One of the most rewarding aspects of space collecting is a chance to learn of the bravery and achievements of the astronauts who, despite their massive contribution to mankind's history, aren't household names.
Before and after Neil Armstrong and Buzz Aldrin's first steps on the Moon came years of hard work carried out in space by brave and unsung heroes. Like the crew of Apollo 9, for instance, who years before played a key role in testing the limits of the lunar module.
Also among the unsung heroes who came after Armstrong and Aldrin was the two-man crew of Gemini 6A - Walter M Schirra Jr and Thomas P Stafford - the mission which achieved the first manned rendezvous between two spacecraft in 1965.
Their craft touched back down on Earth in the North Atlantic Ocean, today in history (December 16) 1965.
The mission was a crucial chapter in the Space Race. While the Russians had previously launched a pair of Vostok spacecraft and achieved radio contact between the two, the craft hadn't flown within several kilometers of each other.
Gemini 6A and its sister ship Gemini 7 came as close as one foot (30 cm) to other another. Indeed, they could have docked had they been so equipped. In the end, the mission was a vital step towards the regular dockings between spaceships that have become a regular factor of space exploration.
What's more, the Gemini missions were just one of a number of projects that the 'unsung heroes' of NASA were a part of. Walter Schirra, for instance, was also involved in project Mercury which put the first American in space, Alan Shepard.
So what does all this mean for collectors? Well, the unsung heroes of the Mercury, Gemini and other missions offer collectors and investors to find strong alternative assets where other buyers may have missed them.
Take, for instance, this signed group photograph by the astronauts behind the Mercury project. Signers include Walter W Schirra, Jr, John H. Glenn, Virgil I. Grissom, M. Scott Carpenter, Donald K. Slayton and Leroy S. Cooper, along with Alan Shepard.
The photograph was sold for £6,950 ($11,470) on the private markets and is set to prove itself as a strong alternative asset in future years. For alternative investors willing to think outside the box, there can be both pleasure and profit in space memorabilia.
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