In a sobering start to the New Year, at least for partisans of manned missions to deep space, new work out of the University of Rochester indicates that galactic cosmic radiation may accelerate the onset of Alzheimer’s disease. The study, led by the university’s Kerry O’Banion, is hardly the first time that the impact of radiation in space has been studied, with previous work aimed at cancer risks as well as cardiovascular and musculoskeletal issues. But O’Banion’s work points to radiation’s effects on biological processes in the brain, reaching striking conclusions:
“Galactic cosmic radiation poses a significant threat to future astronauts,” said O’Banion. “The possibility that radiation exposure in space may give rise to health problems such as cancer has long been recognized. However, this study shows for the first time that exposure to radiation levels equivalent to a mission to Mars could produce cognitive problems and speed up changes in the brain that are associated with Alzheimer’s disease.”
Neurological damage from human missions to deep space — and the study goes no further than the relatively close Mars — would obviously affect our planning and create serious payload constraints given the need for what might have to be massive shielding. I’m already seeing this work being referred to (not by these researchers, to be sure) in the context of the Fermi paradox, which is an interesting speculation in itself, the idea being that if space is inherently hostile to human biology, these conditions may have prevented other species from tackling interstellar journeys. But before we get into that, let’s take a closer look at how the study was put together.
Image: An artist’s illustration of a cosmic ray striking the Earth’s atmosphere and creating a shower of secondary particles detectable on the surface. That high energy fundamental particles are barreling through the universe has been known for about a century. Because ultra high energy cosmic rays are so rare and because their extrapolated directions are so imprecise, no progenitor objects have ever been unambiguously implied. 2007 results from the Pierre Auger Observatory, however, indicate that 12 of 15 ultra high energy cosmic rays have sky directions statistically consistent with the positions of nearby active galactic nuclei. Whatever the source, does such space radiation present a show-stopper for manned missions to deep space? Credit: Robert Nemiroff & Jerry Bonnell / Pierre Auger Observatory Team.
At the heart of the work are high-energy, high-charged particles (HZE) which exist in low but continuous levels in deep space. Among the different HZE particles, the focus of the O’Banion team’s work is 56Fe — iron particles — which are speedy and massive enough to create serious shielding problems. To examine the issue, O’Banion exposed laboratory mice to doses of radiation comparable to what astronauts would experience on a trip to Mars, working partly at NASA’s Space Radiation Laboratory at Brookhaven National Laboratory (Long Island).
The mice were then put through a variety of experiments to gauge the cognitive and biological effect of the exposure. The result: Their encounter with radiation resulted in what the paper calls ‘enhanced AD [Alzheimer’s disease] plaque pathology,” with higher than normal accumulations of beta amyloid, the protein plaque now considered a marker for the disease. From the paper (internal references omitted for brevity):
The doses used in this study are comparable to those astronauts will see on a mission to Mars, raising concerns about a heightened chance of debilitating dementia occurring long after the mission is over. Increased plaque progression could be due to a variety of mechanisms. A primary mechanism of radiation injury is DNA damage and reactive oxygen species production that can contribute to overall cell dysfunction. In addition, radiation is also known to cause glial activation and inflammatory cytokine production, both of which have been implicated in neurodegenerative diseases like AD. In our study, GCR exposure could amplify the chronic inflammatory AD state and speed up pathology.
The mice were also run through experiments involving recall of objects and locations, with the researchers finding that the group exposed to radiation was far more likely to fail at these tasks, suggesting an earlier onset of neurological impairment than normal. The paper stresses this caveat: The mice were exposed to a single kind of galactic cosmic radiation at acute levels of exposure. “It is not known how the CNS [central nervous system] will respond to the complex and chronic low-dose GCR environment of space. Moreover, astronauts will not likely be familial AD carriers. Therefore, while many of the pathological processes are believed to be similar, this model does not reflect the complete human condition.”
So the model is tightly focused, but the one aspect of deep space radiation the researchers can replicate is troubling. Whole body exposure to 56Fe particle HZE radiation appears to enhance the progression of Alzheimer’s disease. You can read more about this work in this University of Rochester news release. The paper itself is Cherry et al., “Galactic Cosmic Radiation Leads to Cognitive Impairment and Increased A? Plaque Accumulation in a Mouse Model of Alzheimer’s Disease,” PLoS ONE 7(12): e53275 (available online).
Back briefly to the Fermi issue, which in my judgment remains unaffected by the question of radiation danger. We do not need to assume that a wave of interstellar probes, whether self-replicating or not, would have to be manned by biological creatures. In fact, assuming they’re not, we can stop worrying about mission times of a human life-span or less and think about a galaxy penetrated by artificial intelligence gradually moving from star to star, perhaps leaving observation stations along the way. Given enough time, the galaxy would be infused with the technology of a single species which would never need to expose itself to deep space.
Yes I saw this article about new hazards of hard radiation to add to the others we already knew for manned space flight.
I , have not kept up with it, what ever happened to magnetic shielding?
I had thought I had seen , not so many years ago, advancements in light weight magnetic field generators but have lost and forgotten the references.
The study by O’Banion et al is important wrt to space travel but a mouse is a mouse. There are many instances where mouse cancer models do not conform to the human models. It could turn out that cosmic radiation is much worse for humans but it could equally be much less harmful. Thus, until we actually do perform deep space journeys, we are unlikely to discover the real situation. This study should add to the long list of “things” (such as cancer, bone loss, muscle loss, etc) that have to watched out for when undertaking deep space travel but it should not be used as a poster for those with an agenda to appose it.
Jack Williamson’s 1948 “The Humanoids” shows one path to the stars open to humanity. We’ll never own the deed to the universe anyway, and the character, called Ironsmith, is the path to follow, traveling beside his mentor, the machine, traveling in the guise of anthropomorphism.
Do you want to live forever? Accept the faults of interstellar
voyage, then die happy, and move on to the next dimension.
I have been posting on this subject for years- after I read Eugene Parkers article in Scientific American “Shielding Space Travelers.” It is a troubling fact of life to many space advocates and they mostly just go into denial. The most common response is something to the effect that “radiation mitigation is trivial.” When this study is discussed on various forums you will doubtless read all about how private space does not need any radiation shielding and can take you to your retirement condo on Mars without it.
The reality is that just as I changed my worldview after being informed by one of the leading authorities on space radiation so must the space advocates who are proposing hobby rockets and billionaut tourists as the future of space exploration. But they will not. Nothing makes a dent in their dogmatic mindset of cheaper smaller is better. They will continue to worship the idea of fuel depots that will not work and chemical propulsion in deep space which also will not get human beings anywhere.
14 feet of water is what it takes to stop heavy nuclei. That is about 400 tons for a small capsule. The only propulsion system that can push this mass around the solar system is Nuclear Pulse Propulsion; bombs. Which is why I wrote “Water and Bombs.”
http://voices.yahoo.com/water-bombs-8121778.html?cat=15
There is no cheap.
Shielding can prevent whole body exposure to 56Fe particle HZE. It takes a few meters of water but since a Mars expedition can usefully carry that much, this may be less of a problem. Especially in a teathered habitat swinging on a cable, with the min drive (nuclear probably) on the other end as counter weight, surrounding the habitat with water imposes no big weight problem; they need the water to live.
Bob Zubrin dealt with this in his books and I used it in THE MARTIAN RACE. Curious indeed that NASA does no real shielding research at the ISS. This probably means they have no real intention of ever sending interplanetary expeditions, as many of us suspect. Same reason they do no centrifugal grav experiments.
this only proves that low possibilities for genetic susceptibility to Alzheimer needs to be taken in consideration when developing screening tests for astronauts.
But beyond these, is natural (and artificial) selection that needs to be weed out the genes of human shortcomings for space travel.
“-what ever happened to magnetic shielding?”
It will not stop heavy nuclei. Well….as Parker explained, it is possible- but not without a nuclear power plant running full blast powering a system so powerful it will rip the keys out of your trousers. Might as well go with a water shield- it will mass about the same when life support and other factors are considered.
And it will work.
“It could turn out that cosmic radiation is much worse for humans but it could equally be much less harmful. Thus, until we actually do perform deep space journeys, we are unlikely to discover the real situation.”
Consider the Apollo Astronauts who had trouble sleeping because of the flashes of light in their field of vision- each flash representing cosmic radiation blowing a hole through their brain as detected by the optic nerve.
I very strongly doubt years of exposure on long duration missions will have a happy ending. We need to move past denial and move on to what will work- no matter how upsetting to everyone’s vision of space exploration that is.
As Gregory Benford mentioned, the real problem is ZERO funding for the technologies required for safe (or survivable) long duration missions outside of the Earth’s magnetosphere:
1 – In orbit or deep space research and development in advanced shielding methods (beyond just water) – magnetic shielding, polyethylene formulations, etc.
2 – Artificial Gravity. Other than on Gemini 11, no form of centrifugal artificial gravity has been tested in space. There’s plenty of ground based research (often contradictory) on the minimum radius and maximum rotation rate that can be well tolerated by humans. Same goes for the minimum artificial gravity. Is simulated lunar gravity enough? Martian gravity? Or do we need 1g to minimize long term health effects?
3 – Advanced propulsion methods. Other than ion engines and VASIMIR (which may or may not work), there’s zero or close to zero engineering work going into testing new deep space propulsion methods. There’s no lack of candidates, though.
Without the above, we will never go beyond the Moon safely. We’ve wasted 30+ years and a huge opportunity with the Shuttle program and I don’t think long duration manned spaceflight will recover from that disaster for decades to come.
I apologize for posting over and over again. When famous people like Benford comment I get excited.
IMO the whole mindset about going into deep space in the traditional super-lightweight-evolved-from-aviation vehicles is bound to fail.
The first requirement is for Earth gravity and Earth radiation and a closed loop life support system. All the interesting places to go are in the outer system starting with Ceres all the way out to Neptune. These missions will take years even with very powerful propulsion systems (actually there is only one practical system; bombs).
Launching such missions is going to take a Moonbase. Chemical propulsion and HLV’s are entirely appropriate for getting us to the Moon to build such a base- but not for much else. We can assemble, test, and launch nuclear missions from the Moon without contaminating the Earth’s magnetosphere and we can fill up radiation shields using Lunar ice resources.
I do not believe in a flexible path- it seems straight and narrow to me and the public is completely unaware. Incredibly frustrating.
Whatever happened to those studies for the ship to generate its own magnetic shielding ?
That would still leave neutrons and gamma rays though. How wonder how much of a problem these two are.
“Moreover, astronauts will not likely be familial AD carriers”
or have family history of cancer, or heart disease, or mental illness, or diabetes, or warts, or hangnails, or…….
I don’t see this. With the progress being made in the field of AD, including potential preventative measures, persons with familial links will probably be treated and therefore less likely to see effects.
Also, unless you ban entire family lines from space, there is no test to reliably determine who will fall victim. My grandmother was said to have Alzheimer’s disease when she died in her late nineties and one of her eleven children recently died of the same disease. Should the other ten and all their descendants be denied space travel? (none of whom have shown signs of the disease) Or if it were cancer, mental illness, etc..? Sorry if I offend, but this reminds me somewhat of the mindset which led to leper colonies.
Off my soapbox now.
Hi Frank
“advanced shielding methods (beyond just water) – magnetic shielding, polyethylene ”
http://science.nasa.gov/science-news/science-at-nasa/2005/25aug_plasticspaceships/
Water is the best choice because we can get it from the Moon instead of Earth, but RXF 1 works also. Launching hundreds of tons of plastic into space from Earth instead of water from the Moon is second best.
“maximum rotation rate that can be well tolerated by humans.”
Tethers can be tbousands of feet long for little added penalty and thus alleviate any rotational intolerance. This was recognized all the way back in the thirties by Willy Ley.
“deep space propulsion methods. There’s no lack of candidates, though.”
Not really. After a half century there is no real contender to Nuclear Pulse Propulsion. Several trillion dollars in classified weapons research have made bombs the singular resource for interplanetary travel.
I agree with you on the Shuttle. The public is really unaware of the mistakes made in the shuttle program which is pretty disturbing in itself.
Huh…curious. I’m going to go talk to some people upstairs who work on related topics.
I’ll comment again if they have any strong opinions.
I love how every wanna-be rocket geek on the internet is convinced they know EXACTLY how to conduct space exploration (or not to conduct it). It seems to me that the only way to actually conduct flights beyond LEO is to first find all the technical requirements and challenges, and fund the necessary research programs to find solutions. For some time it has been clear that going into space poses medical risks to the astronaut, including loss of bone and muscle mass in microgravity and debilitating space radiation.
These problems do have potential solutions. Centrifugal pseudogravity will prevent the harmful effects of weightlessness. Nuclear propulsion (required to put any send big payloads across the solar system anyway) can help minimize trip time. Shielding can be use to screen out cosmic rays on space stations and spaceships, hopefully reducing the background dose to a safe level.
Once a superconducting magnetic coil is energized with current, that current will continue to flow and the magnetic field will maintain itself without requiring any power input, as a permanent magnet does. It is the same with the Earth’s magnetic field, which deflects charged particles from the sun without requiring an extension cord to the nearest outlet. I’d imagine that something similar to a halbach array could be used to cancel out the magnetic field within the space craft so it would not adversely affect ship systems.
Discussing a “small capsule” is somewhat misleading. If we are using material shielding to stop cosmic rays, the cube-square law is in effect here. For every square meter of hull surface, the astronauts will require a thick layer of shielding, probably something like water that they need to bring anyway. A small capsule requires as thick a layer of shielding as a big one- but, the larger the ship is, the smaller its surface area is in relation to its volume!!
Something small like Gemini would look ridiculous, floating around in some huge bathtub, but a giant rocket hundreds of meters long will only have to devote a small portion of its internal volume to shielding. Since we probably need lots of space, equipment, and life support systems anyway, why not build big if we are going to cross the solar system?
I don’t think that human issues with space radiation have much bearing on the Fermi paradox. Shielding against cosmic rays is possible, and if we have the propulsion technology for a slow interstellar journey, we can carry some extra shielding. Fast interstellar flights, at say 10%-70% C, or even faster, will require shielding from induced cosmic rays and bits of interstellar dust- especially truly relativistic spaceflights at nearly the speed of light.
We already handle very high speed particles in the LHC, and future rocket engines will need strong magnetic fields to handle the very high temperature exhausts required to achieve the specific impulse needed for interstellar travel, so we may be well capable of using magnetic deflection systems to protect the ship from induced cosmic rays- and if we can protect ourselves from those, why not ordinary GCRs? Unless these iron nuclei are so difficult to stop even a relativistic headwind is not comparable, I don’t see how a truly interstellar species can be stopped by them. Don’t forget that at high fractions of C, the cosmic rays get progressively “beamed” to the forward direction and can be stopped by the main deflection system.
We may be ignoring another possible answer. Aliens may not have our physiological limitations. We have already found extremophiles resistant to radiation on Earth. Scorpions are unusually resistant to radiation, too. If the aliens evolved in a environment that periodically is hit by radiation from a solar flare, they might evolve resistance to radiation- perhaps the ability to self repair. If we are talking of all possible intelligent species throughout the galaxy, assuming they all have our limitations is silly.
Speaking of radiation resistance, I have heard talk of adapting humans for radiation resistance with genetic engineering- we must also keep in mind that whoever actually goes may have been reengineered to deal with the hazards encountered in deep space.
All that said, cosmic rays are a hazard we have to consider, although not a hazard that has no solution. It is a problem for a near term flight to Mars, one that suggests we must add shielding and/or limit the amount of flight time. If we are already constructing a generation ship (let alone a relativistic rocket!!) we will already have means to protect ourselves from GCR’s, even if that is just a very thick layer of shielding around the hull, so I don’t really see how space radiation applies to the Fermi Paradox.
Energetic particles affecting cognitive abilities is almost a no-brainer conclusion (sorry, couldn’t resist). The particles are breaking the neural connections which is obviously disruptive to cognitive functions.
Using water as shielding makes sense, because the crew needs the consumables anyway (enough water for frequent bathing would be a morale booster) and also for reaction mass. The water can also be frozen, allowing it to be part of the spacecraft structure.
If we are concerned about accelerating/decellerating large masses, why not use cyclers for most of the journey? (until we can build fast ships.)
The neural damage from radiation is a problem that is not fixable by future gene engineered humans. Therapies for Alzheimers are being studied, but I fear that the only solution for radiation damaged brains is to grow new neural tissue and relearn lost faculties. They may also need to use mental tricks to reduce losses due to damage. I think shielding makes more sense.
Where there is water there is life (old Hawaiian saying). That is why my Ultimate Project space vessel concept has always had its 5-meter-thick outermost level full of water, both to provide the needed radiation shielding and to supply all the agricultural and biological necessities. And, of course, the mass that’s required for that is silly to put on a small spaceship, which is why we should work toward a generations ship with on the order of a million passengers/crewmembers. I think the water “solution” is much more comprehensive than are attempts to keep a magnetic shield operating.
I have been saying for about 5 years (*) that the radiation problem forces the solution of setting up permanent cycler station links between Earth and Moon and between Earth and Mars (the latter concept strongly supported in recent years by Buzz Aldrin and collaborators). Obviously, radiation shielding can be built up over a period of time, sourced from the near-Earth asteroids, and once it has been placed on a suitable transfer trajectory it can stay there forever.
I would be interested to know if anybody has thought of problems with this concept which have not yet occurred to me.
Stephen, Oxford
(*) See http://www.astronist.demon.co.uk/astro-ev/ae029.html, and scroll down to item 3 on the page.
On an interstellar scale, if you think big enough the radiation problem simply goes away. In their classic 1984 worldship design in JBIS, Alan Bond and Tony Martin came up with such thick walls (to hold a multi-km sized ship together as it rotated) made of maraging steel that radiation protection in the interior would be better than on Earth’s surface, and they discussed with straight faces whether it would be necessary to import sources of radioactivity into the interior in order to simulate the natural background radiation on Earth’s surface!
Maybe there really is a practical need for tinfoil hats.
Could metameterials be a solution to route space radiation around space craft?
Also, wouldn’t GCR affect everything aboard ship to some degree? It doesn’t matter much if a water molecule gets zapped, but wouldn’t computers or other equipment on board be subject to the same random destruction and gradual erosion? Of course computers can be hardened against radiaiton, but I would imagine on especially long voyages, particularly intestellar voyages requiring decades to centuries, some degradation would still occur and would need to be accounted for.
As a radiation oncologist, I find today’s post and the comments fascinating! One interesting side fact: I’ve heard rumors that Virgin Galactic has considered suborbital tourist flights through the Aurora Borealis. Supposedly, after consulting space radiation experts, this idea was nixed. I wonder what the dose rates are at suborbital altitude through an aurora?
I spend about 3 days out of the year on international flights at whatever altitude they cruise at….whats the likely damage? I don’t remember seeing any lights but sometimes stuff does dribble out of my ears.
@Gary Church – Almost all the research on radiation shielding has been limited and earth-bound. Surly a small satellite with some human equivalent radiation detectors and a variety of shielding methods can’t be that expensive to launch.
I agree that nuclear propulsion (a la Orion or its modern equivalents) is the only currently technically feasible way of getting astronauts from Here to interesting Theres in a hurry… but unless you break some international laws, that won’t be happening.
M2P2 and similar magnetic sail designs could (theoretically) provide both a high specific impulse propulsion and strong magnetic shielding, but I probably have more change in my pocket than the amount of money that has been spent in cutting metal for a space based test.
Almost all of these technologies could have been tested, improved or discarded many times over for the price of a single Shuttle launch.
Many good things said above on the issues and possible solutions.
I have a few comments on the paper itself:
1) Keep in mind that the radiation used in the experiments was almost 10,000 times stronger than that present in space. The dose was comparable, but administered over 1-2 hours instead of 6 months or so. This is called acute dose, and generally its effects are much more damaging than that of an equivalent chronic dose. This is because the body gets a chance to repair the damage while it is occurring.
It needs to be understood that there is tissue damage all the time from causes other than radiation, and I am not yet convinced that the HZE component of the GCR even stands out from the noise in this respect. It was my impression that the solar wind radiation is much more of a problem, albeit much easier shielded against.
2) The statistics are less than overwhelming, in my view. There were 8-14 animals per group, so the error-margins are very high. The methods used (ANOVA and t-test) assume normal distribution. Looking at some of the plots, I see some significant deviations from that, which can easily lead to false positives and, as far as I can tell, is not discussed by the authors. Where there is a significant effect in the females, there is none in the males. In some cases (fig. 1a and fig. 2), the trend in males is counter to that in females (i.e. less AD with radiation), which does not make sense.
Addendum: The regulatory limits for occupational exposure are 0.5 Sv/year, while the dose given to the mice is 1 Gy, which is roughly 1 Sv. Thus the dose that these researchers are saying is expected from GCR HZE on a Mars trip is only 1-4 times the regulatory limit, which seems rather non-alarming to me, considering the usual conservative nature of such regulatory limits.
There are other possible ways to mitigate these effects. For example – astronauts could take drugs and/or nutrients to provide a broad-spectrum anti-inflammatory response in the body and/or to reduce the accumulation of beta amyloid. Not only that – proper timing of travel could be useful as it is well known that GCR penetration to the Earth’s surface falls as the solar cycle approaches solar max (implying that the subsequent increase in the IMF is providing shielding).
About 20 years ago Duncan Lunan suggested a Fermi Paradox solution based on the hazards of cosmic-rays (you think this latest study is something new?) and the possibility that the deadliest variety come from a just few intermittent sources. What if we’re in an unusual time in cosmic history? A time of a far higher GCR flux. Now imagine how ETIs faced with a much more benign environment might have lived – all those “flimsy” space habitats and starships they could’ve built. Then the wave of high-energy iron nucleii hit – and those civilizations collapsed… There might be a galaxy full of ETIs who remember, vaguely, how they lived amongst the stars, before the Death Waves arrived. They abandoned the Heavens, those who survived, and tell tales to frighten children about the heights they’d fallen from.
Instead of whining about the GCR threat, we need to learn to live with it. And we might just be what the Galaxy needs to help regain what was lost.
The fact remains that with current technology, it is hazardous to travel to other planets. Basic research needs to be done to provide spacecraft with “Star Trek” shields. Also, it’s a simple fact of biology that as we as a species move into different enviroments, we will mutate, so homo sapiens will become several different species. The birth of homo novus.
@Greg Benford
Greg,
Even tho I retired 2 years ago I still work as a consultant at JSC, mostly to do documentation , engineers hate writing documentation! It gives me a site badge and I am back in the old engineering simulation group , a department where I spent the last two years.
These guys build the engineering simulators for evaluation of flight software and cockpit layout before they ever build the training simulators , over on the other side of JSC (tho we do have a high fidelity SSRMS simulator , Jim has flow it.)
Anyway these guys have been sent down marching orders since before Shuttle retirement to built a Beyond Earth Orbit generic spacecraft, first we had Lunar Orbit missions, Lunar Rover Missions, rendezvous with an asteroid mission and Deimos rendezvous mission, a ‘Orion’ capsule simulator and lately they are working on an L2 mission simulator. There are about 5 low fidelity simulators in the high bay in bldg 16 now.
That gets really exasperating the guys say they fell like they are running from one side of the boat to the other!
Headquarters can’t make up it’s mind , stating the obvious, there is not enough money to get the SLS, and what ever Beyond Earth Orbit vehicle built before 20??. It’s a mess.
Lord only knows how much NASA’s budget will be cut in the future.
I think the private enterprise guys , like Space X, can get a manned ISS vehicle built.
For Beyond Earth Orbit , I think that too, but seems like on a long long time scale.
@Frank
I see the problem as one of self similarity; trying to go cheap being the downfall of all these schemes to work around human physiology.
When I first became interested in space travel several years ago I would comment on a couple blogs and find myself constantly arguing with private space proponents- and saying over and over again, “there is no cheap.” I was finally excommunicated from that bunch and banned from posting. They would start calling me an idiot and other insults and when I tried to return the favor the moderator would block my replies. The person who runs those two sites works for a firm promoting space tourism- go figure.
The problem is that while the aerospace industry made some money off the space program as an outgrowth of the military industrial complex, it soon became clear that spaceships are hard money- they have to work. The example of this is the outrage over the Apollo 1 fire and subsequent oversight of contractors- a practice which disappeared after Apollo and resulted in the Space Shuttle being such a poor design. A portion of the shuttle development money reportedly went under the table into the B-1 bomber program; how much we will never know. Swing wings are not easy to build which is why you do not see it anymore; cuts into profits.
The easy money of cold war toys has since defeated any move by industry to take up the cause of space exploration. No easy money in spaceships. People who want something for nothing rarely end up with anything worth anything. Trying to find cheap ways around furnishing explorers with the physcial conditions human beings evolved in is going to fail. On the other hand if we start with a baseline of one gravity and Earth level radiation we are bound to succeed.
The engineering solutions to this baseline requirement are as I have already detailed; a tether for gravity and a massive moonwater shield with bomb propulsion. That is EXACTLY how to do it and I do not see any one else offering anything else that will work except waffling and spewing about R&D.
We have been doing R&D for over half a century. It is a reason to go that is supposedly lacking.
When that crater in Mexico was discovered in 1980 the cold war was reaching it’s crescendo and the massive extinction it caused was overshadowed by the threat of nuclear weapons. Impact defense is still the way to get all that sweet DOD money for a Moon base. IMO
Sorry Gary Church, but all that money that needs to be spent doesn’t exist.
I agree with the poster above who says that an acute dose difference is different from the exposure an astronaut would actually receive in space. Comparing the two is like comparing exposure to a flame and exposure to the same amount of heat energy over a week-long period.
The “Phantom Torsos” (i.e. Fred and Matroshka) used on the ISS for radiation model calibration: http://science.nasa.gov/science-news/science-at-nasa/2009/27may_phantomtorso/
Paper on organ dose measurement using the Phantom Torso: http://www.nasa.gov/mission_pages/station/research/experiments/Torso.html
I suggest we send a probe with a few of these (different body configurations) to, say, the L1 point. (Unfortunately – probably too large a payload and too late to include on DSCOVR which will basically replace the aging ACE. Also – DSCOVR is under NOAA’s umbrella – not NASA’s – so effects on living tissue are not even on their RADAR. ).
http://science.nasa.gov/media/medialibrary/2012/03/01/Nguyen-DSCOVR-Mission-Briefing-HPS-v01b.pdf
I don’t pretend to be an expert at astronautics and I’m not a rocket scientist or engineer. I won’t pretend I have the solutions to the problem that others lack. Yet, being a space advocate, I won’t dwell into denial either. Of course radiation is a serious health hazard, as is zero-g and and a whole list of other things.
But have we really devoted any serious effort and resources as a technological civilisation to address these health hazard issues of space travel? We’re just at the point where we are only identifying the problems: bone loss, eye damage, radiation risk and the lisk goes on. Have we done any serious work to mitigate these negative effects? The only thing we’re hearing is how much deadly the space environment can be (and of course it can be-there’s no denial about it).
50+ years after Gagarin, we haven’t even tried to test some type of artificial gravity in space, to see if it works and if it’s a solution at all. And we haven’t even tested or tried to innovate any form of radiation shielding for long-term missions beyond Earth orbit. Well, maybe because we’re stuck in LEO for the past 40 decades.
Space travel isn’t easy or risk-free, as this new radiation effects study in the article suggests, but it seems at least premature to me to conclude that space travel is ultimately prohibitive for humans, without taking the time and effort to really try and address the issues at hand.
Just to use a crude analogy, and I know it isn’t exactly the same with deep space, but is Antarctica suitable for humans? It can freeze you to death. But with the use of heavy clothing and suitable equipment you can win a foothold there.
Sorry, I meant 4 decades, not 40!
I just read what Adam Crowl was saying, and did this b.o.t.e. calc…
If the scale factor for our distance from the galactic core is 500 times less than that for our distance from active galaxy nuclei (and centaurus A should stand as a good proxy for this distance), then if our galaxy became active, we should expect HZE in the order of a quarter of a million times greater. So I must ask somewhat timidly – does anyone know how suddenly can galaxies become active?
“all that money that needs to be spent doesn’t exist.”
According to the DOD.
Yet a single program- the F-35 stealth fighter, will cost ONE TRILLION dollars over the next half century. That is a conservative estimate because it does not work as advertised and probably never will.
But that money does not exist according to you.
The last paragraph in the article about AI probes and radiation prompted this thought. Radiation is a hazard to us biological types because at the scale of our molecular machinery the energy that can be deposited by the particles or photons can cause significant damage.
Given the trends in electronics, any presumably electronic AI, is likely to have structures on about the same scale as biology, so I wonder if such AIs might be as radiation sensitive as ourselves. Remember that radiation is already a significant design issue in space bound electronics.
As an aside, do the Apollo astronauts have any significantly elevated rates of Alzheimers? I realize that the sample is too small and trip times too short to be statistically significant. Just wondering.
Actually the more I think of that crazy idea brought up by Adam Crowl, the more I like it. It is obvious that the fastest and least cautious of early ETIs that has expansionist tendencies, always wins the race and will end up dominating until the Crowl-Lunan disaster. Then it would all have to start from year zero.
I also love that one epoch matches what might be expected of an ETI domesticating Earth. The end Permian seemed mighty strange before that suggestion, but all is clear now.
1) Terraforming causes unprecedented changes in the oceans and atmosphere, as never seen before or since.
2) The delta C13 shift was larger than expected if the entire biosphere collapsed, and thus can only be explained if massive quantities of fossil fuels were released.
3) an unusual monoculture of fauna (90% Lystrosaurus) appeared around that time with global distribution. This has only otherwise been in agricultural situations.
Admittedly though, I do have a penchant for crazy ideas.
Eniac makes some extremely good points above. Did the researchers even take into account the relative number of neurons in a mouse compared to a human? A mouse probably doesn’t have all that many to lose before effects become significant, if, as Eniac pointed out, they ARE significant. Reminds me of a paper I saw a while back that just completely discredited many of the hyped fMRI studies one reads so much about. I admit that I’m prejudiced, as I work around many ph.d. biologists that are functionally innumerate…..
I don’t see the radiation problem as being a show-stopper, but as another engineering problem that can–with sufficient effort and hard stars (money)–be solved. For example, multiple-layer shielding consisting of different materials such as aluminum, paraffin, and various plastics has been used for radiation shielding on Earth, and such shielding can be, if memory serves, thinner and lighter than shielding made of just one material. Also:
There is no reason why a combination of passive and active (electro-magnetic) shielding could not be used. For any given set of spaceship performance criteria, optimization analyses would indicate the best (in terms of minimum mass) combination of passive and active shielding. As the active shielding technology improved (high-temperature superconductors, as several other commenters have noted, are one solution), it could take over a larger “share” of the shielding task, allowing less of the passive shielding to be used. For interplanetary journeys, the whole spaceship needn’t be shielded; as far back as the 1960s, the concept of an onboard solar flare “storm cellar” was well-known in the astronautical literature, and:
Even now, the shielding mass problem could be significantly reduced if we set up a lunar base that was equipped with electromagnetic launchers, which (among other useful applications) could launch interplanetary spaceships from the Moon *without* using rocket power. Since such a Moon-launched ship would only need propellant for the return leg of the trip, plus a little for mid-course trajectory correction maneuvers (it could enter orbit around any planets possessing atmospheres via aero-capture, needing only a small amount of propellant for orbit circularization), it could be much smaller and lighter than a spaceship that must use onboard propulsion for *both* legs of a mission, and some of this “mass dividend” could be devoted to radiation shielding.
@Ivan – too few astronauts to be significant. But if you look at the astronauts, many are still surviving in their late 70’s or died in their 80’s. Those that died earlier were mostly from accidents of heart attacks.
Of the 4 moon walkers who died, only Shepard died of cancer. AFAICS none have/had Alzheimers.
Brief exposure does not seem to be a major problem.
I actually agree with Eniac’s first post [although his second one…. grumble grumble ;)].
But I do think this is an interesting question in terms of how does long term space travel affect potential future health (specifically neurodegenerative diseases). If there is a simple dose/day limit that a person can handle, then you can imagine ways to get around this possible problem without having to shield the ENTIRE ship. You could have isolated sleeping chambers that are reinforced to reduce exposure while the rest of the ship has “normal” levels of shielding.
It’s an interesting set of questions.
Astronist wrote:
[I have been saying for about 5 years (*) that the radiation problem forces the solution of setting up permanent cycler station links between Earth and Moon and between Earth and Mars (the latter concept strongly supported in recent years by Buzz Aldrin and collaborators). Obviously, radiation shielding can be built up over a period of time, sourced from the near-Earth asteroids, and once it has been placed on a suitable transfer trajectory it can stay there forever.
I would be interested to know if anybody has thought of problems with this concept which have not yet occurred to me.
Stephen, Oxford
(*) See http://www.astronist.demon.co.uk/astro-ev/ae029.html, and scroll down to item 3 on the page.]
The only “problem” that jumps out at me is what you *didn’t* write. Rockets are no longer “the only game in town” for crossing space. A lunar space elevator (with a “way station” at the L1 Lagrangian point) could be built today out of existing high-strength fibers such as Kevlar and Spectra; in fact, the LiftPort Group is working on such a project now (see: http://liftport.com/overview/ ). Such elevators would also permit easy access from and to asteroids. Also:
Rotating space tethers are another option for rocket-less space travel, as are electromagnetic launchers on the Moon (and later also on Ceres, Pallas, Vesta, Juno, the moons of Mars, etc.). Such electromagnetic launchers would also greatly increase the utility of cyclers, and vice-versa; the cyclers could be re-stocked periodically with propellant and other supplies shot off the Moon (or Phobos or Deimos, or asteroids). The empty cycler cargo delivery ships could separate and aero-brake (using the terrestrial or martian atmospheres) into orbit around those planets in order to return to their natural satellite bases for re-loading and reuse.
“People who want something for nothing rarely end up with anything worth anything. Trying to find cheap ways around furnishing explorers with the physcial conditions human beings evolved in is going to fail.”
Going back over the comments I see the same result as every other discussion on radiation I have participated in. I am amazed once again at the very common and predictable phenomenon of denial. If you do not like the facts…… ignore the problem.
This is the difference between those with a self-gratifying fantasy and those with a vision for the future.
Tesh says “There are many instances where mouse cancer models do not conform to the human models.” And I’m not so sure about that.
Instead I will side with, possibly, New Zealand’s most awarded ever scientist Francis Brian Shorland”. Note that we tend to use lab mice that have been deprived of all their genetic variation and selected to be immunocompromised freaks for these tests. So what started off this self fulfilling prophecy?
Shorland dated it to WWI where test done on the amino acid content required to keep adult rats active (“fighting fit”) were directly applied to humans by German scientists, and as a result their civilian population nearly starved. If they realised that they could have changed to a vegetarian diet, they should have won.
Shorland pointed out the model (works on rats = works on humans) still fitted perfectly if we realised that rats grow nearly their entire lifespan. If we test at the end of this growth, we find rats can fight on the front lines on a vegetarian diet – so we must be able to be too.
“There is no cheap.”
Historically the manned space program is an example of extreme K selection in biology – minimal risks to very few crews. The more the crew needs to be safe, the higher the costs and the fewer the flights. This is a vicious circle that gets us nowhere. In contrast, most human migration, e.g. of the European exploration and colonization of the Americas, is more like r selection – high risk and mortality experienced by very many people.
Since radiation damage is going to be stochastic, if you can send more crews, you will end up with some of the astronauts with very low neurological damage and no radiation induced cancers. The cost is the individuals with shortened lives. This would not be acceptable currently for publicly funded human spaceflight, but probably acceptable for privately funded flights, especially for those individuals willing to take the risks.
The Mars trips may not be as bad as originally believed. Curiosity found lower levels of radiation on Mars’ surface that expected, allowing astronauts to explore more freely.
It isn’t that private space is trying to do something super cheap compared to Nasa. it is that they may not need to spend the resources on the research for extreme risk reduction.
I’d like to see the idea of personal shielding on manned deep space flight explored. For example if an astronaut slept in a chamber shielded with water, when he’s essentially immobile for eight hours, his exposure to cosmic rays could be reduced by a full 1/3 throughout the trip without dramatically increasing the mass of the vessel. Likewise certain areas of the ship where the astronauts are spending most of their time could have shielding. It could also be provided for certain body organs. If it turns out that the brain is more susceptible to radiation than other organs, special headwear could be worn. A combination of localized or selective shielding could be employed to protect health while still keeping the weight of the spacecraft below a maximum mass. There seems to be a lot of all or nothing thinking on this topic. If risk can be mitigated to acceptable levels, radiation doesn’t have to be a deal killer. This is space exploration after all, and if we want to be cozy and safe we could just stay home.