How engineers designed the America250 time capsule to last a quarter millennia

"We've unburied some time capsules that are more than 200 years old and the contents haven't fared well. When a time capsule is buried in a building cornerstone, or stored in a climate-controlled space as is the Bicentennial time capsule, it's easier to preserve whatever is inside. Outside, though, it's exposed to the elements and could get wet and deteriorate."

"The biggest risk to a time capsule is water. The design team is taking several precautions to ensure the time capsule remains protected from water. They made the 36-inch-tall vessel tubular to reduce structural vulnerabilities. The capsule has three inner layers that lock in its contents and protect them from outside elements, followed by an outer stainless-steel finish."

America250 is creating a time capsule for the U.S. semiquincentennial to be buried in Philadelphia on July 4 and opened in 2276. Traditional time capsules buried underground typically fail within 200 years due to water exposure and deterioration. The design team, including engineers from NIST, implemented multiple protective measures to ensure longevity. The 36-inch vessel features a tubular design to reduce structural vulnerabilities, three inner protective layers, and an outer stainless-steel finish. Interior design includes a metal bell jar creating an air pocket and organized shelving for contents like flags and other commemorative items.

Read at Fast Company