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Podcast: Apollo's Mystery Flashes

The ALFMED, short for the "Apollo Light Flash Moving Emulsion Detector" may go down as one of NASA's weirdest looking physics experiments. Kind of like an Apollo-era Daft Punk.
Image: NASA
Image: NASA

Scientists built it after astronauts on their way to the moon reported seeing mysterious flashes of light, even when their eyes were closed. The experiment was a way to identify these mysterious sprites. You can hear the crew of Apollo 17 using it on this week's podcast.

Inside the contraption, a moving photographic sheet recorded the direction, intensity and time of every cosmic ray particle aimed at the wearer's eyes.

Image: NASA
The Ray-Bans are a nice touch.

Astronaut Ron Evans wore the experiment while his cremates donned blindfolds during the flight of Apollo 17, exactly 41 years ago this week. The crew of Apollo 16 tried a similar experiment, but their data didn't turn out very well.

Image: NASA
Using data from the mission, NASA doctors and scientists were able to say definitively that the pesky flashes of light were caused by cosmic rays hitting the astronaut's retinas.

Later astronauts in orbit around Earth have have also seen these flashes. Other, similar experiments have flown on Skylab, Russia's Mir space station and the International Space Station. Cosmic rays make up most of the radiation astronauts are exposed to. All that radiation adds up, and is a serious issue for mission planners thinking about sending humans to Mars and beyond.


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