Humans will return to the Moon and possibly Mars in the next few decades. However, current radiation exposure standards for long-term spaceflight do not permit such missions. This chapter provides an overview of the discussion in the United States and NASA on the way forward and outlines key recommendations made by NASA's National Academies of Sciences, Engineering, and Medicine in 2021. The Questions related ethics related to human spaceflight and radiation exposure are highlighted and explored with emphasis.
Introduction
Apollo moon landing images are among the most iconic of the 20th century. Neil Armstrong's "One Small" Step for Man, One Giant Leap for Humanity" has inspired millions around the world, helped improve the geopolitical image of the United States around the world, and been the winning aspect of the "space race" between the United States and the Soviet Union. , it was and the Apollo program (a total of 11 missions, 6 moon landings and 12 astronauts on the moon) remains the greatest achievement of manned spaceflight, but the program ended in 1972 and since then people in space have remained very close to Earth Low Earth Orbit (LEO) operations, primarily at space stations such such as Skylab (USA), Mir (Soviet Union and later Russia), International Space Station (USA/Russia/EU/Japan/Canada) and Tiangong-1, 2 and 3 (China). around the Earth in orbits between 350 and 450 km.
However, we are once again entering an age of space exploration beyond Earth, with the Moon as a springboard and Mars as the ultimate goal. There have always been plans for these types of missions, but it looks like humans will be back on the Moon in the 2020-2030s or the next few decades. These plans for the Moon have passed the planning phase and are now in the "operational" phase. ", NASA signing the "Accords of Artemis". ; position: relative; vertical alignment: baseline; top: -0.5 em;">1 and other space agencies adapting their own space programs, or portions thereof, for near operations and/or or on the lunar surface, in partnership with NASA or simultaneously, in accordance with the Sino-Russian plan for an international lunar research station on the moon announced at the Global Space Exploration conference on June 16, 2021.<
Of course, there are a plethora of questions to answer as to "how?" A moon landing or landing on Mars is achievable. There are also several "why" questions related to aiming for an extraterrestrial surface, whether scientific or political.
However, this case study will not address these aspects, but rather focus on whether it is ethical to send people to another celestial body and how agencies companies currently manage to avoid the ethical question that the mere presence of humans in space puts them in danger.
Space Exploration and Effects on Humans
"Space is hard" is a common saying among people working in the space industry. It refers to the complex issues surrounding space travel, an issue that translates also by the cost of space missions This is even more true when traveling beyond LEO given the distances involved In addition to the danger of relying on complicated machinery to get crews to their destinations, the space environment makes it -even is extremely damaging to humans.Interplanetary space and the surfaces of the Moon and Mars are extremely hostile environments, including harsh vacuums, extreme temperatures, space debris, zero or reduced gravity, and harmful radiation. It is on this last aspect that this case study of harmful radiation focuses because it contains the greatest uncertainty in terms of impact and mitigation Corrective actions related to vacuum, temperatures and debris are possible , based on proper construction of spacecraft and astronaut suits and effective operational design. The effects of reduced gravity have been widely studied and countermeasures exist (Blaber et al. 2010). These countermeasures cannot eliminate the side effects of long spaceflight, but they can reduce them enough to keep the crew operational for the duration of the mission. The issue of harmful radiation is much more complex. There is currently no effective strategy for complete protection against space radiation. Therefore, every human in space will be exposed, with exposure depending on the duration and nature of the particular mission.
Space Radiation Physics
The main sources of radiation in space are Galactic Cosmic Rays (GCRs) and Solar Particle Events (SPEs). GCRs are very energetic and therefore very penetrating. They are very difficult to dampen and virtually unstoppable with a shield, because the mass of the shield in space is limited. Spacecraft cannot carry much shielding material (carrying mass into orbit is very expensive), and in fact, a "weak" shield could be worse than no shield at all, because a GCR creates a cascade of secondary particles of shielding material that make the interior of the spacecraft, so it's best to only pass the GCR through the human body.
EPS include particles such as helium ions and other ions. EPS originate from the sun. These events occur sporadically with varying frequencies. The frequency and intensity of EPS are unpredictable, although related to the 11-year solar cycle (solar minimum/solar maximum) Low-energy EPS protons cannot enter spacecraft or astronaut suits, while high-energy particles can and therefore contribute to exposure to radiation from astronauts. However, shielding (especially inside a spacecraft) is effective against EPS. Problems arise with astronauts who are outside the spacecraft (extraspace activities) or exposed on the surface of the Moon or Mars, as astronauts may not have time to take cover with an EPS.
GCR flow can be modeled and predicted exposure calculated. PES can be protected based on assumptions about intensity and frequency and scheduling of activities. , is possible, but with a very slow response time short.
Current Practises
Currently, space agencies have regulations that define radiation exposure standards that astronauts must not exceed. For example, NASA defines permissible exposure limits in the space (SPEL) for its astronauts stating that "Astronauts may not exceed 3." % Risk of Death by Exposure (REID) Cancer". NASA's current standard takes age and gender into account, which not all space agencies do. The SPEL gives an upper 95% confidence limit that the person will die of cancer related to the radiation exposure the person was exposed to in space. Essentially, for every 100 astronauts who have traveled to space, three could die from radiation-related cancer. This is calculated for each astronaut based on gender and age.
Radiation doses are cumulative, so by today's standards a NASA astronaut could fly 30 years for a year or two to fly to the ISS before reaching the limit of his career, while a male astronaut can probably fly even more Longer or longer missions are possible for Russian astronauts , European or Canadian. Note that older astronauts have higher exposure limits. The overall impact on the rest of their life is less than the impact on a younger astronaut.
Effects of Space Radiation on Human Health
Knowing whether an astronaut will develop any of these health conditions, particularly cancer, is difficult to communicate these risks to astronauts, the public, and policy makers.There are several sources of uncertainty.
As mentioned in the previous section, the average GCR flux and solar activity can be simulated and modeled. However, EPS are stochastic events because there is no way to know exactly when and where an SPE will occur, so it can be treated as a random event and so there is always a chance that a high-energy event will exceed the modeling parameters.
Another source of uncertainty is the actual effects of radiation on the human body. This may come as a surprise at first, given that sources of radiation have been available on Earth for decades Long-term radiation exposure (rather than acute radiation exposure) shows how difficult it is to collect data over a long period (decades) for large groups of exposed people in order to conduct statistical studies and conclusions on precise risk rates.
Risk predictions for certain cancers are largely based on data from the Japanese Atomic Bomb Survivors Lifespan Study (LSS). Data sources available to them, such as occupational radiation studies, remain regarding possible long-term effects (Chylack et al.2009; NRC 2006) .
Leaving Earth
Current standards for radiation exposure in space were designed for short space missions and intended for repeated missions (i.e. multiple visits to the ISS) where a return to Earth was possible (and (have access to medical care there) within days. For extraterrestrial travel to the Moon and Mars, this will no longer be the case. For travel to Mars, the round trip may take more than two years with planned technology (by 2030+) Mission profile calls for a six-month cruise, 18-month surface stay (waiting for Mars and Earth to realign in their orbits, reducing travel time required) and a return of six months once an astronaut has started his journey, he cannot decide that he no longer wishes to be part of it. This is very different from what we find usually in rural occupations that involve radiation exposure, rural workers may choose to quit their jobs and end your exposure. Additionally, the radiation environment changes outside of low Earth orbit.
The most important factors contributing to the increased risk of radiation exposure for astronauts during lunar or martian exploration missions can be inferred of the above. Once outside of Earth's protective global magnetic field, which the Moon and Mars lack (there are localized but not global magnetic fields), the radiant flux (origin of both GCR and EPS) increases. In addition, the response window of energetic EPS decreases because solar observatories must observe the event and transmit a signal to astronauts to seek shelter. The farther they are from Earth, the longer it will take for the message to reach them. Additionally, the expected duration of the mission will be significantly increased, essentially exposing future astronauts to a more hostile environment for much longer periods of time than they currently are. with expected radiation doses from future extraterrestrial exploration missions.
9.3. Ethical Space Exploration
The previous section highlights several issues regarding future space exploration destinations.
- The effects of radiation will probably not have a technological mitigation measure in the envisaged timeframe for these countermeasures to be available. Thus, exposure to harmful radiation is a given for any mission.
- Uncertainty still remains about the types of adverse effects that astronauts will incur due to long duration spaceflight. This makes it hard to accurately inform the crew on the impact of each mission on the participant’s long-term health and quality of life.
- For missions to Mars, termination of participation might not be an option. If the astronaut so chooses, he cannot just stop participating in the mission. The physical distances and planetary alignment might make it impossible to return to Earth, outside the planned window.
Given that exposure is cumulative, Lunar and Mars missions might necessitate inexperienced astronauts as crew (no previous exposure).
Current lifetime radiation exposure standards for astronauts do not actually allow participation in missions to Mars, as nominal mission scenarios would exceed the permitted limits.
The above Points This ultimately leads to the fact that a future mission to Mars puts the crew at risk from the radiation received during the flight and increases the risk of negative health effects. This section now describes the official (Space Agency) response and efforts to remedy this situation.
Space is an endeavor that many (of society, scientists, future astronauts, etc.), but the risks are borne by a few (astronauts and their families), in particular health risks. The Astronaut Corps can be considered an elite group, chosen from a wide range of volunteer applicants. Given the education and training astronaut candidates receive once selected, it's hard to say they ignore and disapprove of the risks of spaceflight.
The approach taken by NASA and other space agencies considering Mars as an exploration target for astronauts is to provide a mission-specific waiver for astronauts on such missions. Therefore, the explicit declaration of consent of each member of a possible crew is required. Currently, only NASA authorizes such a process, although other space agencies seem to agree with this approach.4 NASA will most likely take the lead on this issue as the United States has more mature plans for the future space exploration. . Therefore, the United States' response to the question will most likely dictate the responses of other agencies.
NASA asked an expert panel convened by the National Academies of Sciences to Engineering and Medicine (NAS) to review the current process for assessing and managing long-term cancer risks for aircrew (NAS 2021). The committee, made up of experts from various related fields such as radiation dosimetry, clinical oncology, biostatistics, physics, communications and risk management, as well as former astronauts, made recommendations to the agency . The full report also discusses NASA's plan to introduce a different exposure limit that will increase the common PEL for all astronauts (male and female). The standard in question is even more conservative than other space agencies with a unified approach (600 mSv for all, compared to 1000 mSv, the standard for other agencies, as shown in Table 9.1). However, even with the proposed new standard, missions to Mars will still require an exception and therefore the situation remains similar to that seen in previous sections.
It is interesting to note some of the recommendations made to NASA on ethical issues by the NAS Committee (2021).
Recommendation 2: "In the In the near future, NASA should reconsider the use of exposure-related death risk (REID) or other metrics or a combination of metrics when establishing the dose-based health standard for the NASA should conduct an independent analysis of the validity of the 3% REID and clearly explain the agency's rationale for the measures it chose.”
The key element in the previous recommendation is the need to explain the rationale for the metrics to be used, regardless of standards This is sound advice and the basis for building trust in the The main problem in the case of astronauts is that the current standards distinguish between male and female astronauts, but the proposed future standard is a common standard (based on a 35-year-old female) that will allow for greater exposure to younger ones, given the physiological differences between female astronauts, but lower exposure to older male astronauts (which the old standard might have allowed). So there is a trade-off between equal opportunity for all and restrictions for a sub-group. Therefore, it is necessary to disclose the justification for the election, which clarifies the reasoning behind the change and presents the ethical arguments that have been weighed against each other, which will help reassure the subgroup who may feel that their opportunities are unjustified to be restricted. and that its position has been taken into account.
For missions related to the exemption, it was recommended to follow the previous recommendations of a document on Health Standards for Space Travel (IoM 2014) and to “establish an ethically-based decision-making framework, NASA shall apply relevant ethical principles and discharge associated responsibilities through an ethically-based decision-making framework. three-level ethics which (i) reviews decisions regarding admissions of the above-mentioned persons risks to the health and safety of astronauts. “what is permitted by health standards, (ii) decisions regarding the conduct of specific missions, and (iii) decisions regarding individual astronaut participation and crew composition” (IoM 2014, Recommendation 4).
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Ola Hansen 
Humans will return to the Moon and possibly Mars in the next few decades. However, current radiation exposure standards for long-term spaceflight do not permit such missions. This chapter provides an overview of the discussion in the United States and NASA on the way forward and outlines key recommendations made by NASA's National Academies of Sciences, Engineering, and Medicine in 2021. The Questions related ethics related to human spaceflight and radiation exposure are highlighted and explored with emphasis.
Introduction
Apollo moon landing images are among the most iconic of the 20th century. Neil Armstrong's "One Small" Step for Man, One Giant Leap for Humanity" has inspired millions around the world, helped improve the geopolitical image of the United States around the world, and been the winning aspect of the "space race" between the United States and the Soviet Union. , it was and the Apollo program (a total of 11 missions, 6 moon landings and 12 astronauts on the moon) remains the greatest achievement of manned spaceflight, but the program ended in 1972 and since then people in space have remained very close to Earth Low Earth Orbit (LEO) operations, primarily at space stations such such as Skylab (USA), Mir (Soviet Union and later Russia), International Space Station (USA/Russia/EU/Japan/Canada) and Tiangong-1, 2 and 3 (China). around the Earth in orbits between 350 and 450 km.
However, we are once again entering an age of space exploration beyond Earth, with the Moon as a springboard and Mars as the ultimate goal. There have always been plans for these types of missions, but it looks like humans will be back on the Moon in the 2020-2030s or the next few decades. These plans for the Moon have passed the planning phase and are now in the "operational" phase. ", NASA signing the "Accords of Artemis". ; position: relative; vertical alignment: baseline; top: -0.5 em;">1 and other space agencies adapting their own space programs, or portions thereof, for near operations and/or or on the lunar surface, in partnership with NASA or simultaneously, in accordance with the Sino-Russian plan for an international lunar research station on the moon announced at the Global Space Exploration conference on June 16, 2021.<
Of course, there are a plethora of questions to answer as to "how?" A moon landing or landing on Mars is achievable. There are also several "why" questions related to aiming for an extraterrestrial surface, whether scientific or political.
However, this case study will not address these aspects, but rather focus on whether it is ethical to send people to another celestial body and how agencies companies currently manage to avoid the ethical question that the mere presence of humans in space puts them in danger.
Space Exploration and Effects on Humans
"Space is hard" is a common saying among people working in the space industry. It refers to the complex issues surrounding space travel, an issue that translates also by the cost of space missions This is even more true when traveling beyond LEO given the distances involved In addition to the danger of relying on complicated machinery to get crews to their destinations, the space environment makes it -even is extremely damaging to humans.Interplanetary space and the surfaces of the Moon and Mars are extremely hostile environments, including harsh vacuums, extreme temperatures, space debris, zero or reduced gravity, and harmful radiation. It is on this last aspect that this case study of harmful radiation focuses because it contains the greatest uncertainty in terms of impact and mitigation Corrective actions related to vacuum, temperatures and debris are possible , based on proper construction of spacecraft and astronaut suits and effective operational design. The effects of reduced gravity have been widely studied and countermeasures exist (Blaber et al. 2010). These countermeasures cannot eliminate the side effects of long spaceflight, but they can reduce them enough to keep the crew operational for the duration of the mission. The issue of harmful radiation is much more complex. There is currently no effective strategy for complete protection against space radiation. Therefore, every human in space will be exposed, with exposure depending on the duration and nature of the particular mission.
Space Radiation Physics
The main sources of radiation in space are Galactic Cosmic Rays (GCRs) and Solar Particle Events (SPEs). GCRs are very energetic and therefore very penetrating. They are very difficult to dampen and virtually unstoppable with a shield, because the mass of the shield in space is limited. Spacecraft cannot carry much shielding material (carrying mass into orbit is very expensive), and in fact, a "weak" shield could be worse than no shield at all, because a GCR creates a cascade of secondary particles of shielding material that make the interior of the spacecraft, so it's best to only pass the GCR through the human body.
EPS include particles such as helium ions and other ions. EPS originate from the sun. These events occur sporadically with varying frequencies. The frequency and intensity of EPS are unpredictable, although related to the 11-year solar cycle (solar minimum/solar maximum) Low-energy EPS protons cannot enter spacecraft or astronaut suits, while high-energy particles can and therefore contribute to exposure to radiation from astronauts. However, shielding (especially inside a spacecraft) is effective against EPS. Problems arise with astronauts who are outside the spacecraft (extraspace activities) or exposed on the surface of the Moon or Mars, as astronauts may not have time to take cover with an EPS.
GCR flow can be modeled and predicted exposure calculated. PES can be protected based on assumptions about intensity and frequency and scheduling of activities. , is possible, but with a very slow response time short.
Current Practises
Currently, space agencies have regulations that define radiation exposure standards that astronauts must not exceed. For example, NASA defines permissible exposure limits in the space (SPEL) for its astronauts stating that "Astronauts may not exceed 3." % Risk of Death by Exposure (REID) Cancer". NASA's current standard takes age and gender into account, which not all space agencies do. The SPEL gives an upper 95% confidence limit that the person will die of cancer related to the radiation exposure the person was exposed to in space. Essentially, for every 100 astronauts who have traveled to space, three could die from radiation-related cancer. This is calculated for each astronaut based on gender and age.
Radiation doses are cumulative, so by today's standards a NASA astronaut could fly 30 years for a year or two to fly to the ISS before reaching the limit of his career, while a male astronaut can probably fly even more Longer or longer missions are possible for Russian astronauts , European or Canadian. Note that older astronauts have higher exposure limits. The overall impact on the rest of their life is less than the impact on a younger astronaut.
Effects of Space Radiation on Human Health
Knowing whether an astronaut will develop any of these health conditions, particularly cancer, is difficult to communicate these risks to astronauts, the public, and policy makers.There are several sources of uncertainty.
As mentioned in the previous section, the average GCR flux and solar activity can be simulated and modeled. However, EPS are stochastic events because there is no way to know exactly when and where an SPE will occur, so it can be treated as a random event and so there is always a chance that a high-energy event will exceed the modeling parameters.
Another source of uncertainty is the actual effects of radiation on the human body. This may come as a surprise at first, given that sources of radiation have been available on Earth for decades Long-term radiation exposure (rather than acute radiation exposure) shows how difficult it is to collect data over a long period (decades) for large groups of exposed people in order to conduct statistical studies and conclusions on precise risk rates.
Risk predictions for certain cancers are largely based on data from the Japanese Atomic Bomb Survivors Lifespan Study (LSS). Data sources available to them, such as occupational radiation studies, remain regarding possible long-term effects (Chylack et al.2009; NRC 2006) .
Leaving Earth
Current standards for radiation exposure in space were designed for short space missions and intended for repeated missions (i.e. multiple visits to the ISS) where a return to Earth was possible (and (have access to medical care there) within days. For extraterrestrial travel to the Moon and Mars, this will no longer be the case. For travel to Mars, the round trip may take more than two years with planned technology (by 2030+) Mission profile calls for a six-month cruise, 18-month surface stay (waiting for Mars and Earth to realign in their orbits, reducing travel time required) and a return of six months once an astronaut has started his journey, he cannot decide that he no longer wishes to be part of it. This is very different from what we find usually in rural occupations that involve radiation exposure, rural workers may choose to quit their jobs and end your exposure. Additionally, the radiation environment changes outside of low Earth orbit.
The most important factors contributing to the increased risk of radiation exposure for astronauts during lunar or martian exploration missions can be inferred of the above. Once outside of Earth's protective global magnetic field, which the Moon and Mars lack (there are localized but not global magnetic fields), the radiant flux (origin of both GCR and EPS) increases. In addition, the response window of energetic EPS decreases because solar observatories must observe the event and transmit a signal to astronauts to seek shelter. The farther they are from Earth, the longer it will take for the message to reach them. Additionally, the expected duration of the mission will be significantly increased, essentially exposing future astronauts to a more hostile environment for much longer periods of time than they currently are. with expected radiation doses from future extraterrestrial exploration missions.
9.3. Ethical Space Exploration
The previous section highlights several issues regarding future space exploration destinations.
Given that exposure is cumulative, Lunar and Mars missions might necessitate inexperienced astronauts as crew (no previous exposure).
Current lifetime radiation exposure standards for astronauts do not actually allow participation in missions to Mars, as nominal mission scenarios would exceed the permitted limits.
The above Points This ultimately leads to the fact that a future mission to Mars puts the crew at risk from the radiation received during the flight and increases the risk of negative health effects. This section now describes the official (Space Agency) response and efforts to remedy this situation.
Space is an endeavor that many (of society, scientists, future astronauts, etc.), but the risks are borne by a few (astronauts and their families), in particular health risks. The Astronaut Corps can be considered an elite group, chosen from a wide range of volunteer applicants. Given the education and training astronaut candidates receive once selected, it's hard to say they ignore and disapprove of the risks of spaceflight.
The approach taken by NASA and other space agencies considering Mars as an exploration target for astronauts is to provide a mission-specific waiver for astronauts on such missions. Therefore, the explicit declaration of consent of each member of a possible crew is required. Currently, only NASA authorizes such a process, although other space agencies seem to agree with this approach.4 NASA will most likely take the lead on this issue as the United States has more mature plans for the future space exploration. . Therefore, the United States' response to the question will most likely dictate the responses of other agencies.
NASA asked an expert panel convened by the National Academies of Sciences to Engineering and Medicine (NAS) to review the current process for assessing and managing long-term cancer risks for aircrew (NAS 2021). The committee, made up of experts from various related fields such as radiation dosimetry, clinical oncology, biostatistics, physics, communications and risk management, as well as former astronauts, made recommendations to the agency . The full report also discusses NASA's plan to introduce a different exposure limit that will increase the common PEL for all astronauts (male and female). The standard in question is even more conservative than other space agencies with a unified approach (600 mSv for all, compared to 1000 mSv, the standard for other agencies, as shown in Table 9.1). However, even with the proposed new standard, missions to Mars will still require an exception and therefore the situation remains similar to that seen in previous sections.
It is interesting to note some of the recommendations made to NASA on ethical issues by the NAS Committee (2021).
Recommendation 2: "In the In the near future, NASA should reconsider the use of exposure-related death risk (REID) or other metrics or a combination of metrics when establishing the dose-based health standard for the NASA should conduct an independent analysis of the validity of the 3% REID and clearly explain the agency's rationale for the measures it chose.”
The key element in the previous recommendation is the need to explain the rationale for the metrics to be used, regardless of standards This is sound advice and the basis for building trust in the The main problem in the case of astronauts is that the current standards distinguish between male and female astronauts, but the proposed future standard is a common standard (based on a 35-year-old female) that will allow for greater exposure to younger ones, given the physiological differences between female astronauts, but lower exposure to older male astronauts (which the old standard might have allowed). So there is a trade-off between equal opportunity for all and restrictions for a sub-group. Therefore, it is necessary to disclose the justification for the election, which clarifies the reasoning behind the change and presents the ethical arguments that have been weighed against each other, which will help reassure the subgroup who may feel that their opportunities are unjustified to be restricted. and that its position has been taken into account.
For missions related to the exemption, it was recommended to follow the previous recommendations of a document on Health Standards for Space Travel (IoM 2014) and to “establish an ethically-based decision-making framework, NASA shall apply relevant ethical principles and discharge associated responsibilities through an ethically-based decision-making framework. three-level ethics which (i) reviews decisions regarding admissions of the above-mentioned persons risks to the health and safety of astronauts. “what is permitted by health standards, (ii) decisions regarding the conduct of specific missions, and (iii) decisions regarding individual astronaut participation and crew composition” (IoM 2014, Recommendation 4).
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