NASA Astrobiology Institute (NAI)

The Virtual Planetary Laboratory’s primary mission is to support NASA’s ongoing planet-finding efforts by building computer simulated Earth-sized worlds to discover the likely range of environments for planets around other stars. To that end, we are developing web-based community tools that allow researchers to collaborate on planetary climate models. These tools combine models and data that help predict the observable properties of planets orbiting other stars.

The VPL has developed a suite of models that can self-consistently describe planetary environments under conditions not observed in our solar system. Our suite works on a modular approach: users enter the data of their planetary system such as planet mass, stellar type, surface properties, atmospheric constituents and atmospheric thermal properties. This information is then used to run a coupled climate-chemistry model that self-consistently determines the atmospheric properties of the planet. The results can then be used to generate a simulated spectrum of the proposed planet, allowing the user to examine the observable properties. These models have the following components:
The molecular absorption coefficient visualizer – Accessing the HITRAN molecular spectral database, the user can determine if a given molecule will have absorption properties in the spectral range of interest.
The climate module – The climate module uses the properties of the planet’s atmosphere (temperature, pressure, atmospheric composition, etc.) and surface, along with the incoming stellar radiation, to determine a self-consistent model of the planetary environment.

Atmospheric chemistry module – The thermal properties and initial atmospheric constituents of the atmosphere are then fed into the atmospheric chemistry module, which calculates the evolution of the atmospheric composition.

The spectrum visualization module – The resulting planetary environment (which encompasses atmospheric constituents, temperature and pressure profiles, and surface properties) along with the spectrum of the planet’s parent star, is input to a line-by-line radiative transfer model, and used to generate a synthetic disk-averaged spectrum of the planet.
The major accomplishments this year were:

• Parallelized the line-by-line absorption and spectral mapping code


• Continued development on the Virtual Planetary Laboratory Community tools for release in October, 2008.