NRC to NASA: Don’t Lower Radiation Standards for Lunar Missions

In a potential blow to NASA’s human spaceflight efforts, the National Research Council released a report today calling on the space agency to conduct more research on cosmic radiation before sending astronauts to the moon and Mars. NASA should not lower its radiation exposure standards to reach these goals.

The Committee on the Evaluation of Radiation Shielding for Space Exploration’s report (PDF) said the “lack of knowledge about the biological effects of and responses to space radiation is the single most important factor limiting prediction of radiation risk associated with human space exploration.”

As a result, prolonged operations on the moon could be curtailed. Mars exploration, which would require long transit times and stays on the the surface, could be ruled out entirely until scientists and engineers develop better ways of protecting astronauts.

The committee’s chairman, James van Hoften, told Reuters that NASA doesn’t fully understand the radiation risk, nor is the agency adequately funding research into how to properly protect astronauts. NASA is using old data, including research done on Hiroshima and Nagasaki atomic bomb survivors.

“One of the big issues is they have really cut funding for biology issues. It is tough on them when they don’t have any new money coming in. They are using old data,” the former shuttle astronaut said.

“Given today’s knowledge and today’s understanding of radiation protection, to put someone out in that type of environment would violate the current requirements that NASA has,” van Hoften added.

The committee’s report highlights the “central trade-off” that NASA faces on cost vs. safety for human lunar and Martian missions.

“On the one hand, increased mass is required to reduce exposure to radiation; on the other, costs limit the power and energy available for propulsion to put that mass into space and to operate it. At any accepted level of exposure to radiation, the requirement for additional mass may exceed the project costs; and at a given level of cost, exposure to radiation may exceed the acceptable level of risk,” the report states.

“The committee agrees that current permissible exposure limits, as specified in NASA standards, are appropriate. The committee strongly recommends that the permissible exposure limits specified in current NASA standards not be violated in order to meet engineering resources available at a particular level of funding.”

Astronauts on lunar and Martian missions will be exposed to more radiation than their colleagues in low Earth orbit. Additional radiation shielding will be required for astronauts living and working on the surface.

The committee made a series of recommendations to NASA to deal with these issues. The committee:

  • strongly recommends that the NASA’s Space Radiation Biology Research program be adequately funded. NASA should perform research at the NASA Space Radiation Laboratory aggressively to take advantage of the existing window of opportunity while this facility is still available. The results of the biological research will thus be able to impact the Project Constellation missions in the short term, as well as provide knowledge essential for management of space radiation risk in the long term.
  • recommends that all elements of Project Constellation employ the radiation protection and risk management limits necessary to meet the NASA radiation standards presented to the committee.
  • recommends that an independent radiation safety assessment continue to be an integral part of mission design and operations.
  • recommends that the nation’s space weather enterprise integrate its scientific expertise with operational capability through coordinated efforts on the part of NASA, the National Oceanic and Atmospheric Administration (NOAA), the National Science Foundation (NSF), and the Department of Defense (DOD).

What effect this would have on NASA’s lunar efforts was not immediately clear. It’s uncertain where the space agency would find money for the additional research given its tight budget.

NASA also has been battling weight problems on its Orion and Altair vehicles, resulting in efforts to lighten both of them. The space agency is also trying to close what could be a five-year gap between the retirement of the space shuttle in 2010 and the first flight of its Orion successor.