Monday, March 24, 2008

To "Glow" Where No One Has Gone Before

I didn't make up the title of this post -- it's from an article on the Medscape site called: To "Glow" Where No One Has Gone Before: The Risk for Radiation to Space Exploration.

If you happen to be a physician, you can actually earn 0.75 CME credits after reading this article. Interestingly enough, the legal disclaimer for physicians includes the following morsel of text:
These materials may discuss therapeutic products that have not been approved by the US Food and Drug Administration and off-label uses of approved products.
Hmmm.... medical care in space? Off label? You think?


Despite this generic, mealy-mouthed caveat, the article itself is well-written and informative. It gives a very nice discussion of the issues you may face on your next trip to the moon.

For one thing, I hadn't been aware of the "great solar storm" of August 4, 1972. Fortunately, this storm occurred between the last 2 Apollo lunar landing missions. If it had hit while we had folks on the moon, they would have received a rather large, and possibly lethal dose of radiation. Yikes!

Of course, radiation from space affects folks who fly much lower than astronauts. At the altitudes used by commercial flights, one receives radiation from space that would normally be absorbed by the atmosphere. For example, 3 round-trip flights from LA to NY roughly equal the dose from one medical chest X-ray. I've know for years about this increased dose from high altitude flight, but had not given much thought to the further increase in exposure at the earth's poles.
Solar particle events (SPEs) are primarily responsible for generating high-energy proton emissions from the sun during solar storms.

The earth's magnetosphere tends to protect most objects in low earth orbits, but this effect has its minimum at the poles. I had no idea that
...airlines routinely work around the impact of SPEs (solar particle events) on polar flight trajectories...
Eek. A polar flight trajectory would describe any number of my flights to Europe. Who knew that the airlines are already factoring in space weather along with the much more prosaic terrestrial weather we expect!

Another interesting quote from this article:
Is there a risk to the central nervous system and brain from exposure to heavy ions at the level that would occur during long missions into deep space? In other words, to quote Derek I. Lowenstein of Brookhaven National Laboratory, "If every neuron in your brain gets hit, do you come back being a blithering idiot, or not?
NASA appears to be hard at work studying the effects of long-term radiation in space. For example:
"Fred" the Phantom Torso -- "part-dummy, part dosimeter-imbedded torso [that] is a mock-up of a human's upper body, minus a set of arms" -- was flown to the ISS and set up in Node 2 (the attachment point for the US Laboratory). Its purpose: to yield a more accurate portrait of human radiation exposure in the station.
Thanks for taking one for the team, "Fred" -- if that is your real name.

Commercial space travel is still a bit pricey for my pocketbook. Thus, the bottom line for me is pretty simple: don't log an excessive number of polar flights. Chances are that my travel budget (and increasing gas prices) will help to keep that under control as well.


Zorg said...

You may be interested in this article as well. Mars Mission Risk 29 - Radiation Induced Brain Damage, describing NASA research into the maximum amount of comic radiation the brain can sustain before suffering FSS (fried synapse syndrome).

Yes, I coined that term. Feel free to use it in your next radiology journal article.

I was intrigued by the reference in the article to the fact that with sufficient shielding to protect the astronauts from cosmic radiation, the ship would be too heavy to move.

The Samurai Radiologist said...

@ zorg:

Cool article -- thanks for posting that!

Good points about shielding and weight. However, a ship built like Project Orion could probably get them to Mars and back quickly enough to avoid FSS. It could also carry enough mass to provide some decent shielding.

For a short but extremely cool video on Project Orion, see George Dyson's talk at TED.