The poster child of extremophiles, the tardigrade, is well known for its abilities to survive the heights of the Himalayas and the vacuum of space. Also, it has the fitting nickname of the “water bear”, and the similarities to a bear might extend further past just looks. Tardigrades have been completely reanimated after being dried for 8 years, and, though never replicated, a scientist claimed that there was slight reanimation of tardigrades dried in moss for 120 years. This species has been the subject of much experimentation, naturally, but many questions remain as to just how they are able to survive these insane situations. One interesting development that has been made is in regards to how they are able to survive the radiation that exists in space. It has been found that they protect the dismembering of their DNA by having a cloud of occluding proteins that block the radiation. The abilities of this species has been recognized for over 300 years, and there is evidence of their presence in the Cambrian period over 500 million years ago. The main question I still have after learning all this is why, specifically in regards to the protein protection of DNA. What conditions on Earth were so similarly dire to that of the vacuum of space, that this species was able to develop defense mechanisms that protect them in both places? The water bear is truly an astonishing organism, and could unlock answers to many questions we still have.
Will in the Solar System 
Hey Will! Thanks for the post, tardigrades are fascinating and I enjoyed your discussion of them. It left me wondering however: what about the occluding proteins mentioned in your post is exceptional that allows them to block space radiation? What grants this ability?
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That’s a great question, I tried to see if I could figure this out, but was only able to find that the proteins are highly disordered compared to normal proteins. My best guess is that the proteins act as a barrier that absorb the energy of the radiation so it can’t break down the DNA, and instead breaks down these proteins. Hopefully we’ll find out sooner rather than later though!
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The resilience of this species always continues to fascinate me! If something that shares our basic genetic building blocks can evolve to adapt to such conditions, I wonder what a possibly non-DNA-based life form could take shape as.
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