Autonomous Spacecraft in Asteroid Missions

Abstract

Autonomy in space applications has gained progressive attention. A great motivation is in using space for economic purposes. Asteroid missions do not escape that trend, especially when considering the economic motivations such as asteroid mining. However, whether it is for mining asteroids or increasing the capabilities of science missions, much still needs to be done for the complete autonomy of these missions. Asteroids are known to exert a small gravitational force due to their small size, making the effect of perturbations even more drastic, leading to impact or escape if not well handled. Moreover, an asteroid's environment is often little known before the spacecraft's arrival, with enormous uncertainties in shape and mass. Thus, it constitutes a highly challenging environment for the operation of a spacecraft. For that reason, missions to these bodies tend to be very conservative, taking months of pre-characterization before they begin to carry out the mission for which they were intended. This study intends to make an integrated analysis of the guidance, navigation, and control of spacecraft that have the purpose of operating autonomously about asteroids. To do so, it builds on previous studies that showed that an autonomous and bold operation on an asteroid is possible within current technology. At first, it is intended to elaborate new guidance and control laws that benefit from the action of disturbances instead of canceling them. These laws are verified to work in simulations that consider the actual asteroid environment. Measurements and their uncertainties are also modeled to obtain a navigation solution. In a second part of the work, more reliable algorithms linked to autonomous navigation, such as optical navigation and on-board reconstruction of the asteroid's shape, are developed and implemented to show that the proposal is robust.