VPL at University of Washington
The Virtual Planetary Laboratory
Identifying a habitable or inhabited planet around another star is one of NASA’s greatest long-term goals. Major advances in exoplanet detection place humanity on the brink of finally answering astrobiology’s over-arching question “Are we alone?” But there are still many scientific steps required before we can identify a living world beyond our Solar System. The unifying intellectual focus of the Virtual Planetary Laboratory is to learn how to recognize whether an extrasolar planet can or does support life. All aspects of this team’s research work towards that specific goal and, to achieve that goal, they have developed the team and modeling toolbox required to analyze planetary habitability as a multi-dimensional, interdisciplinary parameter space. The VPL team will use this improved knowledge of planetary habitability to determine the planetary characteristics, and the measurement capabilities required to discriminate between planets with and without life.
Objective 1: Characterize Habitability and Biosignatures for an Earth-like Planet.
The VPL team will use their existing, rigorous, well-validated radiative transfer model of Earth to produce a definitive dataset on the photometric and spectral characteristics for the Earth seen in direct imaging and transit. They will also upgrade the model to read in 3-D GCM data. Products from the Earth model will be used to explore the detectability of signs of habitability and life for the Earth, to validate the retrieval techniques developed in Obj. 5, and to expand 3-D spectral visualization capability to planets other than the Earth.
Objective 2: Characterize the Environment, Habitability and Biosignatures of the Earth Through Time.
For several critical periods throughout the Earth’s history this team will undertake an interdisciplinary synthesis of field, laboratory and modeling efforts to constrain planetary environmental parameters including surface temperature, atmospheric pressure and composition, and to determine biogeochemical cycling and greenhouse effects consistent with these constraints. This work will provide an improved understanding of the environmental parameters, climate and atmospheric biosignatures for ecosystems and environments dominated by a wide range of different metabolisms.
Objective 3: Develop Interdisciplinary, Multi-Parameter Characterization of Exoplanet Habitability.
The VPL team will undertake an interdisciplinary exploration of the interdependent effects of the Galactic environment, parent star, planetary system environment and planetary characteristics on planetary habitability. One focus will be on factors affecting M dwarf planets, as these are likely to be the first targets amenable to spectroscopic follow-up. This work will provide a more complete picture of planetary habitability, and result in an enhanced toolbox of coupled codes. They will use these modeling tools to assess and rank newly discovered planets for likely habitability, and prioritize them for follow-up.
Objective 4: Determine the Impact of Life on Terrestrial Planet Environments and the Generation of Biosignatures.
Through field and lab research integrated with coupled chemical, climate and ecosystem models the VPL team will engage in an interdisciplinary exploration of life’s co-evolution with its environment, and the limits of photosynthesis. They will use this work to identify new remote-sensing atmospheric and surface biosignatures and understand how photosynthesis may adapt to extrasolar light environments.
Objective 5: Define Required Measurements and Optimal Retrieval Methods for Exoplanet Characterization Missions.
The VPL team will use Kepler data of multiplanet systems to constrain planetary mass, and develop an optimal exoplanet spectral retrieval system for determination of planetary atmospheric and surface properties from exoplanet spectra. This new retrieval technique will be designed specifically for exoplanet data, and will incorporate consistency with known data on the planet, along with basic physical and chemical constraints on planetary atmospheres. With this new capability they will be able to assess the detectability of signs of habitability and life for the early Earth and exoplanet environments generated by the previous four tasks.