The SeaWiFS subsystem can best be accom- 
modated by the spacecraft system if it is designed 
to utilize the smallest possible amount of the 
growth-weight allocation and does not signifi- 
cantly increase the demand for critical power 
subsystem resources. This goal will be achieved 
best if the data-processing requirements on the 
spacecraft and ground segments are integrated. 
A more detailed System Integration Study is being 
conducted by EOSAT to better integrate the Sea- 
WiFS and the ETM data requirements and to de- 
termine optimal ways of accommodating SeaWiFS 
on Landsat-6. 
Required Modifications to the 
Landsat-6 Spacecraft for Integra- 
tion of SeaWiFS 
Although the baseline for the SeaWiFS equip- 
ment is still being developed at this time, NASA/ 
GSFC has proposed a potential configuration for 
it. Figure 24 shows the block diagram for this 
configuration. 
It is assumed that the SeaWiFS scan motor 
will be running continuously. However, the in- 
Figure 24. 
Block dia- 
gram of pro- 
posed con- 
figuration of 
the Sea- 
WiFS on the 
Landsat-6 
spacecraft. 
SEAWIFS 
SENSOR 
"MIRP" 
SEAWIFS 
ELECTRONICS 
+ ENCODED 
40 MINUTES DAY- 
LIGHT PORTION/ 
ORBIT 
(4 KM) 
* HRPT FORMAT 
665 KBPS 
strument will take data only during the 40 minutes 
per orbit when useable data can be acquired 
and will provide recorded data and real-time data 
transmission. During the instrument's operating 
phase, the sensor, data formatter, and signal 
switching unit will be operating, as well as record- 
ing units for global area coverage data and one 
S-Band or UHF transmitter. Other tape recor- 
ders will be used for up to 10 minutes during the 
40 minutes of data-taking on each orbit to record 
high-resolution data. After the data are collect- 
ed, the recorded information will be transmitted to 
an EOSAT ground receiving station and then re- 
layed to the NASA ground-processing facility. In 
the recorder playback mode, the signal switching 
unit, one recorder unit, and one S-band transmit- 
ter will be operating. SeaWiFS equipment and 
their key features are listed in Table 12. 
The projected total subsystem weight of 153 
pounds is well within the 360 pounds available for 
growth in the currently proposed spacecraft. 
Hence, the spacecraft can support the SeaWiFS 
mission and might also be able to satisfy an 
EOSAT goal of adding a third, spare wideband re- 
corder weighing 157 pounds. 
TAPE TAPE 
RECORDER RECORDER 
IMPLEMENTATION PANEL 
57 
