The GOES (Geostationary Operational Environmental Satellite) system is the high altitude U.S. civilian weather satellite system, nominally comprised of an East spacecraft over the Atlantic and a West spacecraft over the eastern Pacific. GOES-13, the first of the Boeing GOES N-P series, was launched in May, 2006 from Cape Canaveral, Florida. Post-Launch Testing (PLT), executed by NASA with the support of the Boeing team, occurred from June, 2006 through GOES-13 acceptance in December, 2006. The GOES N-P series delivers improved Image Navigation and Registration (INR) performance compared to that of the previous generation. This paper describes the GOES-13 INR verification process from conceptualization through system acceptance and demonstrates the improved INR capabilities of GOES-13 that will ultimately benefit end users.

PLT preparation and execution presented formidable technical challenges. Unique analytical tools and techniques were developed for calibrating and measuring on-orbit performance of instruments and new spacecraft precision pointing technologies introduced on GOES N-P. Ground system improvements included the addition of supporting services throughout eclipse, enhanced propulsion modeling, eclipse modeling, and improvements to the Image Motion Compensation (IMC) implementation. New performance assessment statistical tools were developed for interpreting measured INR system performance during the specification testing period. PLT and system acceptance was initiated by design verification with an end-to-end high fidelity simulator, the Performance Evaluation System (PES), and a closed-loop end-to-end INR System Functional Test (SFT). PES and SFT facilitated the evolution of the INR operational concept and the PLT process.

PLT was divided into two principal phases: the bus/payload Activation & Calibration (ACT) phase and the Systems Performance and Operations Testing (SPOT) phase. The ACT phase was 30 days long, commencing with spacecraft engineering handover and ending with Imager and Sounder cooler cover deployments. The SPOT phase was approximately 150 days and ended with the in-orbit acceptance of GOES-13. Key ACT phase testing and calibration included Stellar Inertial Attitude Determination (SIAD) alignment and Dynamic Motion Compensation (DMC) filter calibration. SPOT focused on INR operations and testing and included INR startup and calibration, INR normal mode specification testing, imaging during eclipse, yaw flip operations and system preparation and performance before and after all thruster maneuver operations.

The GOES N-P INR system design represents an evolution of the INR architecture and an infusion of advanced spacecraft pointing technology. Specified improvements for the N-P series include tighter navigation and frame-frame registration requirements. The important innovations for GOES N-P include:

• Stellar Inertial Attitude Determination

• Optical Bench

• IMC Implementation Improvements

• Closed-Loop DMC

• Accommodation of Thruster Maneuvers

• Eclipse and Yaw Flip Operations

The paper surveys these features, their verification through PLT, and their performance benefits to the meteorological community. It will also demonstrate the improvements in navigation from four to six km on GOES-12 to less than two km GOES-13, as a basis for improved weather predictions, ice flow measurements and other meteorological events. INR improvement from GOES-12 to GOES-13 is vividly seen in side-by-side movie loops.