We have received certs for crossing the Atlantic a couple years ago and for a New Year's sailing.
Kelly gave his eighth and final Beyond the Podium presentation this morning. It was titled "The Sputnik Years". At the conclusion of his presentation, someone in the audience asked him when his next cruises are. He said that his next cruise was in August--he didn't mention which ship, but he did say it was a Reykjavik to Boston sailing. He lives in Boston (where the highest concentration of professional astronomers work) and he is pleased with the idea of the cruise terminating at his home town. He also said that we was going to be on an Equinox trans-Atlantic this year. So it sounds like you will see him on your Eclipse sailing this August because the Iceland to Boston itinerary sounds pretty unique. I didn't attend it, but one of Kelly's presentations was devoted to auroras which I am sure will draw some interest on your northerly sailing.
After having attended 5 of his presentations, I can tell you he is smart and an excellent communicator. Perhaps comparing him to the late Carl Sagan may be a stretch, but Kelly's combination of skills lay in that direction. I was entertained by the number of astronomy themed neckties that he wore.