TRADESPACE EXPLORATION OF PARAMETERS FOR AEROCAPTURE AT MARS

Open Access
- Author:
- Kim, Sung Jun
- Area of Honors:
- Aerospace Engineering
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- David Bradley Spencer, Thesis Supervisor
David Bradley Spencer, Thesis Honors Advisor
Robert Graham Melton, Faculty Reader - Keywords:
- Mars
orbital
mechanics
aerocapture
Mars-GRAM
atmosphere
density
drag
tradespace
exploration
orbit
atmospheric
interplanetary
astrodynamics - Abstract:
- This thesis explores the tradespace of different parameters that affect the capability of aerocapture by the atmosphere of Mars. Aerocapture is an attractive technique that uses the atmospheric drag of a planet to reduce velocity and place a spacecraft into a final orbit. In this thesis, periapsis altitude that captures the spacecraft is examined with variance in parameters. The parameters that are investigated include hyperbolic excess velocity entering Mars (v∞) and spacecraft ballistic coefficient. The atmospheric model ‘Mars-GRAM’ was used to calibrate a simple exponential atmospheric density model. This model was further modified using a linearization with the cubic spline function since the Mars-GRAM model has a discontinuity at the altitude of near 112.5 km. Equations of motion due to gravitational force and atmospheric perturbation were integrated with initial position and velocity defined. Then, the information of trajectory was used to calculate orbital energy over time. Since the change in orbital energy represents the variations in characteristics of the orbit, the orbital energy after encountering the atmospheric drag near periapsis region was examined. Lastly, capture altitude that leads orbital energy to approach to zero, where the orbit switches from hyperbolic to elliptical, were extracted for a given range of v∞ with different ballistic coefficients. In addition, heat transfer rate and loading were calculated to explore the general trend of the physical effect on the spacecraft during the aerocapture. The results of the analysis discuss the sensitivity of capture altitude with variance in v∞ and area-to-mass ratio and the importance of the accuracy in the flight system of the spacecraft for the aerocapture in Mars exploration.