Tardigrades! – November 20, 2019
Did you know that there are thousands of tardigrades stranded on our Moon?
First off, what is a tardigrade? Also known as “water bears,” they are near-microscopic (0.15 to 1.2 millimeters long) animals with 8 legs and long plump bodies. We’re interested in them because these animals are nearly indestructible! Here’s a link to a paper that found some species of tardigrades could survive 10 days at low Earth orbit, while exposed to the vacuum of space: https://www.cell.com/current-biology/…/S0960-9822(08)00805-1
Tardigrades can withstand environments as cold as -328 degrees F (-200 C) and highs of more than 300 degrees F (148.9 C). This begs the question, how do they do it? In many conditions, they survive by going into an almost death-like state called cryptobiosis. They curl into a dehydrated ball, called a tun, by retracting their head and legs. When reintroduced to water, the tardigrade can come back to life in just a few hours. Their organs are protected by a gel called trehalose (this is a sugar made up of two molecules of glucose). They also seem to make a large amount of antioxidants, which may be another way to protect vital organs. Finally, water bears produce a protein that protects their DNA from radiation damage.
Now, why on Earth are they on the Moon? When the Israeli lunar lander, Beresheet, attempted a landing on April 11, 2019, it unfortunately crashed. So, assuming they survived the crash, there are potentially thousands of dehydrated tardigrades on the Moon’s surface just waiting for some liquid water to bring them back to life!