The Coolest Place in the Universe

The Coolest Place in the Universe

The Cold Atom Lab of NASA can reach up to -459o F.

The Cold Atom Laboratory (CAL) is a fundament Physics user facility that is operational on the International Space Station (ISS). This instrument is used to produce clouds of ultra-cooled atoms called Bose-Einstein Condensates (BEC). Their temperature can drop as much as only a fraction of a degree above Absolute Zero (-273o C). The term ‘Absolute Zero’ refers to the coldest temperature that can be achieved by any known form of matter. These atoms provide researchers with an opportunity to study quantum characteristics in a better way as they can demonstrate this behavior at larger scales.

CAL was originally expected to launch in June 2017 but was delayed due to some reasons. It was ultimately sent towards the ISS on 21st May 2018 from the Wallops Flight Facility of NASA. The initial mission of this laboratory has a duration of 12 months which can be extended to a period of 6 years. A total of 5 experiments is to be performed on CAL during the first year of its operation (3 of them are already in progress). The scientists at the Jet Propulsion Laboratory (JPL) of NASA believe that CAL could prove instrumental in developing extremely sensitive quantum detectors, which will help researchers to monitor the gravity of Earth and other planetary bodies.

The gravitational pull of Earth drags down a BEC due to which it can only be observed for a fraction of a second. On the other hand, the microgravity environment of ISS increases the observational time of BECs. According to an estimate, ultra-cold atoms can be 200,000 times slower than room-temperature atoms. Consequently, these atoms can be viewed for as much as 10 seconds. The ultimate objective of CAL is to understand the mechanisms of nature at the most fundamental level. It offers 6.5 hours of experimentation every day without any assistance from an astronaut. Rob Thompson, the Mission Scientist for CAL who works as a Cold Atom Physicist at JPL, talked about the impact of these experiments in the following words:

With CAL we’re starting to get a really thorough understanding of how the atoms behave in microgravity, how to manipulate them, how the system is different than the ones we use on Earth. This is all knowledge that is going to build a foundation for what I hope is a long future of cold atom science in space.”

The process of cooling begins with the use of a laser which slows the atoms down. After that, radio waves are used to remove the warmest atoms from the group, which decreases the average temperature even more. Lastly, the atoms are allowed to expand as they are released from the magnetic field. This sudden reduction in pressure causes another drop in the temperature of the cloud. The fact that this cloud gets more time to expand (in space) results in even lower temperatures than what we can manage on our planet.

The development of a cold atom laboratory for space is easier said than done. The first and foremost challenge was about the size of the CAL. Generally, ultra-cold atom facilities on Earth occupy an entire room but that was simply not possible on ISS. For this reason, researchers reduced the size of the laboratory and transported it to the station in 2 pieces (a metal box about the size of a mini-fridge and another one of the size of a carry-on suitcase).

Secondly, CAL was built as a fully enclosed facility because it was to be operated remotely from Earth. Contrary to that, most of the apparatus is left exposed, in case of an Earthly laboratory. Similarly, CAL needed to bear the extreme forces experienced during the flight to the ISS. Robert Shotwell, the Project Manager of CAL who also serves as the Chief Engineer for Astronomy, Physics, and Space Technology Directorate at JPL, referred to the difficulties they faced during the designing of this lab by saying,

Several parts of the system required redesigning, and some parts broke in ways we’d never seen before. The facility had to be completely torn apart and reassembled three times.”

CAL is a unique tool which could help humanity to unveil the mysteries of nature and scientists hope that it will do exactly that during its operation.

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