Tarter discusses possibility of extraterrestrial life

BY ELIZABETH MCMAHON ’13
Senior Staff Writer

This week’s Common Hour, “Life in the Universe,” featured Dr. Jill Tarter, the Bernard M. Oliver chair for the Search for Extraterrestrial Intelligence at the SETI Institute. Tarter spoke about the search for and possibility of life on other planets.

Tarter is a recipient of the Lifetime Achievement Award for Women in Aerospace, and in 2004 she was named one of the hundred most influential people in the world by Time magazine.

She began her talk by inviting audience members to imagine how our lives would change if a signal showing signs of extraterrestrial life were detected in outer space.

“For millennia, [humans] have been on a journey, trying to answer questions about who we are and why we are and whether or not there’s anybody else questioning along with us — somewhere else beyond the Earth,” Tarter said.

She went on to discuss the different types of life that exist on Earth, including life that has been found in obscure places, such as beneath the Earth’s crust.

“We find life just about everywhere we look,” Tarter said. “The limits of life on this planet seem to be set by the limits of water.”

Tarter then disputed her own statement by saying scientists are not actually sure water is necessary for life. There could be forms of life humans are unaware of that do not need water. This concept of life extends to the rest of the universe.

“Maybe there is life on other planets or moons in the solar system; we just don’t know,” Tarter said. “If we do find life out there that’s independent from our own life then that will prove a theory put forth that life is a cosmic imperative.”

There is also a possibility life exists beyond our solar system.

“Until 1995 we weren’t sure if other stars out there that were like the sun actually had orbiting planets,” Tarter said. “In 1995 we found the first one, and, thanks to this spacecraft, Kepler, we’re finding thousands.”

Finding new planets orbiting stars is the first step to answering the question of whether or not there is other life in the universe.

The spacecraft Kepler is currently analyzing a one-hundred-degree-section of the sky above the Milky Way. Kepler is looking for small planets the size of the Earth and trying to find a place that can sustain life, called the Goldilocks Zone.

Kepler selected 150,000 stars to focus on and constantly measures the amount of light coming from them. It is able to find planets orbiting by tracking the stars’ blink, which occurs when a planet’s orbit crosses in front of the star and momentarily blocks some of the star’s light.

“The second time [a star blinks] defines a period, if that’s a planet and it’s going around the star we now know that we can expect it to, one period later, happen again,” Tarter said. “Kepler has been amazingly successful and has found 2,740 exoplanet candidates. There are 58 of them that appear to be at just the right distance from their star that they might be in the Goldilocks, where we might expect to find life.”

Kepler has benefits in addition to searching for life.

“Kepler has found stars that have multiple planets that orbit around them,” Tarter said. “When we look at the dynamics — the motion of those planets around their stars — and compare it with the motion of our planet around the sun, we see there’s a lot of different things going on here, which we had no clue of before Kepler showed us what other planetary systems might look like. We’re learning a lot more about how planets have formed and what it takes to make a solar system.”

These discoveries open the possibility of finding a planet similar to Earth. If scientists do find one, Tarter believes the world will wonder if it is possible for humans to go there and if anybody lives there.

Whether humans could travel to a newly discovered planet depends on how far away it is — the stars Kepler is studying are too far away for us to reach. SETI is working on discovering if there is life on other planets.

“My group tries to find the intelligent patterns that might be there,” Tarter said.

Because intelligence is something that is extremely difficult to define and measure, Tarter and her team are trying to find signs of technology, which they believe would be a sign of intelligent life.

“Two technological civilizations have to be close to detect one another,” Tarter said. “They have to be close not only in space, but they have to line up in time.”

This means technology has to last for a substantial amount of time for two technologically advanced races to be able to find each other. SETI uses a 42-dish Allen Telescope Array in California and eventually wants to increase its number to 350.

SETI also uses a waterfall plot to map out signals the telescopes find. The institute studies these plots to try to find a pattern, or something that points to technologically-made objects being used. SETI primarily searches for signals given off by engineered objects, not natural ones.

Tarter explained that if evidence of other technology in outer space is found, scientists can assume the civilization has a lifespan of about 100,000 years.

A new method of searching for life involves looking at biological signatures in the atmospheres of other planets.

“If you were to look at our atmosphere from a distance, you would see something that is very strange; it doesn’t really agree with the atmospheres of any of the other planets in our solar system,” Tarter explained. “You would find molecular oxygen and methane gas.”

In addition, Tarter is interested in getting more people involved in the SETI project.

“SETI is intrinsically a global question and should be a global project,” Tarter said.

Common Hour ended with questions from the audience, ranging from inquiries about paradoxes to why humans are so interested in finding extraterrestrial life.

Tarter asked audience members to consider the idea that humans might not be alone in the universe and think about how that affects them as individuals.

“SETI and this question of life beyond the earth is, in fact, an opportunity to hold up a mirror to every human on the planet and say, ‘Think about it, compared to someone else out there. All you humans, you’re all the same,’” Tarter said. “So I hope one of the benefits of getting the world involved in this search will be to trivialize the differences among humans. We need to work together globally to solve these great challenges we have ahead of us so we can have a long future.”

Questions? Email Elizabeth at emcmahon@fandm.edu.

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