Joe Walker (February 20, 1921 – June 8, 1966) flew the X-15 rocket plane 25 times, and exceeded a 50 mile altitude three times, qualifying him as an astronaut by US Air Force standards.
Joe Walker was killed on June, 8 1966, when his F-104 Starfighter collided with a North American XB-70 Valkyrie. Walker's Starfighter was in a tight formation for a General Electric publicity photo when his F-104 collided with the XB-70's right wingtip.
Due to his untimely death at the relatively young age of 45, Walker is a desirable and uncommon autograph... especially in 8x10 photograph format. Expect to pay a few hundred dollars for a postal cover and $600 - $700 or more for a signed 8x10 photograph. Due to the high value and demand, Joe Walker forgeries exist in quantity.