A team of UC Berkeley astronomers and a Stanford physics professor will receive $3.25 million over the next four years from NASA to search for planets capable of supporting life.
Headed by UC Berkeley astronomy professor James Graham, the “exoplanets unveiled” project is one of 16 new projects NASA will fund as part of its Nexus for Exoplanet System Science. The UC Berkeley and Stanford team will focus on exoplanets’ “formation, evolution, and potential to harbor life,” according to a Tuesday press release from NASA.
The project’s most innovative development — conceived by Graham and Stanford physics professor Bruce Macintosh — is the use of a special camera attached to the massive Gemini South Telescope in Chile. The camera, called the Gemini Planet Imager, can directly image certain types of planets in other star systems.
“The idea behind this camera is utterly unique,” said Geoffrey Marcy, a UC Berkeley astronomy professor. “This is a camera that has the ability to block the light from a star and allow the light from a dim planet to shine through.”
According to Marcy, part of what makes the GPI “better than any other planet imaging device ever” is its use of improved adaptive optics, which involve shining a laser beam through the sky and creating an artificial star. By measuring how the Earth’s atmosphere distorts light from this artificial star, astronomers can correct for the distortion of light collected from real stars and planets.
So far, the GPI can only image planets called “young Jupiters,” which are large gaseous planets that emit infrared light with a wavelength approximately three times longer than the human eye can see. A much more sensitive camera would be needed to directly view rocky planets such as Earth.
“Light from rocky planets is about a billion times fainter than light from the sun,” Graham said. “Currently, we can image planets that are about a million times fainter than the stars they orbit, which is already astounding, but to pick up light from rocky planets that may be home to life, we’d need to get in the billion-to-one range.”
While Marcy said the chance of life existing on young Jupiters is “very small” because of these planets’ intense heat, the team will use another method, the “Doppler wobble” method, to indirectly detect the presence of planets that may in fact be habitable.
The Doppler wobble of stars refers to slight changes in the wavelength of light that astronomers receive from stars whose orbiting planets cause them to move toward and away from Earth. This is the same effect that causes the sound of police sirens to change frequency when the police car passes an observer.
“Using the Doppler wobble technique, we’ve been able to find planets that are Earth-like in size,” Graham said. “This is our best method right now of finding potential sites for life outside the solar system.”