Page 208 - Intro to Space Sciences Spacecraft Applications

Table 8-1 1 Spacecraji Systems 195
Satellite Personality of Generic Systems
Communication Navigation Remote Sensing Planetary
~ __ ___ ____~
Orbit Geosync, Molniya, High Earth Low Earth Circular All Types
LEO C i r c u 1 ar High Eccentric
Geosync
Power Solar Solar Solar Nuclear, Chem.
Solar
Attitude Spinning, 3-Axis 3-Axis 3-Axis, Grav Grad 3-Axis
Data High Low High + Proc Low
Size Moderate to Large Small 500 kg Moderate to Large Small to Moderate
1,000-5,000 kg 1,000-5,000 kg 500-5,000 kg
Mission Data Relay X-Mit Position Collect Info various
Lifetime 8-12 Years 8- 1 2 Years 3-5 Years Years
cost $50-80M $5-30M $50-500M $0.1-5B
Complexity Moderate Low High New Horizons
Lead Time 2 Years 2 Years 4 Years 5 Years

and dissemination ground sites that allow him to best utilize his airborne,
surface, and subsurface assets. Every time you pick up the phone and
make a long-distance call or watch cable TV at home, you become a user
of spacecraft systems.

SPACE SYSTEM EVOLUTION

The space system design process has evolved over the nearly four
decades in which it has been conducted. Table 8-12 provides a historical
perspective of the evolution of spacecraft systems over this period. Early
space systems were small (due to the existing launch vehicle constraints)
single-purpose systems. As launch capabilities increased, so did the size
and complexity of spacecraft designs, and billion-dollar, multimission
spacecraft have been built and launched. Lessons were learned with these
systems when small failures of single systems either decreased the effec-
tiveness of the spacecraft or rendered it totally useless.
Modem spacecraft design uses both multiple-use, modular construction
spacecraft designs with interchangeable systems using more common
(and inexpensive) off-the-shelf equipment and the recent resurgence of
smaller, single-purpose, highly integrated spacecraft that bear the mantle
of SMALLSATs and LIGHTSATs. More and more spacecraft are being