This self-portrait was taken by Mars rover Curiosity's MAHLI camera on Sept. 19 (its 44th sol, or Martian day, if you're keeping track). It shows off one of four logos on its arm--logos for NASA, the Jet Proulsion Laboratory, and the Curiosity mission itself are also represented. But this piece of anodized aluminum swag is unique for causing the most spontaneous shouts of U-S-A! U-S-A! back at home.
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.