EdX runs a cool course:
Introduction to Aerospace Engineering: Astronautics and Human Spaceflight
The course is presented by MIT Professor Jeffrey Hoffman, a former NASA astronaut who made five spaceflights and the first astronaut to log 1000 hours on the Space Shuttle
He teaches you the core principles behind space travel and exploration. The course will cover how rockets work and learns you some basic calculations about rockets and orbits.
It also teaches, how spacecraft move in orbit, how we create artificial environments inside spacecraft to keep astronauts alive and healthy.
It also discusses, what it’s like living in a world without gravity, how the human body adapts to space, and how spacewalks happen, plus more. Many lessons will be illustrated with Professor Hoffman’s own experiences in space.
The is in it’s second week, but you can still enroll for free. But be quick the due date of the second week questions are due on the 20th of March.
More info course info in this PDF