André Füzfa (UNamur)

Title: Fundamentals of relativistic astrodynamics and rocketry

Abstract:

Astrodynamics traditionally denotes the study of controlled flight paths of human-made spacecraft (Kaplan, 1976). This term originates from the prehistory of the space age, at a time where only archaic Newtonian dynamics were used for determining interplanetary spaceflights at extremely low velocities (in the km/s range).

After briefly reviewing basic rocketry in this primitive language, we will introduce space cadets to the modern geometric formalism that is now state-of-the-art for interstellar navigation. Relativistic trajectories in curved space-time are described by non-geodesic worldlines of particles submitted to the action of an external four-force. We will show how to use your relativistic inertial guidance system to monitor the evolution of both the rest mass of your starship and the apparent weight inside it, through the space-time orientation of the total four-force. Then, several well-known models of deep space propulsion will be reviewed: Ackeret’s rocket and the relativistic Tsiolkowsky equation, thermal and radiation rockets, Bussard’s ramjet and finally lightsails. We will end the course by two relativistic astrodynamical applications : basic interstellar transfer and ascent trajectories from a compact object.

The seminar will take place in Room S08 at the Faculty of Sciences.