Currently known bugs/limitations:

Some browser compatibility issues - see below.
Drag calculations use a constant drag-coefficient though it really changes a bit with speed.
We do not currently do drag for tethers.
Simulations have not been validated against real data or other simulations. Some sanity checks have been done. For example, circular orbits do go in circles. Any help in this area greatly appreciated. Since this is a hobby, and only started in December of 2002, it is not "mature code" like some Fortran code that has been around for 30 years and had many people paid to work on and test it. :-)
Many features that could be added ...

Browser compatibility

The Java applets are not totally portable. If you install a new Internet Explorer or Netscape Navigator it should work. You could also just install the newest versions of the Java JRE.

Tested and working browsers

Netscape 7.01 on Windows NT
Internet Explorer 6.0
Internet Explorer 5.5 with new JRE (Java-2)
Netscape 6.2.1 / Mozilla 5 on Windows NT
Netscape 7.0 on Linux
Konqueror on Red Hat Linux 8.0
Opera 7 - M2
Epiphany 1.0.4 on Linux with Java JDK 1.4
IE with Windows XP, service pack 1, using MS Java VM

Tested and failed browsers

IE that came on Windows95.
WebTV does not support Java

Contact

If you know of any other bugs or compatibility problems please let me know at vince@offshore.ai.