https://news.uci.edu/2016/10/10/mar...entia-risk-from-galactic-cosmic-ray-exposure/
Mars-bound astronauts face chronic dementia risk from galactic cosmic ray exposure
UCI study raises questions about long-term brain health after extended spaceflights
on October 10, 2016
Irvine, Calif., Oct. 10, 2016 — Will astronauts traveling to Mars remember much of it? That’s the question concerning University of California, Irvine scientists probing a phenomenon called “space brain.”
UCI’s Charles Limoli and colleagues found that exposure to highly energetic charged particles – much like those found in the galactic cosmic rays that will bombard astronauts during extended spaceflights – causes significant long-term brain damage in test rodents, resulting in cognitive impairments and dementia.
Their study appears today in Nature’s Scientific Reports. It follows one last year showing somewhat shorter-term brain effects of galactic cosmic rays. The current findings, Limoli said, raise much greater alarm. (Link to study: www.nature.com/articles/srep34774)
“This is not positive news for astronauts deployed on a two-to-three-year round trip to Mars,” said the professor of radiation oncology in UCI’s School of Medicine. “The space environment poses unique hazards to astronauts. Exposure to these particles can lead to a range of potential central nervous system complications that can occur during and persist long after actual space travel – such as various performance decrements, memory deficits, anxiety, depression and impaired decision-making. Many of these adverse consequences to cognition may continue and progress throughout life.”
For the study, rodents were subjected to charged particle irradiation (fully ionized oxygen and titanium) at the NASA Space Radiation Laboratory at New York’s Brookhaven National Laboratory and then sent to Limoli’s UCI lab.
Six months after exposure, the researchers still found significant levels of brain inflammation and damage to neurons. Imaging revealed that the brain’s neural network was impaired through the reduction of dendrites and spines on these neurons, which disrupts the transmission of signals among brain cells. These deficiencies were parallel to poor performance on behavioral tasks designed to test learning and memory.
In addition, the Limoli team discovered that the radiation affected “fear extinction,” an active process in which the brain suppresses prior unpleasant and stressful associations, as when someone who nearly drowned learns to enjoy water again.
“Deficits in fear extinction could make you prone to anxiety,” Limoli said, “which could become problematic over the course of a three-year trip to and from Mars.”
Most notably, he said, these six-month results mirror the six-week post-irradiation findings of a 2015 study he conducted that appeared in the May issue of Science Advances.
Similar types of more severe cognitive dysfunction are common in brain cancer patients who have received high-dose, photon-based radiation treatments. In other research, Limoli examines the impact of chemotherapy and cranial irradiation on cognition.
While dementia-like deficits in astronauts would take months to manifest, he said, the time required for a mission to Mars is sufficient for such impairments to develop. People working for extended periods on the International Space Station, however, do not face the same level of bombardment with galactic cosmic rays because they are still within the Earth’s protective magnetosphere.
Limoli’s work is part of NASA’s Human Research Program. Investigating how space radiation affects astronauts and learning ways to mitigate those effects are critical to further human exploration of space, and NASA needs to consider these risks as it plans for missions to Mars and beyond.
Partial solutions are being explored, Limoli noted. Spacecraft could be designed to include areas of increased shielding, such as those used for rest and sleep. However, these highly energetic charged particles will traverse the ship nonetheless, he added, “and there is really no escaping them.”
Preventive treatments offer some hope. Limoli’s group is working on pharmacological strategies involving compounds that scavenge free radicals and protect neurotransmission.
Vipan Kumar Parihar, Barrett Allen, Chongshan Caressi, Katherine Tran, Esther Chu, Stephanie Kwok, Nicole Chmielewski, Janet Baulch, Erich Giedzinski and Munjal Acharya of UCI and Richard Britten of Eastern Virginia Medical School contributed to the study, which NASA supported through grants NNX13AK70G, NNX14AE73G, NNX13AD59G, NNX10AD59G, UARC NAS2-03144 and NNX15AI22G.
About the University of California, Irvine: Founded in 1965, UCI is the youngest member of the prestigious Association of American Universities. The campus has produced three Nobel laureates and is known for its academic achievement, premier research, innovation and anteater mascot. Led by Chancellor Howard Gillman, UCI has more than 30,000 students and offers 192 degree programs. It’s located in one of the world’s safest and most economically vibrant communities and is Orange County’s second-largest employer, contributing $5 billion annually to the local economy. For more on UCI, visit www.uci.edu.
Media access: Radio programs/stations may, for a fee, use an on-campus ISDN line to interview UCI faculty and experts, subject to availability and university approval. For more UCI news, visit news.uci.edu. Additional resources for journalists may be found at communications.uci.edu/for-journalists.
https://phys.org/news/2017-06-collateral-cosmic-rays-cancer-mars.html
Study: Collateral damage from cosmic rays increases cancer risks for Mars astronauts
June 5, 2017 by Kevin Dunegan
astronaut
Credit: CC0 Public Domain
The cancer risk for a human mission to Mars has effectively doubled following a UNLV study predicting a dramatic increase in the disease for astronauts traveling to the red planet or on long-term missions outside the protection of Earth's magnetic field.
The findings appeared in the May issue of Scientific Reports and were presented by UNLV scientist Francis Cucinotta, a leading scholar on radiation and space physics.
Previous studies have shown the health risks from galactic cosmic ray exposure to astronauts include cancer, central nervous system effects, cataracts, circulatory diseases and acute radiation syndromes. Cosmic rays, such as iron and titanium atoms, heavily damage the cells they traverse because of their very high rates of ionization.
Conventional risk models used by NASA and others assume DNA damage and mutation are the cause of radiation cancers. This is based on studies at high doses where all cells are traversed by heavy ions one or more times within much shorter-time periods than will occur during space missions.
"Exploring Mars will require missions of 900 days or longer and includes more than one year in deep space where exposures to all energies of galactic cosmic ray heavy ions are unavoidable," Cucinotta explained. "Current levels of radiation shielding would, at best, modestly decrease the exposure risks."
In these new findings, a non-targeted effect model—where cancer risk arises in bystander cells close to heavily damaged cells—is shown to lead to a two-fold or more increase in cancer risk compared to the conventional risk model for a Mars mission.
"Galactic cosmic ray exposure can devastate a cell's nucleus and cause mutations that can result in cancers," Cucinotta explained. "We learned the damaged cells send signals to the surrounding, unaffected cells and likely modify the tissues' microenvironments. Those signals seem to inspire the healthy cells to mutate, thereby causing additional tumors or cancers."
Cucinotta said the findings show a tremendous need for additional studies focused on cosmic ray exposures to tissues that dominate human cancer risks, and that these should begin prior to long-term space missions outside the Earth's geomagnetic sphere.
"Non-Targeted Effects Models Predict Significantly Higher Mars Mission Cancer Risk than Targeted Effects Models," appeared online May 12 in the journal Scientific Reports.
Explore further: Research uncovers potential health risks of travel to Mars
More information: Francis A. Cucinotta et al, Non-Targeted Effects Models Predict Significantly Higher Mars Mission Cancer Risk than Targeted Effects Models, Scientific Reports (2017). DOI: 10.1038/s41598-017-02087-3
https://www.wired.com/2014/04/radiation-risk-iss-mars/
Space Radiation Remains Major Hazard for Humans Going to Mars
Image:
NASA
During a conference this week in Washington D.C., enthusiasts are attempting to rouse support for a manned mission to Mars sometime in the next two decades. NASA is there, as are many key players in the spaceflight community. But there continue to be major obstacles to manned Mars missions.
A new study highlights one of the big problems with extended space travel: galactic cosmic ray radiation. According to the report, astronauts on the International Space Station would receive doses that exceed their lifetime limits after just 18 months for women and two years for men. A Mars mission crew would be spending at least this long in the harsh radiation of deep space.
Cosmic rays are a unique type of radiation in that they are difficult to shield against. And the new research points out that the cancer an astronaut could develop after too much cosmic ray radiation is bound to be very dangerous.
“The type of tumors that cosmic ray ions make are more aggressive than what we get from other radiation,” said Francis Cucinotta a radiation expert at the University of Nevada, Las Vegas, and author of the new report published Apr. 23 in PLoS One.
The news isn’t all doom and gloom. During certain periods in the solar cycle, galactic cosmic rays are reduced. Biologists are also working out exactly what kinds of medicine, from antioxidants to aspirin, could help deal with cosmic ray damage in the body. But more than anything, Cucinotta and other radiation experts recommend that NASA gather far more data about the health risks their astronauts are exposed to.
Approximately 41 percent of people in the U.S. will be diagnosed with some type of cancer at some point in their lives. Certain types of work—like cleaning up after nuclear disasters or flying in space—will increase your risk of developing it. NASA’s guidelines prohibit its astronauts from increasing their probability of dying from cancer by more than 3 percent. If you’ve flown out in space too many times and accumulated too much radiation, that’s it, you’re grounded.
The problem is that nobody knows exactly how much is too much. We have information about your odds of getting cancer after a nuclear explosion but that’s because we have historical data on large populations that have been exposed. Just over 500 people have flown in space, a sample size too small for epidemiological studies. And the most harmful type of radiation in space is very different from that which people are exposed to after an atomic bomb. Astronauts are exposed to galactic cosmic rays, the nuclei of atoms careening through space with incredible speed and energy. If they hit an important cellular structure, like DNA, they can generate mutations.
Because they move so fast, galactic cosmic rays aren’t stopped much by shielding. And there are a lot of them. Out in space, it is estimated that it would take about three days for every single one of your trillions of body cells to be hit by a high-energy proton (the lightest and most common galactic cosmic ray). Over the course of a year, each of your cells would likely have encountered at least one heavy and damaging iron nuclei. Other types of radiation are relatively weak and diffuse, sort of like a BB pellet, making a galactic cosmic ray a cannonball – large, weighty, and packing a punch.
One way to reduce astronauts’ exposure to galactic cosmic rays could be to send them to space only during the peak of the sun’s natural 11-year solar cycle. During solar maximum, the sun’s radiation blows counteractively against the cosmic rays streaming in to our solar system, reducing an astronaut’s exposure. Of course, being in space during this time also means the sun could unleash a potentially deadly solar flare, frying astronauts in their spaceship.
What kind of extra exposure are astronauts normally dealing with? People living in the U.S. are exposed to about 3 millisieverts of radiation from natural background sources each year (millisieverts are units of radiation exposure in the human body). A nuclear accident, like Fukushima, might raise this by about 1 millisievert. An astronaut on a round-trip, two-and-a-half-year Mars mission, by contrast, can expect to receive around a sievert of cosmic ray radiation, nearly 1,000 times more.
If 41 percent of people in the U.S. can expect to be diagnosed with cancer that means, out of 100 people, on average 41 of them will get cancer. If you exposed 100 people to the 1 sievert of cosmic ray radiation that a Mars astronaut would get, there would now be 61 total incidents of cancer, an increase of 20, according to reports from the U.S. National Academy of Sciences (.pdf) and United Nations Scientific Committee on Atomic Radiation (UNSCEAR). About half of those tumors would result in death.
Certain types of cancer, including lung, breast, and colorectal cancer, are the most likely to appear from cosmic ray radiation and tend to be more aggressive than normal. Cucinotta estimates that an astronaut’s lifespan after exposure to radiation on a Mars trip would be shortened between 15 and 24 years from the average.
So the concerns from radiation are very real. But there could be a number of biological ways to mitigate cancer for long-duration spaceflight, said oncologist and cell biologist Mary Helen Barcellos-Hoff of NYU, who was not involved in the recent study. Radiation doesn’t just damage DNA; it also seems to change the ways that cells signal to one another. Tumor cells are helped along, for instance, by impairment in the immune system’s macrophages, which seek out and destroy defective cells. If macrophages aren't doing their job, it can promote the tumor’s growth, allowing it to invade and metastasize in the body.
These kinds of immune response changes are similar to those in chronic inflammatory diseases, which produce oxidants that mess up intercellular signaling. It’s possible that antioxidants and non-steroidal anti-inflammatory drugs, like aspirin, taken during spaceflight could help hold back some of the worst effects of cancer, said Barcellos-Hoff. There will always be a higher chance of developing tumors during a deep-space mission, “but getting into a rocket and shooting to Mars is not exactly a risk-free activity,” she said.
NASA is planning one-year stays on the ISS (astronauts currently take six-month shifts) and mulling over the idea of sending humans to an asteroid or beyond. A recent report from the Institute of Medicine stated that NASA should develop an ethical framework for exposing its astronauts to the health hazards of long-term spaceflight.
One of the major problems in our understanding of cancer risks for astronauts is the high amount of uncertainty. Cucinotta’s data is based on studies where mice here on Earth were exposed to heavy ions from particle accelerators. These mice tend to be engineered to be more susceptible to certain tumors and are often inbred, which most humans are not.
These are all complicating factors in making the most recent cancer risk estimates for astronauts. The most important thing for him would be to simply get more and better data. NASA has not done a great deal of studies on the biology of radiation. Some were conducted decades ago. But our knowledge of cancer is constantly being renewed and studies from more than ten years ago tend to be out of date.
Before humans are sent to the Red Planet, NASA should do a focused decade-long study on all the potential health problems that radiation could cause. Hopefully, this would bring up new ways to combat some of the worst effects.
“Once we know better, we can find the true answer, and it could lower our risk estimate,” said Cucinotta.
Cosmic cancer threatens manned Mars mission
Published time: 26 Sep, 2017 00:13
Get short URL
Cosmic cancer threatens manned Mars mission
© NASA / Reuters
Exploring deep space or colonizing Mars could be far more difficult than previously believed, according to new research looking at cancer-causing cosmic rays.
Health scientist Frank Cucinotta teamed up with Eliedonna Cacaoat, of the University of Las Vegas, to investigate the effect of cosmic rays. In the study, published in the journal Nature, the team examined results of previous studies into tumors in mice and found that the animals were twice as susceptible to cancer in deep space than previously thought.
The team believes previous studies failed to recognise that cosmic rays can spread from both the directly affected cell to secondary cells, damaging the DNA and turning them, too, into cancerous cells.
Shielding methods were also said to have only “modestly decreased” the amount of radiation the mice were exposed to.
Cosmic rays, which can also cause cataracts, nerve damage and problems with blood circulation, are made up of high-energy atomic and subatomic particles that emanate from exploding stars and black holes.
READ MORE: China selects site for simulated Mars colony, doubling as tourist attraction
Astronauts are exposed to much higher radiation levels than people on Earth, as the planet’s atmosphere provides a natural protection from harmful energy. Crew members aboard the International Space Station are also protected by the Earth’s magnetic field which diverts cosmic rays away from Earth’s orbit.
While there are “significant differences” between the cancer rates in mice and humans, the findings could still hinder manned deep-space exploration in the future.
Various agencies are developing methods of withstanding the effects of radiation in space, including a radiation-absorbent vest and a satellite capable of deploying an artificial magnetic shield to divert radiation away from a chosen site.
NASA is aiming to send human missions to Mars in the 2030s, while China has said it hopes to get there sooner, beginning with its first independent Mars landing mission in 2020.
Mars-bound astronauts face chronic dementia risk from galactic cosmic ray exposure
UCI study raises questions about long-term brain health after extended spaceflights
on October 10, 2016
Irvine, Calif., Oct. 10, 2016 — Will astronauts traveling to Mars remember much of it? That’s the question concerning University of California, Irvine scientists probing a phenomenon called “space brain.”
UCI’s Charles Limoli and colleagues found that exposure to highly energetic charged particles – much like those found in the galactic cosmic rays that will bombard astronauts during extended spaceflights – causes significant long-term brain damage in test rodents, resulting in cognitive impairments and dementia.
Their study appears today in Nature’s Scientific Reports. It follows one last year showing somewhat shorter-term brain effects of galactic cosmic rays. The current findings, Limoli said, raise much greater alarm. (Link to study: www.nature.com/articles/srep34774)
“This is not positive news for astronauts deployed on a two-to-three-year round trip to Mars,” said the professor of radiation oncology in UCI’s School of Medicine. “The space environment poses unique hazards to astronauts. Exposure to these particles can lead to a range of potential central nervous system complications that can occur during and persist long after actual space travel – such as various performance decrements, memory deficits, anxiety, depression and impaired decision-making. Many of these adverse consequences to cognition may continue and progress throughout life.”
For the study, rodents were subjected to charged particle irradiation (fully ionized oxygen and titanium) at the NASA Space Radiation Laboratory at New York’s Brookhaven National Laboratory and then sent to Limoli’s UCI lab.
Six months after exposure, the researchers still found significant levels of brain inflammation and damage to neurons. Imaging revealed that the brain’s neural network was impaired through the reduction of dendrites and spines on these neurons, which disrupts the transmission of signals among brain cells. These deficiencies were parallel to poor performance on behavioral tasks designed to test learning and memory.
In addition, the Limoli team discovered that the radiation affected “fear extinction,” an active process in which the brain suppresses prior unpleasant and stressful associations, as when someone who nearly drowned learns to enjoy water again.
“Deficits in fear extinction could make you prone to anxiety,” Limoli said, “which could become problematic over the course of a three-year trip to and from Mars.”
Most notably, he said, these six-month results mirror the six-week post-irradiation findings of a 2015 study he conducted that appeared in the May issue of Science Advances.
Similar types of more severe cognitive dysfunction are common in brain cancer patients who have received high-dose, photon-based radiation treatments. In other research, Limoli examines the impact of chemotherapy and cranial irradiation on cognition.
While dementia-like deficits in astronauts would take months to manifest, he said, the time required for a mission to Mars is sufficient for such impairments to develop. People working for extended periods on the International Space Station, however, do not face the same level of bombardment with galactic cosmic rays because they are still within the Earth’s protective magnetosphere.
Limoli’s work is part of NASA’s Human Research Program. Investigating how space radiation affects astronauts and learning ways to mitigate those effects are critical to further human exploration of space, and NASA needs to consider these risks as it plans for missions to Mars and beyond.
Partial solutions are being explored, Limoli noted. Spacecraft could be designed to include areas of increased shielding, such as those used for rest and sleep. However, these highly energetic charged particles will traverse the ship nonetheless, he added, “and there is really no escaping them.”
Preventive treatments offer some hope. Limoli’s group is working on pharmacological strategies involving compounds that scavenge free radicals and protect neurotransmission.
Vipan Kumar Parihar, Barrett Allen, Chongshan Caressi, Katherine Tran, Esther Chu, Stephanie Kwok, Nicole Chmielewski, Janet Baulch, Erich Giedzinski and Munjal Acharya of UCI and Richard Britten of Eastern Virginia Medical School contributed to the study, which NASA supported through grants NNX13AK70G, NNX14AE73G, NNX13AD59G, NNX10AD59G, UARC NAS2-03144 and NNX15AI22G.
About the University of California, Irvine: Founded in 1965, UCI is the youngest member of the prestigious Association of American Universities. The campus has produced three Nobel laureates and is known for its academic achievement, premier research, innovation and anteater mascot. Led by Chancellor Howard Gillman, UCI has more than 30,000 students and offers 192 degree programs. It’s located in one of the world’s safest and most economically vibrant communities and is Orange County’s second-largest employer, contributing $5 billion annually to the local economy. For more on UCI, visit www.uci.edu.
Media access: Radio programs/stations may, for a fee, use an on-campus ISDN line to interview UCI faculty and experts, subject to availability and university approval. For more UCI news, visit news.uci.edu. Additional resources for journalists may be found at communications.uci.edu/for-journalists.
https://phys.org/news/2017-06-collateral-cosmic-rays-cancer-mars.html
Study: Collateral damage from cosmic rays increases cancer risks for Mars astronauts
June 5, 2017 by Kevin Dunegan
astronaut
Credit: CC0 Public Domain
The cancer risk for a human mission to Mars has effectively doubled following a UNLV study predicting a dramatic increase in the disease for astronauts traveling to the red planet or on long-term missions outside the protection of Earth's magnetic field.
The findings appeared in the May issue of Scientific Reports and were presented by UNLV scientist Francis Cucinotta, a leading scholar on radiation and space physics.
Previous studies have shown the health risks from galactic cosmic ray exposure to astronauts include cancer, central nervous system effects, cataracts, circulatory diseases and acute radiation syndromes. Cosmic rays, such as iron and titanium atoms, heavily damage the cells they traverse because of their very high rates of ionization.
Conventional risk models used by NASA and others assume DNA damage and mutation are the cause of radiation cancers. This is based on studies at high doses where all cells are traversed by heavy ions one or more times within much shorter-time periods than will occur during space missions.
"Exploring Mars will require missions of 900 days or longer and includes more than one year in deep space where exposures to all energies of galactic cosmic ray heavy ions are unavoidable," Cucinotta explained. "Current levels of radiation shielding would, at best, modestly decrease the exposure risks."
In these new findings, a non-targeted effect model—where cancer risk arises in bystander cells close to heavily damaged cells—is shown to lead to a two-fold or more increase in cancer risk compared to the conventional risk model for a Mars mission.
"Galactic cosmic ray exposure can devastate a cell's nucleus and cause mutations that can result in cancers," Cucinotta explained. "We learned the damaged cells send signals to the surrounding, unaffected cells and likely modify the tissues' microenvironments. Those signals seem to inspire the healthy cells to mutate, thereby causing additional tumors or cancers."
Cucinotta said the findings show a tremendous need for additional studies focused on cosmic ray exposures to tissues that dominate human cancer risks, and that these should begin prior to long-term space missions outside the Earth's geomagnetic sphere.
"Non-Targeted Effects Models Predict Significantly Higher Mars Mission Cancer Risk than Targeted Effects Models," appeared online May 12 in the journal Scientific Reports.
Explore further: Research uncovers potential health risks of travel to Mars
More information: Francis A. Cucinotta et al, Non-Targeted Effects Models Predict Significantly Higher Mars Mission Cancer Risk than Targeted Effects Models, Scientific Reports (2017). DOI: 10.1038/s41598-017-02087-3
https://www.wired.com/2014/04/radiation-risk-iss-mars/
Space Radiation Remains Major Hazard for Humans Going to Mars
Image:
NASA
During a conference this week in Washington D.C., enthusiasts are attempting to rouse support for a manned mission to Mars sometime in the next two decades. NASA is there, as are many key players in the spaceflight community. But there continue to be major obstacles to manned Mars missions.
A new study highlights one of the big problems with extended space travel: galactic cosmic ray radiation. According to the report, astronauts on the International Space Station would receive doses that exceed their lifetime limits after just 18 months for women and two years for men. A Mars mission crew would be spending at least this long in the harsh radiation of deep space.
Cosmic rays are a unique type of radiation in that they are difficult to shield against. And the new research points out that the cancer an astronaut could develop after too much cosmic ray radiation is bound to be very dangerous.
“The type of tumors that cosmic ray ions make are more aggressive than what we get from other radiation,” said Francis Cucinotta a radiation expert at the University of Nevada, Las Vegas, and author of the new report published Apr. 23 in PLoS One.
The news isn’t all doom and gloom. During certain periods in the solar cycle, galactic cosmic rays are reduced. Biologists are also working out exactly what kinds of medicine, from antioxidants to aspirin, could help deal with cosmic ray damage in the body. But more than anything, Cucinotta and other radiation experts recommend that NASA gather far more data about the health risks their astronauts are exposed to.
Approximately 41 percent of people in the U.S. will be diagnosed with some type of cancer at some point in their lives. Certain types of work—like cleaning up after nuclear disasters or flying in space—will increase your risk of developing it. NASA’s guidelines prohibit its astronauts from increasing their probability of dying from cancer by more than 3 percent. If you’ve flown out in space too many times and accumulated too much radiation, that’s it, you’re grounded.
The problem is that nobody knows exactly how much is too much. We have information about your odds of getting cancer after a nuclear explosion but that’s because we have historical data on large populations that have been exposed. Just over 500 people have flown in space, a sample size too small for epidemiological studies. And the most harmful type of radiation in space is very different from that which people are exposed to after an atomic bomb. Astronauts are exposed to galactic cosmic rays, the nuclei of atoms careening through space with incredible speed and energy. If they hit an important cellular structure, like DNA, they can generate mutations.
Because they move so fast, galactic cosmic rays aren’t stopped much by shielding. And there are a lot of them. Out in space, it is estimated that it would take about three days for every single one of your trillions of body cells to be hit by a high-energy proton (the lightest and most common galactic cosmic ray). Over the course of a year, each of your cells would likely have encountered at least one heavy and damaging iron nuclei. Other types of radiation are relatively weak and diffuse, sort of like a BB pellet, making a galactic cosmic ray a cannonball – large, weighty, and packing a punch.
One way to reduce astronauts’ exposure to galactic cosmic rays could be to send them to space only during the peak of the sun’s natural 11-year solar cycle. During solar maximum, the sun’s radiation blows counteractively against the cosmic rays streaming in to our solar system, reducing an astronaut’s exposure. Of course, being in space during this time also means the sun could unleash a potentially deadly solar flare, frying astronauts in their spaceship.
What kind of extra exposure are astronauts normally dealing with? People living in the U.S. are exposed to about 3 millisieverts of radiation from natural background sources each year (millisieverts are units of radiation exposure in the human body). A nuclear accident, like Fukushima, might raise this by about 1 millisievert. An astronaut on a round-trip, two-and-a-half-year Mars mission, by contrast, can expect to receive around a sievert of cosmic ray radiation, nearly 1,000 times more.
If 41 percent of people in the U.S. can expect to be diagnosed with cancer that means, out of 100 people, on average 41 of them will get cancer. If you exposed 100 people to the 1 sievert of cosmic ray radiation that a Mars astronaut would get, there would now be 61 total incidents of cancer, an increase of 20, according to reports from the U.S. National Academy of Sciences (.pdf) and United Nations Scientific Committee on Atomic Radiation (UNSCEAR). About half of those tumors would result in death.
Certain types of cancer, including lung, breast, and colorectal cancer, are the most likely to appear from cosmic ray radiation and tend to be more aggressive than normal. Cucinotta estimates that an astronaut’s lifespan after exposure to radiation on a Mars trip would be shortened between 15 and 24 years from the average.
So the concerns from radiation are very real. But there could be a number of biological ways to mitigate cancer for long-duration spaceflight, said oncologist and cell biologist Mary Helen Barcellos-Hoff of NYU, who was not involved in the recent study. Radiation doesn’t just damage DNA; it also seems to change the ways that cells signal to one another. Tumor cells are helped along, for instance, by impairment in the immune system’s macrophages, which seek out and destroy defective cells. If macrophages aren't doing their job, it can promote the tumor’s growth, allowing it to invade and metastasize in the body.
These kinds of immune response changes are similar to those in chronic inflammatory diseases, which produce oxidants that mess up intercellular signaling. It’s possible that antioxidants and non-steroidal anti-inflammatory drugs, like aspirin, taken during spaceflight could help hold back some of the worst effects of cancer, said Barcellos-Hoff. There will always be a higher chance of developing tumors during a deep-space mission, “but getting into a rocket and shooting to Mars is not exactly a risk-free activity,” she said.
NASA is planning one-year stays on the ISS (astronauts currently take six-month shifts) and mulling over the idea of sending humans to an asteroid or beyond. A recent report from the Institute of Medicine stated that NASA should develop an ethical framework for exposing its astronauts to the health hazards of long-term spaceflight.
One of the major problems in our understanding of cancer risks for astronauts is the high amount of uncertainty. Cucinotta’s data is based on studies where mice here on Earth were exposed to heavy ions from particle accelerators. These mice tend to be engineered to be more susceptible to certain tumors and are often inbred, which most humans are not.
These are all complicating factors in making the most recent cancer risk estimates for astronauts. The most important thing for him would be to simply get more and better data. NASA has not done a great deal of studies on the biology of radiation. Some were conducted decades ago. But our knowledge of cancer is constantly being renewed and studies from more than ten years ago tend to be out of date.
Before humans are sent to the Red Planet, NASA should do a focused decade-long study on all the potential health problems that radiation could cause. Hopefully, this would bring up new ways to combat some of the worst effects.
“Once we know better, we can find the true answer, and it could lower our risk estimate,” said Cucinotta.
Cosmic cancer threatens manned Mars mission
Published time: 26 Sep, 2017 00:13
Get short URL
Cosmic cancer threatens manned Mars mission
© NASA / Reuters
Exploring deep space or colonizing Mars could be far more difficult than previously believed, according to new research looking at cancer-causing cosmic rays.
Health scientist Frank Cucinotta teamed up with Eliedonna Cacaoat, of the University of Las Vegas, to investigate the effect of cosmic rays. In the study, published in the journal Nature, the team examined results of previous studies into tumors in mice and found that the animals were twice as susceptible to cancer in deep space than previously thought.
The team believes previous studies failed to recognise that cosmic rays can spread from both the directly affected cell to secondary cells, damaging the DNA and turning them, too, into cancerous cells.
Shielding methods were also said to have only “modestly decreased” the amount of radiation the mice were exposed to.
Cosmic rays, which can also cause cataracts, nerve damage and problems with blood circulation, are made up of high-energy atomic and subatomic particles that emanate from exploding stars and black holes.
READ MORE: China selects site for simulated Mars colony, doubling as tourist attraction
Astronauts are exposed to much higher radiation levels than people on Earth, as the planet’s atmosphere provides a natural protection from harmful energy. Crew members aboard the International Space Station are also protected by the Earth’s magnetic field which diverts cosmic rays away from Earth’s orbit.
While there are “significant differences” between the cancer rates in mice and humans, the findings could still hinder manned deep-space exploration in the future.
Various agencies are developing methods of withstanding the effects of radiation in space, including a radiation-absorbent vest and a satellite capable of deploying an artificial magnetic shield to divert radiation away from a chosen site.
NASA is aiming to send human missions to Mars in the 2030s, while China has said it hopes to get there sooner, beginning with its first independent Mars landing mission in 2020.
