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Guest: Dr. Christopher Morrison; Topics: Space radiation, lifetime radiation limitations, legal limits, rodent GCR and radiation experimentation, terrestrial radiation simulations, space nuclear power & propulsion, supercooling conductivity.
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We welcomed Dr. Morrison back to The Space Show for a 67 minute discussion regarding space radiation issues for human spaceflight. Please check our blog from time to time as Chris will be posting new information on the subject over the near term. An early key discussion subject dealt with space radiation, GCRs, radiation experiments with mice and extrapolating such experiments to human spaceflight. Chris spent time talking about legal lifetime radiation imitation levels, made some comments about women astronauts, age, and radiation exposure as compared to men (that drove some controversy!), plus we talked about some of the radiation experiments by Dr. Charles Limoli and the Dr. Zubrin response. Our guest posted some of this information on our blog plus both Dr. Limoli and Dr. Zubrin were on the show talking about this research back in 2015. If you want to hear the program with Dr. Limoli, you can hear it here: https://www.thespaceshow.com/show/07-jul-2015/broadcast-2503-special-edition-0. Dr. Limoli's research and Space Show comments will be addressed later in this summary.
Chris took multiple phone calls during this program. Dave from Chicago called to talk about his Navy submarine nuclear experience plus his work later on in the commercial nuclear industry. Marshall called and raised the issue of flight time to Mars as compared to how the rodent radiation experiments were carried out. This subject was a major part of the program as our conversation continued. As for radiation, Chris talked about the GCRs being a bigger risk than the space radiation, why such risks were not here on Earth or a big item in in LEO spaceflight. Listener Ted then sent in emails suggesting that since crews to Mars would be volunteers, they would override the radiation lifetime limits. Chris seemed supportive of this as well though as I understand it, these are legal limitations and overriding them by volunteering might not be so easy. Tim called from Huntsville with similar volunteering comments. Ted sent in another note suggesting the laws could be changed.
At times during this discussion, Chris suggested that it was a problem dosing mice with a big radiation dose up front which would be roughly equivalent to what a human would get on a slower process over a year flying out to Mars for example. He suggested we need experiments that expose the mice over a long period of time to lower levels of radiation as a human would absorb. I commented that when Dr. Limoli was on the show back in 2015, this issue came up and explained why the experiments did not do that but I was unable to remember why. Listeners did not call or email us with the reason so before writing this summary, I listened to the 2015 Limoli interview. Within the first 20-30 minutes, the issue of radiation and GCR terrestrial simulation experiments with rodents came up, especially as to how rodent were being exposed to radiation for the experiments. Dr. Limoli said the mice/rodents were exposed to space relevant doses, usually equal to what an astronaut might get in a flight to mars but in one month. He said that the labs do not have the technology or the funding to low dose mice for a year or longer in a terrestrial radiation experiment and that doing so was neither financially nor technically feasible. He went further to say that terrestrial radiation simulation experiments do have problems but it is all that we can do at this time. We have no way to do these radiation experiments in space over a long period of time though such an experiment would produce better quality information. He went on to explain how the information from the terrestrial experiments was evaluated and extrapolated to be significant for human spaceflight. I strongly urge listeners to go back and listen to his interview. I would also urge caution in dismissing the research because of limitations with the methodology. Furthermore, I would strongly urge our community to avoid suggesting experiments that cannot be carried out due to funding and technological feasibility issues. Do keep in mind that the folks making policy and developing missions do not dismiss this simulation research, nor does the Aerospace Medical Research community. If enough you let me know that you would like to hear more programming on the issue of how these research studies are done, let me know and I will work to bring on additional guests on the subject. In considering this, don't forget the recent radiation study using mice showing astronauts might be subject to a higher level of stomach cancer incidents. I am working on getting his study doctor on The Space Show for early next year.
In the remaining minutes of our 67 minute program, we talked about space based reactors, the Decadal Survey meetings that our guest attended and more. We then took a call from John in Ft. Worth who picked up on some of the introductory comments by Chris regarding supercooling conductivity. Chris and John had much to say about super conducting magnets and the way the technology is advancing. In fact, Chris talked about the possibility of room temperature super conductivity magnets in the future. Chris explained how all of this was working, then John and Chris talked about using such devices to repel space radiation as a type of shield. Don't miss this exciting discussion.
Before the program ended, we returned to the biological radiation mice experiments. Chris also talked about the Russian radiation experimentation program. Then our guest suggested that early next year he might have news to announce regarding his company and the licensing of a type of reactor for use in the northern parts of Canada. We talked about this during his first appearance back in October on The Space Show. Before we ended, I asked Chris for a look at nuclear propulsion possibilities for 2019. Don't miss what he said.
Please post your comments/suggestions on TSS blog for this show. You can reach Chris through me or his company website, https://usnc.com/ for the UltraSafe Nuclear Corporation.