The Expanse was dropped a fortnight ago by SyFy, not over ratings but over their difficulties in monetising the show; their deal with Alcon meant that SyFy didn't get a cut from their streaming deal (with Amazon in the US and Netflix in the rest of the world), nor the DVD and Blu-Ray sales, making them unusually reliant on first-night viewing figures.
Jeff Bezos personally announced the pickup at the National Space Society, during a talk an hour after the Expanse cast and crew held a panel of their own.
I'll just let him say it...#TheExpanse#RocinanteIsSafe#BreakingNews— Cas Anvar (@Casanvar) May 26, 2018
Thank you @JeffBezos pic.twitter.com/wxHN31zgJs
The news came after two weeks of hard campaigning by fans, the cast and crew, which resulted in an aircraft flying over Amazon's HQ trailing a "SAVE THE EXPANSE" banner for four hours and even resulted in a model of the Rocinante spacecraft being sent into space.
With the sets still standing and preliminary work on a fourth season apparently already underway, we can expect to see The Expanse join Amazon Prime's line-up in 2019.