Long exposure to microgravity conditions does some bad things to the human body. The heart shrinks, bones become weaker and cells are exposed to damaging radiation.
The impacts will become more acute as NASA launches astronauts to the moon and Mars, which lie outside of the protection of the Earth’s Van Allen belt. The space agency has been conducting research aboard the International Space Station to find ways of addressing these risks before flights begin in the 2020’s.
The Trump Administration wants to end direct federal support for the station in 2024 to free up funding for human lunar missions. However, a recent NASA Inspector General audit indicates doing so could leave some vital human health research being left uncompleted, resulting in greater risks to astronauts on deep-space missions.
Below is an excerpt from the audit that discusses the human health research being conducted on the space station and the risks involved of ending station support in 2024.
NASA’s Management and Utilization of the International Space Station
Office of Inspector General
July 30, 2018
Remaining Research Tasks and Impact
of Maintaining the ISS on Future Exploration Plans
After nearly 20 years in orbit, the ISS is nearing a crossroads when NASA needs to make decisions regarding crucial, unfinished research needed to enable deep space travel and competition for funding by the next generation of exploration systems to enable that travel. In order to travel deeper into space for extended periods of time, NASA is working to understand and mitigate the human health risks that environmental factors such as radiation have on astronauts.
The Agency is also using the ISS’s microgravity and vacuum environments as a test bed to demonstrate technologies for potential use in future space systems. Balanced against all of these accomplishments and opportunities are the tremendous costs required to maintain the ISS and – absent a significant increase in NASA’s overall funding – the necessity to redirect much of those funds to future space missions beyond low Earth orbit.
Human Health Research
Understanding and mitigating risks to astronaut health and performance for long-duration spaceflight has been a top priority for the Station since its inception. Multiple NASA offices have a role in developing procedures, medications, devices, and other strategies to mitigate these risks. The Human Research Program within the Human Exploration and Operations Mission Directorate serves as the Agency’s primary resource for addressing human health and performance issues related to space travel.
To track its progress in mitigating health risks such as space radiation exposure, sensorimotor alterations, and cardiac rhythm problems, NASA created an “Integrated Path to Risk Reduction” in 2014. The plan’s matrix assigns a rating denoting likelihood and consequence of occurrence. “High Risk” threats are listed in red, “Medium Risk” threats in yellow, and “Low Risk” threats in green. Risks requiring research on the ISS are listed in gray, and ISS-specific milestones are displayed as orange triangles. The Agency updated the plan most recently in February 2018 (see Figure 4).
a Each risk is given a rating based on the likelihood of the risk occurring and the potential consequence of the risk occurring. Risks are assigned a “likelihood” rating of 1 to 3: 1 for low likelihood (less than 0.1 percent); 2 for medium likelihood (between 0.1 percent and 1 percent); or 3 for high likelihood (equal to or more than 1 percent). Risks are also assigned a consequence rating of 1‐4 (low to high) based on assessment of the risk’s in‐mission health and performance outcomes and long‐term health outcomes. The risks are then assigned a color based on their composite likelihood and consequence ratings – red for “High Risk,” yellow for “Medium Risk,” and green for “Low Risk.” More information on each of these risks can be found on HRP’s website: https://humanresearchroadmap.nasa.gov.
Not all Human Health Risks and Technology Gaps will be Addressed by 2024
Despite NASA’s efforts, multiple human health risks and technology gaps will remain after the end of FY 2024 when funding for the Station’s operation is scheduled to end. Specifically, as of the February 2018 update to the Integrated Path to Risk Reduction, NASA forecasts that research for 6 of 20 human health risks requiring the ISS will not be complete by the end of 2024.22 In addition, another 2 risks will not be complete until sometime in 2024, increasing the potential that schedule slips could push their completion past the end of that fiscal year.
Human Health Risk Gaps
Under the Agency’s current plan, at least 8 human health risks will continue to need testing on the ISS in the 2024 time frame or after, including research into cognitive or behavioral conditions, inadequate food and nutrition, team performance decrements, spaceflight associated neuro-ocular syndrome, long-term storage of medication, sensorimotor alterations, altered immune responses, and host-microorganism interactions (see Figure 6).24
According to NASA officials, while it would be optimal to conduct research for 5 of these 8 risks onboard the ISS, the Agency may be able to use ground-based testing methods to finish the research if the ISS is no longer available. NASA has developed preliminary plans for such ground-based testing, but it has not created detailed contingency plans that would address factors such as cost, schedule, and technical risks if the Agency was required to rely on these alternate platforms instead of the ISS.
Furthermore, officials stressed that three risks – spaceflight associated neuro-ocular syndrome, sensorimotor alterations, and altered immune response – will need to be fully tested in a microgravity environment due to a lack of suitable ground‐based testing methods. If these risks cannot be tested on the Station, NASA could be forced to accept higher health risks than planned for future exploration missions.
a NASA is investigating whether the ISS will be required to mitigate cognitive or behavioral conditions risk from Medium Risk to Low Risk.
b Research into countermeasures for the sensorimotor alterations risk is currently on hold.
c Each risk is given a rating based on the likelihood and potential consequence of the risk occurring. Risks are assigned a “likelihood” rating of 1 to 3: 1 for low likelihood (less than .1 percent); 2 for medium likelihood (between .1 percent and 1 percent); or 3 for high likelihood (equal to or more than 1 percent). Risks are also assigned a consequence rating of 1‐4 (low to high) based on assessment of the risk’s in‐mission health and performance outcomes and long‐term health outcomes. The risks are then assigned a color based on their composite likelihood and consequence ratings.
Several NASA officials also stressed that additional one‐year missions may be required to increase the fidelity of human health risk data and further characterize risks. According to the Integrated Path to Risk Reduction, as many as 11 human health risks would benefit from these additional one‐year missions because they would provide more data than standard 6‐month ISS missions on how spaceflight impacts the human body over extended periods of time.25
For example, NASA’s lone one‐year mission conducted from March 2015 to March 2016 revealed previously unknown phenomena, including changes in astronaut gene expression, evidence of increased problems with fine motor skills, and slower recovery of mobility functions upon returning to Earth. A NASA official explained that the Agency would need to initiate these one‐year missions by 2019 in order for them to be complete by 2024. As of April 2018, NASA had yet to formalize plans for such missions.
Spaceflight Associated Neuro-Ocular Syndrome
According to NASA officials, the top human health risk that requires ISS-based testing through 2024 or later is research into spaceflight associated neuro-ocular syndrome.26 This risk occurs with astronauts on long-duration ISS missions who experience changes in eye structure and vision deficits. The underlying cause of these changes is unknown and therefore NASA is using the ISS to characterize the condition and develop countermeasures.
NASA officials stressed the importance of ISS testing for this risk due to its unique microgravity environment. The Agency is investigating ground-based testing methods. However, the Agency’s current Integrated Path to Risk Reduction predicts that countermeasures will not be fully tested on the ISS until the end of FY 2024, which leaves no margin for delay. NASA officials stated that predicting when this risk will be resolved is difficult because researchers have struggled to understand and mitigate it.
The officials further stated that additional one-year missions are needed to better understand this risk. Current mitigation options are limited to preflight screening, corrective lenses (in-flight and post-flight), aerobic exercise on-orbit, reduced sodium diet in-flight, frequent on-orbit ocular assessments, and reduction of carbon dioxide levels.
Among the countermeasures NASA is investigating are mechanical interventions, such as Lower Body Negative Pressure or selected compression devices worn on the lower body to redistribute body fluids. If NASA is not able to mitigate this risk, astronauts may face vision deterioration on long-duration exploration missions, likely impacting mission performance. Several NASA officials we spoke with stated that if mitigation options are not identified the risk could be a “showstopper” for long-duration crewed missions.
Another human health risk that requires the ISS for testing is research into sensorimotor alterations or the impairment of certain motor functions such as balance due to the transition from a microgravity environment to an increased gravity environment. This risk manifests itself with astronauts returning to Earth from the ISS who experience balance and coordination issues, making it difficult to walk and perform other simple motor tasks for up to several days after they land.27
According to the Integrated Path to Risk Reduction, NASA has put research into sensorimotor alterations on hold because mitigation strategies are only needed for missions that involve a Mars landing, and the Agency does not anticipate such a landing until at least the late 2030s. NASA officials cautioned, however, that the ISS is the best platform to conduct this research to prepare for future Mars landings because ground-based methods are currently not able to sufficiently replicate the effects of microgravity and spaceflight.
Altered Immune Response
The third human health risk that requires the ISS for testing through 2024 or later is research into altered immune responses. Crew experiencing this risk have noted changes to their immune systems, including atypical allergic symptoms and hypersensitivity reactions. NASA officials believe that altered immune response represents a significant risk for orbital missions 6 to 12 months in duration and exploration missions of extended duration due to prolonged exposure to stressful hazards such as isolation, confinement, and elevated radiation levels.
NASA is researching the clinical significance of altered immune response and plans to use the ISS to characterize risks and identify countermeasures. The Agency does not expect to mitigate this risk until FY 2025 because of the time needed to obtain inflight evidence to supplement post-flight data. NASA officials also said additional one-year missions are needed to further understand this risk; however, no plans have been formalized for such missions.
The Agency is also investigating this health risk using research in Antarctica to determine if the phenomenon is triggered by the space environment or simply extreme environmental conditions, but scientists are unsure whether a ground analog sufficiently simulates the space-induced phenomenon.
22 These risks include cognitive or behavioral conditions, inadequate food and nutrition, long-term storage of medications, sensorimotor alterations, altered immune response, and host-microorganism interactions.
24 Team performance decrements refers to the risk that the conditions on space missions may lead to inadequate functioning within a team, such as poor cooperation, coordination, and communication, and the associated impact to performance and behavioral health. Spaceflight associated neuro-ocular syndrome is induced by the microgravity environment and causes intracranial pressure changes that can lead to vision alterations. Sensorimotor alterations refer to the risk of impairment of functions like eye-head-hand control as a result of long-duration spaceflight. Host-microorganism interactions refer to the potential increased risk of susceptibility to certain viruses in the spaceflight environment.
25 The 11 risks that would benefit from additional one‐year missions include space radiation exposure, cognitive or behavioral conditions, inadequate food and nutrition, spaceflight associated neuro‐ocular syndrome, sensorimotor alterations, altered immune response, reduced muscle mass, reduced aerobic capacity, sleep loss, orthostatic intolerance, and bone fracture.
26 This risk was formerly known as “vision impairment due to intracranial pressure.”
27 Astronauts returning from 1-2 week Space Shuttle missions also experienced this phenomenon, but their symptoms generally dissipated within hours to days of landing.