In the early days of space exploration, astronauts used pencils to take important notes during their missions. Before long, however, concerns arose, and the practice was discontinued. Because graphite—the material in pencil leads—is a conductor1), the dust from worn-down leads and broken fragments drifting in zero gravity could come into contact with the spacecraft’s electronic systems, potentially causing malfunctions or even fires.
Some might think, “Why not use a ballpoint pen instead?” But in space, ballpoint pens are useless. They rely on gravity to draw ink down to the tip, where a tiny rotating ball spreads it onto the paper. Without gravity, the mechanism fails.
The problem was solved by American entrepreneur Paul Fisher, who invented the “Space Pen.” In use by astronauts since 1969, it employs a pressurized ink cartridge that pushes the ink toward the tip. In other words, instead of gravity pulling the ink downward, pressure pushes it forward.
We may not notice it, but we benefit from gravity every day. Even the simple ballpoint pen in your hand is a quiet reminder of that fact.
1) A substance that allows electricity to pass through
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