Session
Technical Session VIII: Attitude Control Technologies
Abstract
This paper presents the Attitude Control System (ACS) design for the Wide-Field Infrared Explorer (WIRE) mission. The WIRE spacecraft, the fifth in the series of NASA Small Explorer (SMEX) spacecraft, is currently scheduled for launch in September 1998. WIRE is a momentum-biased, three-axis stabilized stellar pointer which must meet a radial pointing stability requirement of 6 arcsecond. The spacecraft will slew to a new target 8 to 10 times per orbit, and perform small (approximately 1 arc-minute) offset maneuvers every 48 seconds while on a target. As a means of providing the most science for the cost, the third SMEX spacecraft was used as the baseline in the development of the WIRE ACS subsystem. Key drivers forcing modifications to this design are the short mission duration and the instrument sun and earth avoidance constraints. The WIRE attitude control system implements a hierarchy of modes where the "higher" modes are of increasing complexity and accuracy. These ACS modes are utilized in conjunction with fault detection and handling logic to autonomously insure the safety of the instrument and spacecraft. The WIRE ACS will provide high pointing accuracy capability, robust maneuvering, and autonomous safing packaged in a small, low cost spacecraft.
The Attitude Control System Design for the Wide-Field Infrared Explorer Mission
This paper presents the Attitude Control System (ACS) design for the Wide-Field Infrared Explorer (WIRE) mission. The WIRE spacecraft, the fifth in the series of NASA Small Explorer (SMEX) spacecraft, is currently scheduled for launch in September 1998. WIRE is a momentum-biased, three-axis stabilized stellar pointer which must meet a radial pointing stability requirement of 6 arcsecond. The spacecraft will slew to a new target 8 to 10 times per orbit, and perform small (approximately 1 arc-minute) offset maneuvers every 48 seconds while on a target. As a means of providing the most science for the cost, the third SMEX spacecraft was used as the baseline in the development of the WIRE ACS subsystem. Key drivers forcing modifications to this design are the short mission duration and the instrument sun and earth avoidance constraints. The WIRE attitude control system implements a hierarchy of modes where the "higher" modes are of increasing complexity and accuracy. These ACS modes are utilized in conjunction with fault detection and handling logic to autonomously insure the safety of the instrument and spacecraft. The WIRE ACS will provide high pointing accuracy capability, robust maneuvering, and autonomous safing packaged in a small, low cost spacecraft.
