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Apollo astronauts who have ventured out of the protective magnetosphere of mother Earth appear to be dying of cardiovascular disease at a far higher rate than their counterparts—both those that have stayed grounded and those that only flew in the shielding embrace of low-Earth orbit. Though the data is slim—based on only 77 astronauts total—researchers speculate that potent ionizing radiation in deep space may be to blame. That hypothesis was backed up in follow-up mouse studies that provided evidence that similar radiation exposure led to long-lasting damage to the rodents’ blood vessels. All of the data was published Thursday in the journal Scientific Reports.
[...] In the new study, [Michael] Delp [at Florida State University] and coauthors compared health data on 42 astronauts that had traveled into space—seven of which got past the magnetosphere and to the Moon—to the medical records of 35 astronauts that were grounded for their careers. The death rate from cardiovascular disease among the Apollo lunar astronauts was a whopping 43 percent, which is around four to five times the rate seen in the non-fliers and low-fliers (nine and 11 percent, respectively).
To figure out if deep-space ionizing radiation or, perhaps, weightlessness might explain the apparent jump in cardiovascular disease deaths, the researchers turned to a mouse model. Mice were either exposed to a single dose of radiation, had their hind limbs elevated to prevent weight-bearing for two weeks, or received both treatments. The researchers then let the faux-astronaut mice recover for six to seven months, which in human terms would be about 20 years.
[Continues...]
The researchers found that the mice exposed to radiation, or both radiation and simulated weightlessness, had sustained damage to their blood vessels. Namely, the mice had impaired vasodilation, or problems expanding their blood vessels to adjust for blood pressure. This can be a precursor to heart attacks and stroke. The mice that just experience simulated weightlessness, on the other hand, seemed normal.
While the rodent data complement the findings in real astronauts, the authors were clear about the limitations of the study. “Caution must be used in drawing definitive conclusions regarding specific health risks,” they concluded. The astronaut numbers are very small for an epidemiological study, there may be other factors in the space environment that could explain the possible health effects, and the type of radiation given to the mice wasn’t exactly the same as the type astronauts experience.
Delp and his colleagues are working with NASA on follow-up studies of astronauts’ health.
-- submitted from IRC
That seems to be a very small sample from which to draw any kind of conclusion, but it does suggest that outer space may be more hazardous that we thought. How will/should this affect future manned (personed?) space flight plans? With SpaceX planning to create a Mars Colonization Transport ship, maybe they would launch a hundred or so mice on a trip around the moon for their own edification?
Other coverage:
University Herald
The Guardian .
(Score: 3, Interesting) by Anonymous Coward on Monday August 01 2016, @02:49PM
The Apollo astronauts were selected from the population of astronauts because they were special in some way. Why would we expect people selected for being special to be the same as the rest? For example, I see that the Apollo astronauts were all male but they are comparing to a population that includes females.
Looking at this paper more, I see that the increased proportion of Apollo CVD deaths came directly at the expense of a decrease in accidental deaths relative to the other astronauts. So, I don't think there is any mystery at all here that if astronauts die less due to accidents they are more likely to die from a heart attack/etc. I only skimmed the text of this paper so maybe they mention this in there... I would hope they do. I mean were the safety precautions stricter during Apollo, were there cultural differences, etc?
Another interesting thing is that life expectancy for astronauts in general is pretty low. It is only 53.3 years for non-flight to 65.2 years for the Apollo astronauts, so being an astronaut is far worse for your life expectancy than smoking.
http://www.nature.com/articles/srep29901 [nature.com]
(Score: 2) by NCommander on Monday August 01 2016, @03:05PM
If this is the same paper I've seen before, the damage is consistent with mice they subjected to radiation+zero-g. Given the small amount of people who have ever left the planet, let alone LEO, I suspect we won't know for decades the true health risks of going beyond Earth orbit.
Still always moving
(Score: 2) by takyon on Monday August 01 2016, @03:19PM
There are a few ideas that could reduce exposure. Small-scale 10-100 MW fusion power would be ideal not only for increasing the power available for active shielding, but reducing the time-to-Mars or other targets. Better passive shielding could also be built. Combining both could get the 4-fold reduction NASA seems to be looking for.
Ultimately the best solution is to work on the SENS targets [wikipedia.org]. If you can periodically repair the damage caused by radiation, or even do it within a couple decades after the end of the mission, you mitigate the problem and much more.
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(Score: 2) by NCommander on Monday August 01 2016, @03:26PM
True, but shielding (at least with our current tech levels) is extremely heavily, and getting that sort of payloads into orbit, let alone BEO is extremely expensive. You need approximately 9-10k km/s to get something into very low earth orbit, and another 3k dV just to throw it out of Earth's SoI. Even if you assemble in orbit, you'd need considerable addition reserves of fuel to then get your hypothetical space craft to Mars and back with the additional weight the shielding would add.
Still always moving
(Score: 2) by VLM on Monday August 01 2016, @04:15PM
Might be cheaper to build a nice retirement home on the moon. Not even joking. Sure your heart won't last long at 1G on the earth, but the earth is boring and here's a really cool moon retirement colony at reduced gravity.
As a side issue not to be too ghoulish but building a colony is likely very dangerous compared to living in one, so the first moon colonists are not likely to die of old age. Worrying about heart disease in 20 yrs is futile if you're tunneling thru lunar regolith while the tunnel collapses or you discover the hard way that a certain airlock plastic seal isn't lunar environment compatible or WTF. So astronauts dying "young" in their 60s is not likely to be a problem for a century or two until the moon is damn near fully colonized.
Maybe the problem with lunar astronauts is banging all the hotties who think that counts as joining the 230000 mile high club. The guys who didn't fly lunar missions are not getting nearly as much action. You'd think it would show up in prostate issues but their hearts are giving out first, all that exertion. I'm sure there's some joke about inserting the docking probes and wearing them out from overuse or something. "Open the pod bay doors HAL"
(Score: 2) by takyon on Monday August 01 2016, @04:46PM
I agree that we should do these things before health concerns can be addressed. However, I am optimistic about anti-aging therapies making radiation concerns obsolete eventually.
Nah. Colonies should be built with robots, preferably including manufacturing of parts on-site. Everything needed to live should be set up in advance by robots. That includes the manufacturing capability, living quarters, and the greenhouses. There should be food being grown, picked, and stored (dehydrated?) before any human steps on the base.
I bet if you reach deep enough, there is a fertilizer joke in there too. With a few dead astronaut bodies.
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(Score: 2) by VLM on Monday August 01 2016, @04:54PM
Nah. Colonies should be built with robots, preferably including manufacturing of parts on-site. Everything needed to live should be set up in advance by robots. That includes the manufacturing capability, living quarters, and the greenhouses. There should be food being grown, picked, and stored (dehydrated?) before any human steps on the base.
Agreed but still the first guys there are going to be subject to plenty of "whoops didn't consider that" class of problems.
Especially wear and tear. "Ah those bearings will last 6x longer because 6x lower gravity, right?" Or whatever the scaling factor for reduced rotating loads, and then it turns out whoops nope not on the moon. Or some unanticipated effect of lunar soil grinding away at ... everything. Unanticipated metal fatigue due to unanticipated temperature swings.
Aside from the somewhat more predictable simple bad engineering, whoops imperial vs metric or whatever.
Moonquakes. Meteor strikes. Simple dumb accidents.
(Score: 2) by takyon on Monday August 01 2016, @05:11PM
Sure. The Moon might be an atypical example, because if it becomes the site of our first permanent off-planet base/colony, it will involve less semi-autonomous robots, with worse capabilities, and the least commitment to sustainability, since the inhabitants are just days away from returning to Earth or getting a resupply.
Ultimately there must be no umbilical between space colonies and Earth. If we're looking at asteroid mining like it's exciting, we must also be able to set up manufacturing on larger worlds. The Mars colony should be able to produce fresh water, computer chips, robots, chemicals, and whatever is needed. Larger colonies or networks of colonies (on Mars) will get to think about producing more frivolous goods, like basketballs and Wensleydale cheese (with lactose from yeast instead of cows).
I doubt meteor strikes will be a problem. They aren't a common problem here on Earth. If and when it becomes a problem, there should be years of advance notice that Apophis will strike the Moon or Mars or whatever.
Accidents and wear/tear will be a problem, but there will be some redundancy built in. It should also be possible to evaluate whether the accident that killed all 5 astronauts on Moon Base One is going to be a recurring problem or was a fluke. Bases with a hole blown in them and dead astronauts laying around could probably be repaired with a fraction of the time and money it took to build them. If the national appetite for replacing dead NASA astronauts is too low, private settlers will claim the property instead.
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(Score: 2) by VLM on Monday August 01 2016, @07:24PM
I doubt meteor strikes will be a problem.
I was worried more about scaling with size. So turning the entire base into vapor is not a statistically likely serious concern, but whoops that tempered glass window was supposed to be safety glass but isn't, when a little sand grain sized meteor hits it. Or even smaller it just kinda abrades something until metal fatigue can do its worst or the component shatters.
Or even silly-ish stuff like grit kicked up lands in just the wrong spot on a sliding joint either weakening it or jamming it, not even a direct hit but dust from a sand grain impacting nearby. That stress fracture on the crane arm didn't originate in a corrosion stress riser like you'd see on the earth, it was a piece of meteor sand, resulting in the crane arm cracking and falling off in 1/6 G and the astronaut and the end having a bad day.
Or tertiary stuff like autonomous robot prospector #23626 gets hit providing a nice sharp edge and some dude goes out there to pick it up for debugging and research, slices the entire palm of his hand glove open, passes out before he can apply a patch kit or the patch kit doesn't work, or even worse the patch kit works but now he runs out of O2 before getting in range of more.
(Score: 2) by takyon on Monday August 01 2016, @08:20PM
Well, for the Moon in particular, putting the majority of your buildings underground could solve the problem. That could have its own challenges, obviously. Redundant life support systems will be a must, so that if one surface building gets the window blown out, there is somewhere to retreat to. Maybe even have the lunar dwellers sleep separately.
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(Score: 3, Interesting) by VLM on Monday August 01 2016, @08:45PM
putting the majority of your buildings underground could solve the problem.
That seems to be a given for dealing with thermal issues and radiation. A couple feet of rock is incredibly expensive as a spacecraft shell because its really heavy, but once you're on the ground its just a couple hours of robotic bulldozer work.
Personally I like the idea of robotic rock processing as one of the first things sent up. That way you can crush and sieve rock for minerals but crucially you can sieve for a specific range of sand size and engineer the modules to tolerate being buried in standard size synthetic sand rather than any old lumps a bulldozer pushes around.
And you need a bucket to hold the sand, so obviously you build base components in a crater, then bulldoze sand on top to fill the crater. Digging thru solid rock moon bedrock will take a while industrially speaking, and just using sand piles will result in more material use than relying on crater walls. Or you could manufacture walls onsite very crudely by sintering dust into wall blocks.
Either way I think a major very early colonization project will be precision robotic manufactured synthetic lunar sands for thermal and radiation shielding. A whole quarry would be very handy as there's going to be low spots to fill in, road surfaces to improve, etc. Even if its mostly robotic heavy trucks trundling around the roads instead of humans, they'll still need the roads... The geologists would find a lunar quarry very fascinating. I would imagine great arguments between the engineers who want to expand into consistent strata whereas the geologists want to dig up interesting stuff that might not be the best building material.
Obviously failure of sand is going to lead to interesting building problems. Sand contaminated with dust or heavy rocks could be a bit of a problem for the residents.
(Score: 1, Insightful) by Anonymous Coward on Monday August 01 2016, @03:22PM
There really is no damage to explain here. This is quite a ridiculous paper. The difference between Apollo lunar astronauts and the other astronauts is due to dying less often from accidents (thus living longer, ~10 years longer on average, and being more likely to die from cardiovascular disease). The difference between Apollo astronauts and the normal US population is non-existent. There were 7 Apollo Lunar Astronauts, apparently 3/7~0.43 died from CVD. The US population data says 27% of people died from CVD, which is pretty much 2/7~0.29. So we are talking about a difference of a single death.
There is nothing here other than figuring out what was done to keep them from dying in accidents.
(Score: 2) by frojack on Monday August 01 2016, @05:33PM
There is nothing here other than figuring out what was done to keep them from dying in accidents.
Perhaps nothing special (outside of the mission itself) was done there either. It was all in the astronaut selection process.
When some NASA chief was interviewed on TV (probably by Walter Cronkite) about why the requirements for being selected into the Astronaut program included having no traffic tickets (as well as no traffic accidents), he replied that it wasn't that NASA was worried about five or ten miles over the limit, or rolling a stop sign.
They were more interested in getting people with great situational awareness who would spot the traffic cop before putting their foot into it.
No, you are mistaken. I've always had this sig.
(Score: 2) by frojack on Monday August 01 2016, @04:35PM
Except the mice simply had their rear legs elevated. That's not zero G.
Any effects, if there are indeed any, are due solely to radiation.
The time between lunar orbit travel and the onset of cardiovascular disease is more than sufficient for life style changes to take effect.
A few years of intense training, large amounts of stress over short periods, followed by a return to a far more sedentary life, with rich foods, and alcohol. Astronauts have more in common with retired football (either variety) athletes than your ordinary Joe Random.
The rest? Small sample size.
No, you are mistaken. I've always had this sig.