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A manhole cover in space

In celebration of the recent and successful landing of the Mars rover Perseverance, this week's collection of whimsical and curious stories will take a look at human-made objects in our solar system. However, in keeping with the theme of this format, we will ignore space stations, satellites, and telescopes, and instead focus on the more bizarre objects - most importantly a supersonic manhole cover floating through the Kuiper Belt*.

Unlikely ambassadors to alien life - While space flight is mostly a serious undertaking in the pursuit of science, national prestige, and even military capabilities, sometimes it can also provide cause for levity. Once we learned how to shoot objects into orbit and beyond, we apparently could not resist to include some less serious cargo. The most famous among those is probably a Tesla roadster that served as dummy payload in the 2018 test of a Falcon Heavy rocket. The car (complete with an astronaut mannequin known as "Starman") acquired enough velocity to escape Earth's gravity and enter an elliptical heliocentric orbit (passing Mars once in a while).

View of a Tesla Roadster leaving earth, 2018

However, Elon Musk was certainly not the first one to think about silly objects in space. The International Space Station is home to a bagpipe (below is a video of astronaut Kjell Lindgren playing Amazing Grace), a gorilla costume (used by Scott Kelly to prank his fellow astronaut, Tim Peake - Link), and of course, a Lego model of itself.

Kjell Lindgren playing Amazing Grace aboard ISS


However, by far the most interesting among this collection is arguably a very fast manhole cover. It was likely also the first human-made object to enter orbit (and quite likely fly beyond it) - a full year before Sputnik achieved this feat.

The first human-made object in outer space - You see, in the mid-1950s, scientists at Los Alamos were looking for a way to test ever more powerful nuclear bombs while also trying to contain the blast and nuclear fallout. In 1957, engineers drilled a 150m borehole to conduct the world's first underground nuclear test. The plan was to test a "small" bomb at the bottom of the shaft and contain the blast with a 2-ton concrete plug capped by a 10cm thick metal "manhole cover". While it was expected that the cover could be blown off (and high-speed cameras were installed to capture it), the experimenters vastly underestimated the yield of the bomb (by a factor of a few hundred)**. The blast of the bomb instantly vaporized the concrete plug launching the cover enthusiastically upwards. A high-speed camera actually caught one frame of the flying metal cover and based on its recording speed (one frame per millisecond), it was estimated to travel at around 60km/s (or 216,000 km/h). Given that this is five times the escape velocity of our planet, it could have left our orbit that day with the great distinction of being the first human-made object to do so. Even if it lost 2/3 of its speed through the atmosphere, it would still make it faster than Voyager 1 (widely considered the most distant human-made object from Earth).*** Depending on trajectory, intelligent alien civilizations beyond our solar system might first encounter a speedy manhole cover before encountering the famous (and purpose-made) golden disk on Voyager 1 - seen on the left-hand side below)

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*the Kuiper Belt is a large disc of mostly frozen methane, ammonia, and water beyond the orbit of Neptune. Controversially, Pluto is one of the objects of the Kuiper Belt (after it was demoted from being a Planet) (Link)

**The bomb had a predicted yield of 0.4-0.9kt of TNT equivalent. However, the actual yield turned out to be 300kt (Link)

***Unfortunately, the manhole cover would have most certainly burnt up in our atmosphere - so this is all mostly speculation from here on

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