In August 1971, President Nixon was said to be in favour of cancelling all the remaining lunar landings (meaning no Apollo 16 or 17 missions).
It was Nixon's Office of Management and Budget Deputy Director, Caspar Weinberger, who persuaded the President to continue with Apollo - and to only consider cancelling the other missions if Apollo 15 gathered enough data for the US to proceed with its other planned endeavours.
At the time, these future missions included the US's first Space Shuttle and NERVA (involving the use of nuclear thermal rocket engines). And it was in the shadow of these plans that the Apollo 15 mission had a greater emphasis on science than any other Moon mission before it.
Apollo 15 was also the first "J Mission", a term given to long stays on the Moon. In total, Commander David Scott and Lunar Module Pilot James Irwin spent three days on the Moon and a total of 18½ hours outside the spacecraft on lunar extra-vehicular activity (or EVA).
EVA, of course, referred to the astronauts' first-ever use of the Lunar Rover. As a result, they could travel much father from the Lunar Module craft than had been possible in prior missions, and gather more lunar surface material than had previously been possible.
While Scott and Irwin traversed the lunar surface, Command Module Pilot Alfred Worden orbited the Moon using a Scientific Instrument Module (or SIM) to study the Moon's surface and environment in great detail.
It was on this day (July 26) in 1971 that Apollo 15 launched for the Moon. It's impressive to think that, in today's terms, the crew wouldn't be due to touch back down on Earth for another two weeks, on August 7.
Upon the crew's safe return, NASA called Scott, Irwin and Worden's mission "the most successful manned flight ever achieved." But this was before the notorious "Stamp Incident" - which you can read more about here - brought the whole mission into disrepute...
Scandal aside, the bravery of Apollo 15's crew remains woefully unacknowledged in mainstream history. By the time of their mission, the optimism of the 1960s had waned and, to this day, Apollo 15's intrepid crew don't enjoy the same celebrity as Neil Armstrong or Buzz Aldrin.
However, this equals good news for collectors and investors with an eye for space memorabilia - placing the onus on collectors to preserve the legacy of Apollo 15, while the untapped space collectibles markets continue to present a wealth of opportunities.
For instance, Apollo 15 memorabilia currently on the market includes Commander David Scott's sweeping diagonal signature on the bottom left corner of a letter. And this is no ordinary letter, but the historic Nuclear Test Ban Treaty of 1963 (pictured above).
The treaty is a seminal piece of history in itself: an important step in global diplomatic efforts to moderate the armaments race between nations. In brief, the treaty prohibited nuclear denotation tests in the atmosphere and underwater, but allowed them in confined underground facilities.
Measuring 11 x 7.5 cm, the printed page is billed as being in "very good condition" and is currently for sale to collectors, and will be sure to appreciate in value in coming years.
Meanwhile, earlier this year Paul Fraser Collectibles had the privilege of selling a set of 12 autographs of every man ever to have walked on the Moon (among them Armstrong, Aldrin, Scott and Irwin). You can read more about the sale of this exceptional one-of-a-kind portfolio here.
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