56 
Spacecraft Integration 
Spacecraft Configuration 
The current spacecraft configuration into 
which the SeaWiFS sensor would be integrated, 
differs from the original Landsat-6 spacecraft 
configuration due to programmatic changes and 
changes in the launch vehicle; the baseline 
launch vehicle is now expected to be a Titan Il. 
The concept is derived from a DMSP/TIROS-type 
system, but it has been extended to meet the 
Table 11. 
Capacity: 
Orbit: 
Power: 
Batteries: 
Solar array: 156 sq ft 
150 A-hr capacity 
Sun-oriented array 
needs of the EOSAT mission and will change the 
spacecraft's flight orientation; the Titan II thrust 
axis (spacecraft long axis) is now the roll axis of 
the spacecraft and is perpendicular to the local 
vertical and in the plane of the orbit. Table 11 
tabulates the key performance features of this 
spacecraft. 
The design concept utilizes equipment that is 
currently under NOAA contract for the STS ver- 
sion of the Landsat-6 spacecraft, combined with 
the latest versions of the DMSP S-15 program 
hardware. 
Spacecraft Characteristics, Exclusive of Payload 
6000 pounds including the apogee kick motor 
Sun synchronous, 98.2° inclination; 705 km altitude 
28V regulated power bus 
1310W EOL array power to the load 
1140W peak power at night 
Attitude: 
Star-referenced inertial guidance 
0.01° about all axes 
Magnetic torquers and reaction wheels for attitude control 
Propulsion: 
Thiokol Star 37 XFP solid motor 
Hydrazine engines: 100 lbs and 0.5 Ib 
Cold gas control system 
Hydrazine orbit adjust subsystem 
Thermal: 
Communications: 
Louvers and heaters combined with thermal blankets 
X-Band System for the ETM mission data with three 
transmitters redundantly multiplexed to high-gain 
steerable antennas, S-Band command, telemetry, and 
ranging on an omnidirectional antenna 
Command Telemetry: 
Command and telemetry subsystem derived from the 
DMSP system of hardware in conjunction with Landsat 
units where appropriate. 
