UC Santa Cruz astrophysicist Jonathan Fortney is one of 15 principal investigators for a new NASA initiative that is embracing a team approach to the quest for life on planets around other stars. The Nexus for Exoplanet System Science (NExSS) will benefit from the expertise of several dozen scientists across the NASA science community in an effort to find clues to life on faraway worlds.
Fortney, an associate professor of astronomy and astrophysics at UC Santa Cruz, will lead a team exploring how novel statistical methods can be used to extract information from the light emitted and reflected by planetary atmospheres in order to understand their atmospheric temperatures and the abundance of molecules. Astronomers routinely analyze the light from distant stars by spreading it out into a spectrum of different wavelengths. Fortney is developing tools for analyzing the spectra of distant planets to determine molecular abundances in their atmospheres.
"In the future, when we obtain spectra of Earth-like planets around other stars, we'll want to know if we can see things like methane and oxygen in their atmospheres, and we'll want to quantify the amounts of those different gases," he said. "In the present era, we can retrieve the abundances of molecules in the atmospheres of brighter, hotter, well-studied objects like brown dwarfs and giant planets. This allows us to test and hone our tools for the future."
In bringing together the "best and brightest," the NExSS team hopes to better understand the various components of an exoplanet, as well as how the parent stars and neighbor planets may interact to support life.
The study of exoplanets--planets around other stars--is a relatively new field, with the first discovery in 1995. Researchers at UC Santa Cruz pioneered techniques for detecting exoplanets. The launch of NASA's Kepler space telescope six years ago greatly increased the rate of discovery. More than 1,800 exoplanets are now known, with thousands of additional candidates waiting to be confirmed. Some of these worlds are potentially habitable, so now scientists are developing ways to confirm the habitability of these worlds and search them for signs of life (biosignatures).
Key to this effort is to understand how biology interacts with the atmosphere, geology, oceans, and interior of a planet, and how these interactions are affected by the host star. This "system science" approach is what NExSS will use to better understand how we can look for life on exoplanets.
NExSS will solve this problem by tapping into the collective expertise from each of the divisions in NASA's Science Mission Directorate. Earth scientists developed this systems science approach by studying our home planet. Planetary scientists have applied systems science to a wide variety of worlds within our solar system. Heliophysicists add another layer to this systems science approach by looking in detail at how the sun interacts with the planets that orbit it. Astrophysicists are providing data on the exoplanets and host stars for the application of this systems science framework.
These different research communities, often unaware of work outside of their own disciplines, will be brought together by NExSS to share their perspectives, research results, and approaches. This collaboration will help classify the diversity of worlds being discovered, understand the potential habitability of these worlds, and inform the development of tools and technologies needed in the search for life beyond Earth. Through this work, NExSS will play a key role in the pursuit of one of humanity's deepest questions: Are we alone?
NExSS will be led by scientists from the NASA Ames Research Center, the NASA Exoplanet Science Institute at the California Institute of Technology, and the NASA Goddard Institute for Space Studies. It will include team members from 10 different universities, three NASA centers, and two research institutes. These teams were selected from proposals from across NASA's Science Mission Directorate.