Blacksmiths have been superheating and then quickly cooling metals on Earth for years to make everything from swords to horseshoes. But if you're a scientist looking to study exactly what this process does to metal here on Earth, there are issues. For one, there's all that pesky gravity. Plus, when you pour molten metal into a mold prior to cooling it, some of the heat from the metal is instantly transferred to the mold, gunking up a pure scientific experiment.
So, what do you do you if you want to really get a clear picture of metal's behavior unencumbered by Earthly concerns? Send a space forge up to the International Space Station that can superheat and supercool metals in midair, of course.
That's exactly what the European Space Agency just did on a recent cargo mission to the ISS. The electromagnetic levitator it launched up there was turned on by astronaut Alexander Gerst on November 7 and is able to heat metals up to a temperature of 2100 degrees Celsius (3812 Fahrenheit) and then cool them rapidly, all while they're held in midair by a powerful magnetic field.
ESA astronaut Samantha Cristoforetti, who just arrived at the ISS on Monday, will now be taking over the experiments -- which consist of inserting different cartridges into the machine and then letting its microgravity furnace process the metal and record the results.
One experiment is called "Coolcop," and it involves investigating cobalt and copper -- two metals that don't mix well on Earth -- to see if observations of surface tension can yield insight into how to better combine them into an alloy. Another, called "Metcomp," will investigate how weightlessness affects the metallic structure of a nickel-titanium alloy.
"When particles come into contact with a liquid they can be pushed away or engulfed by the liquid, like a ball floating on the sea," the ESA says about the experiment. "Depending on the size of an incoming wave, the ball could be pushed forwards like a surfer or submerged by the water. On an atomic scale, a similar process occurs with metals as they come into contact with other liquid metals. Understanding this process could lead to more exotic metal alloys or improve existing complex alloys."
When Gerst installed the machine on the ISS earlier this month, he ran into some trouble with a bolt that was stuck in an inaccessible place. At first it looked like the experiment might fail, but Gerst and engineers came up with a creative fix.
"In the end, I sawed off the stuck bolt with a hacksaw blade and shaving cream to stop metal shavings to float into the delicate optics of the machine," he says on his blog. "It was an operation that has never been done on orbit this way, but we succeeded. This is a fine example for what human spaceflight can achieve -- had this experiment been launched on a satellite it would have failed. Needless to say, I was thrilled by our success."
(Via New Scientist)