But it's the rare occasion that these theories and assumptions come from a United States Congressman.
Such was the case at a hearing on Tuesday, as officials from NASA answered questions from the House Committee on Science, Space, and Technology about upcoming missions "Mars Rover 2020" and "Europa Clipper."
What began as a typical hearing suddenly took a turn about an hour into the questions, when California Congressman Dana Rohrabacher started asking about life on Mars.
"You have indicated that Mars had a — was totally different thousands of years ago," the Republican Congressman began.
"Is it possible that there was a civilization on Mars thousands of years ago?"
Not microbial life, but actual civilizations.
Kenneth Farley, NASA Mars 2020 rover project scientist, first corrected Rohrabacher's question, saying, "So, the evidence is that Mars was different billions of years ago, not thousands of years ago."
He then began saying, "there is no evidence that I'm aware of —" before being interrupted by Rohrabacher, who attempted to rephrase his question.
"Would you rule that out? That — see, there are some people — well, anyway," he fumbled before Farley stated, "I would say that is extremely unlikely."
Luckily for us, the exchange was captured on video:
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