# Fundamentals of Astronautics

A lecture series exploring the basic topics of space travel.

## Orbital Mechanics

Fundamental equations of motion ; the two-body problem ; Keplerian elliptic and hyperbolic trajectories ; Hohmann transfers ; changes of inclination and apsides ; the three-body problem ; restricted solutions ; the Lagrange equilibrium points.

(Tuesday, 17 November 2015, 8 PM)

## Space Propulsion

The rocket equation ; solid and liquid chemical propellants ; nuclear thermal rockets ; ion rockets ; nuclear pulse propulsion ; photon rockets ; lightsails and beamed-energy propulsion.

The rocket presents a paradox, because the exponential relation between the ratios of initial and final masses, and those of exhaust and mission velocities, means that a reasonable spacecraft requires a very high exhaust velocity ; but the relation between momentum and kinetic energy means that energy consumption per unit impulse rises rises as the square of the exhaust velocity.

In the limiting case of a photon rocket, we find the following result :

Newton's relation, F = d/dt (mv)

Einstein's relation, E = mc_{0}^{2}

As v = c_{0} in this case, mv = E / c_{0}

Recognizing that c_{0} is a constant, and that dE/dt is power, we find that

F = P / c_{0}

And each newton of thrust requires three hundred megawatts of power.

(Tuesday, 1 December 2015, 8 PM)

## Our Solar System

A tour of the planets and moons, with an emphasis on reaching them from Earth.

(Saturday, 21 November 2015, 6 PM)