I have been going through my late father's office paperwork and found an empty folder with a few pieces of paper that don't explain it. He was an astrophysicist researcher at one of the research universities in the United States and occasionally worked with federal and international agencies on various projects, all classified. The folder I found only had a hexadecimal designator and a piece of paper with "Project: Polar Bill" written. I don't know what it means, but my father's research usually dealt with the natural forces in the universe, like gravity. Has anyone heard of this or have any idea what it may refer to at all?