Goodness, gracious, great balls of ... protons and neutrons!

[Cryogenic]

Hello all! [img]/phpBB/images/smiles/icon_smile.gif[/img]

For my very first post on the board of a fantastic site, I have a question to pose. Admittedly, it wasn't very helpful of me to use such a silly thread title, but I couldn't resist a little play with words. [img]/phpBB/images/smiles/icon_razz.gif[/img] Here's my real question...

Can anyone shed light on the "white flashes" Apollo astronauts reported experiencing in their vision while on the moon?

I was wacthing a science programme some time earlier this year (though unfortunately, I have seen so many, I can't for the life of me remember which one) when this issue was raised. I seem to recall the programme makers claiming that NASA wanted to keep the astronauts' reports "hush hush" at the time, for they didn't immediately have an explanation to offer. As I also seem to recall, the programme stated that NASA discovered its astronauts were actually subjected to an unexepcted dose of "cosmic radiation from a distant supernova"; atomic nuclei which penetrated the astronauts' suits and bodies.

I am aware that radiation exposure is a constant hazard in space, not least from our own sun: but does anyone have details of this particular phenomenon -- and was it a freak occurence or is it a regular hazard faced by those that leave the safe confines of our own planet?

[Tim Thompson]

The most common explanation for the flashes seen by astronauts is that they are flashes of blue-white light, generated inside the eyeball's fluid interior, by particles traveling through the eye faster than would light. Much as a supersonic aircraft generates a "sonic boom", a superluminal particle will generate a "luminous flash", specifically known as Cherenkov radiation. However, it seems that those in the know favor a flash generated directly by ionization processes inside the retina cells (rather than the gelatinous eyeball fluids), as the cosmic ray particles strike the cells directly.

• Visual Light Flash Observations on Skylab 4

[overrated]

So is it harmful, or just an odd optical effect? Not that I'm going to be going into space anytime soon... just curious.

[Cloudy]

Radiation from outside the solar system('galactic' radiation) is thought to be harmful over time when you are outside the protection of earths magnetic field. In fact, it is a bigger worry than radiation from the sun if the possiblity of a solar storm or flare is excluded.

If you are in low orbit, the Earth's magnetosphere still gives you allot of protection. During the moon missions - the exposure was insignificant because of the short time involved. But astronauts on a Mars mission may get enough of a dose to up their long term chance of cancer, etc. significantly. This is a major reason we want to shorten the trip time to Mars.

I do not know if the main danger is from cosmic rays(in the narrow, scientific sense)or from other forms of radiation from outside the solar system. Perhaps one better informed than I can tell us.

[John Kierein]

Look here on page 76.
http://history.nasa.gov/SP-404/ch5.htm

There was a clear correlation of light flashes with the times when Skylab passed through the region of the Van Allen belts that are closer to earth and therefore Skylab's orbit. Other flashes were seen when Skylab was at its most northerly or southerly portion of the orbit where the aurora are seen.

Bob Forward wants to use electrically conducting tethers to clear out the charged particles from the Van Allen belts.
http://space.com/scienceastronomy/ra...ts_020916.html



<font size=-1>[ This Message was edited by: John Kierein on 2002-09-18 06:59 ]</font>

[David Hall]

On 2002-09-13 18:03, overrated wrote:

So is it harmful, or just an odd optical effect? Not that I'm going to be going into space anytime soon... just curious.

My WAG is that they're generally not very harmful on their own. They're only little particles after all, a few of them wouldn't cause too much damage for your body to repair. We even occasionally get cosmic ray flashes here on the ground. It's just that they're more common outside of the atmosphere.

I don't know what kind of damage exposure might cause in the long-term though. But even then I think other radiation effects would be more worrisome.

[Donnie B.]

Shortly after Supernova 1987a (the one in the Magellanic Cloud), somebody calculated its neutrino flux, the probablility of interaction between neutrinos and water, and the total volume of all the human eyes in the world, and determined that something like four people probably "saw" the supernova as a tiny flash of light in their eyes.

I guess that doesn't say much about the hazards of space travel, but it's kinda cool anyhow. [img]/phpBB/images/smiles/icon_biggrin.gif[/img]

[Wiley]

On 2002-09-18 13:04, Donnie B. wrote:
Shortly after Supernova 1987a (the one in the Magellanic Cloud), somebody calculated its neutrino flux, the probablility of interaction between neutrinos and water, and the total volume of all the human eyes in the world, and determined that something like four people probably "saw" the supernova as a tiny flash of light in their eyes.

And I thought the odds of winning the lottery were small...
[img]/phpBB/images/smiles/icon_smile.gif[/img]