The video says it all, but read on below for a bit more background:
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That’s SEAL Cmdr. Chris Cassidy aboard the International Space Station, giving a quick glimpse (very quick, thanks to sped-up video with an appropriately lighthearted soundtrack) at how to shave one’s head in zero gravity. Key quote: “I don’t think I’ve looked like this since Plebe Summer.”

Brothers in arms (and heads): Italian astronaut Luca Parmitano, left, and Navy SEAL Cmdr. Chris Cassidy aboard the International Space Station. (NASA photo)
The 1993 Naval Academy grad shed his hair late last month in anticipation of the arrival of Luca Parmitano, an Italian astronaut who, well … who saves on barbershop bills. Parmitano and two other flight engineers arrived aboard the ISS on May 28. He posed with Cassidy shortly thereafter.
Even the ground crew got into the act, according to a NASA release, sending up a wanted poster seeking the return of the missing hair so they could avoid confusing the spacemen. They even suggested a workaround: “Assemble wig from kapton tape and bungees.”