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Comment Re:The treaty says no such thing. (Score 1) 68

Getting things *to* locations in space is inherently expensive. The cost of getting them *back* is not inherently so, if you don't insist on each return having a custom reentry vehicle and instead just shape it as its own reentry vehicle, with full expectation that it'll suffer some ablation during atmospheric entry. Some NEOs have only dozens of meters per second delta-V to reach earth intercept with an optimal trajectory and timing - a good baseball pitcher could do that unaided ;)

Comment Re:Problem with the definition of a planet (Score 3, Interesting) 54

They'll say, "oh, it's okay, there's enough of a size difference between those bodies that they don't count". But the thing is that there's no way that most of the current "8 planets" would have cleared their orbits without help from the giants. It's pretty much accepted science in astronomy that Jupiter, and to a lesser extent Saturn, scattered most of the bodies in our solar system. Mars has a Stern-Levison parameter (rating of the ability of a body to scatter small bodies) two orders of magnitude less than Neptune, and Neptune has multiple Pluto-scale bodies in its orbit. Pluto may be small compared to Neptune, but it's not so small in comparison to Mars, yet Mars has two orders magnitude less ability to scatter them. Mars didn't scatter these things away - Jupiter did. Heck, a number of the models show that the planets didn't even form in their current locations.

There's all this misuse of the Stern-Levison parameter out there to say things that it doesn't. The parameter is based around a probabilistic simulation of the body and a bunch of "small bodies" with a mass distribution and orbital distribution similar to our asteroid belt. But of course, that tells you very little - our asteroid belt only has the size and mass distribution that it does today because of the influence of other planets - and when I say "other planets", I really mean overwhelmingly Jupiter (only a tiny fraction of asteroids are in Mars resonances). Jupiter has stopped these bodies from coalescing into larger bodies and scattered the vast majority of its mass elsewhere. That's not the situation that the solar system was in during formation. There were numerous large "planetissimals" scattered around. The Stern-Levison parameter says absolutely nothing about the ability of a body to scatter large planetissimals. And even concerning scattering asteroids, it doesn't state that the scatters are enough to "clear the orbit", only that their angle changes on a pass by more than a given number of degrees.

Basic point: a standard based around the "8 planets" having cleared their orbit is a lie. The science says that most of them aren't responsible for clearing their own orbits.

And while we're at it: what sort of stupid standard puts Mars and Jupiter in the same group but in a different group than Pluto and Ceres? There was a perfectly reasonable standard under discussion at the IAU conference shortly before they switched what they were voting on: a definition built around hydrostatic equlibrium. A lot of the planetary scientists left thinking that this was the version that was going to be voted on, and being happy with either "no definition" or an "equilibrium definition", saw no need to stick around for the final vote. Hydrostatic equilibrium actually is valid science, and it's very meaningful. A body not in hydrostatic equilibrium is generally made of primordial minerals. It's the sort of place you'd go to research, for example, properties of how the solar system formed. A body in hydrostatic equilibrium has undergone mass conversion of its primordial minerals to new forms. It's undergone massive releases of energy (which may still be present, depending), associated action of fluids, etc, and are the sorts of places you would go to study mineralization processes, internal processes or search for life. They're very different bodies, and there's a very simple dividing line - one that's much easier to calculate/measure than a pseudoscience "cleared the neighborhood" standard.

Comment Re:Things are looking up (Score 1) 161

Things were great in early 1914 too.

* We've lost privacy.
* We've lost 12 minutes per hour of our entertainment to advertising.
* The quality of fruits and vegetables are down for most people.
* There's a growing set of food intolerance diseases- most likely due to issues with the food.
* If we have another widespread war- it's going to be fast and horrific compared earlier wars.
* If we have another financial panic get thru- it's going to be worse than the great depression.
* If a terrorist group gets hold of increasingly cheap bioweapons, it could end human civilization.
* If automation proceeds as expected- our current economic system breaks down as over half the population loses the ability to trade their time and labor for products.

A lot of plates are spinning. We might pull it off. Or things could fall apart astonishingly fast.

We could have had a war break out with Russia just last week via Turkey. And we would have been pulled into it by treaties- just as happened in world war one.

Generally- I agree we are doing better- but things are much more "brittle" than they used to be. We've reduced redundancy and if things go badly over a large area, it will impact ability to get food and power to a lot more people.

So... as the guy falling past the 6th floor window said.... "So far so good!"

Comment Depends if you want to support it (Score 4, Informative) 268

That really is the big issue with a self build: If something goes wrong, you have to track it down and handle all the support. If you get a pre-built from a good vendor, they'll handle it all. Say what you want about Dell, but all you have to do is run their diags (baked in to the UEFI) and call them with the code, they'll send a dude with the parts needed.

So that should be the major thing you think about. If you don't want to do support, then buy it from a vendor that will provide you with support to the level you require. I tend to recommend Dell because their hardware is reasonable and they have support available everywhere. They subcontract it, but it all works well. We use it at work all the time.

If you are willing to do support yourself, then building it gets you precisely what you want. I build my system at home because I have very exacting requirements for what I'm after and nobody has that kind of thing for sale. Like I don't want a "good large power supply", I want a Seasonic Platinum 1000, nothing else.

Also you'll find that generally at the higher end of things you save money building a system. For more consumer/office range stuff it usually is a wash: They build the mass market systems around as cheap as you could afford to. However when you start talking higher end gaming stuff, you can pay a large premium for things.

As an example I just built a system for a good friend of mine. He wanted some very, very high end hardware and pretty specific requirements. Origin PC would get him what he wanted... for about $9,000. I put it together for around $6,000. The gamer stuff often commands a hefty premium.

Comment Re: Getting a car repair (Score 1) 470

Brake fluid is clear to brown and slick (in my car it's clear).
Power steering is reddish or light brown and thin (in my car it is reddish).
Transmission fluid is reddish or magenta and smells sweet
Oil is amber.

I tell the service rep what happened before and that I'll be checking before I leave the lot. (this is the most important part)
When done, I get the service rep and we pop the hood and check each of the fluids to make sure they look/smell/feel right (this is less important since the car is probably screwed at this point anyway).
"They design the rubber used in the braking system for high pressure sealing. Manufacturers also design this type of rubber for use only with brake fluid. Severe damage results from even the smallest amount of petroleum-based fluid added to the brake system. Oil-based fluid causes the rubber in the braking system to swell and very rapidly deteriorate.

The most common mistake is adding power steering fluid to the brakes*

power steering fluid will swell and deteriorate brake seals
Power steering fluid contamination will cause seals to immediately begin swelling. As the seals swell, they move forward and block the passages that allow the brake system to function. One example is the return ports in the brake master-cylinder. The swollen seal blocks this port and the return of fluid to the reservoir, when we release the brake pedal. "

* this is what happened to me.

Comment Re:Or just make the diesels hybrids (Score 2) 181

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.

Comment Most of the above (Score 5, Insightful) 175

In the long run, a sustainable mix of the above. Whether that includes nuclear, is open for debate. And preferably with the waste heat being put to productive use (as in: heat buildings, use in industrial processes etc).

In the short run, modern design nuclear might not be so bad. Especially compared to coal, which can't be 'clean' imho no matter how you cut it.

Comment Re:Cost of access is key. (Score 1) 345

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.

Comment Re:The guy aint no Sagan... (Score 1) 345

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.

Everybody needs a little love sometime; stop hacking and fall in love!