Flashes of Reality

In space I see things that are not there. Flashes in my eyes, likeluminous dancing fairies, give a subtle display of light that is easy tooverlook when I’m consumed by normal tasks. But in the dark confines ofmy sleep station, with the droopy eyelids of pending sleep, I see theflashing fairies. As I drift off, I wonder how many can dance on thehead of an orbital pin.

The retina is an amazing structure. It’s more impressive than film ora CCD camera chip, and it reacts to more than just light. It alsoreacts to cosmic rays, which are plentiful in space.

Cosmic rays are fragments of atoms—some the pieces of farawayexploded stars, some leftover debris from when the universe formed.These atomic fragments move at high speeds, and like X-rays, penetratedeep into material where they are eventually absorbed. Fortunately, ouratmosphere absorbs most of them, so they do not pose significantproblems for Earth dwellers (except for the many unfortunate effects toour bodies that we have collectively named “the aging process”).Sometimes our cameras catch cosmic rays in action. Here's one streaking diagonally across the frame.

Space is different. Free from the protection offered by theatmosphere, cosmic rays bombard us within Space Station, penetrating thehull almost as if it was not there. They zap everything inside, causingsuch mischief as locking up our laptop computers and knocking pixelsout of whack in our cameras. The computers recover with a reboot; thecameras suffer permanent damage. After about a year, the images theyproduce look like they are covered with electronic snow. Cosmic rayscontribute most of the radiation dose received by Space Station crews.We have defined lifetime limits, after which you fly a desk for the restof your career. No one has reached that dose level yet.

When a cosmic ray happens to pass through the retina it causes therods and cones to fire, and you perceive a flash of light that is reallynot there. The triggered cells are localized around the spot where thecosmic ray passes, so the flash has some structure. A perpendicular rayappears as a fuzzy dot. A ray at an angle appears as a segmented line.Sometimes the tracks have side branches, giving the impression of anelectric spark. The retina functions as a miniature Wilson cloud chamber where the recording of a cosmic ray is displayed by a trail left in its wake.

The rate or frequency at which these flashes are seen varies withorbital position. There is a radiation hot spot in orbit, a place wherethe flux of cosmic rays is 10 to 100 times greater than the rest of theorbital path. Situated southeast of Argentina, this region (called theSouth Atlantic Anomaly) extends about halfway across the Atlantic Ocean.As we pass through this region, eye flashes will increase from one ortwo every 10 minutes to several per minute.

Our brain interprets its sensory input and creates a map of reality.Philosophers have for centuries contemplated this question. As Platowrote, we see only the shadows of a larger and richer reality. On SpaceStation, I drift off to sleep, thinking of the nature of the “real”universe while observing my personal reality of dancing fairies.

Don’s blog also appears at airspacemag.com.

13 thoughts on “Flashes of Reality”

  1. Ummm, very interesting. From 1 each 10 minutes to several per minute. Is there any probability to experiment those flashes on earth surface? I mean if it’s a described effect also down here.
    And, is there any way to issolate the ISS from those rays?

  2. your esay was most informative scientifically but also by the way you explain the reality of the flashes which do not exist. I have been most impressed by your clarity of thought and the ability to educate from Space. I am a 62 year old man who has followed every mission that mercury,gemini,Apollo and the space scuttle. Every launch is as exiting as the previous. I think man’s presence in space viewing earth will help in many fiefs of learning. I hope that viewing earth and having humans on earth view themselves will help improve our knowledge about our planet and we can get nations to work together to regulate our own delicate geosphere planet Earth.

  3. It is a very interesting text. Thank you very much for sharing! What effects those cosmic particles can create on the human body. Do astronauts experience unusual situations because of these particles?

  4. I enjoy reading all of these spaceblog entries. I am not a scientist, but I have always had a very deep interest in space. I truly wish I could have had the opportunity to participate in the space program. I couldn’t, but as a teacher of many fifth grade classes I hope I planted a seed in my students to sharpen their interests in space. I especially like this blog because it addresses subjects that are not expected, yet are personal reflections or reactions to being in space. I look forward to many more articles.

  5. I would love for an animation by a computer graphics person who could illustrate what this must look like to you, so Earth dwel
    lers could better imagine what it is you see.Amazing post.

  6. Your musings about life in space open a door to the imagination. What a wonderful, alternative perspective.

    This is reason enough for space exploration.

  7. hi, i’m not much of scientist brain,but i lovesome amazing things about science.
    and the way you’ve described the cosmic rays I think I ‘d love to read a book if you’ve written any…and thanx for such a nice post.

  8. Thanks so much for these personal notes, Don. Your blog has become one of my favorite inbox items!

    I had heard about the retinal flashes many years ago and always found the notion fascinating, but your eloquent description of the phenomenon really adds to my perspective in a way that only someone in your position can do.

    Again, thanks for letting those of us Earthbound join you on your journey.

  9. Thank you for the description of the phenomena. I knew of the eyeball effect, but had no detail. It was also interesting to read about the cameras and PCs. . . . Thanks again.

  10. Wow, this is amazing. I can’t believe such things exist out there in outer space . Maybe one day soon we can garner a better understanding of these intriguing and important discoveries. Keep up the great work guys! There are definitely people who really appreciate the work you are doing up there in space. Hope all is well with the whole crew, you guys are amazing!

  11. Greetings !

    This is very informative and very well written.
    Thanks Don Pettit.
    With Best wishes to your crew,
    Uma Karedla

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