For those asking "Why now?" ... here's a couple wild takes: The Interstellar Squid have arrived. They're hanging out around Saturn (cf "largest comet ever"). Even after a century of preparation and propaganda, there is a large fraction of humanity who refuses to conceive of intelligence other than human. This is the last gasp at preparing them. That, or the political corruption has gotten so rank that they're scrapin…
The simplest answer is the most probable.