Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)


Aerospace, Physics, and Space Sciences

First Advisor

Daniel R. Kirk

Second Advisor

Paula do Vale Pereira

Third Advisor

Madhur Tiwari

Fourth Advisor

Eraldo Ribeiro


Advancements in liquid propellant management science and technologies are key to increasing safety, decreasing cost, and increasing payload mass of space missions. Propellant usually comprises a large portion of the total mass of launch vehicles and spacecraft, so liquid propellant sensing, as well as predicting and controlling the motion of it, are important. Electrical Capacitance Tomography (ECT) is an emerging sensing technology that is capable of measuring the distribution of liquid anywhere inside of a tank, potentially making it useful for measuring slosh and gauging mass. An ECT-instrumented tank was successfully tested in microgravity for the first time. Basics of ECT measurement theory, details of the experiment setup, data processing, ground test results, and the flight test results are discussed. The results suggest ECT will be useful as a propellant mass gauging technology in both accelerated and microgravity environments. The accuracy of the ECT-measured 3D liquid distributions is also assessed. Computational fluid dynamics (CFD) programs are critical to predicting slosh dynamics, but CFD programs require extensive experimental validation before the results can be trusted. Microgravity slosh test data is lacking, and most of what is available is inadequate for CFD validation. The SPHERES-Slosh Experiment (SSE) was created and successfully utilized to acquire long-duration, low-gravity liquid slosh data while operating on the International Space Station (ISS). The SSE test sessions yielded a dataset of correlated inertial measurement unit data and images that can be used by design engineers and space mission planners to benchmark CFD models. The combination of long-duration, low-gravity, measured motion, and known initial conditions aspects of the SSE dataset had not been achieved in any prior slosh experiments, making it unique and valuable. Mechanical, electrical, and software design, fabrication, qualification testing, ground testing, and ISS operations of the SSE, along with CFD validation using the test data, are presented. The duration of good agreement between test and CFD was case-dependent. Improving the trajectories calculated from the measured motion data is necessary before long-duration validation of low-gravity slosh CFD can be claimed.