A recent study tested how well the fungi species Cladosporium sphaerospermum blocked cosmic radiation aboard the International Space Station.
- Radiation is one of the biggest threats to astronauts' safety during long-term missions.
- C. sphaerospermum is known to thrive in high-radiation environments through a process called radiosynthesis.
- The results of the study suggest that a thin layer of the fungus could serve as an effective shield against cosmic radiation for astronauts.
When astronauts return to the moon or travel to Mars, how will they shield themselves against high levels of cosmic radiation? A recent experiment aboard the International Space Station suggests a surprising solution: a radiation-eating fungus, which could be used as a self-replicating shield against gamma radiation in space.
The fungus is called Cladosporium sphaerospermum, an extremophile species that thrives in high-radiation areas like the Chernobyl Nuclear Power Plant. For C. sphaerospermum, radiation isn't a threat — it's food. That's because the fungus is able to convert gamma radiation into chemical energy through a process called radiosynthesis. (Think of it like photosynthesis, but swap out sunlight for radiation.)
The radiotrophic fungus performs radiosynthesis by using melanin — the same pigment that gives color to our skin, hair and eyes — to convert X- and gamma rays into chemical energy. Scientists don't fully understand this process yet. But the study notes that it's "believed that large amounts of melanin in the cell walls of these fungi mediate electron-transfer and thus allow for a net energy gain."
Shunk et al.
Additionally, the fungus is self-replicating, meaning astronauts would potentially be able to "grow" new radiation shielding on deep-space missions, instead of having to rely on a costly and complicated interplanetary supply chain.
Still, the researchers weren't sure whether C. sphaerospermum would survive on the space station. Nils J.H. Averesch, a co-author of the study published on the preprint server bioRxiv, told SYFY WIRE:
"While on Earth, most sources of radiation are gamma- and/or X-rays; radiation in space and on Mars (also known as GCR or galactic cosmic radiation) is of a completely different kind and involves highly energetic particles, mostly protons. This radiation is even more destructive than X- and gamma-rays, so not even survival of the fungus on the ISS was a given."
To test the "radio-resistance" of C. sphaerospermum in space, petri dishes containing a .06-inch layer of the fungus were exposed to cosmic radiation aboard the ISS. Dishes containing no fungus were exposed, too. The results showed that the fungus cut radiation levels by about 2 percent.
Extrapolating these results, the researchers estimated that a roughly 8-inch layer of C. sphaerospermum "could largely negate the annual dose-equivalent of the radiation environment on the surface of Mars." That would be a significant benefit to astronauts. After all, an astronaut who is one year into a Mars mission would have been exposed to roughly 66 times more radiation than the average person on Earth.
International Space Station
To be sure, the researchers said more research is needed, and that C. sphaerospermum would likely be used in combination with other radiation-shielding technology aboard spacecraft. But the findings highlight how relatively simple biotechnologies may offer outsized benefits on upcoming space missions.
"Often nature has already developed blindly obvious yet surprisingly effective solutions to engineering and design problems faced as humankind evolves – C. sphaerospermum and melanin could thus prove to be invaluable in providing adequate protection of explorers on future missions to the Moon, Mars and beyond," the researchers wrote.
The changes in brain structure aren't the only bodily changes caused by zero gravity.
- A new study finds that long term weightlessness can cause changes in brain structure, with an increase in white matter lasting a year after returning to Earth.
- The researchers believe it to be caused by an increase in fluid pressure on the brain.
- Potential solutions include creating artificial gravity.
I think my desire to go to space just declined a bit.
Eleven astronauts, ten men and one woman, were given MRI tests before they went for extended stays on the International Space Station. They were then given follow up scans the day after their return and at several points during the year after.
Not only did the researchers find that long-term exposure to zero-gravity increased the amount of cerebrospinal fluid in the brain, but that the amount of white matter in the brain increased as well. Several of the astronauts also had deformed pituitary glands, the gland that tells all the others what to do, as a result of the increased pressure on it.
These changes lasted for some time, just as other astronauts' vision problems have continued for years after returning to Earth. This suggests that some of the effects, particularly the increased amount of fluid, might be permanent. The higher amount of fluid also flowed through the cerebral aqueduct at an increased velocity.
The researchers hypothesized that these changes, like the previously mentioned vision problems, were caused by increased pressure in the head itself caused by an increased amount of fluid present, including blood. While Earth's gravity causes fluid to flow out of the head and pool towards the lower part of the body, weightlessness removes this tendency, and fluids begin to shift their locations. This effect has been known for a while and is also why many astronauts look like they skipped leg day or have puffy faces when they take pictures in space.
What does this mean? Are astronauts in danger?
It is too early to say what these changes to the brain mean. While some of the changes are associated with other symptoms, none of those have been seen in any of the astronauts yet.
However, ideas for how to reduce the build-up of fluids in the head are already being put forward. One suggestion is to create artificial gravity through the rotation of a centrifuge, like the spaceship in "2001: A Space Odyssey" has, or to create negative pressure around the lower parts of the body to draw fluid to them. Either of these mechanisms would cause less fluid to remain in the head.
The human body evolved to function decently in an environment where gravity is always a factor. As humanity ventures out towards the stars, the problem of how to keep that body working in such an alien environment will be a substantial obstacle. However, if we can solve the problem of getting into space in the first place, the issue of keeping fluid out of our heads seems comparatively simple.
Here's a look at the space agency's astronaut candidate requirements.
- NASA has begun accepting applications for its next class of astronauts and plans to have its final selections for candidates in mid-2021.
- U.S. citizens have until March 31, 2020 to apply.
- Basic qualifications include either holding a master's degree in a STEM field, having completed a doctor of medicine or doctor of osteopathic medicine degree, or have two years of work toward a STEM Ph.D. program.
They said to shoot for the moon, and the time to apply has come. On March 2, 2020, NASA began accepting applications for its next class of astronauts for trips to the moon and the International Space Station.
U.S. citizens can apply here until the deadline on March 31, 2020 at 11:59 p.m. EDT. The salary ranges from $104,898 to $161,141 per year, and (for obvious reasons) extensive travel is required. Though the hiring process takes a while, NASA plans to have its final selections for astronaut candidates in mid-2021. The agency hasn't given word yet on the number of people who will be chosen, but you can bet that the competition will be cutthroat. During the last selection in 2017, the agency only picked 12 out of a total of 18,300 applicants. Of those selected, 11 graduated and became eligible for spaceflight earlier this year.
Photo Credit: Wikimedia
The qualifications are extensive to say the least, and those selected typically exceed the basics. NASA asks that applicants meet at least one of the following education requirements to be considered for the position:
- Hold a master's degree in a STEM field, which could include engineering, computer science, biological science, physical science, or mathematics.
- Have a completed doctor of medicine or doctor of osteopathic medicine degree.
- Have two years of work toward a STEM Ph.D. program.
- By June 2021, have completed a nationally or internationally recognized Test Pilot School program. Additionally, if Test Pilot School is the only advanced technical degree you have, NASA requires that you also have a bachelor's degree in a STEM field.
In addition to the minimum educational qualifications, NASA has specialized experience requirements that must be met in order to be considered. This includes having at least 1,000 hours of experience as a pilot-in-command of a high-performance jet aircraft, or having two years of "progressively responsible" work in your specialized STEM field.
Alright, so you have the advanced STEM degree, you've mastered command-piloting jet aircraft, and you've spent years working in the field of astrophysics. But, are you fit enough? Astronaut candidates will have to undergo a rigorous fitness test, a swimming test, and a medical and psychiatric examination. NASA also typically interviews new recruits about their experience working in treacherous or psychologically taxing environments. For example, SPACE notes that Christina Koch, who recently returned from her year in space, did research for months in Antarctica previous to her career with NASA.
Once selected, the candidates have to undergo grueling training for long-duration missions aboard the International Space Station, which can last 12 months or longer. Basic training requires extensive travel, including long periods of time away in other countries. Because of the arduous astronaut duties, selected candidates will be exposed to physically taxing activities in hazardous environments during their training. This includes being underwater for extended periods of time and being in confined spaces.
It takes around two to three years before the candidates are eligible for missions. Furthermore, International Space Station missions typically require at least 18 months of crew training before liftoff.
"Becoming an astronaut is no easy task, because being an astronaut is no easy task," Steve Koerner, NASA's director of flight operations and chair of the astronaut selection board at NASA's Johnson Space Center in Houston, said in a news release. "Those who apply will likely be competing against thousands who have dreamed of, and worked toward, going to space for as long as they can remember. But somewhere among those applicants are our next astronauts, and we look forward to meeting you."
Think you've got what it takes? Visit NASA's application page here and find out more about applying to become an astronaut.
When you have the opportunity to take gravity away from the human body, the results are pretty fasninating.
Space may be the final frontier, but it's really interesting what it does to our bodies. Scientists are studying the effects of space on the body, says former astronaut and current physician Scott Parazynski. The results are pretty fascinating, especially when you have the opportunity to take gravity out of the equation. Scott Parazynski is the author of The Sky Below: A True Story of Summits, Space, and Speed.