Some of NASA's brightest minds were invited to Capitol Hill on Tuesday to tell members of Congress about water that once ran across Mars, and the possibility of life on Europa and missions to explore them.

“Good questions,” the chairman of the space subcommittee said after an hour or so. Then he turned the microphone over to Rep. Dana Rohrabacher, who would save his most important question for the end.

“Thank you,” the California Republican began.

“One of the benefits, I should say, of your activities, is that, well — you have all these robots all over the universe and beyond.”

A boy seated behind Rohrabacher had been fiddling with his hair, but now looked up at the congressman.

“Let me just note,” Rohrabacher said by way of disclaimer, “that I've been around for a while.”

So he had.

Elected to his office 14 consecutive times, he has sat on the House Space and Technology Committee for decades and run for the chairmanship at least twice, without success.

I love science,” Rohrabacher once told Science Magazine.

His passion for the subject is occasionally expressed in puzzling ways.

Rohrabacher once told a hearing that “dinosaur flatulence” might have caused global warming — a bad joke, he said later.

In a 2014 speech titled “Global Warming as a Power Grab,” he railed against the government “putting fluoride into our water.”

On Tuesday, seated across from NASA officials planning missions to Mars, a moon around Jupiter and an asteroid between them, Rohrabacher shared his thoughts on space with them.

The space shuttle and space station programs were inspiring, he said — but also very expensive.

NASA had a lot of projects going on, he said. Maybe too many; the agency should prioritize more — though, he said, “I'm certainly not an expert enough to tell you what those priorities should be.”

He asked about NASA's plan to land a rover on Mars in 2020 — and about Martian rocks and space fuel. He said we should go back to the moon.

And then, at the end, “the most important thing.”

“I ask for permission for one minute for this question,” Rohrabacher said.

It was granted, and he began.

“You have indicated that Mars was totally different thousands of years ago,” he told the scientists.

Behind him, the boy whispered something to a seat mate.

The congressman continued: “Is it possible that there was a civilization on Mars thousands of years ago?”

Silence filled the room,

A scientist with the Mars 2020 project, Kenneth Farley, leaned toward his microphone and ventured a reply.

“So, the evidence is that Mars was different billions of years ago. Not thousands of years ago,” Farley said.

“Billions, well. Yes,” Rohrabacher said.

He began to form another word, but Farley cut him off.

“There's no evidence that I'm aware of.”

The scientist did not mention that he had already explained this half an hour earlier, when he told the panel that ancient Mars once had rivers, lakes and hot springs — but that nothing more advanced than microbes was likely to have lived there.

And yet, Rohrabacher persisted.

“Would you rule that out?” he asked. “See, there's some people, well, anyway … "

“I would say that is extremely unlikely,” Farley said.

“Okay. Well.”

Rohrabacher still had 30 seconds to ask about ancient civilization, but he gave up at that point.

“Thank you for the good job you're doing,” he told the scientists. “God bless.”

The next congressman to address the hearing would quote a 19th century poem — “For I dipped into the future, far as human eye could see” — and wonder aloud about the meaning of life.

But when reporters wrote about Tuesday's hour-and-a-half discussion, they wrote mostly about Rohrabacher's final minute.

“No, Congressman, There's No Evidence of an Ancient Mars Civilization,” wrote, noting for good measure that previous reports of canals and a sculptured face on the Red Planet had also been debunked.

Ars Technica accused the congressman of marring an otherwise respectable discussion, and recalled that earlier this month a NASA official had been forced to deny rumors that children were being kidnapped to the planet.

Other outlets were even less kind to Rohrabacher, whose office suggested to The Washington Post that — as with the dinosaur comment in 2007 — the congressman had not seriously entertained the notion.

“Because of his position on the space committee, he not infrequently gets inquiries about this from far and wide,” Rohrabacher's spokesman, Ken Grubbs, wrote in an email Wednesday.

“He was looking for something definitive. Apparently, many of those who covered the exchange didn’t hear the wink in his voice.”

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