Cannon Java applet http://www.phys.virginia.edu/classes/109N/more_stuff/Applets/newt/applet.html
From Fowler's Physics Applets http://www.phys.virginia.edu/classes/109N/more_stuff/Applets/home.html
These applets can be run on-line or can be downloaded for use on a Windows PC. This site also has a link to a lecture about the history of Newton's discoveries about gravity, and how an orbit works based on Newtonian physics.
the World http://wwwssl.msfc.nasa.gov/msl1/ground_lab/aroundtheworld.htm
From NASA's Marshall Space Flight Center.
Satellites Using the Internet http://solar.physics.montana.edu/YPOP/Classroom/Lessons/Orbits/
From the Yohkoh Mission Education and Outreach.
Introduces the concepts of orbital period, altitude; is partly based on the use of algebra
Satellites Work http://octopus.gma.org/surfing/satellites/index.html
From the Gulf of Maine Aquarium. Makes use of satellite tracking software, has a nice Orbit Model lesson which can be easily be adapted to the RHESSI mission by using an altitude of 600 km for the orbit, a launching lesson based on Newton’s cannon, and a hands-on lesson about the forces in an orbit.
Simulation Java Applet http://www.mcasco.com/p1aso.html
From M. Casco and Associates. An excellent applet that students can use to learn about the properties of satellite orbits, and the difficulties of getting an object into a stable orbit.