Wernher von Braun's PhD thesis sold for $33,000. Credit: BONHAMS

A formerly top-secret document produced by controversial rocket scientist Wernher von Braun for his PhD dissertation sold for US$33,000 at auction in New York last week.

The 166-page thesis, Design, Theoretical and Experimental Contributions to the Problem of the Liquid-Fuel Rocket, was classified as 'top secret' by the Nazi government and, although written in 1934, was not published until 1960.

After working on rockets for the Nazis during the Second World War ? his exact motivations are still debated ? von Braun was spirited to the United States to work on missiles. He later became the first director of NASA's Marshall Space Flight Center in Huntsville, Alabama.

After what the auction house Bonhams describes as ?heated bidding?, the thesis sold for $3,000 more than its original estimate.