Richard Feynman handwritten document, written by Feynman during the investigation into the Space Shuttle Challenger disaster. Single sheet with writing on both sides is penned by Feynman in black ink, with a diagram on one side underneath notes regarding O-rings and struts. At the top of one side he writes, ''How much does Thiokol know about straps...Stress on roll how on struts. / Strut broke - roll - was computer making[?] special forces.'' He continues with notes, trying to solve the mystery of what took down the Challenger, writing ''Thermal Stress?...Why 200 lbs...Paint mark for two years.'' On the opposite page he writes in part, ''O-ring inside putty compression. Or rubber thick layer?'' He then writes ''Strut ordinance failure? tell Fichtl'', referencing Howard Fichtl, a supervisor at Morton-Thiokol, the company contracted by NASA to build the solid rocket booster which failed because the O-rings couldn't withstand sub-freezing temperatures. Morton-Thiokol, in fact, recommended that the Challenger not launch the morning of 28 January 1986, as the weather was too cold. With much more information handwritten by Feynman, including calculations, and many questions. Single page measures 8'' x 10.5''. Near fine condition. From the estate of Richard Feynman.