[News] Too much radiation for astronauts to make it to Mars

[Moontanman]

Too much radiation for astronauts to make it to Mars

 

FORGET the risk of exploding rockets or getting sideswiped by a wayward bit of space junk. Radiation may be the biggest hurdle to human exploration beyond low-Earth orbit and could put a damper on a recently proposed mission to Mars orbit.

 

Too much radiation for astronauts to make it to Mars - space - 16 September 2009 - New Scientist

[UncleAl]

NASA says asstronaughts can jam into a tiny shielded safe room, enjoying each other's stinks after a few months of field hygiene, and not get fried. The NASA-reported incidence of radiation cataracts in long duration astronauts (Skylab, Mir, ISS FUBAR) is 95% - still within the magnetosphere.

 

The Earth's atmosphere is equal to, mass/area of 14.7 lbs/in^2, a full yard thickness of lead shielding. GeV cosmic ray protons in heavy atom shielding give inelastic electron scattering then Bremsstrahlung plus pair prodiction, annihalation, and 911 keV gammas. That's gonna be some "safe room." Crew the first flight with NASA upper management and watch how fast vehicle parameters change.

 

--

Uncle Al

UNDER SATAN'S LEFT FOOT

Vote a 10 for doing the experiments!

[RCP/CRT/RRT]

A New York Times opinion piece by LAWRENCE M. KRAUSS Published: August 31, 2009

 

Revisits a really not so new concept of a 1 way trip, Mars Mission. Citing standard carry with you resources issues, along with the idea that cosmic radiation would probably be the death of the astronauts upon return, so why not stay and die there. Probably would be no shortage of volunteers. Their fate would be realized in a relatively short time. Is there water, in any form that could be broken down into oxygen for obvious reasons, hydrogen for fuel sources. Can green houses be sustained for food production. Would there be a wagon train of 1 way colonists to follow.

 

Interesting?

[Pyrotex]

There just MIGHT be a way to stop the radiation without tons of lead or water.

 

It is the Mössbauer Effect

 

The Mössbauer effect is a physical phenomenon discovered by the German physicist Rudolf Mößbauer in 1957, and refers to the resonant and recoil-free emission and absorption of gamma ray photons by atoms bound in a solid form.

 

I did an experiment with the Mössbauer Effect in college. At the time, I must admit I failed to really understand what it was. But I do know that it permitted a thin crystaline film to absorb gamma rays with almost 100% efficiency. Gamma rays of just one narrow energy (or wavelength, if you prefer). The film had a crystaline distance between atoms equal to this wavelength, and so a kind of resonant absorption took place -- it was completely absorbed by the crystal as a whole, NOT by any one atom in the crystal.

 

The trick was, the film had to be moved back and forth at a particular speed so that the Relative spacing between the atoms was just exactly right. Otherwise, the gammas came straight through. I set the speed at zero, took a gamma count for one minute; set the speed at some small value N (say, 1 cm/sec), took a gamma count for one minute; set the speed at 2N, took a gamma count for one minute; set the speed at 3N, ... you get the picture. The resulting plot was a constant linear count of gammas, except for one small range of speeds where the count dipped to zero, and then went back up to the constant linear count.

 

Consider a "shield" around the module; segments of the shield are moved radially outward and inward at highly varying speeds. The segments each contain dozens of films, each with a slightly different atom-atom crystaline distance.

 

Gammas trying to get through the shield have some chance of entering a film with a relative crystal distance equal to the wavelength of the gamma. If the absorbing wavelengths can be spread out over a wide enough bandwidth, some protection would occur.

[Moontanman]

Would these shields have any effect on high energy particle radiation such as cosmic rays and alpha particles from the sun?

[UncleAl]

Mössbauer spectroscopy - Wikipedia, the free encyclopedia

 

The Co-57/Fe-57 couple is specific and exquisite. The entire scan range is typically less than 1.5 micro-eV. A "Mossbauer effect shield" would be silly at face value and impossible to engineer for simultaneous absorption across even a narrow radiation spectrum. It would be inert to particulate radiation.

 

ASK DR. SCHUND

There is another... Dr. Schund's neutrino squeegee

[Theory5]

ummm I thought it was established a while ago that the only reason we havent gone to mars yet is the solar radiation. Atleast I've know that for years, I think I read it in Popular science or Popular mechanics. A while back they tried the idea of a "basment" to protect the astronauts from rads on their way there. I wonder if they have found material to sheild the entire ship yet... Would a reflective material work?

[freeztar]

Here's some interesting reading regarding radiation and shielding.

 

http://marsjournal.org/contents/2006/0004/files/rapp_mars_2006_0004.pdf

[Pyrotex]

Would these shields have any effect on high energy particle radiation such as cosmic rays and alpha particles from the sun?

No. It only works on EM radiation -- gamma, in this case. The wavelength of the EM radiation blocked is determined by the inter-atomic distances of the atoms in a crystal.

[Pyrotex]

...A "Mossbauer effect shield" would be silly at face value and impossible to engineer for simultaneous absorption across even a narrow radiation spectrum. It would be inert to particulate radiation....

I have to agree.

 

hmmm... I wonder what effect it would have if the absorption crystal was vibrated at, say, microwave frequencies? Probably none. But I wonder...

[Pyrotex]

...protect the astronauts from rads on their way there. I wonder if they have found material to sheild the entire ship yet... Would a reflective material work?

Nix on reflection. The reflector must have inter-nodal distances much smaller than the wavelength of the radiation you wish to reflect.

 

For 12-cm microwaves, you can use metallic mesh or screen as the reflector. The "nodes" are where the wires cross, and may be up to 3 cm apart.

 

For 600 nanometer radiation (yellow light), the nodes are the silicon atoms in, say, glass, and the surface must be polished.

 

But there is no material with atoms so close together that gamma will reflect off it.

 

Of course, there is Brewster's Angle (BA). For a given EM wavelength, a sufficiently flat surface will reflect 100% of the radiation, IF it hits the surface at an angle < BA. For visible light, BA is quite large, say ~~10 degrees (I'm too lazy to look it up right now). For X-Rays, you can build a telescope element that will reflect them to a focus, but the BA is waaaaay smaller than 1 degree. Talk about glancing blows. For Gamma, the BA would be orders of magnitude smaller. No help at all.

[UncleAl]

Regarding the pdf,

 

1) "Recent shift in emphasis from "point estimates" to 95% confidence intervals adds significantly to the challenge in designing human space missions." Translation: previous numbers were politicized lies.

 

2) "In cases where the 95% CI has been modeled, the 95% CI dose is typically 3 to 4 times the point estimate." Translation: Medium-rare is now well-done.

 

3) "If a major SPE occurred during a transit, the crew would receive a sufficient dose to reduce their life expectancy by more than the 3% limit." Translation: dead.

 

One does not require an elegant sheaf of differential equations and a century of supercomputer time to arive at an inescapable conclusion. If numbers to the left of the decimal point say "dead," the numbers to the right of the decimal point are irrelevant. There is no "Manned Mars Mission." Any lunar base would need be buried under ten or more feet of compacted regolith. Folks in ISS FUBAR are being cooked in general and specifically by every solar coronal ejection.

 

The new NASA mission is driving up to Home Depot or Lowe's to collect a truckload of asstronaught day workers. Now, frosting on the cake,

 

4) "Radiation exposure limits have not yet been defined for missions beyond low Earth orbit." Translation: As with CO2, it Officially matters who farts not the fart itself.

 

5) "The career limits were based on dose equivalents to blood-forming organs, and not on effective dose to the entire body." Translation: Go to Mars, real world die of radiation.

[Moontanman]

Well uncleAl it looks like it's time for the wussies to get off the pot and break out the nuclear reactors and make the trip in couple of weeks! If humanity is going to exploit space at all, we need to dance with the devil give him a kiss and get the honeymoon started!