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Review of NASA Plans for the International Space Station (2006) / Chapter Skim
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4 Biomedical Research Issues
Pages 18-25

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From page 18...
... However, during 6-month stays at a lunar outpost on a 3-year round trip to Mars, the exposure to radiation has the potential to produce significant long-term effects that may not be limited to cancer induction.6,7 Classically, the radiation risk was predominantly thought to be associated with damage to the proliferating cells in organs whose function relied heavily on cell renewal systems to replace their damaged components.8,9 Recently, this concept has been called into question by a number of human and rodent studies.10-12 For example, 20 to 50 percent of brain tumor patients who receive fractionated largefield or whole brain irradiation and survive longer than 6 months have measurable cognitive deficits;13-15 of these, 10 to 15 percent progress to a condition similar to that seen in Alzheimer's patients. In rodents, the late radiation effects produced by single dose or short fractionation schemes are not predictive of the late effects produced by prolonged fractionation schemes in brain, kidney, lung, and heart, where the functionality is predominantly the nondividing cells.16-19 Mechanistic studies have demonstrated that ionizing radiation produces a chronic increase in the intracellular reactive oxygen species, which leads to a chronic inflammatory response.20 Importantly, the level of reactive oxygen species and inflammation in nondividing cells never returns to its original level after irradiation, and so these cells, which do not die, function abnormally for months or years after 18
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From page 19...
... Importantly, the low linear energy transfer (LET) radiation damage to the kidney and the brain, including cognitive impairment, appears to be modifiable in both humans and rodents using pharmacological interventions.36,37 Although there are no data on mitigating the late effects in liver, kidney, lung, and brain produced by high-LET radiation or mixed radiation fields, there are suitable pharmacological agents that could be tested on the ISS or on the Moon now.38,39 Finding: There is insufficient information about the mixed-beam radiation effects on biological systems to confidently derive risk estimates for a Mars mission.
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From page 20...
... Previous reports have identified problems of adaptation to capsule living such as anxiety, depression, withdrawal, interpersonal hostility directed against crewmates and/or mission controllers and the home organization, sleep disturbances, psychosomatic symptoms, and counterdependence.54 A 2006 IOM and NRC report commented on the added difficulties of communicating and establishing positive relationships within groups that are diverse (with respect to ethnicity, gender, education, organizational norms, and general culture) and between spacefarers and their home organizations, and the tendency of these difficulties to exacerbate other problems.55 Although there is a sufficiency of data from spaceflight to establish the psychosocial realm as one that must be seriously considered, considerable corroborative evidence has been derived from research in simulated and analog environments.a Many of these environments involve isolation, confinement, and remoteness from "normal" social networks and accustomed sites; some are in locations where the outside environment is dangerous, life support systems are crucial, and access is limited.
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From page 21...
... DATA Life Sciences Data Archive and the Longitudinal Study of Astronaut Health The end points of all research are new knowledge, technologies, and products. In the realm of medical operations and biological responses to spaceflight, this information is codified in the Life Sciences Data Archive and the Longitudinal Study of Astronaut Health.57 These data will never be recreated and therefore constitute unique resources for future mission planners.
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From page 22...
... Recommendation: NASA should critically analyze both disaggregated and aggregated data (such as that in the Longitudinal Study of Astronaut Health and the Life Sciences Data Archive) to derive confidence bands for medical risks.
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From page 23...
... 2004. Chronic oxidative stress and radiation-induced late normal tissue injury: A review.
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From page 24...
... 1985. Evidence for similarities between radiation damage expressed by beta-ara-A and damage involved in the interaction effect observed after exposure of V-79 cells to mixed neutrons and gamma irradiation.
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From page 25...
... 2001. Safe Passage: Astronaut Care for Exploration Missions, p.
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Key Terms

  • late effects
  • radiation effects
  • sciences data
  • bone mineral
  • mars mission

  • exploration missions
  • astronaut health
  • fractional gravity
  • late radiation
  • radiation field

  • radiation damage
  • duration space
  • mixed radiation
  • radiation exposure
  • radiation risk

  • space environment
  • space radiations
  • current data
  • bone loss
  • bone density

  • late normal
  • data archive
  • future mission
  • trabecular bone
  • biological effects

  • effects produced
  • animal experiments
  • life support
  • normal tissue
  • astronaut care


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