Page 184 - Intro to Space Sciences Spacecraft Applications

Table 8-1 Spacecraft Systems 171
Typical Launch Performance Database for
Pegasus XL Aircraft

Lift Capacity (kg) Inclination (degrees)
Altitude (km) 0 28.5 90 98

200 410 395 295 280
400 390 375 275 260
600 370 355 255 245
800 345 335 240 230
1,000 325 310 225 210
1,200 305 290 205 190
1,400 280 265 190 170
1,600 260 245 175 155
1,800 235 225 155 140
2,000 210 205 135 115
Fairing (L x Diu, m): 1.7, 1.1
Launch Cost ($M):
13
Pegasus data from “Commercial Pegasus Launch System Payload User’s Guide” (Rel. 3.00, I Oct
I993 ).

with each subsystem. The designer has many choices of design architec-
ture, including types of stabilization, solar array architectures, combined
TT&C and data handling functions, and computer control of subsystem
functions. In addition, the design process can select various contemporary
and advanced technologies such as the type of solar cell, battery, or
propulsion fuel, to name a few. Trade-offs can be tried to improve perfor-
mance, to reduce weight and power, or for other considerations until the
designer is satisfied with the result.
The subsystems are ordered in a logical, interdependent progression, as
shown in Figure 8-2. For example, selection of the attitude stabilization
technique (spin, 3-axis, gravity gradient) determines the number of solar
cells that view the sun at any point in time, which has an important influ-
ence on the power subsystem. Selection of the stabilization method will
also have an influence on the thermal design. Spin-stabilized satellites
evenly expose subsystems to hot and cold space, while 3-axis stabilized
satellites can have large thermal gradients caused by specific surfaces
exposed to hot or cold conditions for extended periods of time.