Slashdot Mirror
Developing New Materials With Space Science
Scientists at the European Space Agency are using techniques inspired by their experience with outer space to make new and better products here on Earth. Certain compounds and alloys which are not normally viable can be made in different ways once forces such as gravity are removed from the equation. From BBC News:
"The near absence of gravity (microgravity) has a profound influence on the way molten metals come together to form intermetallics and 'standard' alloys. With no 'up' and 'down' in the space environment, a melt doesn't rise and sink as it would at the planet's surface and that means solidification can turn out very differently. 'Gravity induces a lot of segregation of the elements,' explains IMPRESS scientist Dr Guillaume Reinhart. 'For instance, tantalum and niobium are heavy atoms and in doing the solidification process on the ground, they will segregate in different places and produce a very heterogeneous material. If you do this in microgravity, you obtain a very homogenous material because you prevent separation; and you have a much more efficient material, mechanically.'"
The time to heat, mold, cool a new metal could take hours, no practical way to setup an hour long freefall.
Ignoring the deceleration problem at the bottom, with a 5 km shaft (which is not cheap to make) you only get 30 seconds of free fall to work with. And that's in a vacuum! In any shaft on earth, you are going to have air, which means you will hit terminal velocity at some point, which will ruin the effect.
:)
This duration of free fall is comparable to the Vomit Comet, which can produce brief periods of free fall without the ugly smashing part at the bottom of a mine shaft.
This is exactly what we need to jump-start serious commercial investment from companies like Dow Chemicals in space exploration. They'll never give more than token amounts to a project which is for the "betterment of mankind and improvement of human knowledge".
But...if they think that they can make products superior to their competitors (or even better, products which are unique) then you can bet they'll be very interested in setting up orbital refineries and finding economical ways of doing it.
This is the first really hopeful news about a continued human presence in space that I've heard in quite some time (Virgin's space gimmicks notwithstanding).
Back when the Shuttle was called the "National Space Transportation System" and NASA was claiming that launch costs would come down, NASA used to talk about materials processing in space. That was a long time ago.
The trouble with materials processing in space is that for small things, gravity is dominated by surface tension and other forces like Brownian motion. So biological processing in space never amounted to much. Some early Shuttle flights carried an electrophoresis apparatus designed for zero-G operation to make some kind of diabetes drug. But bioengineering went beyond that approach; today it's easier to engineer some bacterium to crank out whatever you need.
For big objects, there would be some advantages (and many disadvantages) to working in zero G. Handling molten metal in zero G safely would be tough. One molten droplet could puncture anything we currently send into space. With gravity and in air, molten droplets don't travel very far and cool. In space, they can go a long way. Steel mills use floors of dirt or refractory brick in molten metal areas; concrete will blow up when its water content boils. Welding in space has been tried, but on a very small scale, and very nervously.
Lift to orbit is far too expensive to justify flying heavy metal up there for casting and welding. This is one of those ideas that won't be feasible unless and until lift to orbit costs about what long distance air travel costs now.
That's where that "NASA approved" memory foam came from!
We figured out a long time ago that it's easier to elect seven judges than to elect 132 legislators.
Sure. But what if you keep rotating the mold as it cools down? Or do something similar?
But yeah, people often don't want a homogeneous material, they want stuff like the material being different at the edges from the core. So maybe "weightless" environments might help (lots more control), but without real numbers - significant difference in alloy strength or other characteristics, it's just not very exciting to me.
Mining of asteroids and the moon will have to be developed obviously.
And this is why companies should understand that science projects that are for the betterment of mankind and for the improvement of human knowledge are long term investments.
The problem is that the goal of corporations is to make a lot of profit in the short term. Rare are the corporations that are planning their growth in the long term. They plan for the coming years, not the coming 25 years.
After all, where could useless theoritical research from imbeciles that live in their heads like James Clerk Maxwell possibly lead us? Surely if you don't see an application at the time, the research is a waste of time...
Haven't single crystal superalloy tech already solved the problems caused by gravity and metallurgy? http://en.wikipedia.org/wiki/Superalloy I don't know, just asking...
Terminal velocity can be overcome by generating a partial vacuum in the tower, and by accelerating the falling cabin downwards past terminal velocity, on some sort of rail system.
I think there is one free-fall tower for scientific experiments that does both of these already but I do not remember where I read that.
The short duration of freefall for any realistic height for a tower remains thought
Everyone loves the overpowered monstrous Gundams, but there's something in me that likes the simpler Zakus. I also like the RK-92 Savage from Full Metal Panic. There's just something about clunky, mass-produced military technology.
Admit it. You post strawman arguments as AC so you get modded Insightful for refuting them, rather than Troll
Earths magnetic field? Centerfugal (spelling?)
Actually, orbiting is considered free falling, and that can obviously last much longer than a few hours. That's one of the main reasons that newbie astronauts vomit in space, because even though it looks like they experience no sensation, they actually feel like they are falling 24/7 (an extremely nauseating event).
Help fight spam
Can you get a similar gravity situation on Earth by having the chemical reactions happen in free fall?
Consciousness is a myth. Trust me.
you are off by a factor of 2.
you are correct that a 5km drop gets you ~30 seconds of freefall (0.5at^2). but you could start at the bottom of the shaft and launch up (with a brief high-g acceleration) and then be in freefall all the way up and all the way down, for ~60 seconds of uninterupted freefall. The high-g at lauch would be the same as the breaking g at the end of the trip.
you could get 30 seconds of freefall with only 1.125 km worth of shaft.
just a nitpick, but...
-Rob
Why do you think they keep cement trucks' mixers rotaing slowly during transportation?
Have gnu, will travel.
...to Gundanium, one step closer to Gundams. I hear the Japanese Department of Agriculture is in charge of that project.TFA: The near absence of gravity (microgravity) ...
JFTR: At 400km above ground (the ISS's orbit), the gravitational acceleration
the Earth exerts is still about 88% of the acceleration on the ground.
It is a very common misconception that gravity somehow instantly vanishes as you
arrive in space. It isn't so - in fact, gravity is crucial for that weightlessness in orbit.
You speak like a physicist, not an engineer. In theory, you are correct. In reality, how will you launch the material, such that it travels at exactly 0 degrees from vertical, at the required velocity? Solving for v in m*h*g=0.5*m*v^2 I get 150 m/s launch velocity. At perfect vertical. On a payload that contains a manufacturing process, probably including a molten metal. More than a kilometer below ground level.
It is dangerous to be right when the government is wrong.
I've always liked the idea of microgravity materials processes, but with launch costs the way they are, there isn't any way you're going to manufacture some novel material in space for use on the ground. There remains a lot of "interest" in microgravity processing in space, but largely it's because there's nothing else you can work on to justify having a space station.
One caveat that there might be some scientific value to cranking out samples in orbit (e.g. creating samples large enough to do x-ray crystallography on, and thus learn something about the structure of the exotic materials). On the simplest level, I would expect that if you crystallized a material in space that looked like it had some industrial use, that would provide the motivation to figure out how to manufacture it using ground-based techniques.
This is another application of the rule-of-thumb that while launch costs are high, the only thing that's practical to ship is something that doesn't weigh anything: information (think communication satellites).
I would still bet that the next big step in space industrialization would be the solar power satellite. After that we can start working on mining the moon, the asteroids, and maybe finally reduce earth-to-LEO launch costs, one way or another.
But that would take an actual commitment to a real project... so for the forseeable future, we'll continue to see lots of make-work-in-space like this.
You don't need vacuum. Terminal velocity is based on the maximum speed of a falling object due to drag. If it's not falling, but instead being pushed, then it's not subject to terminal velocity, just loss of energy due to drag, like your car... until you drive off a cliff anyway.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
Time to prepare for Apophis and dig it when it'll come close enough!
I can't call that English
Here are the guys that create a partial vacuum in their drop tower. I thought they also used some sort of rail system, but that might have been another tower.
I think I see your point - it might be just a semantic one, but an interesting point anyway.
True, the gravitation attraction of the earth still exists in orbit. In fact, it is what keeps the fast-moving ISS from flying off into space, because gravity keeps pulling the sideways-moving ISS down towards the Earth's center. This constant falling-but-never-landing state is called orbit.
But can anyone please explain how this gravitation system affects experiments onboard the ISS? Common sense seems to indicate that from the ISS's frame of reference, there is no effective gravity. Not that it doesn't exist, but just that it doesn't matter.
But is that really true? Would an experiment on the ISS in orbit around Earth, result in the same findings as the same experiment carried out in deep, non-galactic space, far way from large masses and stationary to distance reference objects? Although the only real difference is that the second frame of reference is just much larger than the first, as both still exist within the large structures of the universe which are whizzing around an inflationary space-time bubble.
Even in orbit/'weightlessness', there is still the large mass of the nearby Earth. Does the presence of this large mass, around which the experiment is orbiting, have actual effects on the experiment? Is it just that it is such a small effect to be insignificant vs. sea-based-experiments? (But parent's calculation of relative strength of the gravitation attraction at 400km high vs. sea level = 88% might be relevant).
Or it is entirely about the POV from inside the frame of reference of the experiment?
IIRC, lead shots were made by dropping molten lead down a tall chimney-like structure, they'd be cool enough to stay solid by the time they got to the bottom. Know how a raindrop is a sphere? Same principle.
Drill baby drill - on Mars
http://en.wikipedia.org/wiki/Drop_tower
h=y0+y*t+0.5*g*t^2=0+0+0.5*10*(10/2)^2=125m
E=m*g*h=m*1250
Thus, you've got 1250 J for every kilo in the Bremen facility.
Your 1125m shaft from the previous post requires almost ten times the energy.
It is dangerous to be right when the government is wrong.