Tardigrades: An Intro to Astrobiology
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What is Astrobiology?
Astrobiology is a branch of science that deals with life outside of our planet. It deals with topics such as the origins, evolution, and future of life in the univese. Astrobiologists also have many important jobs, such as the evaluation of planets to see if they are habitable for life, the study of potential life in outer space, and more.
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What are Tardigrades?
Tardigrades have had many names over the years, such as water bears or moss piglets. They grow to be about 1.5 millimeters long, which makes them hard to study. The first known record of them is from 1773, when a german zoologist discovered them. They were not characterized until years later. However, astrobiologists, especially in the 2000s, began to study tardigrades further and extensive research has been carried out on these creatures. The biggest discovery to do with these creatures was that they were able to survive in the cold depths of outer space for weeks before dying.
What makes Tardigrades so resilient?
Tardigrades are able to withstand lethal amounts of radiation for extended periods of time, with no effect to their DNA or body. They can survive without oxygen, water, and food for incredibly long periods of time, as well. This is because tardigrades can go into something called "tun" form, a state where they become pretty much indestructible.
When in extreme conditions, tardigrades instinctively go into tun state. First, the tardigrades go into cryptobiosis, a state where metabolic activity is reduced to almost 0. This means that tardigrades require little to no energy to survive while in this state. As tuns, tardigrades also produce glycerol, an anti-freezing agent, and trehalose, a sugar with preservative properties. This trehalose crystallizes, forming a crystallized armor around the tardigrade. Some species of tardigrades are more adapted to certain conditions than others. For example, some species have evolved to produce heat-shock proteins in very high temperatures, which prevent their proteins from denaturing.
Tardigrades in Space Because of these incredible properties, tardigrades can live amazingly well in impossible conditions. A study showed that tardigrades could live for up to 10 days in the vacuum of space, exposed to raw radiation. After returning to Earth, 1/3 of them died, but they were still able to reproduce before dying, even after living in space.
Tardigrades are able to survive on the moon and even on Mars. This discovery is increedibly profound, especially for astrobiologists all over the globe.
What this Means
Tardigrades provide valuable insight into the future of life in space. If humans were ever to colonize another planet or moon, studying tardigrades and the processes they implement to stay alive could be very helpful.
Until then, we can just marvel at the fact that we have finally found an organism able to survive on not only other planets, but the cold vacuum of space as well.
Bibliography:
https://www.vox.com/science-and-health/2017/7/15/15972854/tardigrades-end-of-the-world
https://en.wikipedia.org/wiki/Tardigrade
https://www.nationalgeographic.com/animals/invertebrates/t/tardigrades-water-bears/
https://www.popularmechanics.com/space/a11137/tardigrades-water-bears/