Beyond Earth’s protective atmosphere and magnetosphere, there is the threat of long-term exposure to solar and cosmic radiation. However, while radiation exposure can be mitigated with appropriate shielding, there are few strategies available to address the other major risk: long-term exposure to microgravity. On the International Space Station (ISS), astronauts rely on a rigorous regimen of exercise and resistance training to mitigate the physiological effects. These include muscle atrophy, loss of bone density, organ function, vision and effects on cardiovascular health, gene expression and the central nervous system. But as a recent NASA study revealed, long-duration missions to Mars and other deep space locations will need to be equipped with artificial gravity. This study examined the effects of microgravity on fruit flies on the ISS and showed that artificial gravity provides partial protection against these changes.
Artificial gravity to the rescue
The study was conducted by researchers from institutions including the Space Biosciences Division at NASA Ames Research Center, the COSMIAC Research Center at the University of New Mexico, and the University Space Research Association (USRA). Their findings were published Sept. 6 in the journal Cell Reports. In this study, the team conducted a month-long survey using the Multipurpose Variable Gravity Platform (MVP), a commercial centrifuge-based testbed that arrived at the ISS in 2019. This experiment has separate compartments and provides the flies with fresh food as they live and reproduce. This allowed the team to house different generations of flies separately and under different levels of gravity, with one exposed to microgravity (like their astronaut counterparts on the ISS) and another to Earth-like gravity (9.8 m/s2 or 1 g ). . The research team then monitored their behavior using cameras built into the hardware. At different points, some of the flies were frozen and returned to Earth for analysis to see how different levels of gravity affected their gene expression and its impact on their nervous systems. As Janani Iyer, USRA program scientist at NASA Ames Research Center, explained in a recent NASA press release: “Microgravity poses risks to the central nervous system, suggesting that countermeasures may be needed for long-duration space travel. As we return to the Moon and Mars, reducing the harmful effects of microgravity will be key to keeping future explorers safe. This study is a step in the right direction for investigating the protective effects of artificial gravity in space and understanding adaptation to Earth conditions after return from space.”
Why fruit flies?
Fruit flies are an ideal organism for this type of research because of their similarities to humans in terms of cellular and molecular processes and their short lifespans and reproductive cycles (two months and two weeks, respectively). Nearly 75 percent of the genes that cause disease in humans are shared by fruit flies, meaning that changes in their gene expression would resemble potential changes in humans. In addition, the three weeks spent in space is equivalent to about thirty years of a human life, allowing scientists to observe decades worth of biological information in a short period of time. Once the experiment was complete, the flies were returned to Earth in a SpaceX Dragon capsule and flown to NASA Ames for further analysis. For two days, the scientists conducted behavioral and biochemical tests on these “fliers” that consisted of monitoring their movements in their environment, cellular changes in their brains, how changes in gene expression affected their nervous systems, and more . They then combined their observations with footage from the MVP’s cameras and compared the results to a control group that had remained on Earth. Among the behaviors studied, the scientists looked at how the flies climbed the walls of their container – a natural response that fruit flies have when knocked down. They found that flies in microgravity were more active than those exposed to artificial gravity, but had difficulty during the climbing test on their return to Earth. Post-flight analysis also revealed that flies exposed to microgravity showed neurological changes, while those exposed to artificial gravity aged differently and faced less severe acclimation challenges upon return.
Planning for future flights
These results suggest that spaceflight induces stress that leads to negative behavioral and neurological effects, as well as changes in gene expression in the fly brain. They also suggest that artificial gravity can mitigate these effects during spaceflight, although there are still long-term challenges to re-climating on Earth. Although these results cannot accurately predict human health effects, they offer an approximation and a good starting point for future research. As Dr. Siddhita Mhatre, senior scientist at KBR Wyle in Ames and author of the paper, summarized: “With upcoming long-duration deep space missions where astronauts will be exposed to different levels of gravity, it is imperative to understand the effects of altered gravity on neurological function. If we can use artificial gravity to delay space-related deficits, we may be able to extend future mission timelines. And flies in space, along with astronauts, will help advance our efforts to keep astronauts healthy.” NASA is currently investigating centrifuges and artificial gravity for space stations and deep space missions. Examples include NASA’s “Nonatmospheric Universal Transport for Long Range Exploration of the United States” (NAUTILUS-X) concept study, a rotating torus-shaped module that would provide artificial gravity. NASA further proposed that a demonstration unit (the ISS Centrifuge Demo) could become a sleep unit for the ISS crew. This unit would have a diameter of 9.1 m (30 ft), an inner diameter of 0.76 m (2.5 ft), and provide between 0.08 and 0.51 g of partial gravity. It was also intended to provide a proof of concept for a larger torus that could be incorporated into a potential spacecraft known as the Multi-Mission Space Exploration Vehicle (MMSEV). This idea and similar research studies highlight the importance of astronaut health and safety measures for long-duration space flights. As NASA and other space agencies send astronauts to the Moon (to stay this time) and pursue manned missions to Mars and beyond, artificial gravity may become a regular feature of spacecraft, space stations, and even surface habitats . This article was originally published on Universe Today by Matt Williams. Read the original article here. LEARN SOMETHING NEW EVERY DAY.
