NASA wanted to talk about science. A congressman wanted to ask about Martian civilizations.

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.