run parts of it if it gets damaged. It has already been used extensively in space. Simple forms of it could probably be constructed in situ. So yea, the idea that we're not using nuclear reactors for stuff like this because of the opinion you quoted, that is the real education failure. It only shows you do not understand how difficult nuclear power is, especially in space.

On a global scale it doesn't matter, but on local scales, it might. One should also have the entire life cycle in mind, and remember that many common types of power generation do have an impact on water supplies. Yet another example of how efficient transports may be more important than alternative fuels.

Not in the forseeable future. If you ever get a job where you're supposed to make robots do advanced tasks, you'll realize just how bad robots suck. I mean, even extremely good robots really suck at some very simple things. Great, so you have a robot that sweeps the floors perfectly, better than any human could. Want that same robot to also dust the book shelves? Extremely difficult. Not impossible, sure, but somewhere in the development you'll be like "Well the cleaning lady was a bit lazy, but honestly, if you told her to dust the books, she'd do it once in a while..." So i know that some people will reply to this with "Well, we will eventually design robots that are adaptive and learn", but I actually don't think so. That's exactly what humans are good at. Why would you need machines that mimic humans? No, I think robots will keep on being quite specialized and genereally do boring, uncreative stuff, because that is where humans are weak and actually need help.

Sure, but water and fuel alone could be a big market. I'm not going to stick my head out too far here, but it seems to me that 1 billion turnover should be possible on that basis alone, even if launch costs drop somewhat and even if lower costs do not lead to more space exploration. For example I think the SLS Block 2 will have an upper stage with room for 100 tons of fuel. If you had a system that could completely refuel that once a year, it would be incredibly valuable, possibly on the scale of a billion dollars, even though it's hard to put a figure on it. And then there are smaller, commercial satellites that might be launched to LEO, refuelled and then pushed on to GEO with fuel left to spare for deorbiting. So yeah, you don't even have to look at rare earth metals to see there's a business here... Even if that's what you talk about when investors are around, if you're planning to go there. As for making it profitable - I think you can only figure that out by trying it on a small scale. First step is controlling a small asteroid though. How is that done? No one knows for sure right now.

Well, the horizontal velocity is on purpose. In case of engine failure, they don't want to crash hard into the barge. I don't think it's necessary to get rid of that feature anyway, even if it probably would be slightly easier if they did.

It's funny how technology that does not yet exist always seems so simple. Get back to me when we actually have closed eco systems that can support a number of astronauts for many years. Then we can discuss how to fit that on a space ship that's too far from the sun to use direct solar energy.

That is one possibility, but that will be for the BFR/MCT. Another speculation for that vehicle I've seen is that the upper stage will be refueled in orbit, brought to mars, perhaps even landed and refuelled again and then used to bring back the MCT. Something along those lines. If anything remotely like that will happen is uncertain, but i guess it could count as reusability.

Coming in fast and quickly landing is how you want to do it anyway for efficiency. For a human it might be easier to hover for a bit, but for a computer it shouldn't matter that much.

Just thin steel plate then. Or just a steel grid which the legs clip into. Really, there are so many simple ways to do this...

Well, jokes aside, I can think of ways of saving partial landings. Such as spiked legs and landing on thick rubber carpet. Perhaps the idea is that a landing that needs support like that is failed anyways due to stresses it might put on the rocket, I don't know.

And the reaction from an old player who used reject the new ideas is of course "well, maybe they do have a point, but they're taking it too far". Still though, Ariane 6 is not reusable at all and will be used in a similar time frame. I think it's good that we're seeing a multitude of very different systems. Not because I think Ariane 6 or Vulcan will really be able to compete, but because it will further underline which general design is the way to go. It will be interesting to see what China will do in the coming years. On one hand, they can possibly cut costs in other ways that are not available to western manufacturers so that they don't need reusability to be competitive. On the other hand, demonstrations of technological proficiency might be important for them, even if it isn't really cost effective.

Maiden launch in 2019, and they won't save the engines straight away. I can't help but to think "what will SpaceX be doing by then?".

Don't underestimate the difficulties of nuclear power... Getting people comfortable might not be the most difficult part, in some sense that has already been done. And before anyone says "RTGs": that's a very different thing. We're talking a big reactor here that has to be quite effective in terms of energy to weight AND electrical energy to heat, that can't rely on gravity or massive input of coolant in the form of air or seawater in case of emergency, which humans would depend on for several years for their survival. It's probably not impossible, but I don't think we'll see it until it's actually really needed, ie, for manned missions beyond Mars. However, a research reactor in, for example, lunar orbit, would be interesting. Basic functions could be based on solar, while the reactor either powers electric propulsion experiments or simply converts water ice to fuel. 10 years later we would have a proven system, while the experiments and fuel created would somewhat make up for the cost.

Why doesn't the Falcon Heavy use a larger 2nd stage, does anyone know? I mean, I only know rocketry from KSP, but it seems to me that with all that extra thrust in the beginning, the rocket will be very high and going very fast when the central core of the first stage drops away, making reusability more difficult. But maybe that is intentional, for practice? Theories?

I don't get why people are so negative, I think this is perfect. 1) This is a perfect demonstration mission of a asteroid redirect mission. This is possibly the simplest way to do it. Send a probe. Grab a heavy rock. Use the force of gravity to redirect much larger rock that would be difficult to move otherwise. Using some kind of direct force might not work because the target is a pile of rubble. 2) It was never an option to move a huge asteroid. The only other real short-term alternative was to find a free asteroid about the size of this rock. Maybe some day humans will be directly moving huge asteroids, but starting small is the way to go. And grabbing a rock on a bigger asteroid is probably simpler than docking a free floating, small asteroid, which is both difficult to find and likely spinning fast. 3) This is relevant experience for asteroid mining. Again, we want to start small and this may very well be the simplest way to do that. In asteroid mining terms, a few meters across is not tiny. If you can find a dirty icecube that size and grab it, you have A LOT of potential fuel. I think asteroid handling is much more interesting than manned mars missions in the near term.

I live in a city where people commute by bike daily. This winter it never got to -20 C, but that's a rare occurance. In Sweden we have this saying: There's no such thing as bad weather, only bad clothing. It's so true in this case. Once people get used to it, dressing for -20 degrees C biking is really no big deal. You need insulating pants, a jacket, gloves, and a good cap. Thats it, ready to go. As for public transport that's faster than cars: That's really very easy to make IF you design cities around public transport instead of cars! But since that rarely happens, we get attitudes that make it seem like it's impossible. In america, I'm sure it is. But the fact is, if you make ciites dense enough, there's very little reason for people to ever go more than a few kilometers. As I've said several times now, cities are designed around cars, and sadly, that design itself is what increases demand for car usage. Doing something different from what you've been doing forever is not inherently a bad thing.

They both suck. Cars take up space, both in terms of parking and in terms of roads. The more space you need in a city per capita, the longer the distances to everything will be, and the more roads you need, which takes up space, etc... Future cities will need to be based around bikes, public transportation and high and dense city blocks. What we use for fuel in the few cars we have left by then is unimportant. Might as well use what little fossil fuels we have left for that. If there's anything they're good for it is transportation, actually. But if I have to choose, i'd say electric. I don't think it's impossible that electric cars will take over primarily because they simply perform better and are easier to maintain.