Love the quality of the debates here on Slashdot.
Come on, you two haven't called each other poopy-heads yet!
Love the quality of the debates here on Slashdot.
Come on, you two haven't called each other poopy-heads yet!
And even the best public transport system generally isnt going to start and stop *exactly* where you need it, so there still is going to be *some* walking. Which some people with disabilities or health problems simply can't manage. And to achieve a good public transport system - with frequent stops, densely placed stops, relatively direct routes and affordable prices - is entirely dependent on population density far more than it is on "will". In places with high density, it's a relatively straightforward process to have a good public transport system. In places with moderate to low density, it can be difficult to nearly impossible. And weaknesses in public transport system are a viscious cycle: the less frequent the stops, the further spaced out they are, the longer the transit times, and the more expensive the rides - the fewer people will ride them. The fewer that ride the less frequent you have to have the stops, the further apart they need to be, the less direct the routes, and the less affordable the prices.
I don't want to pay some clown a bunch of extra money because he got stuck in traffic or took a longer route because he had no idea where he was going.
The one good thing about driving a cab is it teaches you how to handle arseholes - I would have thrown you out of the cab at the next bus stop
And the taxis I see are 15 year[s] old
Unadulterated bullshit. I drove taxis for 3yrs, the oldest one I drove was 5yo, it had 1.2 MILLION kilometres on the clock.
That was not my point. Ofc we can improve ISP. No idea how much that improves either 'performance' or drops price.
It improves performance a *lot*. As for price, it depends on how expensive that rocket system is. For first stages, an improvement in ISP's effect on the size of the rocket isn't that much greater than linear. But the further up the delta-V chain the engine is used, the more of an impact it has on everything that was used to get it there. An extra hundred sec ISP on a first stage might reduce the system mass by a third; on a second stage up to LEO, maybe cut it in half; on a kick stage for a Mars transfer orbit, maybe cut it by two thirds. On an ascent stage from the surface of Mars... well you get the idea. Shrinking down a rocket to a small fraction of its size - fuel, tankage, and engines - well, that's really significant. ISP is very, very important for upper stages. So you can afford to pay quite a bit for those top stages if it improves their performance. Just not an "unlimited" amount.
There is no way a high tech electrical engine will improve its performance by 10% regardless how much money or time you put into it: the efficiency is already between 98.5% - 99.5%, up to 99.9% in some cases.
This is getting a bit offtopic, but at least the electric engines in EVs don't usually run at nearly that high. Depending on the type they might average 85 to 94% on average. It varies over their load cycle.
Regarding rockets: there is simply not much margin anymore in changing the form of the exhaust tube, burn chamber etc
Actually you can. The general principles of how rocket engines work are fixed, of course - your exhaust will never exceed its local speed of sound in the throat, and then you want to expand it as close to ambient pressure as you want. But the details vary greatly. There's bell nozzles, linear nozzles, annular nozzles, aerospikes, throatless nozzles, atmospheric wake compression, and on and on. There's tons of different ways - developed, in development, and in theory - to pump and inject your propellants - where they need to be pumped at all. Even many propellants that are traditionally thought of as being in one state can be implemented in other states. There's various ways - developed, in development, and in theory - to prevent nozzle erosion. To improve regeneration. To reduce mass. And on and on and on. Rocket combustion is a rather complex thing and we're still trying to get a handle on it. Do you know that we still really don't know how aluminum burns in solid rocket propellant? There's something like five different competing theories. I mean, things like this are a Big Freaking Deal(TM), especially when such small improvements in upper stage ISP have such significance for lower stage mass. And even on your lower stages there's a lot of things that have a big effect on your system cost. For example, how to stop resonant shocks from ripping them up - a lot of people don't realize that one of the main benefits of adding aluminum first stage to propellant mixes is that the droplets of burning aluminum damp shocks. (yeah, it increases ISP too by raising the exhaust temperature, but it also has disadvantages, such as not contributing to expansion, slowing down gases (particularly near the nozzle), and impacting/eroding the throat (or even forming an accumulating slag)
Re, nuclear+chemical. There are proposals for this. The main issue isn't efficiency - the extra chemical energy doesn't make that much of a difference - but thrust. The downside to nuclear thermal is that the reactor is so heavy (fission is like that, unfortunately) that the mass ratio is only something like 3-4:1. That's really bad (you generally get 15-20:1 or even better for a chemical first stage). So the approach is to inject oxygen early in the ascent phase for added thrust, but only run on hydrogen higher up when gravity losses are lower. I'm really not that sanguine about nuclear thermal rockets getting a serious development program any time soon, though. The public overestimates the risk, of course - not only am I sure they'd well seal the fuel elements against whatever damage would be incurred by explosion or reentry, but there's the simple fact that the fuel is "fresh", not contaminated with the more hazardous actinides. But it's going to be a hard sell. And a really hard development project, if they ever did try again. Gigawatt-scale flying nuclear reactors that pose radiation hazards during assembly and test aren't exactly childs' play.
Asia Minor was the Ancient Greek term for it. I don't think it's actively used these days, other than in historical accounts; at least not in English. Anatolia is the more common word for that region.
Ural mountains are the eastern boundary of Europe, not the northern one (they stretch from north to south). The northern boundary is the Arctic ocean. Black Sea is the southern boundary, along with the straights, and further east it's Caucasus mountains and then Caspian sea.
However, this boundary is not only arbitrary, it's relatively (as in, only a couple of centuries) new. There were other definitions before, with various major rivers used as the eastern boundary (e.g. Don or Dnieper). This is because there really isn't any good geographic definition, nor is there a particular need for one - the continent is a single one, Eurasia. Historically, Europe has been more of a political division than geographic (geography played into it only to the extent of defining easy to protect natural boundaries, like rivers and mountains, which then tend to become state boundaries.).
Afghans are actually not Arabs at all (and Arabs are themselves Semitic people). The majority of Afghans are Pashtun, which is an Iranian sub-ethnicity, and the language that they mostly speak is Pashto, an Indo-Iranian language closely related to Persian; the second most popular language is Dari, which is a dialect of Persian. The second largest group are Tajiks, which are also an Iranian sub-ethnicity and speak an Indo-Iranian language very close to Persian. Then come Hazara, who speak Dari and are also Indo-Iranian; Uzbeks, which speak a Turkic language; and Balochi, who are again Indo-Iranian. So none of these are Arabic or Semitic in any way. Arabs and Arab-speakers are a tiny minority in Afghanistan (which kinda makes sense when you realize that it's basically all former territories of Persian Empire dating all the way back to Achaemenids, so ethnically and linguistically it's rooted in Iranian culture.
Also, just FYI, in contemporary American usage, "Oriental" is seen at best an archaism deliberately used to evoke the atmosphere of the times when it was heavily used, and at worst is actually considered derogatory (or culturally alienating; either way, carrying a distinctive implication of racism).
You forgot to exclude operational expenses.
Yes, people to run robots and comm time on the DSN. We're not talking about massive expenses here. The real expenses are the capital costs.
And also didn't mention that you can't just lob chunks of metal straight to Earth's surface,
Actually, you really just can. Even random rocks from space - not shaped for optimal entry shape, not cemented together by anything yet what nature chose to gie them - do this all the time. They have to be between a certain size range (too little and the whole thing ablates; too large and it explodes, either in the atmosphere or on impact), but the random creations of nature do it; delberately shaped and sintered projectiles should have no trouble with it, with (proportional to their mass) relatively little burnoff.
You would, of course, need a rather large area designated as the impact area; even with very precise aiming, by the time they get to Earth and undergo reentry the random variables will spread them out over a sizeable chunk of land. A large salar might be ideal, since they get resurfaced periodically so the impacts wouldn't be damaging the landscape.
By your same logic, the mining of minerals on Earth would be zero dollars per gram if the equipment was solar powered and automated
It's almost as if I didn't discuss capital and ongoing costs in my above post.
Launch costs really are key to the rate of development at the very least, in that they limit the rate in which funding can be raised for the necessary exploratory and test craft to be launched. Even if the economics for operating a mine on a NEO works out really well at present launch costs, you have to prove that you can do it before you can raise the billions to build it. And to prove that you can do it you have to launch a number of missions while you're still relatively poorly funded. They face the same problem that Bigelow has faced - a probably reasonable business plan but the early phases hinging around factors that they don't control.
It does nobody any good to pretend that the lack of a space economy is because investors are cowards and morons
I think you need to go back and read my last post again, particularly all of the "it's too early to say"/""we don't know"/"but time will tell"/etc lines. I'm not saying that at all. I'm saying that there very well could be a compelling case for asteroid mining even without any radical changes in space technologies. But there's a great deal of work to prove that before we can get to that point.
I'm well aware of that. But OP's point wasn't that Israel is as bad in that regard as some Muslim countries - it's certainly not - but rather that it is a theocratic state. I disagree with that as a broad categorization, but it certainly isn't a secular state in a sense most Western countries are, and it has some pretty heavy-handed policies rooted in religion, marriage laws being one of them. I mean, when the state basically gives a monopoly by law, not even to a single religion, but to a single denomination of that religion, to conduct all marriages (with specific exclusions for a couple other recognized religions, but no provisions whatsoever for other denominations or for non-religious people), and their policy on it is restrictive enough in practice that many people have to travel abroad to marry, that's pretty messed up as far as I'm concerned. And it's not the only such thing there, just one that came to mind first. Unfortunately, a lot of that crap dates back to compromises made when the country was founded, and demographics ensure that the Orthodox minority is an important enough voting block that they get away with it.
How does a Pi with a remote text terminal session compare performance wise to a PDP-11
Way faster, way more capable. I worked with a PDP11 on a summer job. If I remember correctly, it had 2x64KB memory (data and code pages); the Pi has more main memory than the PDP had hard rive storage.
It managed to support about a dozen concurrent users that used it for monitoring an industrial process. It was tight enough, though, that we had to stop people using a full-screen clock application, since it couldn't cope with all terminals running it at the same time.
If Data and Lore had been configured with different host keys, a whole lot of anguish could have been avoided.
When a signal transmission is detected from Data's quarters, Wesley Crusher arrives to investigate. He finds Lore, now impersonating Data, who explains that he had to incapacitate his brother after being attacked. Wesley is doubtful, but since Lore and Data were misconfigured with identical host keys, he has little option but to pretend to accept the explanation.
The First Amendment to the
It is sad and sickening to see so called liberals
By way of example: if I paid you $10 to put a sign on your lawn saying X would it be wrong for you to refuse to put a sign saying Y on your lawn for $10?
And that's where we are at with this. The theatres refuse all religious / political ads. That way they do not endorse X or Y. Nor can they be seen as supporting Y.
"The Avis WIZARD decides if you get to drive a car. Your head won't touch the pillow of a Sheraton unless their computer says it's okay." -- Arthur Miller