Almost ten years before Sally Ride the first American woman in spacetwo modest little ones mummichogen became the first fish in space. In 1973, these little fish shot into space aboard one of the famous ones Apollo crew capsules as part of Skylab 3a three-month mission to NASA's early space station. For three weeks the fish tumbled around in the plastic-bag tank, completely disoriented by the lack of Earth's familiar gravity, until they finally regained their footing and were able to swim straight again.
These two mummichogs (plus another 48 that hatched from eggs aboard Skylab 3) were the first records in a long history of circling fish that have taught us a lot about how microgravity affects living things. Nearly 50 years later, Four zebrafish are now swimming aboard China's Tiangong space stationadapting to their strange environment in space – only now instead of living in a simple plastic bag, they live in a unique, self-sustaining ecosystem.
Four zebrafish swim in a tank aboard China's Tiangong space station. Credit: CNSA
Last week, Chinese astronauts (aka taikonauts) reported that the zebrafish, which was launched on April 25 along with some algae, is alive and well. This experiment is designed to see how microgravity will affect the life cycle of the fish and other natural cycles within their closed environment.
The effects of microgravity extend far beyond the weightlessness that humans experience in space. It leads to changes in almost all our bodily functions, from our bones to our hearts and our brains. To spend more time in space, such as on long missions to Mars, it is absolutely crucial that we understand these biological changes. However, humans are complicated and difficult to study, especially if you want to track changes from birth. That's where fish comes in.
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Zebrafish are a good example of a model organism, a species that has been extensively studied to help us understand some aspect of biology, often in ways that we cannot experiment on humans. Although zebrafish may seem very different from us, they actually have “many of the same major organs and their bodies generally work in the same way as ours, in many cases even down to the cellular level,” explains University of Applied Sciences developmental biologist Washington out. Aaron van Loon.
Zebrafish are also small, easy to care for, and actually completely transparent before hatching, making it possible for scientists to look inside them as they develop. It's also a lot easier for scientists to manipulate the genetics of these fish, allowing “a lot of important experiments that simply wouldn't be possible or ethical to do with humans,” Van Loon adds.
Here on Earth, zebrafish have already been used in countless medical experiments that will ultimately help humans, “from the inner workings of embryonic development to the function of immune cells during infection, and even insights into genetic diseases,” says van Loon. And they did that in space too already studied in the 1970sas they flew aboard the Russian Salyut 5 space station mission. More recently, in 2015, zebrafish aboard the International Space Station were used to investigate how muscles atrophy under microgravity.
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Many other fish, including the very first mummichogs, have also flown to space.
For example, the slightly larger (and admittedly uglier) oyster toad fish flew along NASA's Space Shuttle Columbia in the late 1990s so scientists could see how their brains adapted to Earth's gravity upon return. In fact, there was a whole menagerie of creatures on board that flight Columbia's STS-90including “68,000 freshwater swordtail fish, 5,000 freshwater snails, 2,000 goldfish, 1,000 crickets and 125 saltwater toadfish” according to a NASA annual report. About the International Space Station in the 2010s, a school of Medaka fish was used to monitor bone density loss and see how the higher radiation in space breaks down their DNA.
NASA archives also contain “several records of research done with jellyfish, goldfish, guppies, salamanders and salamanders,” says NASA archivist Julie Pramislike those on board Space Shuttle mission STS-65 in 1994 to investigate the animals' balance, spatial awareness and mating behavior.
Like human astronauts, fish are carefully chosen to go into space, and always with a specific mission in mind. From mummichogs to zebrafish and beyond, our little aquatic friends show us the way to brave the final frontier safely, with full knowledge of how to keep ourselves safe and healthy in microgravity.
