I do comparative studies of climate evolution, and the interactions between planetary atmosphere and surfaces and their radiation environment, and try to understand the environmental factors that can affect a planet's habitability and how they change over time.

Mars does not have an atmosphere and does not have a magnetic field today, so the planet doesn't have the protection from radiation that our atmosphere and magnetic fields provide us on Earth.

Radiation is one of the important factors in evolution. It causes mutation, and some level of mutation is actually good for evolution.

David Grinspoon Quotes