CADMOS during PK-4 operations

CADMOS control centre during the 12th campaign of the Plasma Kristall-4 experiment. CADMOS Human Spaceflight Department of France's space agency (CNES) and one of Europe's User Support Operations Centres that control and monitor experiments and hardware on the International Space Station.

As Europe celebrates 20 years of ESA astronauts on the International Space Station, a Russian-European experiment has been running quietly in the weightless research centre for just as long: the Plasma Kristall (PK) suite of investigations into fundamental science.

Plasma Kristall takes a plasma and injects fine dust particles in weightlessness, turning the dust into highly charged particles that interact with each other, bouncing off each other as their charge causes the particles to attract or repel. Under the right conditions, the dust particles can arrange themselves over time to form organised structures, or plasma crystals.

These interactions and forming of three-dimensional structures resemble the workings of our world on the atomic scale, a world so small that we cannot see move even with an electron microscope. Add a laser to the mix and the dust particles can be seen and recorded for observation by scientists on Earth for a sneak peak of the world beyond our eyes.

These surrogate atoms are a way for researchers to simulate how materials form on an atomic scale, and to test and visualise theories. The experiment cannot be run on Earth because gravity only makes sagging, flattened recreations possible; if you want to see how a crystal is constituted you need to remove the force pulling downwards – gravity.

On 3 March 2001, “PK-3 Plus” was turned on in the Zvezda module, the first physical experiment to run on the Space Station. Led by the German aerospace centre DLR and Russian space agency Roscosmos the experiment was a success and later followed up by a fourth version, installed in 2014 in ESA’s Columbus laboratory, this time as an ESA-Roscosmos collaboration.