Public defence in Space Science and Technology, M.Sc.(Tech.) Maria Hieta

The title of the thesis: Advancing atmospheric humidity measurements on Mars through improved calibration methods

Thesis defender: Maria Hieta
Opponent: Prof. Axel Hagermann, Luleå University of Technology, Sweden
Custos: Prof. Esa Kallio, Aalto University School of Electrical Engineering

Understanding the behavior of water vapor is essential for characterizing the Martian water cycle, the regolith–atmosphere exchange processes, assessing whether liquid water could briefly exist at the surface, and improving Mars climate models. Accurate near-surface humidity measurements obtained directly at the surface are therefore indispensable as the lowest atmospheric layers cannot be reliably characterized from orbit.

This dissertation focuses on improving measurements from the humidity sensors flown on NASA’s Mars missions, specifically the Curiosity and Perseverance rovers. It presents new laboratory calibrations and an improved calibration methodology in order to obtain near-surface relative humidity measurements that are more accurate than previously possible. The flight calibration of the MEDA HS humidity sensor onboard the Perseverance rover was planned and executed, consisting of extensive calibration measurements at multiple test facilities. The previous calibration of REMS-H, the humidity sensor onboard the Curiosity rover, was re-evaluated using the same
methodology, improving the quality of the dataset. Together, the two resulting datasets constitute the most comprehensive and intercomparable near-surface humidity records obtained from Mars to date, supporting studies of the Martian water cycle and surface–atmosphere exchange phenomena.

Thesis available for public display 7 days prior to the defence at Aalto University's public display page.