This ordinary pen helped save Apollo 11 astronauts, now it has sold at auction for an $857,600

A felt-tip pen used by Buzz Aldrin on the Apollo 11 mission sold at Sotheby's Space Exploration auction for $857,600.

The pen, a brushed aluminum Duro Rocket black felt-tip pen, was used to fix a broken Engine Arm circuit breaker switch inside the Lunar Module Eagle.

The broken switch prevented activation of the ascent engine, which would have stranded Neil Armstrong and Buzz Aldrin on the Moon.

Aldrin inserted the pen into the switch's opening to press the internal metal contact, enabling the engine to start and the astronauts to return to Earth.

The pen was sold from the Buzz Aldrin Family Trust and was estimated to sell between $800,000 and $1.2 million.