Travelers on I-10 near the Mississippi-Louisiana kind of get the idea that something humungous is nearby when they spot a sign that notes they are entering an “acoustic buffer zone” for the Stennis Space Center, a NASA facility.

It’s named for the late Mississippi senator John Stennis, but during the glory days of the Space Race, it was known as the Mississippi Test Facility. Huge rocket engines that powered Saturn moon rockets were tested there, and later, all Space Shuttle engines had to be fired and scrutinized at this location as well before being declared flight-worthy.