Project Title:

Advanced SiC Pointing and Stabilization Mirror Assembly for GEO

SSG, Inc.
150 Bear Hill Road
Waltham, MA 02154

93-1		08.07	0204			Amount Requested $69,690.00

Advanced SiC Pointing and Stabilization Mirror Assembly for GEO 
Mission

Abstract:

High spatial resolution imagery from geo-stationary orbit places 
uncompromising demands on spacecraft stabilization and optical 
system thermal stability.  GEO requires + 8.80 pointing FOR, 1.25 
urad IFOV (10's of urad accuracy) and < 1 urad (rms) jitter at ~ 10 
Hz rate.  Prior solutions have combined complex and costly 
ACS/IMU/Stellar control of spacecraft jitter with detector 
oversampling and image motion compensation (IMC).  The problem is 
heightened for limited weight MicroSpacecraft sensors with 
increased excitation bandwidth and lack of on-board control 
capability.  Ultra-lightweight, thermally stable silicon carbide 
optics and advanced servo control systems permit large aperture 
pointing and high precision stabilization in one lightweight 
assembly.  The core innovation of combining these technologies 
removes the tight slewing and jitter requirements from the 
spacecraft and IMC from the ground station; complexity, weight and 
cost are dramatically reduced.  This program will develop a 0.5m 
aperture, high precision SiC pointing and stabilization mirror 
assembly including servo control electronics.  Phase I will provide 
the conceptual design and analysis of a prototype unit and a 
hardware demonstration of an advanced 6" x 9" SiC mirror in an 
existing 2 urad pointing system.  The closed back SiC mirror, 
replacing a beryllium mirror, has superior thermal stability, 
stiffness and strength.  Phase II will provide the development and 
test of a flight qualifiable advanced pointing assembly for GEO; a 
wide range of micro-spacecraft such as Quick LAWS and commercial 
remote sensors and imagers are supported.

A wide range of future commercial remote sensing missions require 
high angular performance (large aperture) and precise pointing and 
jitter control at affordable cost; e.g., advanced LANDSAT, GOES.  
The proposed SiC P&S development could revolutionize 
optical/pointer systems to permit the integration of sophisticated, 
large aperture sensors onto low-cost launch vehicles (e.g., Micro-
Spacecraft, PEGASUS, TAURUS) with vastly improved jitter control 
and precision pointing.

Pointing, stabilization, mirror silicon carbide, jitter, space