ATMOSPHERIC REENTRY STUDY
OVERVIEW
Atmospheric reentry is the process of a spacecraft or vehicle returning from space to the Earth's atmosphere. Vehicles returning from low earth orbit enter the atmosphere traveling at speeds exceeding Mach 25. The loads from aerodynamics and heating by friction and plasma generation pose many challenges for reentry vehicle design.
This independent study aimed to develop an understanding of the aerodynamic forces acting upon a reentry vehicle and the design decisions that must be made.
REENTRY EQUATIONS
By treating the reentry vehicle as a point mass, I computed the aerodynamic and gravitation forces acting upon it. Then I derived the equations of motion using classical mechanics principles. These equations can then be used to predict the trajectory of the reentry vehicle, taking into account aerodynamic forces and atmospheric drag.
TRAJECTORY SIMULATIONS
By applying the equations of motion for a point mass in flight with a small timestep, I simulated the trajectory of a reentry vehicle in Python. I then analyzed how different parameters, such as entry angle and ballistic coefficient, affect the vehicle's trajectory and the loads its experiences.
VARYING REENTRY PARAMETERS
The ballistic is the ratio of an object's mass to its area multiplied by its drag coefficient. Vehicles with higher ballistic coefficients penetrate deeper into the atmosphere before slowing down abruptly. They will reach the ground quickly but experience high dynamic pressures, high heat transfer rates, and high integrated heat loads. In general, spacecraft reentry vehicles are designed to minimize their ballistic coefficients.
Entry angle is the initial angle that the reentry vehicle enters the atmosphere relative to the local horizon. Higher entry angles cause a reentry vehicle to decelerate quickly and experience higher aerodynamic loads and high heat transfer rates but reduce the reentry time and the total integrated heat load. Entry angle is modulated to meet mission needs.
