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Scientists' Path to Learning If We Are Alone in the Universe


Hubble's view of a galaxy in Ursa Major, 65 million light-years away. (NASA, ESA, A. Riess (STScI/JHU)

The Hubble Telescope has given us spectacular pictures from space, from the dramatic image of the Pillars of Creation in the Eagle Nebula, some 6,500 to 7,000 light years from Earth, to a snapshot of nearly 10,000 galaxies, including some that may be among the most distant known, existing when the universe was just 800 million years old.

Awe-inspiring though they are, they are not detailed enough to help us in our search for life in the trillions of galaxies across the universe. And physicist Justin Crepp says the prospects for finding life out there are very good.

“If tens of a percent of stars have planets that could resemble the earth and potentially have life, then the implications are that there are billions of them just within our Milky Way Galaxy.”

Crepp, an associate professor of Physics at the University of Notre Dame, has been hard at work answering the age-old question, “Are we alone in the universe?” As a member of the National Academy of Sciences Committee on Exoplanet Science Strategy, his job is to make recommendations on how and what the U.S. will explore in space over the next decade.

Up close and personal with planets

Scientists Seek Answers to Are We Alone?
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In September, the committee released its initial 260-page report detailing seven recommendations. First, it encourages NASA to fly a space-based mission to directly image and characterize earth-like planets around other stars and take pictures of them. But Crepp says that’s a very challenging technical problem.

“If you try to image a planet, you run into several difficulties,” he explains. “One is that their separation is very small on the sky. So, you need to spatially resolve and isolate the signal of the planet. So, you need a certain size telescope to do that. The problem is earth’s atmosphere blurs out the images, and so it exacerbates the issue.”

Another issue is that the starlight is so bright, scientists need to find a way to block it to see the planets around it. The committee thinks the technology to do that exists, but they must be able to get above the earth’s atmosphere with the right equipment to make it happen.

Better eyes on the skies

That leads to the committee’s second recommendation, this one, for the National Science Foundation: complete work on the Giant Magellan Telescope in Chile, and start to build the proposed Thirty Meter Telescope in Hawaii. The new technology in these super telescopes will produce images 10 times sharper than those from the Hubble, even though they are ground-based.

Their highly sophisticated equipment will also allow scientists to greatly enhance the work of the third recommendation: completing the partially funded Wide Field Infrared Survey Telescope or WFIRST. When launched into space, it will search for and gather information on planets hundreds of light years away.

WFIRST, the Wide Field Infrared Survey Telescope, shown here in an artist's rendering, will provide astronomers with Hubble-quality images of large swaths of the sky. (NASA)
WFIRST, the Wide Field Infrared Survey Telescope, shown here in an artist's rendering, will provide astronomers with Hubble-quality images of large swaths of the sky. (NASA)

Crepp says that data will help scientists learn what the planets are made of.

“Is it a giant puffy atmosphere, or is it a rock or somewhere in between? Is it a water world? We don’t know the answers to these yet, but we’re just starting to get the first hints and inclinations what these worlds might be like around other stars,” Crepp said.

More importantly, scientists will try to determine if there are any signs of life.

The panel’s other recommendations include building new highly sensitive equipment, creating new ways for multidisciplinary teams all over the world to collaborate on various aspects of the project, and forming a profitable investor program to further laboratory, ground-based and theoretical telescopic research.

The big question

Crepp notes that people have wondered for millennia if our planet was unique in the universe, whether we are truly alone.

“This is a question that impacts not only science but theology, philosophy and other areas. It’s a curiosity. It’s part of being human. Is our world special? Is it isolated? Are there other planets out there that have life? Can we communicate with them? Are they our distant brethren? How are we related to one another? If so, what can we learn from one another? So, that’s the motivation for a lot of people on our panel to go to work on a daily basis.”

The report from the National Academy of Sciences Committee on Exoplanet Science Strategy will be reviewed by Congress. Portions of it may be included in the final 2020-2030 Astronomy and Astrophysics Decadal Survey, which will fund the continuing search for exoplanets and the study of extraterrestrial life.

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