International Telemetering Conference Proceedings / October 27-30, 1997 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Lunar Prospector’s project engineering staff selected a Windows PC platform as the RF test console for the Lunar Prospector spacecraft. The spacecraft test team chose the PCbased RF test console because the PC provides a low-cost, common platform with a graphical user interface. The PC provides point-and-click, menu-driven windows that are common throughout the satellite factory. The PC RF test console is being used to exercise the Lunar Prospector spacecraft RF link for RF commanding, telemetry, and ranging signals during factory test, including thermal vacuum chamber testing. For spacecraft command and control at the factory, the PC-based RF test console is networked to a UNIX workstation over RS-422. The PC RF test console and spacecraft interface are controlled through a coax switch residing in a test rack next to the workstation. The PC RF test console is connected directly to the Lunar Prospector spacecraft using coax cable through the spacecraft Telemetry, Commanding, & Ranging (TC&R) RF antenna hat for both transmit and receive functions. The PC RF test console is also connected hard-line to the spacecraft transponder through the transponder RS-422 connection. This connection provides the ability for spacecraft telemetry to be received at the PC at RF or baseband. The same hard-line spacecraft telemetry data is provided to the UNIX workstation for comparison. NASA’s Lunar Prospector project is the first of the Discovery series of “faster, better, cheaper” missions to be competitively awarded. Lunar Prospector project funding was capped by NASA to ensure that no overruns would occur. The mission was funded to support the scientific community’s desire to verify the presence of ice on the moon and collect environmental data to understand the dynamics that may have led to polar ice deposits. The Lunar Prospector mission received funding in 1996 with a launch planned for September 1997

International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Upgrading or replacing production systems is always a very resource-consuming task, in particular if the systems being replaced are quite specialized, such as those serving any Flight Test Ground Station. In the recent past a large number of Ground Station systems were based in Digital’s VAX/VMS architecture. The computer industry then expanded very fast and by 1990 realtime PCM data processing systems totally dependent on hardware and software designed for IBM-PC compatible micro-computers were becoming available. A complete system replacement in a typical Ground Station can take from one to several years to become a reality. It depends on how complex the original system is, how complex the resulting system needs to be, how much resources are available to support the operation, how soon the organization needs it, etc. This paper intends to review the main concerns encountered during the replacement of a typical VAX/VMS-based by an Intel-Windows NT-based Ground Station. It covers the transition from original requirements to totally new requirements, from mini-computers to micro-computers, from DMA to high-speed LAN data transfers, while conserving some key architectural features. This 8-month development effort will expand EMBRAER’s capability in acquiring, processing and archiving PCM data in the next few years at a lower cost, while preserving compatibility with old legacy flight test data.

Attitude and position determination systems in satellites are absolutely necessary to keep the desired trajectory. A very accurate, reliable and most used sensor for attitude determination is the star tracker, which orient itself in space by observing and comparing star constellations with known star patterns. For on earth tests of movements and docking maneuvers of spacecrafts, the new Spacecraft Maneuvering and Docking (SMD) facility at the chair of Aerospace Information Technology at the University of Würzburg has been built. Air bearing systems on the space ve- hicles help to create micro gravity environment on a smooth surface and simulate an artificial space-like surrounding. A new star tracker based optical sensor for indoor application need to be developed in order to get the attitude and position of the vehicles. The main objective of this thesis is to research on feasible star tracking algorithms for the SMD facility first and later to implement a star detection software framework with new developed voting methods to give the star tracker system its fully autonomous function of attitude determination and position tracking. Furthermore, together with image processing techniques, the software framework is embedded into a controller board. This thesis proposes also a wireless network system for the facility, where all the devices on the vehicles can uniquely communicate within the same network and a devel- opment of a ground station to monitor the star tracker process has also been introduced. Multiple test results with different scenarios on position tracking and attitude determination, discussions and suggestions on improvements complete the entire thesis work.