The one Manned Orbiting Laboratory test flight launched a Gemini spacecraft with huge hole in the heat shield. MOL was the Air Force's 1960s program to carve out its place in space in with an orbiting space station and spy platform. In 1966, the service launched an unmanned test flight the lone flight of the program to prove that the hole in the heat shield didn't compromise its structural integrity. But why did it have a mansized hole in it?

For a much longer and more complete overview of MOL, check out my latest article on Vintage Space (and be warned: it's a long one!): http://www.popsci.com/mannedorbiting...
And of course, there's loads more space history at Vintage Space to explore! http://www.popsci.com/blognetwork/vi...

I get into the genesis of the X15 and DynaSoar programs in my book, Breaking the Chains of Gravity, which is available now in the UK and January 12 in the US, Canada, Australia, and India (I think!). You can (pre)order your copy on Amazon: http://www.amazon.com/BreakingChains...

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