LPL Colloquium:

Tuesday, Dec 3, 2013
3:45 pm — 4:45 pm

Location: Kuiper Space Sciences
Room: 312

Dr. Majd Matta
Postdoc - Center for Space Physics
Boston University

The Complex Martian Ionosphere from Viking to MAVEN
Abstract:
The accessibility of Mars to orbiting spacecraft provides an opportunity to study an atmosphere that differs from our own. Yet, despite the half century of measurements made at Mars, the current state of the neutral atmosphere and its embedded plasma (ionosphere) remains largely uncharacterized. In situ measurements of the neutral and ionized constituents versus height exist only from the two Viking Landers from the 1970s. Subsequent satellite and remote sensing data offer sparse global coverage of the ionosphere. Thermal characteristics of the plasma environment are not well understood. Patchy crustal magnetic fields interact with the Martian plasma in a way that has not been fully studied. Hence, investigating the coupled compositional, thermal and crustal-field-affected properties of the ionosphere can provide insight into comparative systems at Earth and other planets, as well as to atypical processes such as the solar wind interaction with topside ionospheric plasma and associated pathways to escape.

In this talk, I present studies of the composition, thermal structure and dynamics of the Martian ionosphere. Results from these studies are compared with measurements and show that (1) ion composition at Mars is highly sensitive to the abundance of atmospheric hydrogen, (2) lighter ions heat up more efficiently than heavier ones and provide additional heating sources for cooler plasma, and (3) crustal field morphology affects plasma dynamics and structure at Mars in a way that is consistent with observations. Predictions of ion composition and plasma temperatures will be compared with the Mars Atmosphere and Volatile Evolution (MAVEN) orbiter observations, and will likely alter the present understanding of the environment at Mars.
Host: Roger Yelle