February 8, 2013
1 In A Million Stars Host Planets With Intelligent Life
[ Watch the Podcast: The Search For Alien Life With Guest Dr. Eric Mamajek (Part 3): Your Universe Today Podcast ]
Lee Rannals for redOrbit.com - Your Universe Online
A group of astronomers have determined through NASA Kepler mission data that less than one in a million stars in the Milky Way galaxy could have intelligent life.
The University of California, Berkeley team used the Green Bank Telescope in West Virginia to look for intelligent radio signals from planets around 86 of these stars. Although they didn't receive any transmissions back, they did use their study as a statistical sample to conclude that finding ET is one shot in a million.
“We didn´t find ET, but we were able to use this statistical sample to, for the first time, put rather explicit limits on the presence of intelligent civilizations transmitting in the radio band where we searched,” said Andrew Siemion, who recently received his Ph.D. in astronomy from UC Berkeley.
NASA's Kepler mission has found 2,740 planets orbiting stars, and with this information scientists have been able to calculate that there could be even more planets in our galaxy than what has been previously thought. According to UC Berkeley physicist Dan Werthimer, who heads the world´s longest running SETI project, there are a trillion planets in the Milky Way, meaning there are more planets than stars.
Writing in the Astrophysical Journal, researchers said they chose 86 stars last year, based on a list of 1,235 planet candidates known at this time. The team chose stars with five or six planet candidates in orbit, and those that hosted planets are thought to have Earth-like conditions, such as liquid water.
After spending 12 hours collecting five minutes of radio emissions from each star, the team combed through the data looking for high-intensity signals with a narrow bandwidth that are only able to be produced artificially. Most of the stars observed were over 1,000 light years away, so only signals that were intentionally aimed at Earth would have been detected.
Next, the scientists hope to use the Green Bank Telescope, and focus it in on multi-planetary systems to spy on whether these planets are communicating with each other.
“This work illustrates the power of leveraging our latest understanding of exoplanets in SETI searches,” Werthimer said in a recent statement. “We no longer have to guess about whether we are targeting Earth-like environments, we know it with certainty.”
RedOrbit reported in November that SETI received a big donation of $3.5 million from Qualcomm chief scientist and co-founder Franklin Antonio. This big chunk of cash will be used to double the sensitivity of the Alien Telescope Array by replacing a portion of the antenna feed. As technology like this continues to emerge, eventually scientists might be able to use it to focus in on signals being broadcasted by that one in a million civilization.