Robert Ballard, right, with guests at a reception for the National Geographic Museum's exhibition, "Titanic: 100 Year Obsession" on Tuesday. (Karine Aigner/National Geographic Society)

This is the season of Robert Ballard.

With the last of the survivors now gone but the cult of the Titanic still craving more, who better to speak for the great lost ship on its centennial than the man who found it?

“I did NPR today,” the superstar oceanographer, 69, told us Tuesday, 100 years to the day that Titanic embarked on its doomed maiden voyage. “My 153rd interview in the last month and a half.”

In London recently, he sat miked up in a studio all day, doing “one interview every seven minutes” — all Titanic, all the time. On Wednesday, he’ll head home to Mystic, Conn., and open a Titanic exhibit at the local aquarium. On Thursday, he will board a plane to Ireland for commemorations at a new Titanic museum in Belfast, home to the shipyard that built the ocean liner. (Wracked by shame over its role in the tragedy, the city is “finally embracing the Titanic, after a hundred years,” Ballard said.)

Ballard at his mission control room at the University of Rhode Island. (Christopher Wohlert/National Geographic )

At the National Geographic Society on Tuesday, the deep-sea explorer graciously held court at a reception for donors before delivering yet another Titanic speech to a sold-out, overflowing crowd. If he was weary of the Titanic, it didn’t show; he insisted to us that he was still learning things about the ship, 27 years after his team found the wreckage at the bottom of the North Atlantic.

“I just learned — now watch — something I didn’t know. . .” Ballard told us, walking-and-talking us over to a video display in Geographic’s new Titanic exhibit.

“She had more first-class cabins than third-class!” he exclaimed. “I never knew that!”

He then asked us to repeat the numbers we’d scribbled down (370 first-class, 297 third-class); an hour later, he casually worked the data into his speech.

Ballard — star of multiple documentaries and NatGeo’s current cover story, its best-selling in five years — would probably have been a rock star even without the Titanic. For a scientist, he’s a great communicator, with a Carl Sagan swagger that captivates an audience. Speaking to NatGeo’s standing-room crowd, he bemoaned the damage that underwater souvenir-hunters have inflicted on the boat’s wreckage. Ballard, who sees the site as a burial ground, believes all artifacts should be left in place. (“You don’t go to Gettysburg with a shovel, you don’t take belt buckles off the Arizona.”) He explained how he wants to repaint the ship’s bow — yes, underwater — to thwart the slow advance of rust. “People think I’m crazy. Children ask, ‘What color?’. . . You don’t let a historic site rot. I’m convinced I can do it, so I’m gonna do it.”

Does Ballard get tired of being the Titanic guy, of doing all these interviews and talks?

“No,” he said, “this is the final phase.” He mentioned looking forward to retreating to a family getaway in Jackson Hole, Wyo., once all this 100-year madness is over.

So after this centennial, are we done with the Titanic forever?

“Until the next generation,” he said. The Titanic “is on a 15 to 20-year cycle. It gets rediscovered.”

Read earlier: The Washingtonians aboard the Titanic, 4/7/12

Titanic memorial cruise: splendor without the sinking, 4/9/12

Ann Hornaday reviews ‘Titanic 3D,’ 4/4/12