Opportunities in Micro-and Nanotechnologies - Implications of Emerging Micro-and Nanotechnologies - page 186

Space Vehicles and Systems

The miniaturization of systems enabled by micro- and nanotechnologies
while maintaining or increasing capabilities provides an important opportunity
for space systems. These advances will enable satellites to carry out more func-
tions consistent with increased information superiority and to employ lighter
vehicles or arrays of satellites, providing new options for launch vehicles and for
distributed sensing or communications from space. Because of their reduced
weight and cost, nano- or picosatellites may enable new functions (see Box 6-1
for a current example).
At the same time, adopting the manufacturing advances pioneered in the
microelectronics industry—batch processing and increased quality control—
along with anticipated future advances in nanotechnologies such as self-repair
and reconfigurability will significantly expand the range of possible applications.
Low-power systems in combination with more efficient space power and energy
storage systems will enable long lifetimes. Future ultrahigh-resolution sensor
systems will be enabled by microarray technology for imaging sensors, on-board
digital image processing, and wide band communications. Large arrays, made
possible by miniaturization and the associated reduced weight and cost, and
phased arrays will enable continuous surveillance. The ability to monitor with
high spatial resolution over essentially all wavelengths will allow truly realizing
continuous total information systems. Specific areas suggested for further con-
sideration are distributed satellites, integrated spacecraft, and micro-launch ve-
hicles.

Distributed Satellites (Medium to Long Term)

Two or more satellites with suitable coherent signal combining can have the
resolving power of a much larger spacecraft. The angular resolving capability is
roughly equal to is wavelength (about 0.5 micrometers for visible

light and anywhere from millimeters to a meter for radio frequencies) and D is the
separation between spacecraft. Distributed spacecraft are the only practical way
to generate milliradian-wide beam widths in space at UHF frequencies (300-
1,000 MHz); the required kilometer-scale antenna diameters are impossible using
a single antenna structure. Possible applications include battlefield cellular com-
munications systems, where the cells are generated by extremely narrow spot
beams from satellites, and geolocation of UHF jammers. Geolocation can be
accomplished using two spacecraft, while synthesis of a narrow beam antenna for
communications will require hundreds of individual spacecraft swarms in a sparse
aperture array. Mass-produced micro-, nano-, and picosatellites with orbit and
attitude control capability make the latter scenario possible. The key technology
development that is still needed for such arrays to work is handling the phase of
the signal from this multitude of separate transmitters and receivers. Technology

λ / D , where λ