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Dr. Mark Shelhamer, Tuesday, 7-22-14 July 23, 2014

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Dr. Mark Shelhamer, Tuesday, 7-22-14


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Guest:  Dr. Mark Shelhamer.  Topics:  A look at the risks associated with long duration human spaceflight.  Please direct all comments and questions regarding Space Show programs/guest(s) to the Space Show blog, https://thespaceshow.wordpress.com.  Comments and questions should be relevant to the specific Space Show program. Written Transcripts of Space Show programs are a violation of our copyright and are not permitted without prior written consent, even if for your own use. We do not permit the commercial use of Space Show programs or any part thereof, nor do we permit editing, YouTube clips, or clips placed on other private channels & websites. Space Show programs can be quoted, but the quote must be cited or referenced using the proper citation format. Contact The Space Show for further information. In addition, please remember that your Amazon purchases can help support The Space Show/OGLF. See http://www.onegiantleapfoundation.org/amazon.htm.  For those listening to archives using live365.com and rating the programs, please email me as to why you assign a specific rating to the show. This will help me bring better programming to the audience.

We welcomed Dr. Mark Shelhamer, Chief Scientist of the NASA Human Research Program to the show to discuss the critical risks associated with BLEO long duration HSP. You can hear his FISO talk on this topic from April 2, 2014 at http://spirit.as.utexas.edu/~fiso/telecon/Shelhamer_4-2-14/Shelhamer.mp3.  His associated Power Point can be downloaded at http://spirit.as.utexas.edu/~fiso/telecon/Shelhamer_4-2-14/Shelhamer_4-2-14.ppt.  During the first segment of our 95 minute discussion, Dr. Shelhamer started off saying  we would be talking about beyond low earth orbit only and that many of the risks are unknown since we have very little experience with BLEO.  Much of what we do know is extrapolated from our current knowledge base plus our Apollo experience.  Next, our guest defined three major areas/issues.  First he listed medical issues which he later described as onsite medical treatments for various complications, illnesses, surgical needs and such.  He classified physical deconditioning issues such as muscle and bone loss issues, cardio vascular issues in a different category.  The second group he identified had to do with radiation, and the third group included psychological-social issues.  I asked about Microgravity not being in the top three and he said because those issues are likely a constant for both LEO and BLEO missions.  He then talked at length about the challenges needing countermeasures/mitigation.  He did not say these were showstopper challenges but they do require effective countermeasures.  For example, he said humans could probably survive a trip to Mars today providing the hardware & life support was up to the job but their goal is to get the crew there in good condition, to be able to do effective work, and to return safely.  He did not think those goals could be obtained today.  I asked if money was a primary issue and it was not though he said more money is always helpful. He talked about the time needed for some human studies, team studies, and research, sometimes extending even longer than a year.  He then took us through the three categories to tell us what NASA was doing & how it was doing in that research area. You might be surprised by what you hear.  I certainly was.  Later, we talked about ocular/vision issues which are now getting front page attention.  He explained the latest theory causing the problem as possible fluid shifts.  Listen to this discussion.  Note that once we start with BLEO HSF, we may find other problems that do not now show up now.  Also, we may develop a countermeasure for one problem but that opens the door to lots of other problems currently unknown.  One tool he talked about that was being tested on the ISS Russian sector was lower body negative pressure.  Artificial gravity was a big part of our discussion.  While everyone is enthusiastic about it, he made the point of saying we don’t know the needed spin rate nor do we know what level of gravity is needed for humans or for how long. Just spinning a spacecraft without knowing this information is unlikely to be successful let alone cost effective or economic. He also pointed out that artificial gravity is costly, requires lots of energy, a huge spacecraft which means lots of mass to orbit, & to do it, it needs to be done in a way that maximizes the benefits for the crew.  Without knowing the precise spin rate and gravity needs for humans plus how long the crew needs to be in artificial gravity, it is likely it won’t be done just for cost and economic reasons alone.  Charles emailed in about bed rest analog studies.  Joe sent in a question about lower back pain & spine issues.  As the segment ended, I asked him if humans were lousy candidates for BLEO spaceflight.  Don’t miss his answer.

In the second segment, we took a call from Dave about nuclear submarines as an analog for HSF studies.  Our next topic was space radiation which our guest discussed in detail.  I then took two email questions from B John in Sweden.  He asked about the benefits of microgravity for disabled folks, then I read a longer email from him suggesting solutions for the microgravity, psychology, and radiation issues already existed and why was NASA not proposing and developing “these simple non-medical solutions to the problems you describe.”  Dr. Shelhamer responded to his email item by item. For the most part, he agreed with what B John was saying except that his information and perspective were limited and missing key components of the scenarios he was talking about.  Mark explained why our listener’s comments were way too simple and cited some scenarios to illustrate this.  It was a fascinating reply to what many of us believe are already effective countermeasures.  Unfortunately, while what many of us suggest is correct, what we suggest does not go far enough and does not contain the specifics and details of what is actually required to make a specific countermeasure work.  Otherwise, the countermeasures are far more complex than what B John asked about in his email which you will hear me read on the program.  I asked Mark about genetic modification and that took us to the subject of personalized countermeasures.  We talked about pioneering/space settlement, childbirth & children in the space environment, even gender differences for BELO HSF.  I asked about the differences from his perspective of doing HSF to the Moon, an asteroid, Mars, or Deimos.  There are differences, don’t miss his response.  As the program was ending, I asked if a commercial company without gov. funding could decide to do a BLEO mission without all the costs and safety concerns of NASA.  Mark said it might be possible though the costs of the missions and the technology needed would make it very hard for a commercial company to carry out.  He said a short cut bare bones mission might be achieved by a commercial company but the risks for the crew would be extreme.  If you were running a commercial company and funding such a mission, would you accept these risks, plus the risk the crew might not be able to do much or be effective once they got to their destination? As the commercial company CEO, would that be a good use of company money or would you dismiss what people like our guest today have to say about these issues.  Let me know your thoughts by posting them on the blog.

Please post comments/questions on TSS blog above. Mark can be reached through me or through his PPT presentation address.


1. J Fincannon - July 31, 2014

“Artificial gravity completely eliminates microgravity and all of its problem. We can choose what gravity we want to simulate and what coreolis effect we want to go with it. It is only a matter of cable length. Your guest Dr. Shelhamer misunderstood that question and instead described some problems that the immune system has with microgravity. And it costs nothing at all, ……..”

While it is clear that you need some artificial gravity and spinning is the best method one could use at this time, I do not think it costs “nothing at all”. To begin with, “real” cable doesn’t weigh nothing, thus there is a launch cost mass. Spin-up and despin-up fuel weighs something (and how many times, as Dr. Jurist correctly suggests, since correction burns are likely to require de-spin or spin) and the launch cost for that fuel/tanks have launch cost. So you might change the statement to “almost” “nothing at all”. But reading that web page you recommended (which mainly was for Earth orbit), it seems that fixing the cable breakage issue would boost the mass of the cable and its launch cost. Perhaps private companies would take the risk of one cable, but it seems that if you are going to Mars, you will need at least three separate cables since a manned spacecraft would need to be two fault tolerant. So when two cables are severed due to micrometeorites or some problem, one cable must be able to sustain the full force (how such breaks would change the spin stability and platform orientation is another problem!). The other option is to have an adequate propulsion system on at least the manned spacecraft to compensate for completely severed cable(s) since you would be potentially flying off in an undesirable direction. However this is handled, extra cables or propulsion system mass seems to be more than “almost nothing at all” too. Regardless, it seems we definitely need to use this kind of artificial gravity even with the extra mass/cost.

Interestingly Doctor Shelhamer mentioned the effects of long term deep space travel on germs/bacteria/viruses and the immune system. Does the impact of null gravity affect the germ/bacteria/virus or is it the radiation? I suspect it’s the radiation that increases the mutation rate. This increased mutation rate is a benefit to those rapid breeding organisms while for our bodies, not so much. So while we may treat our body with drugs to deal with the cellular damage due to radiation, the same drugs may not work with or apply to the organisms resident within our bodies. I always like the statistic that there are 1/2 gallon’s worth of non-human organisms in our bodies (1-3% total body mass, 500 to 1,000 species of bacteria live in the human gut, ten times as many bacteria as human cells in the body (approximately 10^14 versus 10^13), 10^12 on the skin, 10^10 in the mouth, 10^14 in the gut). So, while getting hit by radiation may generally kill a cell, sometimes you get a toxic mutation that survives. In the body this would be cancerous and hopefully the immune system deals with it (it handles tumors all the time in our bodies which most people don’t realize). In bacteria, helpful bacteria may be turned malignant in subtle ways, maybe not in the first generation, but sometime in the future. And these bacteria are not just sitting in/on the human body but are travelling all the time in a cloud (like the Peanut’s character Pigpen) in skin flakes or water droplets from talking, etc. This seems very complicated and not to be ignored.

B John - August 7, 2014

Joe Carroll, a guest of the Spaceshow, has suggested a way to test spinning artificial gravity for free on a routine flight to the ISS. Here Robert Walker (also a guest of the Spaceshow) describes it on his blog: http://www.science20.com/robert_inventor/crew_tether_spin_with_final_stage_on_routine_mission_to_iss_first_human_test_of_artificial_gravity-136686

Spinning costs nothing. First of all, a 100 meter cable at 1 rpm has a speed of about 5 m/s. LEO orbital velocity is about 8000 m/s. Secondly, almost all of that tiny spinning energy can be recovered during de-spinning, as Joe Carroll explains. Sure, there is the weight of the cable or rigid structure (or an airbeam), but that is a really small fraction of the mass of a crewed spacecraft heading to Mars. Having a second cable for redundancy is not a problem. And the crew will survive for at least a year in microgravity, it is not an immediately critical system. Reconnecting a cut wire during an EVA could be an option. With artificial gravity mass can be saved by less need of exercise equipment and the extra water and calories consumed by several hours a day exercising. Life support systems transporting water, air, heat might also be simplified with gravity compared to microgravity.

Artificial gravity is really a very simple thing to engineer! That’s why it is so attractive and why I find the discussions about health effects of microgravity unnecessary and pretty stupid. It is like claiming that airflight is impossible because one cannot breath at high altitudes. That too has a very simple engineering solution. There is no need to discuss how pilots suffer from lack of oxygen, because they don’t..

Here’s a SETI talk about the horrible medical problems with long term human space flight in micro gravity. It is such a mess of dangers that it cannot be fixed, the only possible solution is to avoid microgravity to begin with:

2. John M Jurist - July 29, 2014

Your thinking about the biomedical issues is simplistic although those issues are not the “explanation for lack of human space travel today.”

First, let’s consider microgravity. You are right in that physics does not rule out creation of “artificial gravity” by spinning the habitat or the entire spacecraft. However, the biomedical uncertainities preclude currently setting the basic parameters for such an abatement approach. What is the tolerable spin rate for continuous, long term exposure? Some people say 3 RPM, others say 1 RPM. How does that change with age? What is the gravitational level needed? Spinning to one gee adds a lot of complication to the design of a viable spacecraft. After the transfer orbit burn and spin-up, can mid-course maneuvers be completed while under spin, or would the spacecraft have to be despun for the mid-course maneuver and then respun? Could a short arm centrifuge be sufficient with crew spending 8 hrs per duty cycle under spin? All of these considerations come with pros and cons that have a direct influence on the major parameters of the spacecraft.

Even spinning to one gee has associated biomedical problems. Bone loss under microgravity or immobilization varies a lot by bone and by exercise pattern. If 1/3 gee could be tolerated nearly as well as one gee life would be great, but the biomedical community does not know how the exposure-response curve is shaped. That poses real unsolved problems related to optimizing gee level, exercise patterns, and other interventions. Much of my time on the faculty in the University of Wisconsin division of Orthopedic Surgery was spent dealing with the issues and complications of fracture healing and with osteoporosis. Most of the patients referred to my laboratory had those kinds of complications and one thing I learned is that a cramped existence leads to bone loss at one gee. How do we optimize the required exercise equipment to deal with the real problems? Without more knowledge, the kinds of questions I posed above are not resolved sufficiently to characterize a space vehicle for human space flight to Mars, for example.

Next, let’s consider radiation. The physics of shielding is pretty well understood, but the characteristics of the free space radiation environment and its effects are not. Water may make a great shielding material, but it is massive. For example, consider the Aquarius proposal. It suggests RP5 for shielding of the habitat. That is, 5% of the shielding effect of the Earth’s atmosphere. That is partitioned into 14.5 gms/sq cm for primary structure and 37 gms/sq cm for water. The RP5 criterion assumes transit times requiring nuclear thermal propulsion and, if SMEs occur, the transit could be very dangerous. The lack of geometric shielding in space doubles the effective dose rate compared to Earth’s surface even with RP100 shielding because of the nearly isotropic radiation field in free space and the lack of the Earth’s magnetosphere shielding component. Parenthetically, every time radiation exposure standards have been revised over the last half century, they have been tightened based on additional knowledge. If future additional knowledge about radiation bioeffects changes the RP5 proposal to RP10 assuming improved SME predictability and avoidance, the water jacket around the habitat must be doubled in thickness from 37 gms/sq cm to 74 gms/sq cm. If the habitat is a 10 meter dia sphere, for example, the postulated structural mass of the shell is 15.2 metric tons and the water jacket mass increases from roughly 39 metric tons to 77 metric tons if my rough calculations are correct. That is an enormous additional mass to be lifted into LEO — especially if ISRU with lunar ice is not feasible for some reason.. Therefore, the issue of the water jacket must be defined more precisely than it presently is. Further, if you don’t want the water to freeze, you must make provisions for stirring it. That adds mass. These kind of uncertainties make the initial characterization of the space vehicle more difficult.

Your blanket statement that the medical problems are overestimated blurs the line between biomedical uncertainty and the certainty of safety and is excessively simplistic. That is both dangerous and silly. Dr. Livingston interviews relevant MDs not to prove his belief system but to educate the listening audience, many of whom come from engineering backgrounds, about the issues and uncertainties confronting human space flight and how those issues influence vehicle conceptualization. You state that “… M.D.s are trained to solve problems. It would be more interesting to learn about the solutions,” but my years holding a professorship in a midwestern medical school as mentioned above showed me that physicians are also taught to identify problems in order to solve them. Until space advocates understand the problems and associated uncertainties, they will continue to discount the potential solutions. That transforms their advocacy from knowledge based into articulation of faith.

B John - August 7, 2014

Even the most conservative approach with 1G and several hundred meters long rotational radius to minimize the perception of spinning is cheap and simple engineering. All you need is a longer cable and you can safely forget the problems with microgravity. Basic physics instead of exotic medicine.

Radiation is dealt with by shielding. AFAIK the health effects of cosmic radiation is stochastic. 10% shielding all of the time has the same effect as 20% shielding half of the time. Astronauts could spend half the time inside very thick shielding, when sleeping and for a few hours of work or leisure a day. As a simple example, four astronauts could share two shielded “beds”. A 2 meter long cylinder with 3 meter diameter with a 1 meter diameter cylindrical bed inside it could hold 12.5 tons of water. Recycled water which they have to bring anyway. That’s a one meter thick layer of water half of the time, practically halving the radiation exposure. Shielding can be provided in a number of ways. During a solar storm the crew could hide beside those beds, getting 2 or 4 meter thick water shielding.

Microgravity and radiation are serious health risks. But it is very straight forward to eliminate both of them to any degree we choose.

Human space flight must involve space ship engineering and a discussion cannot be meaningful if it exclusively focuses on medicine alone.

B John - August 7, 2014

I want to emphasize that the solution is to eliminate microgravity and radiation, to eliminate the root cause of the medical risks. Not to take the hit from them and then try to mend it and the thousands of problems they cause. The latter approach would be great for an endless career in space medicine with no hope of ever reaching any solution…

3. The Space Show - July 28, 2014

Space Show Listeners: I am posting this comment on behalf of BJohn Larsson in Sweden. It was an email sent to me after BJohn listened to this program and heard me read his question to the guest. Please post any replies or responses to BJohn here on the blog. If you do want to email him, you can do so through me at drspace@thespaceshow.com.

“Dr. Livingstone,

I agree with your descriptions of legal, political, cultural obsticles for human space flight. I also think that the economic incentives for commercial human spaceflight are modest. And it is fundamentally unclear why humans should travel in space. Also, “space cadets” tend to blur the border between hitech and scifi and come up with unrealistic plans that never happen.

But the medical problems are overestimated on your show. You are mistaken if you think that medical reasons is the explanation for lack of human space travel today. If so, then we wouldn’t have astronauts 6 month at a time in the horrible microgravity of the ISS (still, their lasting injuries are very small compared to those of, say, a hockey player).

It seems as if you are interviewing M.D.s only to prove your “belief system”. But M.D.s are trained to solve problems. It would be more interesting to learn about the solutions.

To repeat the obvious solutions:

– Artificial gravity completely eliminates microgravity and all of its problem. We can choose what gravity we want to simulate and what coreolis effect we want to go with it. It is only a matter of cable length. Your guest Dr. Shelhamer misunderstood that question and instead described some problems that the immune system has with microgravity. And it costs nothing at all, see this description of the idea of your frequent guest Joe Carroll about how to test it out for free:

– Radiation can be dealt with by shielding. Fuel, water and waste work as shielding as a side effect. And there are light weight hydrogen rich plastics. (Hydrogen is the best shielding material). Of course proper shielding will add mass to a mission, but it is manageble. While there is a simple way to completely eliminate microgravity, the radiation problem can only be partially improved, but to an acceptable level. Except for solar eruptions, the effect of radiation is increased risk for cancer later in life, years after the mission. Astronauts could spend more than half their time, including sleeping and some of the work, inside a very highly shielded compartment, thereby halving the radiation effect.

– Psychology. Well, mutinies throughout history has been so rare that they have gotten famous names. It is a recruitment issue like many others. It is not specific for space travel.

There is no “space environment” per se. Earth is in space. It is just that different places have different gravity and radiation exposure. Space isn’t the problem, gravity and radiation is. And there are good solutions to that.

Best regards
B John”

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