514 
  
    
   
   
   
    
  
Global Postioning 
System Antenna ^ 
Attitude (2) Omni Antenna 
Control Module 
  
    
S-Band Antenna M 
Thematic Mapper Y 
Wideband Module Band Antenna 
  
Multimission 
Modular me 
Spacecraft 
  
  
  
FIGURE 6. THE LANDSAT-4/5 SPACECRAFT 
The TM instrument is introduced with Landsat-4 ‘and 
incorporates many advances. Its detector array includes 16 
detectors each for six visible and near IR bands (as opposed 
to six detectors for each-of-the.four MSS. bands) pius. four 
detectors in the thermal range. (See Figure 9 for spectral 
band comparisons.) It scans actively in both forward and 
reverse directions and has considerably higher resolution 
(smaller IFQV) than the MSS. Data content for a given TM raw 
data image (approximately 185 x 170 km) in terms of pixels 
alone has increased from 7.6 million, 83 meter, six-bit 
pixels per image for MSS to 36.0 million 30 meter eight-bit 
TM pixels. The impact on image processing system design of 
this increase in data volume and resolution is dramatic. 
Processing challenges and solutions are discussed in later 
sections of this paper. 
The TM on Landsat-5 differs from the Landsat-4 TM 
only in certain detector response calibration values, and 
these differences are minor. 
LANDSAT-5 SPACE SEGMENT ENHANCEMENTS 
Several enhancements were made to the Landsat-5 
Space Segment based on operational experience with 
Landsat-4. These modifications and the conditions which 
prompted them are briefly summarized as follows: 
9 The Landsat-4 high gain antenna boom did not deploy 
from its stowed position due to a blockage condition 
which appeared to be elastic such as tape or pliable 
adhesive. The boom was successfully deployed by 
continuously driving it against the blockage 
boundary. For Landsat-9, a release spring for 
initiating boom deployment was installed. | An antenna