With a starting price of 22,000 euros ($24,860), one of the renowned Apollo 15 ‘moon letters’ went under the hammer in Stuttgart on Friday.

After a secret trip to space in 1971, the letters triggered a minor scandal within the US space agency NASA. Astronauts of the "Apollo 15" mission had took them to the moon and back to Earth without permission, with plans to sell them for a high price.

"The astronauts were forbidden to fly anymore or go for the mission after the scandal. And, we have the No. 5 of the 100 letters in the house," the auction owner Ferdinand Eppli said.

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