http://www.eecs.case.edu/laboratory/nasa-iip/software.html

Satellite/Planetary Analysis and Visualization

Link	Description
STK	Satellite Tool Kit (STK), by AGI, is an impressive suite of commercial software tools with many space applications, such as: orbit propagation, mission analysis and more.
SaVi	SaVi is open-source software for satellite constellation visualization.
Celestia	Celestia: A 3D Space Simulator

Network Emulation

Link	Description
ONE	“ONE (the Ohio Network Emulator) is a tool that enables researchers to emulate a network between a pair of interfaces on a single Solaris-based workstation.”
Emulab	Emulab is a network emulation testbed at the University of Utah
NET	The Network Emulation Testbed (NET) at the University of Stuttgart, Germany provides an emulation testbed for the testing of protocols. The NETShaper emulator resources are here as well.

Network Simulation

Link	Description
ns-2	ns-2 is a discrete event simulator for computer networking research. ns-2 is free, open-source software. Hosted at Information Sciences Institute at USC.
OPNET	OPNET Technologies produces commerical software called OPNET for network modeling and simulation. We are participating in OPNET's University program. Here is a web page describing our work with OPNET.
OMNeT++	OMNeT++ is a public-source simulation environment with primary application to the simulation of communication networks.
QualNet	Scalable Network Technologies develops the QualNet network simulation commercial software.