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Comment Re:Am I reading this right? (Score 1) 70

The weird thing, if it is the COPVs, is... there was so much attention focused on them after CRS-7. It'd be weird if this was the cause. And extremely frustrating, too, as they're not manufactured in-house. SpaceX surely tests the tanks, so they too would bear some responsibility for it getting past their test procedures, if this is the cause. Personally (as I mentioned elsewhere in the comments), having a composite vessel sitting in liquid oxygen always strikes me as a dangerous situation to begin with.... if we were good at maintaining LOX-composite compatibility, we'd be making the stages themselves out of composites rather than aluminum.

Of course, the COPVs aren't the only part of the "helium pressurization system". Still concerning that whatever it was slipped past them.

Comment Re:Huh. (Score 3, Interesting) 70

The helium isn't used for cooling; it's a pressurant. It's lower mass to make a small COPV and have that store your pressurant in it than to have the whole LOX tank be strong enough to withstand the pressure.

It's always bothered me, the concept of having a COPV sitting around in LOX, though. Ignoring the thermal cycling, LOX and epoxy aren't exactly fast friends. We don't make LOX tanks out of composites because composites tend to become impact sensitive in LOX (there've been some attempts, but it's still an active reseach field, not a "solved problem"). Not sure there's that much difference between making your whole tank out of composites vs. having a composite tank inside of one. I don't know what SpaceX does, if anything, to try to protect them, but the general concept has always concerned me.

Comment Re:Smarter Aliens (Score 1) 275

To put it another way: the total mass of the universe is about 180000000000000000000000000000000000000000000000000000 kilograms, which is the mass equivalent of 16200000000000000000000000000000000000000000000000000000000000000000000 joules. There is no shortage of "resources" in the universe. Even the rarest of "resources" is available in unthinkable abundance to any entity that has a range broader than a single planet. Not like it's particularly easy to actually exhaust resources on a given planet; you just move from the easiest ones to the much more abundant, but harder to access ones (while simultaneously your technology advances with time, making resources in general more accessible; prices are based on the competition between these two factors, but in the long term generally follow a downward trend)

Comment Re:Why is Windows 10 the benchmark? (Score 1) 200

Pi Zero is $5. Pi 3 at Micro Center is $30. Arduinos run from $4 to $40 and often need shields to do what a Pi 3 will do. They are in similar price ranges.

This thing is five times the price of a Pi 3. I can get a full-size motherboard, CPU, and RAM for $160. Hell, I can get an HP 2 GB Chromebox with a Celeron for $99. http://www.microcenter.com/pro...

Comment Re:same bullshit (Score 1) 134

Russia doesn't seem to be looking to restart a space race. As usual they make grand pronouncements, but meanwhile their funding just keeps getting cut further. On the other hand, China might bring one. We're far from there now, but China keeps trying to push themselves rapidly forward in regards to space; they see it a way to mark themselves as being a legitimate, technologically advanced superpower rather than just a country of factories churning out trinkets. Right now it's things like space stations and simple probes. But suppose it gets to the point where they actually announce and fund an interplanetary mission (and if they announce it, it will actually happen; they don't go through the whole "changing cycles of congressmen" that the US does). How does the US respond? Just let China totally outshine the US on a highly publicized technical field?

Comment Re:"an unmanned exploration mission by 2018" (Score 1) 134

As far as I can tell, they're not actually "giving" NASA any more money of relevance, they're just telling them how they need to spend it. Standard congressional stuff, except this time they're amusingly trying to say "nobody can change this in the future"

I'll take the concept of a government-funded mission to Mars seriously whenever they actually give NASA billions more in annual funding at the same time as mandating it.

Comment Re:Waste of money (Score 2) 134

I assume the whole aluminum oxide = "VERY poisonous" is some sort of joke.

Of the metals in solid rocket fuel, aluminum is the most common, followed by iron. Aluminum and iron oxides in dust form are otherwise known as "clay".

The hazardous chemical that comes out of SRBs is hydrochloric acid. But it's not super-dangerous in the quantities that are released over the areas that it's released over.

The GP is correct, the hypergolic fuels are much worse for the environment. Some experimental ones have been even worse, such as boron-boosted (zip fuels) and fluorine-based fuels. Crazy-high performance - the highest ISP rocket engine ever built was a fluorine-hydrogen-molten lithium triprop** - but they're a nightmare to work with. I can guarantee you that if beryllium wasn't so crazy expensive it would have gotten a shakedown as well.

** The fun thing in that rocket is that the hydrogen both enters and leaves in the same form, H2. It exists solely to function as a working gas, to maximize the expansion potential of the heat released from the lithium-fluorine reaction. A lot of things with rocket propellants are counterintuitive that way - for example, with aluminized hydrocarbon-based rocket propellants, the optimal combustion is to burn the hydrocarbons to H2 and CO, not H2O and CO2. It's not worth the extra energy release to carry more oxidizer, and you need as much light gases as possible to transfer the energy from the aluminum since it condenses out of the gas stream at high temperatures and thus can no longer contribute directly to expansion.

Comment Re:With all due respect to Mr. Hawking and us... (Score 1) 275

Science and physics once said fusion and fision were impossible

Alchemists spent most of early human history trying to change elements into other ones. The concept of the nucleus was discovered at roughly the same time as the discovery that it can change (aka, radioactive decay) - around the end of the 19th century - which immediately launched searches into the possibilities of various means of transmutation. There was no point in time in which the nucleus (aka, a fundamental requirement for either fusion or fission) was known where there was any sort of acceptance that it could not be changed. There was a period of about 75 years where the nucleus was unknown, but the concept of atoms was known. However, fission and fusion wouldn't have made much sense as concepts without the concept of a nucleus.

the sun couldn't possibly exist as it produced more energy than physically possible.

Nobody every believed "the sun couldn't possibly exist". There was a period before the discovery of fusion where there were disputes between geologists and astronomers, with the former believing that the world was older and the latter believing that it was younger (they knew that stars could be powered by collapse - and indeed, they are during their formation - but not of a continued power source). This was a well known dispute and was treated as an unsolved problem, not a "gee, we were all wrong" thing.

couldn't explain how the honeybee flew

There was never any sort of mystery among scientists about how honeybees flew. People can't even track down the origin of this widely cited myth precisely, although there's a number of different theories crediting it to different individuals. A likely source is from a French entomologist, Antoine Magnan, citing secondhand off-the-cuff calculations from an assistant (and had nothing to do specifically with bumblebees). There was never any sort of "scholarly mystery" debated among mystified scientists about impossible-flying bumblebees.

or heavier than air travel.

You're citing Lord Kelvin, but he also had a lot of crazy ideas about things being impossible, even things that had already been invented. During Lord Kelvin's day, there were many respectable teams working on heavier than air aircraft. Not to mention that nature had already more than demonstrated that it was possible, given a sufficient power to weight ratio.

We already have working theories on bendIng space.

Yes, if you can make a continuous chain of black holes along the entire path, for example. Gravity bends space. Inflation bends it in the other direction. We know of nothing else that bends space, and have good evidence that nothing else does.

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