A long-standing urban legend surrounding a nuclear-powered manhole cover has resurfaced, prompting a thorough examination of its veracity. The tale originates from a 1956 nuclear test known as Pascal B, conducted by physicist Robert Brownley at Los Alamos. During this experiment, a cast iron cap was welded atop a borehole to contain an underground nuclear explosion. Contrary to expectations, the cap was propelled into the atmosphere at an astonishing speed, reportedly six times the Earth’s escape velocity, sparking speculation that it may have been the first man-made object to reach space.
The narrative gained traction over the years, fueled by various videos and articles asserting that the cap either successfully entered space or disintegrated upon atmospheric entry. However, many of these accounts lack depth, often neglecting to include calculations that could clarify the outcome. In a recent analysis, Brownley’s original calculations were revisited and expanded upon, aiming to settle the debate once and for all.
To assess the fate of the cap, researchers conducted calculations comparing the heat generated during atmospheric re-entry with the energy required to vaporize the iron cover. By utilizing established equations from NASA on atmospheric heating, they derived a formula that factored in the cast iron’s mass and dimensions—approximately 4 feet wide and 4 inches thick—alongside its heating coefficients and drag coefficient.
The findings were revealing. The calculations indicated that the thermal energy experienced during the cap’s descent through the atmosphere was sufficient to melt and vaporize it long before reaching the threshold of space. When compared to the energy required to transition the cap from solid to gas, it became evident that the intense heating would likely lead to its disintegration.
The results align with historical observations of meteors, which, despite traveling at slower velocities, have been known to spectacularly break apart upon entering the atmosphere. This reinforces the conclusion that the nuclear-powered manhole cover did not make it to space nor achieve the status of the fastest man-made object.
In closing, the enduring myth of the nuclear manhole cover serves as a reminder of the importance of rigorous scientific inquiry. Rather than relying on sensationalized stories, careful calculations and empirical evidence provide clarity. The cap’s fate seems sealed: it was likely destroyed by the very atmosphere it sought to escape, allowing us to finally lay this urban legend to rest.
