The Milky Way as seen from Chile.Serge Brunier/NASA
The House science committee met Wednesday to discuss the search for extraterrestrial life — concluding that it was only a matter of time, and funding, until life on other planets is discovered.
“We stand on a great threshold in the human history of space exploration,” testified Sara Seager, a professor of physics and planetary science at the Massachusetts Institute of Technology.
“We know with certainty that planets orbiting stars other than the sun exist and are common … On the other side of this great threshold lies the robust identification of Earth-like exoplanets with habitable conditions.”
The hearing aimed to collect information on the state of astrobiology — the study of life's origin, evolution, distribution and future in the universe — as well as plans for future research and expeditions.
It followed a hearing earlier this year on the discovery of thousands of exoplanets — planets outside our solar system — and whether NASA provides enough funding to explore the possibility of life there.
The exoplanets were discovered using the now-crippled Kepler telescope. Kepler “opened the floodgates” when it found evidence of billions of Earth-like planets in the Milky Way, said witness Steven Dick, Baruch S. Blumberg Chair of Astrobiology at the Library of Congress.
Scientists found that in our galaxy, one in five stars that are like our sun in size, color and age have planets that are roughly Earth size and are in the so-called habitable zone, where water can be liquid. That means there are thousands of planets with the potential to host life.
Astrobiologists say they aren’t looking for little green aliens, but for exoplanets in habitable zones that have the right "biosignature" — an element, molecule, or other phenomenon that provides scientific evidence of past or present life, like oxygen in an exoplanet’s atmosphere, which allows for vegetation.
“This is a legitimate science … we’re not searching for aliens or UFOs,” said Mary A. Voytek, of Senior Scientists for Astrobiology at NASA, to the committee. “Even today children wonder, 'Where did I come from?' Astrobiology seeks to answer this enduring question.”
Voytek said she believed it was only a matter of time until life outside Earth is discovered.
Seager echoed that sentiment. “This is a unique time in human history … it’s the first time we have had the technology to reach outside our solar system to find these other Earth-like planets in habitable zones.”
The discovery of so many Earth-like exoplanets “corroborates that what has happened here in our own solar system has happened everywhere,” Dick said.
“Now it’s another step to finding life, and another to intelligence.”
Voytek said she anticipates that “the first life we will find will be microbial” rather than intelligent — since there is vastly more of the former, even on Earth.
Besides scouring thousands of exoplanets for signs of life, astrobiologists also aim to find life within the solar system.
Dick said he would love to see another “voyage to Europa (Jupiter’s moon) to find out what’s under the thick ice, or also out to Saturn to detect more about where those spouts are shooting out.”
Scientists believe there is potential for life in Europa’s vast, salty ocean — trapped under a 60-mile-thick ice shell. And one of Saturn’s moons appears to be spouting water, an essential for life, along with heat energy and organic material.
“When I was a kid I was told we’d be on Mars by 1984 … obviously we didn’t do it,” Dick said, calling for a renewed push toward Mars and adding that Curiosity, the Mars rover, found water in the soil.
“The very idea of exploration … embodies the American ideal of exploration.”
All three witnesses said it would be essential for the future of astrobiology that students be encouraged from a young age to embrace their natural curiosity about where they came from.