For centuries, humans have sought to learn whether life exists beyond Earth. That answer is closer than ever to fulfillment, and an ASU team is working on a key part of that quest with NASA’s backing.
“In the field of exoplanets, finding exoplanets that could host life is no longer the goal. The quest is to find the signatures of life,” said Steve Desch, an associate professor in the School of Earth and Space Exploration. “To do that we need to know for which types of exoplanets are oxygen and methane biosignatures, as opposed to natural geochemical outcomes.
Desch is principal investigator of an ASU-centered team that is one of 16 teams funded by a new NASA research coordination network, the Nexus for Exoplanet System Science (NExSS). It will receive $6.1 million over five years to investigate the connections between exoplanets and the compositions of their host stars, and especially to focus on understanding the geochemical cycles on exoplanets with different chemical compositions.
NASA’s new network is part of its Astrobiology program. NExSS includes planetary scientists, astrophysicists and heliophysicists who will carry out research to help NASA define future space missions, determine target selection and craft observing strategies, to aid in the characterization of exoplanets and the search for life on them. It is distinct from the NASA Astrobiology Institute, the program that has previously funded astrobiology research at ASU as far back as 1998.
Under the direction of Desch, the present research team brings geophysicists, petrologists and geochemists into the fold of exoplanet research, which has so far been dominated by the astrophysicists and astronomers who discover and characterize exoplanets.
Broad collaborations across disciplines, like the one to be carried out at ASU, are relatively new in the rapidly changing field of exoplanets.
Just as the Kepler mission found thousands of exoplanets that transit their host stars (pass between us and the star), NASA’s Transiting Exoplanet Survey Satellite will be launched in 2017 with the hopes of discovering thousands more among the closest stars. The James Webb Space Telescope, to be launched in 2018, will measure the infrared spectrum of starlight that passes through the atmospheres of some of these transiting exoplanets, discerning what gases are present.
“Absorption of starlight by oxygen and methane could be detected by space telescopes, and will be looked for, because on Earth they are produced overwhelmingly by life,” Desch said. “But exoplanets won’t be like Earth. Stars have different chemical abundances, and their planets should, too.
To understand those cycles, the team will pursue a multifaceted approach combining astronomical observations, astrophysical and geochemical modeling, and geophysical and geochemical laboratory experiments. They will also conduct biological field studies to better understand how the methane cycle works on Earth, and possibly elsewhere.
The ASU team is centered in the School of Earth and Space Exploration, an academic unit in ASU’s College of Liberal Arts and Sciences, but also involves several faculty members from other college units including the School of Life Sciences, the Department of Chemistry and Biochemistry, and the Beyond Center. The team also includes researchers from partner institutions, including the American Museum of Natural History; the Global Science Institute in Wisconsin; Johns Hopkins University; Northern Arizona University; San Francisco State University; the University of Rochester; and the University of Washington.
From 4:30 to 5:30 p.m., Eastern time (1:30 to 2:30 p.m. Arizona time), April 21, NASA will host a panel discussion about exoplanets and NExSS that will include Desch.
ASU students across all campuses are being asked to "Ditch the Dumpster" by donating their unwanted items from campus residence halls instead of throwing them away.
Arizona State University students across all campuses are being asked to “Ditch the Dumpster” by donating their unwanted items from campus residence halls instead of throwing them away.
Donated and recyclable items not only are distributed to area children and families via community partners and local non-profits, but also are diverted from area landfills.
For a list of drop-off locations, visit moveout.asu.edu and look for “donation locations.” Visit recycle.asu.edu for lists of recyclable items and email ASU Recycling program staff with all Ditch the Dumpster and recycling questions.