# Nexus for Exoplanet System Science

The Nexus for Exoplanet System Science (NExSS) initiative is a National Aeronautics and Space Administration (NASA) virtual institute designed to foster interdisciplinary collaboration in the search for life on exoplanets. Led by the Ames Research Center, the NASA Exoplanet Science Institute, and the Goddard Institute for Space Studies, NExSS will help organize the search for life on exoplanets from participating research teams and acquire new knowledge about exoplanets and extrasolar planetary systems.

## History

In 1995, astronomers using ground-based observatories discovered 51 Pegasi b, the first exoplanet orbiting a Sun-like star. NASA launched the Kepler space telescope in 2009 to search for Earth-size exoplanets. By 2015, they had confirmed more than a thousand exoplanets, while several thousand additional candidates awaited confirmation.
To help coordinate efforts to sift through and understand the data, NASA needed a way for researchers to collaborate across disciplines. The success of the Virtual Planetary Laboratory research network at the University of Washington led Mary A. Voytek, director of the NASA Astrobiology Program, to model its structure and create the Nexus for Exoplanet System Science (NExSS) initiative. Leaders from three NASA research centers will run the program: Natalie Batalha of NASA's Ames Research Center, Dawn Gelino of the NASA Exoplanet Science Institute, and Anthony Del Genio of NASA's Goddard Institute for Space Studies.

## Research

Functioning as a virtual institute, NExSS is currently composed of sixteen interdisciplinary science teams from ten universities, three NASA centers and two research institutes, who will work together to search for habitable exoplanets that can support life. The US teams were initially selected from a total of about 200 proposals; however, the coalition is expected to expand nationally and internationally as the project gets underway. Teams will also work with amateur citizen scientists who will have the ability to access the public Kepler data and search for exoplanets.
NExSS will draw from scientific expertise in each of the four divisions of the Science Mission Directorate: Earth science, planetary science, heliophysics and astrophysics. NExSS research will directly contribute to understanding and interpreting future exoplanet data from the upcoming launches of the Transiting Exoplanet Survey Satellite and James Webb Space Telescope, as well as the planned Nancy Grace Roman Space Telescope mission.
Current NExSS research projects as of 2015:
| Subject | PI | Institution | Description |
| Planetary formation and properties | James Graham | University of California, Berkeley Stanford University | "Exoplanets Unveiled"; Direct imaging, Doppler and transit methods, using the Gemini Planet Imager of the Gemini South Telescope, the Keck Observatory, and the proposed Thirty Meter Telescope. |
| Stellar proximity and Earth-like planet formation | Daniel Apai | University of Arizona | "Earths in Other Solar Systems"; development of computer model; Large Binocular Telescope |
| Planetary formation | Eric Ford | Penn State University | Statistical models applied to Kepler data |
| Atmospheres of Hot Jupiters | Jason Wright | Penn State University | Diffuser-assisted photometry using ground based observatories |
| Chemistry of planetary atmospheres | Hiroshi Imanaka | SETI Institute | Habitable zones; atmosphere of Titan as an analogue to exoplanet atmospheres |
| Geochemical cycle of exoplanets | Steven Desch | Arizona State University | "Periodic Table of Planets"; geochemical modeling |
| Atmospheres of exoplanets | Drake Deming | University of Maryland | Analysis of Kepler data to study exoplanet atmospheres |
| Atmospheric evolution | William B. Moore | Hampton University | "Living, Breathing Planet". Determine past habitability of planets in the Solar System and apply results to exoplanetary habitability |
| Atmospheric structure and spectra of exoplanets | Jonathan Fortney | University of California, Santa Cruz | New tools to analyze exoplanet transmission spectra to identify molecular features in the atmosphere |
| Planetary formation and evolution | Hannah Jang-Condell | University of Wyoming | Modeling planet formation, focusing on transitional, protostellar disks |
| Formation of exoplanets | Neal Turner | Jet Propulsion Laboratory | Computer modeling of exoplanet formation |
| Exoplanet exospheres | Adam Jensen | University of Nebraska-Kearney | Detection and evolution of exospheres |
| Habitable exoplanets | Victoria Meadows | University of Washington | Virtual Planetary Laboratory (VPL) |
| Planetary surface habitability | Anthony Del Genio | Goddard Institute for Space Studies | Planet simulation using the GISS Earth global climate model |
| Tidal dynamics and orbital evolution of terrestrial exoplanets | Wade Henning | University of Maryland, College Park Goddard Space Flight Center | Study of how tidal heating can prevent the ejection of young, Earth-sized planets |
| Detection of Earth-size exoplanets | Debra Fischer | Yale University | Design new spectrometer to detect Earth-size exoplanets; improve access to citizen science with Planet Hunters |