Sadly, most interesting stuff is not open-source. No loss though, I think most of this would be out of scope in Orbiter anyway.
JavaGenes looks like a nicer implementation of the genetic algorithm I use for optimization problems. In the NASA version, you could use it for solving graphical problems, for example placement of instruments in a VC design.
I am sure, some here in the forum could have fun with the Autonomous eXplorer Control System.
The Input Device Framework could be interesting for Orbiter itself... not sure if martins could use it though.
JAT could be interesting if you want to create NASA tools for planning trajectories.
Not sure if OpenMCT could be used for creating mission control software for Orbiter. Its open-source and sounds extensible, but its probably too fat for us.
ut-assert could be one alternative to GoogleTest or CUnit, but I don't think it will make any here happier than the two more common C/C++ test frameworks.
GMAT is already known here, but integrating it better into Orbiter takes a lot more effort.
OpenSPIFE could maybe be interesting for some home projects here, but I don't see much use in Orbiter now.
Maybe some add-on developers could like the Vehicle Sketchpad for initial designs.
EUROPA could be interesting for some projects, I think it won't be used often.
The Core Flight System stuff could maybe be reduced into a simulated avionics runtime environment, but I think it is too fat for 99% of the projects.
MSC-25615-1 could be interesting for the SLS and Orion add-on ... No, just kidding, its not open-source.
JPF is another Java tool that could be interesting for some here. But it isn't without non-NASA alternatives in quality assurance.
The NASA Vision Workbench could again be interesting for some hobby projects, but clearly out of scope for Orbiter.
The Evolutionary Mission Trajectory Generator could be a
great tool for Orbiter, no idea why it ended up in the chapter aeronautics.
http://opensource.gsfc.nasa.gov/projects/emtg/index.php
