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What makes a space pen work upside down?

A pen that writes upside down needs a way to deliver ink without relying on its usual orientation. The Fisher Space Pen combines a pressurized cartridge with ink designed to flow at the rolling ball tip. Its engineering story is also a useful check on the familiar claim that NASA spent millions inventing a pen while everyone else used pencils.

3–7 min

Questions you could explore

  • Why would simply adding pressure create a leakage problem?
  • What jobs do the pressurized ink supply and the ball at the tip perform in a space pen?

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Engineering and inventions

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12–15 min

How GPS finds you, and fixes its clock

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8–10 min

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What makes a space pen work upside down? | Speech Topic | speaking.app