This summer, NASA scientists will create the chillest zone in the known universe inside of cooler-sized payload, appropriately named the Cold Atom Laboratory (CAL). The small suite of instruments is scheduled to launch to the International Space Station (ISS) in August, on SpaceX CRS-12 mission, where it will leverage the station's microgravity environment to create the coldest temperatures ever created or observed in the history of Earthling science.
So, what kind of unhinged frigidity are we talking here? Bonkers cold. Once activated in space, the CAL will shimmy down to an unprecedented 100 pico-Kelvin. That's about one billionth of a degree above absolute zero, or zero Kelvin, which is the lower limit of the traditional thermodynamic temperature scale.
That is so blisteringly brisk that the atoms inside the laboratory will form the rare form of matter known as a Bose-Einstein condensate. The CAL team, based at NASA's Jet Propulsion Laboratory (JPL), plan to study the effect of this unusual environment on potassium and rubidium isotopes, which will yield insights into fundamental physics, superfluidity, and new technologies.
"We're going to be getting to a temperature regime that no one has ever seen before," said leading JPL aerospace engineer Anita Sengupta, the project manager for CAL, in a Saturday YouTube interview with TMRO. "It's essentially unknown, what we're going to find in terms of how matter is going to behave at those temperatures."
CAL creates these ultracold rubidium and potassium isotopes by vaporizing them with lasers, then magnetically trapping the gas on a small atom chip apparatus. From there, the isotopes will be further cooled down by an electromagnetic "knife" device that will slice off the hottest, most active atoms, causing the remaining material to be almost motionless—and thus, extremely cold. These gases are sealed into a vacuum chamber where they can be studied without interference from other thermal sources.
It's hard to even conceptualize temperatures generated in CAL's suite of instruments. For context, the coldest weather most humans experience on Earth is around minus 50 or 60 degrees Fahrenheit. The vacuum of space is about nine times colder than that, at around 2.7 degrees Kelvin, or minus 455 degrees Fahrenheit, though that number fluctuates significantly with proximity to thermally conductive entities like planets or stars.
Since inside of the CAL will be only a fraction above absolute zero, or 459.67 degrees Fahrenheit, atoms inside the laboratory will be so low-energy that they will begin to move in unison and take on wave-like properties, "like dancers in a chorus line," according to Sengupta.
Similar attempts to create such super-cool temperatures have been attempted on Earth, but our planet interferes with the results by pulling atoms down into its gravity well, which limits observation time of Bose-Einstein condensates to milliseconds. The orbital freefall environment of the ISS, however, removes this constraint, and Sengupta and her team expect to be able to witness Bose-Einstein condensates for up to ten seconds, well beyond Earth-based capabilities.
"When you get to a microgravity environment like on the International Space Station, you can get orders of magnitude colder and you can also watch [atoms] evolve over a period of seconds," she said. "You get a lot more science."
The goal for the CAL team is to better understand this exotic form of matter and its implications for pure science questions. But Sengupta also predicts that the laboratory's experiments, which are scheduled to last for at least one year, will spur new technologies, including atom-based lasers.
"People are familiar with photon-based lasers, where you have a coherent beam of photons," she said. "We're going to create an atom-later which has a coherent beam of atoms." Possible applications of this research include precision interferometers, quantum sensors, holographic technology, and quantum theory testbeds, but Sengupta thinks there will be many other technological advances beyond those fields.
"You can't know ahead of time what technology you are going to create," she said "That's what engineering is—the application of these observational measurements. You first create, you first understand, and then the technology applications follow from there, and that goes for the entire space program."
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