Radiation, Alzheimer’s Disease and Fermi

by Paul Gilster on January 2, 2013

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 Aβ 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.

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{ 88 comments }

Eniac January 6, 2013 at 2:13

Before we get all riled up about the dangers of space radiation, let us not forget that there quite a number of actual astronauts that spent weeks in interplanetary space and came back without noticeable consequences of radiation exposure. What are we saying, if you stretch the weeks to months suddenly everyone will die gruesome deaths? Not likely.

I am not trying to trivialize the dangers of exposure, and if we want civilians in space we certainly need to mitigate them. But, this will start with the predominant and actually dangerous radiation, that from the sun, which does not require a 5 m shield all around the craft.

Dismissive assertions without any supportive argumentation like the following:

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.

are not at all helpful in this discussion. Address directly what has been said. Show where the errors are. Don’t complain about hypothetical adversaries that have it all wrong and obviously are unworthy of the bother of trying to talk sense into them with well-reasoned arguments.

Brett Bellmore January 6, 2013 at 9:27

Is this some kind of news? I recall back in my L-5 days, nearly 40 years ago, we were talking about this, which is why the O-Neil colony designs involve so much shielding. Really, it’s been known for decades that any trip beyond the Moon would have to either involve thousands of tons of radiation shielding, (And, no, the water wouldn’t be dual use.) an extremely fast trajectory to minimize trip time, or some kind of advance in magnetic shielding.

Of which I think the last is by far the most plausible.

Brett Bellmore January 6, 2013 at 9:36

And, short of engineering humans to regenerate like Hydra, you’re not going to genetically engineer humans for resistance to cosmic rays: They’re so energetic they utterly destroy entire columns of cells through the body from their entry point to exit. You might try to replace those cells, a feasible approach outside the brain, but I’m not sure how you’re going to regenerate the long axon runs through the “white matter” which are key to connectivity within the brain. They’re generated during early development, and then must persist for a lifetime.

GaryChurch January 6, 2013 at 13:22

“minimal risks to very few crews. The more the crew needs to be safe, the higher the costs and the fewer the flights.”

I am afraid that is not true at all. The Space Shuttle had no escape system. Fear of failure was all about costing more money when launches did not happen- it was not about the politics or the mission like in Apollo. The result of going cheap was two dead crews.

The big compaint about the shuttle was it was so expensive; it was designed on the cheap and this translated into high cost- the cost of a Saturn V class launch vehicle that only lifted a quarter of what the previous HLV vehicle could.

It was expensive because it lifted a huge and never full cargo bay, wings and landing gear- essentially a 737 size hypersonic glider- into LEO so it could come right back down again. An escape system would have cut into the payload so much as to make it not just marginal, but very close to useless.

Without the orbiters to inspect and turn around the STS would have launched twice a month and lifted four times the useful payload for the same money- and been able to land payloads on the Moon for a base.

“lower levels of radiation on Mars’ surface that expected”

Red Herring; we are talking about space radiation, not the surface of that too deep gravity well everyone somehow believes is “just close enough” to get to with chemical propulsion. Mars is a rock; the interesting destinations are the moons with subsurface oceans in the outer solar system.

“There seems to be a lot of all or nothing thinking on this topic.”

That is because of secondary radiation Christopher. When an iron nuclei hits a spaceship at relativistic speeds it causes a shower of secondary radiation that ends up being worse than no shielding at all. Which is why it has to either stop all of it- or none of it.
There is no cheap.

GaryChurch January 6, 2013 at 13:51

“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.”

Actually SpaceX, really the only company that qualifies as private space, uses NASA labs and personell for token payment, and uses the taxpayer funded technology that Reagan signed away to private industry. Everything they claim to have innovated, their engine design, heat shield, stir welding…….all of it was paid for orginally by the taxpayer and now we are getting charged again.

As for risk reduction, the Dragon capsule will reportedly be using a hypergolic “pusher escape system.” Compare to a solid rocket abort system this is not effective at all and results from the need to use the capsule as a tug to keep private blow up tent tourist stations in the right orbit. It is no substitute for an escape tower.

Eniac January 6, 2013 at 15:34

Brett Bellmore:

They’re so energetic they utterly destroy entire columns of cells through the body from their entry point to exit.

This is interesting. Is this an established fact? Do you have a reference for it?

Cells are very large compared to the traces of single ions,. It would seem to me that interactions along a track are relatively few and far between, no matter how energetic the particle. After all, in order to see tracks at all you need to have a super-sensitive detector such as fog or bubble chambers, or photographic emulsions, all of which are designed to amplify single molecular events into visible dots. In a cell, the only single molecular event that has a chance of causing death of the whole cell is a double strand break of the DNA. Most of the cell is not DNA.

Rob Henry January 6, 2013 at 16:13

Eniac wrote “the predominant and actually dangerous radiation, that from the sun, which does not require a 5 m shield all around the craft.”

GaryChurch wrote “When an iron nuclei hits a spaceship at relativistic speeds it causes a shower of secondary radiation that ends up being worse than no shielding at all. Which is why it has to either stop all of it- or none of it”

And the counterposition of these two factors means that I can never get a handle on this problem.

Alex Tolley January 6, 2013 at 18:36

@Brett “And, no, the water wouldn’t be dual use.”

Can you elaborate on this point?

Alex Tolley January 6, 2013 at 18:44

My understanding is that the cascade of secondaries is far more damaging than the primary. Because of that, GaryChurch is correct – either do not use shielding or use a lot.

Alex Tolley January 6, 2013 at 18:47

@GaryChurch “As for risk reduction, the Dragon capsule will reportedly be using a hypergolic “pusher escape system.” Compare to a solid rocket abort system this is not effective at all and results from the need to use the capsule as a tug to keep private blow up tent tourist stations in the right orbit. It is no substitute for an escape tower.”

So you would predict that SpaceX will not get their Dragon capsule man rated?

Eniac January 6, 2013 at 23:54

Rob Henry:

And the counterposition of these two factors means that I can never get a handle on this problem.

Good point.
The optimum may be to have a small, thick shield between the sun and the craft, close enough to shield a large enough hiding spot from SEPs for shelter in case of solar storms, but far enough to allow secondary radiation generated by GCR inside the shield to dissipate away from the craft. Otherwise, keep the walls thin to minimize secondary radiation, and take the dose that comes with the GCR in stride.

There seems little hard data on biological effect of GCR, at least none that I found that was easily decipherable to address the question. Please come forward if you know of such. The fact that Apollo astronauts appear more or less unharmed is a good sign, but admittedly not readily extrapolated to more chronic exposure.

Brett Bellmore January 7, 2013 at 8:37

Enac, it’s been a while since I was looking into this, I’ll try to find a relevant reference tonight. The issue isn’t really so much the individual nuclear collisions, as it is the shower generated by the first one, and the Cerenkov radiation generated by a highly charged particle traveling way above the speed of light inside the tissue. At least, if I recall right.

GaryChurch January 7, 2013 at 15:38

“So you would predict that SpaceX will not get their Dragon capsule man rated?”

SpaceX will close their doors eventually. I wish it would have happened already. Take a look at the Delta IV heavy with the Orion on top and compare it to the hobby rocket and you can see what is going to take people into deep space and what is going to fail. The whole retire-on-mars-subsidized-by-tax-dollars is an obscene fantasy and I am thoroughly sick of it.

GaryChurch January 7, 2013 at 16:14

“Address directly what has been said. Show where the errors are. Don’t complain about hypothetical adversaries that have it all wrong and obviously are unworthy of the bother of trying to talk sense into them with well-reasoned arguments.”

“The optimum may be to have a small, thick shield between the sun and the craft, close enough to shield a large enough hiding spot from SEPs for shelter in case of solar storms, but far enough to allow secondary radiation generated by GCR inside the shield to dissipate away from the craft.”

Your statement on what may be the optimum is completely wrong. SEPs permeate space and do not just fly directly from the sun in a straight line. Interposing a “small, thick shield” will not work. Secondary radiation will not “dissipate away from the craft”- it is the craft that causes the secondary radiation.

So I am complaining Eniac; you seem bright enough but you need to do your homework before scolding others for their efforts that you find inconvenient.

Eniac January 7, 2013 at 22:44

Gary Church:

Secondary radiation will not “dissipate away from the craft”- it is the craft that causes the secondary radiation.

You did not understand this correctly. I was referring to the secondary radiation from he shield, not the craft. The further away that is, the less radiation, obviously.

If you are right and SEPs are not directed, then this scheme will indeed not work.

Eniac January 7, 2013 at 22:52

Gary Church:

So I am complaining Eniac; you seem bright enough but you need to do your homework before scolding others for their efforts that you find inconvenient.

If you look back, I think you will (grudgingly) agree that the quote I scolded you about did not take a lot of effort on your part. It was devoid of facts or reason. Not that this one of mine is any better, but, heck, it had to be said….

GaryChurch January 10, 2013 at 15:53

Eniac….you are just as obnoxious as me. Do not try to act all polite all of a sudden. We know it is not personal- we are just doing what people do on blogs so let’s carry on. I have made plenty of predictions and supposed a lot of technical stuff that was wrong and had people call me on it; that is what keeps us honest and informed and makes these forums so interesting to the few of us who are really excited about space.

My biggest bomb was that I thought NASA was going to build Sidemount. I believed Shannon was the Obi-Wan Kenobi of human space flight; our only hope. It made so much sense- how could they not build it?
I learned from that.

Christopher Newell January 11, 2013 at 14:10

I agree that cheap and spaceflight should never be used in the same context together, and I’m certainly not asserting that there would be anything inexpensive about having even limited shielding on deep space missions. Although I do find it more useful to search for imaginative solutions to hard problems than to simply repeat a defeatist mantra that something cannot be done.
The secondary cascade of particles would be a limiting factor for body wear type of shielding (although I do wonder about lead body armor) but that still doesn’t exclude the possibility of total shielding for part of the vessel, specifically a highly localized area where the astronauts sleep. I also wonder if the idea of high volume, low density shielding has been examined. The byproducts of high energy collisions are usually short lived. If enough distance is placed between the point of collision and the crew, this might allow additional time for the secondary particles to decay. Maybe there’s someone with training in high energy physics who can address this.
On another note, mountaineering is an inherently dangerous activity. Mountain climbers often suffer from brain damage due to hypoxia at high altitudes. Every year people risk life and limb climbing peaks like Everest. They continue to do this, lining up in droves and paying exorbitant fees just for the adventure. A manned mission to Mars is far more compelling than just climbing a mountain that thousands of people have climbed before, and there is more to be gained in terms of scientific knowledge and technological development. I predict that exposure to cosmic radiation or any other risks will not stop manned exploration of the solar system any more than danger stops people from conquering the world’s great mountains. Our thirst for knowledge and adventure is just far too compelling.

GaryChurch January 11, 2013 at 15:34

“If enough distance is placed between the point of collision and the crew, this might allow additional time for the secondary particles to decay. Maybe there’s someone with training in high energy physics who can address this.”

Well, I did reference Eugene Parker’s 2006 article in Scientific American- “Shielding Space Travelers.” It is the best work I have found over the years explaining space radiation to the public. The distance and mass of air found in the atmosphere is what shields us from GCR by the way.

“-more useful to search for imaginative solutions to hard problems than to simply repeat a defeatist mantra that something cannot be done.”

My “mantra” has always been WE CAN GO NOW. The solutions are crystal clear to anyone who takes a survey of the available technology. What blinds people is their unwillingness to accept the cost of making it happen.
There is no cheap.

Eniac January 12, 2013 at 12:56

Well, I did reference Eugene Parker’s 2006 article in Scientific American- “Shielding Space Travelers.” It is the best work I have found over the years explaining space radiation to the public. The distance and mass of air found in the atmosphere is what shields us from GCR by the way.

Nice article, as popular science articles go.

If you look at the top figure on page 43, you see that cosmic radiation in interplanetary space is only about twice as strong as that in LEO. We have had astronauts staying at LEO for years, i.e. as long as your average Mars trip would take, with no serious health consequences. All in all, it really looks like that radiation will be one of, but far from the most serious risks of space travel.

GaryChurch January 12, 2013 at 22:50

“-cosmic radiation in interplanetary space is only about twice as strong as that in LEO. ”

Uh-huh. That is right. And it is not good.

“-radiation will be one of, but far from the most serious risks of space travel.”

And that is wrong; that is not what the study says.

GaryChurch January 13, 2013 at 14:07

“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.”

Massive shielding.
This is the game changer. The showstopper. The sea change. The paradigm shift.
Whatever you want to call it, it is the reality that most of what we are familiar with concerning human space flight is not going to work in deep space.
Massive Shielding=Nuclear Propulsion=Bombs
M=N=B
We have to transport nuclear materials to the Moon where we can light off a nuclear propulsion system. The Moon is where the ice-derived water to fill up a massive radiation shield is to be found.
Massive Shield=Water=Lunar Base
M=W=L
To put it chronologically: L=W=M=N=B
So, first and last, we need an HLV to get to this Lunar Base (where the water for the shield is) and we need to safely transport Bomb material there (and safely assemble and light off the bombs to push the shield around).

All in all, it really looks like that radiation will be the determining factor in spaceship design and this determines the entire development of space travel.

Eniac January 18, 2013 at 2:29

And that is wrong; that is not what the study says.

With “study”, are you referring to the popular science article? Or, if a real study, what does it say? You mean the study this post is about? See my analysis above for that.

All in all, it really looks like that radiation will be the determining factor in spaceship design and this determines the entire development of space travel.

Assuming, that is, that astronauts cannot withstand the two-fold increase in radiation over that at LEO which has already been proven to be quite harmless. There is no evidence for this, only conjecture and rhetoric.

GaryChurch January 18, 2013 at 15:40

“-which has already been proven to be quite harmless. There is no evidence for this, only conjecture and rhetoric.”

Radiation is not harmless. There is evidence to support this and while you may not like the fact that humans do not stay healthy without earth gravity and earth radiation, the fact remains.

Eniac January 18, 2013 at 23:05

Radiation is not harmless. There is evidence to support this…

Yes, obviously.

As I am sure you are aware, though, we are here concerned with a much narrower question: How dangerous are the radiation levels in interplanetary space for the long-term survival of humans?

… and while you may not like the fact that humans do not stay healthy without earth gravity and earth radiation, the fact remains.

Not so. The evidence here, consisting of actual humans who were there and stayed healthy, clearly says: “Not very”.

Humans have survived remarkably well in space for years without gravity or your favored tons of shielding. They have shown no signs of sickness, with the exception of a somewhat higher incidence and earlier onset of cataracts of the eye.

GaryChurch January 19, 2013 at 16:21

“Humans have survived remarkably well in space for years”

And there is found the real point of this whole discussion Eniac; survival.
We can “survive” without air for a couple minutes, without water for a couple days, etc. But to thrive and live a high quality of life which includes reproducing a follow on generation- that requires more than surviving being irradiated for years by cosmic radiation and debilitated by low gravity.

Sending people on missions that last several years- as many as 6 or 7 years- requires more than floating around in tin cans taking a radiation bath.

Eniac January 20, 2013 at 22:35

But to thrive and live a high quality of life which includes reproducing a follow on generation- that requires more than surviving being irradiated for years by cosmic radiation and debilitated by low gravity.

I don’t think the available evidence indicates that the latter is so bad as to exclude the former.

Which makes this pure, unfounded conjecture and rhetoric:

Sending people on missions that last several years- as many as 6 or 7 years- requires more than floating around in tin cans taking a radiation bath.

Which is to say: Sending people on missions that last several years- as many as 6 or 7 years- may require nothing more than “floating around in tin cans”. Your certainty that this is not the case is not backed up by any evidence. None you presented, nor any I could find.

You would be better served by facts and arguments in place of leading characterizations such as “debilitated”, “tin cans”, and “radiation bath”.

Eniac January 20, 2013 at 22:42

Let me make a bold claim here: The negative effects on human health from cosmic radiation in interplanetary space without protection are less than those from smoking.

I am not sure of this, but it sounds right to me. If you are sure it is untrue, see if you can produce evidence to the contrary.

GaryChurch January 22, 2013 at 15:13

“-it sounds right to me. ”

Of course it does. If you can produce evidence then I will. Extraordinary claims require evidence; I think my claim is less extraordinary than yours. Considering what GCR does to DNA I think your comparison to smoking is a distractor.

http://www.lngs.infn.it/lngs_infn/index.htm?mainRecord=http://www.lngs.infn.it/lngs_infn/contents/lngs_en/research/experiments_scientific_info/experiments/proposed/cryostem/

Eniac January 23, 2013 at 0:59

Well, we do have plenty of positive (and definite, I might add) evidence about the risk of smoking, and only weak and negative evidence about the risk of cosmic radiation in space. You could say the experimental sample size is small, which is true. On the other hand, the hypothesis “years of spaceflight cause irreparable and debilitating damage” is clearly and decisively disproved by the dozens of astronauts leading decades of normal lives after exposure, in some cases for years.

Yes, there are holes in the evidence. Particularly, interplanetary space has about twice the cosmic ray intensity as LEO, and we have data there only for weeks rather than years. But, seriously, do you really expect that factor of two to make the difference between life and death?

I am not sure why you are citing that San Grasso report, it actually seems to support my point in clearly stating that DNA damage is more of a problem in cryopreserved samples, because in living organisms the DNA damage is quickly repaired. It also says that a main agent of destruction from radiation is free radicals, which makes sense. Consider, however, that most free radicals are generated by normal biochemical processes (in the mitochondria, for example), not radiation. Moderate radiation is therefore just one of many elements that constantly attack our cells, which, of course, have evolved to deal with this.

When we are increasing radiation levels 10,000 fold, like in the experiment that is subject of this post, then we are actually starting to do some real damage. But, apparently, still not enough to cause anything more serious than barely detectable behavioral changes (if any, the statistics is weak) in those mice.

Sorry, but I remain convinced that you are standing on very thin ice with your sweeping assertions on the severity of space radiation.

GaryChurch January 23, 2013 at 16:01

“your sweeping assertions on the severity of space radiation.”

This is my assertion;
Go into space giving human beings the same enviroment they have on Earth in terms of radiation and gravity.
Upside; it will probably result in healthy humans over long duration missions.
Downside; it requires a super powerful form of propulsion to move the massive shield and artificial gravity structures.

Go into space on the cheap with high levels of radiation exposure and zero gravity.
Upside; cheap?
Downside; after several years in space astronauts will suffer permanent effects to bone marrow and mass, debilitation, as well as other problems such as immune system depression, radiation exposed meds becoming ineffective and mutated pathogens becoming lethal. This is besides the lifetime dose of radiation.

Eniac January 23, 2013 at 22:16

Downside; after several years in space astronauts will suffer permanent effects to bone marrow and mass, debilitation, as well as other problems such as immune system depression, radiation exposed meds becoming ineffective and mutated pathogens becoming lethal. This is besides the lifetime dose of radiation.

This is where the thin ice is. None of these things have been shown to be necessary consequences of the deep space radiation environment. What experience we have suggests they are not.

Eniac January 23, 2013 at 22:32

If lack of gravity is what you are worried about, that can be remedied cheaply by tying two tincans together and rotating them. So far we have not found it to be worth the trouble, but that would certainly be an option for longer missions.

GaryChurch January 24, 2013 at 14:25

“None of these things have been shown to be necessary consequences of the deep space radiation environment.”

I think all of them have been shown to be possible dangers. You are arguing basically that if fire does not burn a person it cannot be said to be harmful to them until it does.
I guess that solar storm the Apollo 17 crew missed by a couple weeks would not have hurt them? And I have heard astronauts talking about the percentage of bone marrow and bone mass they lose permanently after their 6 month missions. I suppose that was not a necessary consequence?

“- that can be remedied cheaply by tying two tincans together and rotating them. So far we have not found it to be worth the trouble,-”

Uh-huh. There is that cheap word giving the game away.
There is no cheap.

Eniac January 24, 2013 at 23:39

You are arguing basically that if fire does not burn a person it cannot be said to be harmful to them until it does.

Not quite. I am basically arguing that deep space radiation is more like sunshine than fire. You can get burned, but that does not keep us from living with it every day.

Uh-huh. There is that cheap word giving the game away.

There is nothing wrong with finding ways to do things cheap. It is the best way to get them done.

There is no cheap.

You are using this mantra of yours like a premise, when it should be a conclusion. A tough one to make, at that. It involves proving a negative.

GaryChurch January 25, 2013 at 14:52

“You are using this mantra of yours like a premise, when it should be a conclusion.”

My mantra is “We Can Go Now!”
There is no cheap is simple fact.

How long are we going to keep beating this horse? Do you want the last word?

GaryChurch January 25, 2013 at 15:05

“DNA damage is more of a problem in cryopreserved samples, because in living organisms the DNA damage is quickly repaired.”

It is only repaired to a certain extent; much of the radiation damage is cumulative.

In regards to star travel, this inability of cryopreserved DNA to self-repair has been discussed for many years. The solution is first to use massive shielding to minimize the damage and second to revive the crew at intervals to allow them to self-repair and then re-freeze them.

As you may have noticed Eniac- or not- I have a vision for space exploration that does not start when they invent warp drive or someone finds a stargate. The big missing piece in my survey of technology required to launch a mission to another star is revivable cryopreservation. I believe that just as fiction fairly accurately depicted the future development of aircraft and submarines, we can get a fair idea of what star travel will look like. And it looks like we can start now to me.
The key is several times the energy the world now produces available to be transmitted from the Moon to a starship with a beam propulsion system. And slow down upon arrival several centuries in the future using H-bombs.

ljk March 21, 2013 at 23:46

11 of the Weirdest Solutions to the Fermi Paradox

The Great Filter theory suggests humans have already conquered the threat of extinction

It’s difficult to not be pessimistic when considering humanity’s future prospects. Many people do… Read…

Most people take it for granted that we have yet to make contact with an extraterrestrial civilization. Trouble is, the numbers don’t add up. Our Galaxy is so old that every corner of it should have been visited many, many times over by now. No theory to date has satisfactorily explained away this Great Silence, so it’s time to think outside the box. Here are eleven of the weirdest solutions to the Fermi Paradox.

Full article here:

http://io9.com/the-reason-this-isnt-widely-posited-is-that-except-in-c-457048015

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