Analysis of Higher-Order Effects on Low Altitude Lunar Orbits Caused by Irregularities in Mass Distribution
Open Access
- Author:
- Castro Martinez, Guillermo
- Area of Honors:
- Aerospace Engineering
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Robert G. Melton, Thesis Supervisor
Robert G. Melton, Thesis Honors Advisor
Puneet Singla, Faculty Reader - Keywords:
- Moon Gravity
Spherical Harmonics
GRAIL
Orbital Elements - Abstract:
- One of humanity’s greatest challenges is space exploration and conquering the solar system. The exploration and investigation of celestial bodies such as the Moon is paramount to becoming a space-faring civilization. As more spacecraft are deployed to lunar orbits for scientific research, more resources are exhausted for station-keeping. The Moon’s gravitational irregularities, caused by uneven mass distributions, inflict small perturbations on orbiting bodies. These perturbations can over time severely impact the orbits of nearby spacecraft and jeopardize the research being conducted. A deeper understanding of the magnitudes and locations of these perturbations is required for orbiting spacecraft to maintain a stable orbit. A gravitational model of the moon, using higher-order spherical harmonics methods and empirical data collected in the NASA GRAIL mission, was developed, and used to measure the gravitational perturbations of the Moon. Equations of motion accounting for the higher-order gravitational effects were integrated over time in the MATLAB software, given a set of initial conditions, to depict the resulting orbital trajectory of a lunar spacecraft. The effects of these perturbations on the orbital elements of low lunar orbits with different inclinations were analyzed. The results show that the semi-major axis, eccentricity, and inclination of the orbit have a linear relationship in time. Consequentially, the radius of periapsis experiences a gradual linear decrease eventually resulting in a collision with the lunar surface. Thus, systems must be implemented into lunar satellites that counteract the effects of the gravitational perturbations thereby increasing the lifespan of the spacecraft and the mission.