Practically synonymous with high-altitude espionage, the Lockheed U-2 spy plane played an almost legendary role in the Central Intelligence Agency’s activities during the Cold War. Notoriously difficult to pilot and physically demanding (flights of over ten hours at over 70,000 feet were not uncommon), and a formerly TOP SECRET manual uncovered in the Agency archives outlines a strict regimen to keep pilots fit and healthy. Unsurprisingly, the manual touches upon the necessity of maintaining a proper diet, but somewhat surprisingly, the purpose of this proper diet is focused on “obviating the need for frequent defecation.”

In other words, keeping pilots from soiling their flightsuit.