Astronaut Health and Safety Regulations: Ionizing Radiation

Vol. 10 No. 4


Alyssa Megan Sieffert is a mentor for the Youth Space Institute in San Diego and works with Thermo Fisher Scientific Inc. The Youth Space Institute’s recent experiment regarding materials blocking ionizing radiation is expected to launch in May 2014. For questions, please send an email to

In Gravity, Alfonso Cuarón’s science fiction thriller, Sandra Bullock dodges space debris, avoids suffocation, and attempts to land a burning space vehicle when a routine maintenance procedure goes wrong.1 Although these dangers to astronauts are readily apparent and easily publicized in Hollywood films, what about the dangers that cannot be easily publicized? Exposure to ionizing radiation is an issue encountered not only by radiation workers here on Earth, but also by workers in high altitudes and in space. Because modern technology is insufficient to eliminate the dangers associated with exposure to ionizing radiation, health codes attempt to limit ground-based workers’ exposure to radiation. Similar codes, based on various treaties and federal regulations, are used to limit astronauts’ exposure in space. This article provides a general overview of the radiation-related health codes applicable to NASA astronauts and spaceflight participants.

Astronauts on the International Space Station (ISS) are exposed to trapped radiation, galactic cosmic radiation (GCR), and energetic solar particle events (SPE).2 And while ionizing radiation exposure is known to cause cancer,3 short-term exposure to ionizing radiation can also induce nausea, vomiting, depilation, and hemorrhaging.4 Beyond the danger of short-term exposure and the risk of cancer, long-term exposure to ionizing radiation can also cause destruction of the intestinal lining, internal bleeding, damage to the central nervous system, and death.5 Based on ionizing radiation exposure alone, space exploration could be one of the most life-threatening career choices a bright young astronaut could make.6

All of this begs the question, “Do systems exist to assure that the health and well-being of our talented astronauts is being looked after?” After all, it seems logical that if regulations already exist to protect workers exposed to ionizing radiation on the ground (e.g., employees in nuclear power plants or in a dentists’ office), then regulations should exist that protect our astronauts.7 The answer to this question lies in the treaties, statutes, and agency rules that govern space law. Within this framework, the remainder of this article focuses on the United States’s authority to create regulations covering the far ends of the space explorer employment classification spectrum, from astronauts that are employees of NASA to spaceflight participants; the current limitations due to such regulations; and questions that may be encountered as regulations for space travel are developed.

United States Outer Space Jurisdiction

Under the property principle “cujus est solum ejus est usque ad coelum,” the United States would own the air above the nation and could govern space law within the regions of space above the territories controlled by the United States.8 The aviation industry bolstered the idea of property ownership by a sovereign nation “to the periphery of the universe” under United States v. Causby.9 Thus, since 1946, any region accessible by aircraft has been considered a “public highway,” which can be regulated by the state below that airspace.10 But what about the altitudes inaccessible by aircraft? The international community has typically recognized the Kármán Line (an altitude 62 miles above the ground, where the atmosphere is so thin that the speed required to generate enough lift to keep the plane aloft would cause the plane to reach orbital velocity) as the demarcation of airspace and outer space.11 The international community has also agreed that altitudes above the Kármán Line are governed by the Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, Including the Moon and Other Celestial Bodies, also known as the Outer Space Treaty (OST).12

The OST prohibits national appropriation of outer space.13 However, under the OST, space objects and their crews are subject to the jurisdiction of the launching state, where the launching state includes any state that procures a space object or serves as the origin of a space object.14 Beyond application to government launches, the OST subjects commercial objects to the jurisdiction of the state from which the space object is launched or the state in which the space object is procured.15 Based on this premise, any astronaut located on a vehicle procured or launched in the United States would be subject to United States laws. Thus, any workplace safety regulations that apply to individuals in the United States would also apply to individuals beyond the Kármán Line who are aboard a craft launched from or procured in the United States. Because the Occupational Safety and Health Administration (OSHA) regulates workplace safety in the United States, any workplace in which workers might be exposed to ionizing radiation would be subject to OSHA regulations, including workplaces in outer space.

OSHA Regulations

OSHA was established in 1970,16 and federal agencies (including NASA) became subject to OSHA workplace safety regulations in 1980.17 Although OSHA does not fine federal agencies, safe work conditions are required by statute and are assured through the escalation of employee complaints.18 In 1982, OSHA declared that astronauts were radiation workers, subjecting their employers to workplace safety regulations that protect employees from the dangers of ionizing radiation.19 Because most space explorers are employees of NASA, NASA must provide a workplace safe from ionizing radiation.

Taking into consideration current limitations on the ability to create radiation-free workplaces, the protection provided for radiation workers is a cap on the amount of ionizing radiation to which an employee can be exposed. Based on the guidelines set forth by OSHA and the National Council on Radiation Protection (NCRP), a worker’s ionizing radiation exposure should be kept “as low as reasonably achievable” (ALARA).20 As defined by the Nuclear Regulatory Commission (NRC), keeping ionizing radiation exposure ALARA includes:

[M]aking every reasonable effort to maintain exposures to radiation as far below the dose limits in this part as is practical consistent with the purpose for which the licensed activity is undertaken, taking into account: the state of technology; the economics of improvements in relation to state of technology; the economics of improvements in relation to benefits to the public health and safety; and other societal and socioeconomic considerations.21

However, ground-based radiation worker limits proved too restrictive for space exploration and, under 29 CFR 1960.18, NASA was granted a waiver by OSHA to institute independent limits for ionizing radiation exposure.22 Health standards for astronauts in all stages of flight are established by NASA’s Office of the Chief Health and Medical Officer (CHMO), including standards for radiation exposure.23 NASA follows the ALARA principal, but additional guidance for radiation exposure may be gleaned from the reports of the National Academy of Sciences, the National Council on Radiation Protection (NCRP, a nongovernmental, not-for-profit public service organization chartered by the United States Congress that disseminates guidance on radiation protection), and various other governmental and nongovernmental agencies.24

Current Dose Limits

Currently, based on NCRP recommendations, NASA limits career exposure to amounts that cause a three percent (3%) risk of exposure-induced death (REID).25 However, setting forth such guidelines is complicated because exposure to ionizing radiation affects individuals of varying ages and genders differently. For example, a 35-year-old male’s REID due to cancer reaches 3 percent upon 720 mSv exposure.26 In contrast, a 35-year-old female reaches the REID due to cancer threshold upon 550 mSv exposure.27 Additional dose limitations to prevent noncancer effects are also set forth by NASA, and to avoid noncancer effects in astronauts’ central nervous systems, exposure must be limited to 100 mSv per year.28 This would be roughly equivalent to receiving about 50 head CT scans per year.29 However, current crew members aboard the space station receive about that much exposure in only a half a year during “good” years. Good years occur when the number of sunspots are high and the Sun’s magnetic field is strong enough to deflect particles (referred to as a solar maximum), while solar minimums result in fewer deflections of harmful particles due to the opposite conditions. During six months at solar maximum, the ISS crew’s exposure averages 80 mSv, and during six months at solar minimum it averages 160 mSv.30 Thus, for the protection of the health and safety of our astronauts, time aboard the station and in space is limited.

Beyond limiting the length of astronauts’ visits to the ISS, dose limitations also pose potential constraints on a 2030 visit to Mars.31 Some sources estimate that exposures for a Mars exploration mission could exceed 1,000 mSv, with a 4.2% REID for 40-year-old males and a 5.1% REID for females.32 This means that under current standards, astronauts’ ability to spend substantial amounts of time in their research environment is limited not only while on the ISS, but also as part of any trip planned beyond the immediate reaches of our planet. Although the current regulatory scheme could be seen as a restriction on future space travel, research is being conducted into materials for blocking GCRs and SPEs, and studies are being conducted to examine the extent to which dose limits can be pushed before causing long-term harm.33 Additionally, not all space explorers can call outer space their workplace since a senator, a congressman, and at least seven “space tourists” have made it into space.

Spaceflight Participant Regulations

Regulation of private space explorers is set forth by the Department of Transportation, as described in Title 51.34 Under the Commercial Space Launch Act (CSLA), the Federal Aviation Administration (FAA) regulates spaceflight by issuing licenses to commercial companies for launches and reentries.35 Any licensed launch or reentry is then subject to regulations protecting spaceflight participants.36 A spaceflight participant is an individual who is not a crew member and likely not a federal employee, and therefore not protected under OSHA regulations.37 Thus, nonemployees are likely to be exempt from dose limitations.

The FAA does have the power to issue safety regulations, but these regulations can only be issued after a design feature or operating procedure has caused an event that poses a risk of, or has actually caused, a serious or fatal injury.38 Furthermore, such limitations only apply to launches where individuals are carried for compensation.39 Thus, some nonemployees may have the capacity to spend extended periods of time in space without regard to OSHA regulations simply based on their provision of consent. However, upon death due to radiation exposure, the FAA could have the authority to create regulations limiting spaceflight participants’ exposure to ionizing radiation. For this reason, it is important to note that all spaceflight participants are required to provide informed consent to the dangers of space launches and reentries prior to participating in spaceflight.40 Thus, no spaceflight participant can enter into space without being aware that he or she will be exposed to ionizing radiation with the potential for serious bodily injury or death. The wait-and-see approach for creating regulations for nonemployees has the potential to allow the space industry to shape technology and internal standards without regulatory restraints and allow the space industry to self-regulate to provide for the safety of spaceflight participants. And although this approach also has the potential to result in legislation when tragic circumstances occur, the system was designed to avoid overregulation of the budding industry and may hold the key to models for future space regulations.41

Additional Considerations

As regulations continue to develop, future questions will include: Do current regulations cause discrimination in the space law workplace?42 Will federal agencies continue to have the authority to regulate spacecraft and their crews?43 What will happen when a private company sends an individual into space, or NASA sends an independent contractor into space and the person is outside the purview of the FAA or OSHA? For the time being, powers granted under the OST allow the FAA to create safety regulations to protect spaceflight participants under certain circumstances, and allow NASA to institute career limits for NASA astronauts. Until medical research expands our understanding of the effects of space radiation or until materials are developed to protect individuals from radiation exposure to extend space missions, the dose limit for NASA astronauts shall remain at 3% REID, thus protecting astronauts so that they can continue to embark on “the most hazardous and dangerous and greatest adventure on which man has ever embarked” with assurances of their protection from ionizing radiation.44


1. Warner Bros. Pictures, Gravity, Warner Bros. Entm’t Grp., (last visited Mar. 29, 2014).

2. Space Radiation Analysis Group, Johnson Space Center, Spaceflight Radiation Health Program at JSC, Nat’l Aeronautics & Space Admin., (last visited Mar. 29, 2014).

3. ACS, Radiation Exposure and Cancer, Am. Cancer Soc’y (Mar. 29, 2010),

4. Robert A. Curtis, Introduction to Ionizing Radiation, Dep’t of Labor, (last visited Mar. 29, 2014).

5. EPA, Health Effects, Envtl. Prot. Agency (Aug. 7, 2012),

6. “Astronauts are highly trained, extremely smart individuals, so paradigms for acute risk should perhaps focus more on the effects of radiation on cerebral white matter and nonhippocampal based cognitive functions (e.g., reaction time, fatigue, inefficient memory retrieval), and not so much on hippocampal-based cognitive functions such as new learning and consolidation, let alone novel objection recognition.” Space Radiation Standing Review Panel, 2013 Space Radiation Standing Review Panel, Nat’l Aeronautics & Space Admin., (last visited Mar. 29, 2014).

7. OSHA, Ionizing Radiation, Dep’t of Labor, (last visited Mar. 29, 2014).

8. Gbenga Oduntan, Sovereignty and Jurisdiction in the Airspace and Outer Space, 59–64 (2012).

9. United States v. Causby, 328 U.S. 256, 260 (1946).

10. Id. at 62.

11. Matthew J. Kleiman, The Little Book of Space Law (Am. Bar Ass’n, 2013), at xii.

12. Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, Including the Moon and Other Celestial Bodies art. I, opened for signature Jan. 27, 1967, 18 U.S.T. 2410, 610 U.N.T.S. 205 [hereinafter OST].

13. Id. art. II.

14. Convention on Registration of Objects Launched into Outer Space, opened for signature Jan. 14, 1975, 28 U.S.T. 695, 1023 U.N.T.S. 15 (entered into force Sept. 15, 1976).

15. Benjamin Perlman, Grounding U.S. Commercial Space Regulation in the Constitution, 100 Geo. L.J. 929, 933 (2012).

16. OSHA, Reflections on OSHA’s History, Dep’t of Labor (Jan. 2009),

17. Exec. Order No. 12,196, 45 Fed. Reg. 12769 (Feb. 26, 1980).

18. OSHA Office of Training and Education, OSH Act, OSHA Standards, Inspections, Citations and Penalties, Dep’t of Labor (May 1996),

19. Mark Weyland & Michael Golightly, Monitoring and Modeling Astronaut Occupational Radiation Exposures in Space: Recent Advances, NASA Technical Reports Server (Feb. 1, 1999),

20. Richard S. Williams, NASA Space Flight Human System Standard Volume 1: Crew Health, Nat’l Aeronautics & Space Admin. (Mar. 5, 2007),

21. 10 C.F.R. § 20.1003.

22. 29 C.F.R. § 1960.18(a).

23. NASA, NASA Policy Directive 1000.3D, Nat’l Aeronautics & Space Admin (Mar. 7, 2014), See also 51 U.S.C. 20013(a) (2012).

24. National Council on Radiation Protection & Measures, Our Mission, (last visited Mar. 29, 2014). National Council on Radiation Protection & Measures, Guidance on Radiation Received in Space Activities, Working on the Moon (July 31, 1989),

25. Williams, supra note 20.

26. Id.

27. Id.

28. Id.

29. U.S. Food and Drug Administration, Radiation-Emitting Products, Dep’t of Health & Human Servs. (Aug. 06, 2009),

30. Lyndon B. Johnson Space Center, Understanding Space Radiation, Nat’l Aeronautics & Space Admin. (Oct. 2002),

31. Barack Obama, Remarks by the President on Space Exploration in the 21st Century, Nat’l Aeronautics & Space Admin. (Apr. 15, 2010),

32. Jeffrey R. Davis et al., Fundamentals of Aerospace Medicine 233 (2008).

33. See Sarah Fred, San Diego Science Alliance Youth Space Institute, YouTube (Feb. 21, 2014),; NASA, The Right Stuff for Super Spaceships, Nat’l Aeronautics & Space Admin. (Sep. 16, 2002),; Johnson Space Center, Human Exploration Research Opportunities (HERO) Appendix E, Nat’l Aeronautics & Space Admin., (last visited Mar. 29, 2014).

34. 51 U.S.C. § 50901 (2012).

35. House Committee on Science, Space, and Technology’s Subcommittee on Space, Subcommittee Discusses Updating the Commercial Space Launch Act, Comm. on Sci., Space, & Tech. (Feb. 4, 2014),

36. 51 U.S.C. § 50904(d) (2012).

37. Id. § 50902(17).

38. Id. § 50905(c).

39. Id.


41. U.S. House of Representatives Committee on Science, Space, and Technology Subcommittee on Space, Necessary Updates to the Commercial Space Launch Act, U.S. House of Representatives (Feb. 4, 2014),

42. Miriam Kramer, Female Astronauts Face Discrimination from Space Radiation Concerns, Astronauts Say, (Aug. 27, 2013),

43. See Decisional Order, Michael P. Huerta v. Raphael Pirker (Mar. 6, 2014), available at

44. John F. Kennedy, Moon Speech – Rice Stadium, Nat’l Aeronautics & Space Admin. (Sep. 12, 1962),

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