Human Health on the Moon and Beyond and the Results of the Spaceflight for Everybody Symposium

Radiation.

In space, there is a higher level of radiation. Earth’s atmosphere, magnetic fields, and radiation belts shield humans from significant radiation damage in LEO. Spaceflight radiation is considered low dose-rate exposure compared with acute radiation terrestrial treatment of cancer. Radiation exposure on the ISS ¹⁰ is 30 times Earth’s daily background radiation, on the Moon ⁶⁰ it is 78 times Earth’s background, and for a Mars mission it is 230 times Earth’s background. ⁵⁹ Radiation exposure for cancer treatment is 9 million to 16 million times Earth’s background daily dose. ⁵⁶

The main health and safety concern is the occurrence of an acute solar flare radiation exposure causing tissue damage or death and the development of cancer in the future, as well as possible other health problems related to cardiac or cognitive dysfunction. NASA can construct radiation safe havens using appropriate shielding to protect against acute solar flare biological radiation damage. ⁵⁴ However, there is currently no long-term radiation damage protection from high-speed, high-energy penetrating galactic cosmic rays.

The effects of space radiation are different on men and women because of sex organ radiation susceptibility and increased radiation-induced lung cancer in women. ¹⁰ There is also an age risk. Older people have a greater overall risk of cancer, but younger people exposed to potential cancer-causing radiation, who have longer lifespans, may in the future develop cancer. ³⁷ NASA is using the U.S. Million Worker Study ³⁹ to provide an idea of overall risk, as well as epidemiological data, and a study from the National Council on Radiation Protection on sex-specific lung cancer risk.

Recently the OCHMO changed the radiation standard for missions beyond LEO to a mean 3% extra risk of dying from a space radiation-induced cancer that is not based specifically on sex or age. The new standard effectively increases the career of NASA astronauts and achieves male/female parity. It does this by establishing a universal standard for female and male astronauts of all ages. The career dose limit has been set at 600 mSv. The NASA level of accepted risk is below that allowed by the European Space Agency and the Russian Space Agency. The Japanese Space Agency uses a modified 600-mSv limit that does consider sex and age. This new standard will increase the allowed radiation dose to a 35-yr-old woman by a factor of ∼3 and to a 55-yr-old man by a factor of ∼1.5. ³⁷ Review of NASA radiation exposure data has not shown increased cancer deaths compared to Earth control data. ⁴⁶ The updated standard prior to its implementation was reviewed by the National Academy of Sciences ³⁶ and the NASA Bioethics Panel (Weyland M. Personal communication on the NASA OCHMO Bioethical Panel Report on Radiation Health Issues; 2021).

Spaceflight crews are considered radiation workers. Radiation workers on Earth could have appropriate radiation protection with shielding. However, this is not possible for spaceflight crews because of the mass, power, and cost limitations of shielding for both solar and galactic cosmic radiation. ^{10 , 36} Understanding all aspects of radiation exposure across a variety of space platforms will be critical to the development of effective prevention and treatment countermeasures in the future. Regardless, NASA accepts the “as low as reasonably achievable” level for radiation safety for astronauts. Based on mission length and when the mission occurs, the radiation risk may be significantly higher.

Eye and brain changes.

Spaceflight associated neuro-ocular syndrome (SANS) is manifested during long-duration ISS spaceflight lasting 3 or more months in >70% of crewmembers. Although it was thought to involve both the eye and the brain, the definition was mainly focused on the eye. As more information has been obtained, the definition now includes findings in the eye, brain, and perhaps is even associated with venous blood flow. Documented eye changes include disc edema, choroidal folds, cotton wool spots, nerve fiber layer thickening, globe flattening with permanent scleral remodeling, ^{24 , 25} and hyperopic shift in the eye. In the brain, the gray matter volume decreases around the base of the brain, and regional gray matter volume increases in the sensorimotor cortices. Also noted are ventricular expansion and extracellular fluid shifts, upward position shift of the brain with spaceflight, and intracranium volume increases. ¹⁹ Findings indicate that the changes are greater the longer the mission (i.e., 6-mo crew < 12-mo crew). Full and partial recovery are seen at 6 mo postflight. Some of the findings in which there was only partial or no recovery seen are in choroidal folds, flattening of the back of the eye, and brain ventricular volume. ²⁵ Some of these brain changes may occur with aging alone; however, all the brain changes seen during an ISS mission were greater than the changes expected for aging over the same time. ²⁵

Deep vein thrombosis.

Two observations of left internal jugular deep venous thrombosis occurred on the ISS, one of which was found in real time, resulting in concurrent anticoagulation therapy. ^{1 , 26} Findings included stagnant and reversed jugular blood flow in 6 out of 11 crewmembers studied. ²⁶

Possible mechanisms for the development of SANS and a neck deep vein thrombosis are currently not known, but could include chronic partial intracranium/neck outflow obstruction due to loss of hydrostatic forces, which induces a headward fluid shift, or other possible small secondary increases in intracranial pressure. It is also uncertain at the present time the level of risk to long-duration crewmembers for both acute and long-term health this/these condition(s) cause(s).

Lunar and Mars health care.

CHS serves as the healthcare provider for astronauts who could be assigned a space mission (active astronauts) and provides a comprehensive Astronaut Occupational Health program for the purpose of collecting and analyzing astronaut occupational health data for both active astronauts and any NASA astronaut who is no longer in flying status. This category includes astronauts who are still working for NASA in management positions as well as astronauts no longer working at NASA.

Exploration Medical Capability is a research and development arm of the HRP that advances medical system design and risk-informed decision making for missions beyond LEO to allow for acceptable medical care in extreme environments. Both CHS and Exploration Medical Capability are concerned about how medical care for lunar and Martian missions will change from the current ISS paradigm. Precision/personalized medicine and autonomous medical care are areas they are both investigating and ones that will be important for long-duration spaceflight. Although lunar stays at first will be a month or less, stays for much longer time are in the planning stage. The different potential problems for lunar and Mars healthcare are:

Lunar medical care:

1. Less volume and mass allocation for equipment and supplies;

2. Decreased replenishment of medical supplies;

3. Increased radiation exposure for supplies that may affect/decrease shelf life of nutrients, medications, and laboratory reagents;

4. Repatriation to Earth for health reasons may take up to 30 d;

5. Just-in-time training and medical skills practice requirements; and

6. Continued Earth-based medical consultation as needed.

Mars medical care:

1. Less volume and mass allocation for equipment and supplies;

2. Probable predeployment of equipment and supplies—concern regarding quantity and shelf life;

3. Increased radiation exposure for supplies that may affect/decrease shelf life of nutrients, medications, and laboratory reagents;

4. Repatriation to Earth for health reasons at best would take up to 6–7 mo;

5. Enhanced just-in-time training and medical skills practice requirements; and

6. Communication between Earth and Mars will take from 4–20 min each way based on the distance between the two planets and, depending on the Sun’s location, the communication gap may be much longer.

   1. Need for more autonomous medical procedures.

   2. Medical expertise onboard the mission and at the right location. For example, if two crew are in Mars orbit and two crew are on Mars:

      1. the health care provider would need to be where the problem is;

      2. and not be the one with the problem.

Autonomous medicine.

A Mars mission requires an autonomous medical system that could perform the right diagnostic and imaging test and then prescribe a therapy that works and is available at the time needed. NASA medical planners need to have knowledge of what medical conditions could/will occur and have this information available aboard the spacecraft. If treatments require just-in-time training or operator proficiency, such learning and training facilities will also need to be available at the right location in the Martian spacecraft or habitat.

Personalized/precision medicine.

There are many factors that help determine how a person will react to conditions that cause medical illnesses. This may include their sex and age and their current state of health. Some define personalized medicine as an individual treatment for each person and precision medicine as potential therapy for similar groups of people. In either case, the premise is that by knowing about that person or a similar group, tailored/specific prevention, diagnosis, and treatment plans would be available. Knowledge for these health “plans” would be based on the person’s genes and gene biomarkers. Identifying treatment approaches and preventative care based on an individual’s genomics could shape the behavioral health, environmental, and lifestyle factors to ensure crew health and performance for space missions. ¹³

ISS.

The ISS will be used in preparation for Mars mission scenarios to measure the time courses of physiological and psychological adaptations to spaceflight to inform crew health and performance risks during multiyear deep space exploration missions. ⁴² Abundant health and biomedical data exist for staying 6 mo in microgravity on the ISS, but little exists up to and beyond 1 yr. HRP is seeking to extend systematic data collection to determine if, how, and why anatomical and physiological changes continue in crewmembers for spaceflight durations that would mimic a round trip in microgravity to Mars and back.

The study is called Complement of Integrated Protocols for Human Exploration Research (CIPHER). CIPHER consists of 17 total studies: 12 NASA/HRP studies + 5 International Partners studies (CNES, 2 CSA, DLR, JAXA). It is a highly integrated study that looks across the multiple systems in the human body by collecting data, biological samples, and various measurements before, during, and after an astronaut’s mission in space. ⁴⁴

Analogs.

NASA uses terrestrial analogs for specific aspects of space missions. The three types of analogs include:

1. Those that mimic some of the physiological changes that occur in microgravity. For example, the European Space Agency (ESA)/DLR envihab bed rest research unit that is studying the eye and brain changes of spaceflight using a strict head down bed rest model. ¹⁶ HRP is now studying potential SANS countermeasures. ²⁰

2. Confinement and isolation chambers to study behavioral health and psychological stressors, including changes in circadian rhythms, and effects of culture and mixed sex crews; for example, the Human Exploration Research Analog and the Russian Institute for Biomedical Problems isolation chamber studies for learning the best methods for establishing long-lasting teams and leadership to maximize interpersonal relationships.

3. Real work environments located in remote or harsh environments that mimic the Moon or Mars, such as the National Science Foundation Antarctica Station, where science and living logistics are performed in an isolated, cold, and difficult situation for extraction if some behavioral health or medical problem occurs.

Organizational changes.

The Human Exploration and Operations Directorate that oversaw the ISS and the commercial crew program as well as the human spaceflight research and development activities has been split into two organizations: Space Operations Mission Directorate and the Exploration Systems Development Mission Directorate. The Space Operations Mission Directorate will oversee the operational human spaceflight programs including the ISS, commercial crew, cargo mission, and Human Spaceflight Capabilities’ CHS, medical operations and the HRP, and biomedical research. The Exploration Systems Development Mission Directorate will oversee the Artemis Moon program and the Moon to Mars program. This will include not only oversight of all the spacecraft systems, but also the responsibility for using the experience gained from the Artemis Program and adapting it for a human mission to Mars. Critical to the success of these two directorates is the effective advancement and integration of commercial spaceflight and international partner participation.

Helping advance the commercial spaceflight sector and increasing NASA’s biomedical knowledge.

HRP and the Translational Research Institute for Space Health at the Baylor College of Medicine (TRISH) can share lessons learned and guide and give back to the commercial community from NASA’s 50+ yr of biomedical experience and TRISH’s 6-yr research effort on HRP’s behalf. HRP and TRISH can share ground and space health and medical data while they establish healthy and mutually beneficial relationships as a foundation for future collaborations on space missions. HRP wants to engage in commercial science since giving back is part of NASA’s governmental mandate of using public funds wisely, and to foster the commercial space industry by sharing health and safety knowledge. HRP can be helped by commercial space efforts when there are research opportunities for HRP to obtain a greater N (i.e., a greater number of research subjects to better define space health risks and inform NASA’s medical standards). Therefore, commercial platforms will be the future locations for LEO spaceflight biomedical research and collecting health information.

TRISH has been able to take the lead for these research activities by establishing fast and efficient relationships with the commercial industry, and they successfully managed a biomedical research program for the SpaceX Inspiration 4 mission. TRISH has also announced a medical research program to study astronauts’ health and performance during commercial spaceflights.

The program, called Enhancing eXploration Platforms and Analog Definition (EXPAND), will collect data from multiple flights and keep it in a centralized database in order to improve the health of astronauts and find new innovations for use at home on Earth. The first mission to collect data for EXPAND was the 3-d long orbital Inspiration 4 mission that was in orbit between September 15 and 18, 2021, in which the Inspiration4 crew participated in 6 biomedical research experiments.

HRP and TRISH have taken the first steps. NASA HRP and TRISH and the commercial spaceflight industry can learn to work together while managing their different priorities. Doing so is the future of space exploration, since there are still a lot of health and medical unknowns.

Working with spaceflight international partners.

NASA has had a long history of collaborating with spacefaring international partners. ⁸ An important and significant area has been in space biology and medicine. Starting early in the space era, NASA Life Sciences has benefited from cooperation with Russia on their Bion free flyers to study model organisms and human physiology during the NASA-Mir Program, on the ISS, and in ground-based analog studies. The ESA, as well as Canada and ESA’s individual member states from Germany, France, and Italy, also collaborated with NASA Life Sciences in Shuttle Space Labs, on the ISS, and in ground-based analog studies. NASA and the Japanese Space Agency (JAXA) also have successfully worked together in the Shuttle Spacelab and ISS life science studies.

NASA will continue to value and share spaceflight opportunities with international partners as planning proceeds for the Artemis Program. Together with greater diversity within its own workforce, NASA will continue to improve its mission success.

Improving NASA’s mission.

NASA’s missions are improved by hiring the best employees. This includes everybody who works for NASA regardless of their sex, race, ethnicity, or age. NASA appreciates a diverse workforce. NASA has been voted by its employees as the best place to work in the Federal government for the ninth consecutive year. Over the last 13 yr, led by NASA Administrators Charles Bolden, James Bridenstine, and Bill Nelson, there has been a strong commitment to hire and promote those that can get the job done. ³ This has led to a more inclusive and diverse workforce, where leadership positions are starting to reflect the country’s demographics. The symposium highlighted not only the accomplishments of several NASA women and people of color ^{1 , 28 , 58} as leaders, but also their hard work in breaking barriers so their talents could be appreciated. ^{28 , 47 , 58}

The operational and research life sciences organizations that maintain humans in space, the Human Health and Performance Directorate at the Johnson Space Center, and the HRP have made major strides over the last 10–15 yr ²⁷ in that their workforce is now about 44% women and 56% men. HRP’s research portfolio statistics show that research proposals awarded by sex is 16% for female investigators and 18% for male investigators from the submitted research proposals. Currently about 40% of the proposals come from female investigators and 60% from male investigators. The life sciences organizations, as well as the rest of NASA, continue to promote highly skilled diversity in the workforce so spaceflight exploration missions can be accomplished.