LEO - A Highly Configurable Orbital Display Program

Chris Peat
Chris.Peat@dlr.de
Cray Systems Limited (Space and Defence Division),


Abstract:
LEO is a highly configurable program which provides a real-time 
display of spacecraft orbital data. It was originally developed to 
serve as a control room "big screen" display, but its field of 
application has now spread much wider to include simulation, 
education and general hobby interest. This has been possible because 
the software runs under Microsoft Windows (3.1 or later), is highly 
interactive, and has only modest hardware requirements.

The program is based on a number of different types of display window, 
showing graphical representations of spacecraft orbital positions 
and data in alphanumeric form. The user can select which types of 
window are to be displayed and their size and position on the screen. 
Spacecraft are represented as icons which can be created and edited 
using any standard editor. As well as showing the spacecraft orbital 
position and many additional orbital parameters, ground station 
visibility information is also computed and shown in a variety of 
ways.

As well as functioning as a stand-alone program, LEO components can also 
be easily integrated into other software products. This is 
facilitated by LEO's architecture which is based on the modern 
technology of OLE Controls (OCX's). These are component objects at 
the binary level, which means that they can be manipulated and used 
by other software regardless of what language it is written in.

The program is currently being used operationally at both the 
European and German Space Operations Centres. The paper will describe
the current version of the software in detail, and will provide 
colour screen dumps, architectural diagrams 
and a brief mention of planned future developments. A working 
demonstration of the program will also be provided.