MIT is conducting an online introductory aerospace engineering course through edX. The course began yesterday.
If you want to know more about the physics and mathematics that underlies the 2-line Keplerian element sets that amateurs use to track satellites, the course includes a segment on orbital mechanics. If you have been listening to the ARISS contacts between ISS crew and ground stations, you may have heard astronauts/cosmonauts make reference to spacewalks and the effects of microgravity. Dr. Kate Rubins indicated in her recent ARISS contact with The Children's Museum in Indianapolis that the spacewalk was the most difficult aspect of time on the station. These topics and other are covered in the course which is taught by former NASA astronaut Dr. Jeffrey Hoffman.
More information is available here:
https://www.edx.org/course/introduction-aerospace-engineering-mitx-16-00x-0#...
Todd AL0I