In the history of spaceflight, almost all spacecraft have been manufactured and
assembled on the ground, then integrated into a launch vehicle for delivery into orbit. This
approach imposes significant limitations on the size, volume, and design of payloads that
can be accommodated within the fairing of a single launch vehicle. In particular, fairing
diameter limitations restrict the size and number of instruments that can be fielded in orbit
for science and national security missions. In turn, these constraints place definite limits
on the information that can be obtained from spaceborne payloads. Design of spacecraft
built on the ground requires all the components of each spacecraft to be hardened
(ruggedized) to withstand the harsh launch environment, which includes severe vibrations,
acoustics, acceleration loads, and thermal loads. The hardening processes impose penalties
in terms of mass and size that ultimately limit payload capabilities and increase launch
costs. These penalties are further compounded by the need for inclusion of redundant
backup systems to provide contingency against damage during launch. Some spacecraft or
components for space cannot be built at all on Earth. Examples include ultra-thin mirrors
and gossamer structures that can be bent or otherwise adversely affected by gravity forces.
Similar and additional constraints limit profitability and flexibility of commercial satellite
operations. Taken as a whole, the range of limitations associated with terrestrial
construction of spacecraft may represent a significant constraint on the design, capabilities,
lifespan, and products of space systems that can be realized.
