Banner by Brian Kim

One Microscopic Step For Mankind

By Miranda Scarborough

We have all heard the saying “when pigs fly,” a million times, but what about “when bears become astronauts?” Last year, an Israeli rocket carrying microscopic tardigrades, colloquially known as water-bears, crash landed on the moon. Tardigrades are loved by biologists for their pudgy, bear-like appearances. They are also amongst the most resilient microorganisms on Earth, capable of surviving extreme environments such as volcanoes and underwater sea vents. Scientists aimed to further explore this resilience by studying the effects of space on these water-bears.

The Israeli rocket was part of a space race sponsored by Google with a prize of twenty million dollars. Google was aiming to create low-cost, private missions to land successfully on the moon. The contest was unsuccessful as all participants failed to land their rockets on the lunar surface. However, the Israeli Beresheet mission was awarded one million dollars after becoming the first to enter the moon’s orbit before crashing onto the surface due to a malfunction with the ship’s communication system. The crash spilled the rocket’s contents onto the moon’s surface and left microbiologists wondering what happened to the millions of tardigrades on board.

Microbiologists focus their research on organisms too small to be seen by the human eye. “It is a whole field of biology where you are thinking in all of these different ways to understand life at the microscopic level,” explains Dr. Erica McGreevy, a professor in the Biology Department at The University of Pittsburgh. “A major theme in studying microbiology is extreme environments. Organisms living in extreme environments can teach us about cell biology and physiology. The interesting thing about tardigrades is that they are able to be dormant for years without food or water and can be perfectly fine.”

Tardigrades, first discovered in 1773 by the German zoologist Johann August Ephraim Goeze, are found all over the Earth’s surface and are able to withstand temperatures as low as -200 degrees Celsius and as high as 148.9 degrees Celsius by dehydrating their bodies and entering a state called tun. Their tun state is akin to hibernation where their metabolism drops to zero. Today, with over 1,300 known species, they are used as model organisms in scientific experiments. Model organisms are ideal for scientific study due to their short lifespans, fast reproduction cycles, and the fact that they are relatively cheap to reproduce in a laboratory setting. Other popular model organisms include E. coli, bread mold, yeast, and zebrafish.

“Model organisms are incredibly important for studying biology. They allow us to set up a system where we can perform controlled experiments to test hypotheses about the world around us,” Dr. McGreevy continues. “You can’t study humans, so you want to find something similar to the process you are studying. For breakthroughs in cell division, yeast was discovered to divide in a similar fashion to human cells. Yeast gave us a model for human processes.”

The International Space Station (ISS) has been conducting research to explore the effects of space on model microorganisms for over 50 years. Research aboard the ISS studies the effects of two primary stressors on microbial life: solar radiation from the sun and microgravity caused by the vacuum of space. The first experiments began with the fungus Penicillium roqueforti from which we have created synthetic antibiotics such as penicillin. Scientists are interested in fungi in particular for research into their antibiotic properties and because they can be single celled or multicellular, which can reflect processes in bacteria or human cells. These experiments exposed fungi to spaceflight conditions, resulting in low survivability caused by radiation poisoning. The ISS later found that aluminum foil protects the spores of the fungi from doses of radiation in space by up to 3,000 times, allowing for 100% survivability. NASA and other space agencies now wrap all spacecraft and satellites in aluminum foil. Further research into the effects of space on multicellular organisms will help advance space travel and survivability for humans.

The Isreali rocket and its pudgy passengers presented scientists with a novel opportunity in the field of micro-astrobiology, but their hopes came to a crashing halt once the rocket spilled its contents onto the surface of the moon. Scientists then began to hypothesize if the tardigrades had survived their journey after they were placed in their tun state. Even though the tardigrades were in survival mode, there is little hope of a space-bear colony forming as the moon lacks the fundamental resources needed for life, mainly water. Scientists hoped that recovery was possible to further study if tardigrades could survive not only the vacuum of space, but radiation and lack of water for an extended period. If they could be rescued, rehydration and reanimation is possible.

Alejandra Traspas, a Ph.D. student at Queen Mary University of London, tested the survivability of our chubby friends’ crash landing by placing them into nylon bullets and firing them at speeds of 900 meters per second, leading to impacts up to 1.14 gigapascals. The tardigrades survived momentarily, but the impact damaged their internal structure. The lunar crash was estimated to have a force of 3 gigapascals, high above the survivable range of tardigrades. Hope for the rescue of the micro-bears—if only to study the effects of space and the crash—may have been crushed, but the evolving science behind the effects of space on microorganisms will continue.

The impact tests conducted by Traspas and her team may tell us more about how much force microorganisms can withstand, which can help scientists plan future expeditions to planets such as Mars. Testing microorganisms on Mars would help us determine the survivability of humans in the future. With these results, scientists would be able to better plan for extended travel in microgravity and adapt to the extreme radiation of space. Microbiology, astrobiology, physics, and now these impact tests may also hold the key to our past. Did life come from space? Was there a microorganism that could survive a meteor crashing to the Earth’s surface? Did that microorganism later develop into the microorganisms we know today? By testing earthly microorganisms in space, scientists can determine what life may look like in this galaxy and beyond.