The study of exoplanets – planets around other stars – is a relatively new field, but planet-hunting efforts have been prolific. The discovery of the first exoplanet around a star like our sun was made in 1995, and NASA’s Kepler space telescope has detected more than 1,000 exoplanets in the past six years.
Now a new NASA initiative aims to answer the big question: Is there life on these alien worlds? The NExSS (Nexus for Exoplanet System Science) initiative will bring together the “best and brightest,” according to a NASA press release. NExSS will marshal the expertise of 10 universities, three NASA centers and two research institutes.
The program aims to better understand the various components of an exoplanet, as well as how the parent stars and neighboring planets might interact to support life. The program brings together planetary scientists, Earth scientists, heliophysicists and astronomers to identify and search for biosignatures, or signs of life.
“This interdisciplinary endeavor connects top research teams and provides a synthesized approach in the search for planets with the greatest potential for signs of life,” said Jim Green, NASA’s director of planetary science. “The hunt for exoplanets is not only a priority for astronomers, it’s of keen interest to planetary and climate scientists as well.”
One NExSS project, called “Exoplanets Unveiled,” will specifically address this question: What are the properties of exoplanetary systems, particularly as they relate to their formation, evolution and potential to harbor life? The project is led by James Graham, a professor of astronomy at the University of California, Berkeley, and will draw upon the expertise of Bruce Macintosh, a professor of physics at Stanford and the principal investigator for the Gemini Planet Imager (GPI).
GPI, a new instrument for the Gemini Observatory, began its exoplanet survey at the Gemini South Telescope in November 2014. Most exoplanets are detected through the Doppler technique – measuring the “wobble” of the parent star as an unseen planet’s gravity tugs on it – or though detection of a transit, as the planet’s orbit brings it between the star and Earth.
As the newest generation of instruments for imaging exoplanets, GPI blocks out the bright star to directly see the faint planet next door. GPI has already imaged two previously known exoplanets and disks of planetary debris orbiting young stars where planets recently formed.
“Getting a complete picture of all the incredibly strange planetary systems out there will require every different technique,” Macintosh said. “With this new collaboration, we will combine the strengths of imaging, Doppler and transits to characterize planets and their orbits.”
The first image of an Earth-size exoplanet is still likely years away. GPI is currently only sensitive enough to detect infrared emission from hot, bright planets the size of Jupiter. Detecting the faint, reflected light of cooler, smaller planets will require next-generation technologies and techniques, which MacIntosh said will be developed via instruments like GPI for eventual use on future planet-finding missions such as NASA’s Wide-Field Infrared Survey Telescope (WFIRST).
“If you could see reflected light, you might be able to see the signature of life,” said Paul Kalas, an adjunct professor of astronomy at UC Berkeley and co-primary investigator for the project. “We are just now sowing the seeds to get to that point.”
