Curious about whether there is life beyond Earth? The answer should come within 20 years, astronomers told members of a Congressional science committee on Wednesday.

A three-way race is under way to learn if life exists elsewhere in the solar system or beyond, Seth Shostak, senior astronomer with the California-based SETI Institute, said during a hearing before the House Science and Technology Committee.

So far, most efforts -- and funding -- to find extraterrestrial life have focused on Mars and potential life-bearing moons in the outer solar system.

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“At least a half-dozen other worlds (besides Earth) that might have life are in our solar system. The chances of finding it, I think, are good, and if that happens, it’ll happen in the next 20 years, depending on the financing,” Shostak said.

A second initiative scans the atmospheres of distant planets for telltale signs of oxygen or methane, gases which, on Earth, are mostly tied to life. These searches likewise could yield results in the next two decades, Shostak added.

The third project hunts for technologically advanced aliens that are sending radio or other signals out into space. The idea behind the Search of Extraterrestrial Intelligence, or SETI, is to eavesdrop on signals that are deliberately or accidentally leaked from another world.

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“That makes sense because in fact even we, only 100 years after ... the invention of practical radio, already have the technology that would allow us to send bits of information across light years of distance to putative extraterrestrials,” Shostak said.

Humans’ first television broadcasts, including “I Love Lucy,” and “The Ed Sullivan Show,” have passed 10,000 stars, noted SETI hunter Dan Werthimer, with the University of California, Berkeley.

“The nearby stars have seen 'The Simpsons.' If we’re broadcasting, maybe other civilizations are sending signals in our direction -- either leaking signals the way that we unintentionally send off signals, or maybe a deliberate signal,” Werthimer told legislators.

“The fact that we haven’t found anything means nothing,” Shostak added. “We’ve only just begun to search.”

NASA's Mars rover Curiosity is currently seeking out evidence for past habitability on the red planet.NASA/JPL-Caltech

Though there is no proof of any life beyond Earth, circumstantial evidence is mounting. Results from NASA’s Kepler space telescope and other hunts for planets beyond the solar system have shown that at least 70 percent of the 200 billion to 400 billion stars in the Milky Way have planets, many well-positioned for liquid water, which is believed to be necessary for life.

More recent results from the ongoing Curiosity rover mission on Mars proved there are habitats beyond Earth suitable for microbial life.

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“In our own galaxy there are tens of billions of other planets that are the kind you might want to build condos on,” Shostak said. “And if that isn’t adequate for your requirements, let me point out there are 150 other galaxies we can see with our telescopes, each with a similar complement of Earth-like worlds.

“What that means is that the numbers are so astounding that if this is the only planet in which not only life, but intelligent life, has arisen, then we are extraordinarily exceptional. It’s like buying trillions of lottery tickets and none of them is a winner. That would be very, very unusual,” Shostak said.

“The history of astronomy shows that every time we thought we were special we were wrong,” he added.