So long as humans have wondered about other forms of intelligent life in the universe, we’ve hoped E.T. If the civilization that created them vanishes, even behemoth technosignatures like these would ultimately be doomed without maintenance. “These artificial grains are blown out into the general ISM if the host star is bright enough. Maybe any intelligent aliens out there have already figured that out, and decided to come up with an alternative method of capturing stellar energy. If they have, maybe we have more than a few ten thousand of years to find it.