I study atmospheric escape and chemistry, using observations and models terrestrial planets to understand the evolution of habitability with time.

Much of my work focuses on understanding hydrogen escape from Mars. Observations of the H corona in the ultraviolet at 121.6 nm (H Lyman alpha) allow reconstructions of coronal density and escape rates. Escape of H has been a key control on the history of water availability on the Martian surface and is among the most important controls on the oxidation history of the atmosphere and planet. I have made important contributions to understanding H escape at Mars, including:

  1. The first demonstration that H escape varies by more than an order of magnitude on seasonal timescales (Chaffin 2014),
  2. The discovery of non-spherically symmetric structure in the corona of Mars (Chaffin 2015).

While these discoveries may seem intuitive, they demonstrate that H escape from Mars is more temporally and spatially variable than were previously thought possible, requiring new mechanisms to support the observed variability. I am currently dedicating much of my time to understanding these mechanisms.

My work has produced the most extensive and high-fidelity measurements of the H corona ever made:


The H corona of Mars in Lyman alpha light (Chaffin 2015)

My work is supported by NASA’s MAVEN project, currently at Mars; and by the Emirates Mars Mission, which will launch to Mars in 2020. I have also received independent funding from NASA to analyze data from the European Space Agency’s Mars Express Spacecraft. I contribute to each instrument team in a variety of ways to ensure the scientific success of the investigation.