It is one of the most famous improvisations in the history of spaceflight: a felt-tip pen, pressed into a broken switch, that helped bring the first men on the Moon safely home. Now that pen has sold at auction for $857,600.

The item went under the hammer at Sotheby's space exploration sale, where, according to reports, it exceeded its pre-sale estimate after competition from several bidders. It was sold together with the broken switch component, and had been consigned by Aldrin himself from his personal collection.

A near-disaster on the Moon

The story dates to July 1969. After becoming, with Neil Armstrong, one of the first humans to walk on the lunar surface, Aldrin climbed back into the lunar module, Eagle, for the trip home. At some point his bulky life-support backpack knocked against a circuit breaker, snapping off the small switch that armed the ascent engine, the engine that had to fire to lift the module off the Moon and back to the orbiting command module.

With the switch broken, there was a real risk the astronauts could be stranded. Aldrin's solution was disarmingly simple: he pushed a felt-tip pen into the opening to close the circuit, and the engine fired as planned. The pen, in effect, helped save the mission.

The market for a piece of history

The sale is the latest sign of the enduring, and lucrative, appetite for authentic space memorabilia, especially objects tied to the Apollo programme and its first Moon landing. As Popular Science noted, items flown on missions or drawn from astronauts' own collections command premium prices precisely because of their direct link to the events they helped make possible.

Other lots in the sale reportedly included artefacts from Aldrin's career, from flags carried into space to mission mementoes, but it was the pen, an ordinary object that played an extraordinary role, that captured the imagination. In an age of vast, complex machines, its appeal lies in the reminder that even humanity's boldest ventures can hinge on the smallest things, and on the presence of mind to use whatever is at hand.