Advanced On-board Navigation Techniques for Disrupted Complex Asteroid Rotators

12/13/2024

Apophis' close fly-by to Earth in 2029 will bring a prime opportunity to study its composition, history of similar asteroids, and the effects of a significant gravitational torque on a relatively large body. To study it, a spacecraft will have to estimate its relative position and velocity. Furthermore, if one is to study the disruption of the asteroid's rotation, the Apophis' attitude and angular velocity are also quantities of interest. The estimation of such values needs to be performed using relative sensors, with LiDARs and cameras being prime examples. This thesis presents a navigation strategy that estimates the quantities mentioned, resorting to relative distance and relative direction to the target, alongside the relative direction of unknown features, resorting to a self-initialization method with a simplified model of the asteroid. The solution proposed is based upon the multiplicative extended Kalman filter, a type of filter that separates the states into a nominal and error version, allowing a more convenient handling of attitude representation states. Moreover, the filter can consider parameters, crucial to deal with unobservable measurement biases and dynamic uncertainties, such as the torques exerted by Earth on Apophis. The proposed solution was thoroughly analysed through Monte Carlo simulations, with different filter variants created to compare the solution’s performance. The results are promising, with the proposed solution able to track the Apophis’ attitude and vastly improve the spacecraft's position estimate even if resorting to unknown features.

Authors in the community:

• 

  J

  José António Severino Medeiro

  ist195811

Supervisors of this institution:

• 

  P

  Pedro Tiago Martins Batista

  ist14388

mechanical-engineering - Mechanical engineering

eng - English

Instituto Superior Técnico