From David Bodanis, “E=mc². A Biography of the World’s Most Famous Equation,” Walker Publishing Company, Inc., 2000.
Footnote 191 . . . “there were hundreds of open-air tests: Which is how pre-World War I German battleships—or at least parts of them—have come to land on the moon.”
“In 1919 the Imperial German battlefleet had surrendered to Britain, and was in the confines of the huge Royal Navy anchorage at Scapa Flow, up in Scotland. After a number of months of anxious waiting, the German admiral mistakenly came to believe that the British were about to seize his fleet. The admiral sent out a priorly agreed upon coded signal, and the entire grand fleet scuttled itself. But Scapa Flow isn’t especially deep—this is why it was chosen as an anchorage—and so hundreds of thousands of tons of high-quality steel was now waiting in those waters, only a few yards or tens of yards down. In the 1920s and 1930s, portions of the fleet were salvaged: divers welding the holes, then giant air bladders installed, and some of the half-submerged giants towed all the way to receiving docks at Rossyth in the Firth of Forth.
After 1945, what remained took on a special value. It takes a lot of air to make steel, and all post-Hiroshima steel has some of the radiation from open-air atomic explosions. Pre-1945 steel doesn’t. To this day, three battleships and four light cruisers from the kaiser’s once-grand fleet rest in Scapa Flow (and intrepid readers can dive to see them, setting out from Stromness in the Orkneys). There’s no advantage in using them for ordinary purposes—it’s much cheaper to make fresh steel—but for extremely sensitive radiation monitors, as on spacecraft, such pre-Hiroshima sources are indispensable. Equipment that Apollo left on the moon, as well as part of the Galileo probe that reached Jupiter, and even the Pioneer probe now past the orbit of Pluto and on its way to distant star systems, all carry remnants of the kaiser’s navy, via this salvaged steel from Scapa Flow. The story is well told by Dan van der Vat, in The Grand Scuttle: The Sinking of the German Fleet at Scapa Flow in 1919 (London: Hodder and Stoughton, 1982).”