NASA’s CAL Experiment Aboard the ISS Produces Temperature As Low As 100 NanoKelvin

July 30, 2018


The International Space Station is now officially the home to the coolest experiment in space. NASA’s Cold Atom Laboratory (CAL) has started producing ultracold Bose-Einstein condensates (BECs) that can reach temperatures just above absolute zero (or zero Kelvin). Absolute zero is equal to minus 459 degrees Fahrenheit (minus 273 degrees Celsius)—the point at which atoms theoretically stop moving entirely.

Last week, CAL produced BECs from atoms of rubidium, with temperatures as low as 100 nanoKelvin (or one ten-millionth of one Kelvin above absolute zero). In comparison, the average temperature of space is about 3 Kelvin.

According to NASA, CAL facility was installed in space station’s U.S. science lab in May. The primary aim of installing this facility in space is to study the fundamental laws of nature using ultracold quantum gases in microgravity environment. The space agency believes this multiuser facility—the first of its kind in orbit—will advance scientists’ abilities to solve long-standing problems in quantum physics by allowing them make precision measurements of gravity and explore the wavelike nature of matter.

“Having a BEC experiment operating on the space station is a dream come true,” said Robert Thompson, CAL project scientist and a physicist at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California.

“It’s been a long, hard road to get here, but completely worth the struggle, because there’s so much we’re going to be able to do with this facility.”

Scientists recognize BECs as the fifth state of matter—somewhat different from solids, liquids, gases, and plasma. In this state, atoms act more like waves than particles. Supercooled liquid helium is also a type of BEC.

Usually, the wave nature of atoms can be observed at microscopic scales (such as in subatomic particles like photons), but BECs make the phenomenon much easier to study by making allowing scientists to observe it at macroscopic scales. At ultracold temperatures, atoms assume their lowest energy state and become indistinguishable from one another. In this state, the clouds of atoms appear like a single “super atom.”

However, producing BECs is a very tricky affair. It involves suspending atoms in frictionless magnetic containers, which are then subjected to a series of steps involving magnetic fields, lasers, and evaporative cooling.


The BEC phenomenon was first predicted by physicists Satyendra Nath Bose and Albert Einstein in 1920s. In 1995, scientists for the first time produced BECs in a lab.  In last three decades, scientists have carried out hundreds of BEC experiments on Earth. CAL is the first such facility on ISS that will allow scientists to probe BECs on a daily basis.

“CAL is an extremely complicated instrument,” said Robert Shotwell, chief engineer of JPL’s astronomy and physics directorate.

Shotwell reveals that CAL is about the size of a small refrigerator and can be operated remotely from Earth.

According to NASA, CAL is currently in a commissioning phase. During this phase, the operations team will carry out multiple tests to understand how this facility operates in microgravity environment. After completion of the commissioning phase, the science phase will start (most probably in September) and will last for three years.

CAL has been designed and built at JPL. The experimental facility is sponsored by the ISS Program at NASA’s Johnson Space Center in Houston, and the Space Life and Physical Sciences Research and Applications Division of NASA’s Human Exploration and Operations Mission Directorate at NASA Headquarters in Washington.


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