Science: Immunity in Space
Monday, December 10, 2007; 12:00 PM
Washington Post staff writer Marc Kaufman will be online Monday, Dec. 10 at Noon ET to discuss whether the human body is capable of living in space for long periods of time without suffering serious damange.
Marc Kaufman: Good morning. NASA will be holding a press roundtable today to talk about all the exploration-related developments expected in 2008--most especially the upcoming milestones for the Constellation program that will, they agency hopes, get the U.S. back to the moon by 2020. So the big manned-exploration engine is beginning to rev up again for exploration beyond low Earth orbit. Today's science page story, and the subject of this chat, is the disturbing information coming out about what long stays in space may do to the human body, and especially how it might compromise the immune system. It seems pretty clear that researchers need to understand quite precisely what to expect on this count before astronauts head out for settlements on the moon or trips to Mars. But I think it would be fair to say that at this point, researchers (and NASA) don't really know what weightlessness, stress and cosmic radiation do to the human immune system. Clearly, however, they are all doing something.
San Antonio, Tex.:
Can't weightlessness-induced problems be avoided by going back to 1950s concepts and developing rotating space vehicles and habitats that use centrifugal force as a substitute for gravity?
There might still be a problem on the moon (1/6 earth gravity) or Mars (1/3) where big centrifuges would be hard to build, but in space it certainly seems the way to go.
Marc Kaufman: In my reporting for this story, nobody seemed to think that rotating space vehicles would solve the problems related to weightlessness. The main reason is that building and launching a vehicle with that kind of capacity apparently would be enormously more expensive than current models. But until NASA and others are convinced that weightlessness is the primary and unavoidable cause of reduced immunity -- and other woes such as bone and muscle-tone loss -- I don't see the agency going in that direction.
Windsor, Canada: I know there were three Apollo astronauts who died from cancer (Jack Swigert, Deke Slayton, and Alan Shepard). Has anyone linked this to radiation exposure during their spaceflights? I know the radiation exposure during these missions wasn't considered excessive, but it has been blamed for many of the Apollo astronauts developing cataracts, so obviously it was still a health risk. On the other hand, there are astronauts from the same era who spent much more time in space than the three I mentioned; those three each spent less than two weeks in space. Jim Lovell and John Young spent 29 and 34 days in space, respectively, and they've both survived well into their 70s. What do you think?
Marc Kaufman: The question of radiation exposure, immunity loss and cancer is a very important one, indeed, since the human immune system is killing off potential cancer cells all the time. I don't think there is any consensus on whether the cancers that killed the three astronauts was at all related to their exposure to radiation in space, but I don't think there has been sufficient research done into the subject to rule it out entirely. In retrospect, it's humbling to look back at the risks taken by astronauts in the early Mercury and Apollo programs that were really not understood at all. Famously, there was a major solar eruption not long after Apollo astronauts returned to Earth from the moon, and scientists now think the men would have likely died from that solar radiation if they were still on the lunar surface when the eruption occurred.
Washington, D.C.:"whether the human body is capable of living in space for long periods of time without suffering serious damage."
But ... if I tried to live in space, wouldn't I suffocate within seconds? I don't get it.
Marc Kaufman: To be more precise, "living in space" means living in a spacecraft or space station or some day perhaps in a lunar settlement--all environments that protect against the known dangers of space.
Haymarket, Va.: Enteric microbes are essential to normal functioning of the human gastrointestinal tract and probably serve in other, as yet undetermined, roles. What effect would long term space flight have on the population of gut-dwelling organisms? (I am a physician with a PhD in biophysics/physiology and found your article very interesting - this may ultimately be a showstopper for prolonged human space flight.)
Marc Kaufman: I think the answer is that researchers don't know yet. Several Russian cosmonauts have remained in space for long periods and survived to tell about it, but very few space travelers have been up for more than three months. Remarkably, I'm told by NASA that assembling the international space station has been such a priority that the small crews have had little time to engage in research on human responses to space (as well as other science.) That's supposed to change in the years ahead, but right now the research on this subject is limited and because of budget cuts to basic science programs on the station, will remain limited for some time. That said, the European lab now scheduled to go up to the space station in January has some impressive capacity to test human responses to space.
Fairfax, Va.: How long does it take the body's immune system to return to normal levels once the astronauts are back on Earth?
If zero gravity or cosmic radiation is indeed the cause, shouldn't artificial gravity or better shielding lessen the effects on the human body? Are there plans to include those factors in future experiments?
Marc Kaufman: In the research I saw, immunity remained depressed three days after landing. When it returns to normal, however, was reported in the studies I read. But clearly, most astronauts so far have recovered pretty quickly and continue leading active lives.
Better shielding is indeed a major issue. I'm told that one of the best shields from cosmic radiation is water, and that some astronauts sleep with water-filled bladders around them. Some space officials have also talked of engineering a water layer just under the outer shell of the spacecraft. Regarding artificial gravity, I'll refer back to an earlier response where I said that if it was technically possible to engineer, it apparently would be very, very expensive.
Alexandria, Va.: Given the multitude of organisms that live inside and on the human body, doesn't this slow down any anticipation of human travel beyond the Moon? It seems to me that the the delicate balance that healthy people maintain of intestinal bacteria is going to be next to impossible to maintain in weightlessness for a prolonged period of time and any antibiotic use will only further disrupt the balance. Given that we only have one datapoint for low Earth orbit for a duration of over a year (Valeri Poliakov), will NASA have to go back to the ISS for additional study?
Marc Kaufman: The answer to your final question is that yes, NASA is indeed looking to the ISS as the primary laboratory for exploring issues of immunity loss, bone and muscle tone loss, and the effects of radiation on astronauts. In fact, virtually all other American science efforts planned for the station have been cut in deference to those goals.
Duane Pierson, the NASA chief microbiologists quoted in my story, told me that so far the issue of astronaut health has been manageable and so research has been somewhat limited. But with the known challenges ahead in terms of astronaut health during longer stays in space, that research simply has to expand well before any long missions can be seriously contemplated.
Restin' in Reston: Marc, you write: "In my reporting for this story, nobody seemed to think that rotating space vehicles would solve the problems related to weightlessness. The main reason is that building and launching a vehicle with that kind of capacity apparently would be enormously more expensive than current models."
Um, the main reason that nobody at NASA thinks that rotating vehicles would solve the physiological problems with long term human weightlessness is because those vehicles are more expensive than the current designs?
Sheesh. If NASA is serious about developing long-term capabilities for putting people on the moon for the long term and for subsequent flights to Mars, they need to get serious about it and develop sustainable systems - including for the health of the astronauts - to do so, with realistic budgets.
If your comment really is indicative of the thinking at NASA, Marc, I think that manned space flight and a long term presence in space will become the domain of countries other than ours.
Does NASA - and the USA - have the will to address this?
Again, it seems to me that it would be easier to develop flight technologies rather than reengineering the astronauts.
Or is it...?
Marc Kaufman: To clarify, NASA clearly thinks that it can indeed engineer a spacecraft that doesn't rotate that can nonetheless safely house astronauts for long periods in space. But I think many at NASA would acknowledge that the research remains unfinished and that there certainly could be unpleasant surprises ahead.
Clarkston, Mich: Vitamin D is very important in maintaining a healthy immune system and muscle mass and has often been overlooked in nutritional programs. Vitamin C is also important for staying healthy. Astronauts would have to supplement both of these to maintain their health. How much consideration has been given these and other aspects of nutrition for space travel?
Marc Kaufman: I don't know how much attention is being paid to Vitamins C and D specifically, but NASA does have a robust astronaut health program. After several incidents during the Apollo program -- when three astronauts on a mission all got a head cold at the same time, and when an Apollo 13 crew member famously got severely ill from a usually harmless bacteria -- NASA began putting all astronauts into quarantine for days before launch. The quarantine seems to have been quite successful in limiting the spread of common microbes in flight. But whether it is enough when it comes to long duration travel is a very different, and open, question.
Freising, Germany: You mention briefly that stress decreases immunity. Presumably this is due to some chemical change that the body experiences in stress situations.
Are the researchers certain that the weightlessness is the culprit here and not the stress of being shot into space and living in a tiny bubble hundreds of miles away from a friendly environment?
Marc Kaufman: Different researchers do indeed have different views as to the primary causes of decreased immunity. But Millie Hughes-Fulford, a former astronaut who has done a lot of research on the subject with NASA support, is convinced that weightless is the key issue in limiting the expression of several key genes associated with immune response. She has done some controls that lead her to believe that stress, which certainly does reduce immunity, is probably not the key issue in terms of lowered immunity and space travel.
Philadelphia: This may sound like a stupid question, but why do we need a space program?
We live in a capitalist society. If the market dictates a need for a space program, and the program appears to be profitable, then certainly at least one multi-billionaire will step up. They already are, as we see millionaires building planes that have already dipped into space much more efficiently (and safely) than NASA and their jalopies.
Marc Kaufman: Not a stupid question at all, and one that I (and NASA) hear all the time. The possible answers are many, and range from a desire to promote American technology and know-how, to the American frontier spirit, and to the undeniable military benefits that come from exploring and developing technologies to travel in space. As a reporter still relatively new to the field, I am also constantly impressed by the sheer wonder of the information and images collected by the program.
Many people believe that NASA takes up a significant part of the federal budget, but it does not. It costs something like $20 billion a year, which is serious money. But it is also less than the cost of one month in Iraq, I believe.
Bethesda, Md.: There are many good reasons to study the effects of space on the human body. Not only does the research have relevance for manned space missions, but also for conditions that humans experience here on earth. With such a clear scientific rationale, how do we generate the political will to both require and adequately fund the necessary research?
Marc Kaufman: Good question, with no easy answer. I wrote a story recently about what various presidential candidates are saying about manned space exploration, and truth be told it wasn't much. Hillary Clinton put out a paper that included strong support for NASA and for manned space missions, though she later seemed to hedge a bit. Barack Obama was at the other extreme, calling for a five-year moratorium on funding for the new Constellation spaceship. Generally speaking, the Republican candidates did not respond to my questions, or voiced general support without particular enthusiasm.
I guess this is my way of saying that presidential leadership has always been key to NASA funding, and I hope that the candidates are questioned more about this in the future.
Philadelphia, Pa.: Beyond health issues, how do one stay healthy in space? How easy or difficult is it to exercise properly and to eat food that is kept fresh and edible?
Marc Kaufman: The exercise part seems to be manageable, and fairly frequent deliveries of fresh food to the space station has kept astronauts/cosmonauts pretty health. But when it comes to lowered immunity and bone loss, I think challenges clearly remain.
Many thanks for your questions and interest in this subject.
Until next time...
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