I HAVE SEVERAL "MIKE MARS" BOOKS FOR SALE AT tanuki on eBay AND WILL COMBINE SHIPPING ON THEM. 

Very Good: Donald A. Wollheim Mike Mars #3 "At Cape Canaveral" (1961) Early Edition Ed DJ Slight Curve to spine - see pictures.

Third book in series. Classic boy's adventure series from the Cold War Era.

Blurb
Mike Mars and the six other astronauts of Project Quicksilver are on their way to a secret location in Florida named "Skyhook" to get ready for the first astronaut's trip into space from Cape Canaveral. When Mike gets the chance to fly a Starlighter jet to Florida instead of going by regular transport flight, he snaps it up. He couldn't know, however, that during this flioht he will barely escape with his life.
After a few days of extensive study at "Skyhook," the first astronaut is ready to ride inside the space capsule, attached to a Redstone rocket. All seems to be going well as the rocket rises on naming jet stream, but then it begins to twist and turn in a crazy pattern and the first test ends in failure, as do the next two attempts in similar fashion. Who, or what, is to blame?
Could it be the mvsterious man with the scar on his face, or someone closely connected with Project Quicksilver, or both?
Suspicion and intrigue along with the training and testing for a real astronaut's trip into space make this a fast-moving adventure not to be missed!
Ages up to 14

ABOUT THE AUTHOR
Donald A. Wollheim says of himself:
"I suppose the key to my life is science-fiction. I started reading and collecting it in its earliest appearances in magazines. Today I am still an ardent fan, having one of the largest science-fiction collections in the country, numbering some four thousand books, thousands of magazines, piles of clippings, excerpts, notes, etc."

His interest in interplanetary flight ranks second only to science-fiction.
Mr. Wollheim the American Rocket Society in 1931 and has been an active member ever since. This society is now the largest body of rocket men in the country, including all the space people of any consequence.
Although Mr. Wollheim is a very busy person as an author of science-fiction novels and editor of anthologies, as well as editor-in-chief for a New York publishing company, he took the time to visit nine Air Force bases and fly 20,000 miles around the country gathering material for the Mike Mars Series.
Donald A. Wollheim is a native born New Yorker and a graduate of New York University. He now lives on Long Island with his wife and daughter.