Hardiness of tardigrades tested to simulate transmission of life through space

What does this research tell us of life-travel in space?

Research from the School of Physical Sciences has investigated the hardiness of the microscopic invertebrates known as tardigrades by firing specimens at high speed to simulate extreme conditions similar to those in our solar system.

Tardigrades are known for being profoundly durable in the harshest of conditions. Kent’s researchers examined the extent of their hardiness to understand the potential for survival in high-speed travel to severe space environments such as the Moon and ice planets.

Using a specially made two-stage gas gun, with the propulsion materials of gunpowder followed by pressurised hydrogen, researchers shot groups of two to three tardigrades (freshwater Hypsibius dujardini) aimed towards sand targets at speeds of hundreds of metres per second.

This not only demonstrated the ability of tardigrades to survive extreme impacts, but also great speeds similar to those travelled by celestial bodies such as meteorites.

Prior to the study, the tardigrades were frozen in a “tun” state, which has previously enabled them to survive such extreme conditions of cold and dryness.

The study concluded that tardigrades could survive impact speeds up to 0.9km per second. The higher-speed shots were lethal, in which the tardigrades were physically destroyed as speed increased, demonstrating the limits of survival at great velocity and impact.

It is known that matter from other planets and satellites has been found on Earth and the Moon, which is thought to have originated from the force of impact generated from massive collisions akin to the meteorite that killed the dinosaurs. This is known as ‘impact ejecta’.

This research provides a new basis for understanding this possibility of tardigrade-like organisms being able to be transmitted between planets via impact ejecta.

Alejandra Traspas, first author on the paper, conducted the research for her Master’s thesis at Kent. She said: ‘This research shows that there are limits to the survivability of tardigrades, which is particularly relevant to the understanding of transmitting organisms across the solar system. Typical impact ejecta speed will not permit viable transfer of tardigrade-like organisms, but if just a fraction of such an organism had a lower impact speed, survival may be possible.’

Mark Burchell, Professor of Space Science and part of the Centre for Astrophysics and Planetary Science at Kent and co-author of the research said: ‘This unique research goes a long way to answering some basic questions about transmission of life in space. Alejandra worked hard, partly during the unusual COVID lockdown period, and her Master’s thesis has produced this excellent piece of work of international interest’.

The paper, ‘Tardigrade Survival Limits in High-Speed Impacts—Implications for Panspermia and Collection of Samples from Plumes Emitted by Ice Worlds’ (University of Kent: Alejandra Traspas, Professor Mark Burchell) is published online by Astrobiology and is available via Early Access

DOI: 10.1089/ast.2020.2405

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