Researchers want to know if a centuries-old tool could be used in emergency navigation situations for future spacecraft. To test it out, astronauts aboard the International Space Station will verify the accuracy of this handheld sextant – which uses star sighting in microgravity! Learn more about this tool: https://nasa.tumblr.com/post/175053575324/navigating-space-by-the-stars | NASA - National Aeronautics and Space Administration