AAWSAP DIRD, Laser Lightcraft Nanosatellites, November 2010

Text

This text came with the file. It may have mistakes. When the text and the image disagree, the image is right.

UNCLASSIFIED/,'rOR: orrlCIAL USE O14Lf
that has runways of reasonable length. An air-launched Lightcraft launch vehicle
mission, involving the transport of lasers and Lightcraft on medium-sized bombers or
transport aircraft, is also recommended if additional funding would become available.
FUTURE NANO-/PICO-SATELLITE MISSION CONCEPTS
Coherently cooperating "swarms" are a novel innovation for replacing structures with
information by placing many formation-flown small satellites into a loose "swarm" and
cause them to cooperate coherently. This is very different from the so-called
distributed small satellite LEO constellations currently pursued in which individual small
spacecraft perform essentially the same functions as larger satellites but at lower
spacecraft mass (or weight) and cost. These smaller spacecraft can be proliferated to
provide greater geographical coverage for the same cost. The lower mass also saves
launch costs, so the total system costs less for the same function performed with larger
spacecraft.
In contrast, the swarms, as described in the following sections, cooperate coherently
and form a real distributed system in which the whole is more than the sum of the
parts. A generic description would be a constellation of small spacecraft each
performing its separate function, but these functions combine to create at a central
location a much larger virtual spacecraft, or sensor aperture, that exists solely because
of the cooperation of the spacecraft. The following sections provide several examples
of the implementation of such systems in which each of a large number of small
satellites in a swarm or other constellation will radiate or receive signals and combine
them in phase, or coherently, regardless of their actual location in orbit. This creates
coherent RF or optical apertures that are essentially unlimited in size.
Each satellite's position is only crudely station kept, and the satellites adjust the time
delay or phase delay of the signals they repeat to compensate for their position errors,
causing their repeated signals to add coherently at a collection point. This technique
can be easily applied to RF transmitters and receivers, and with more demanding
accuracy to optical transmitters and receivers. The result in either case is a large
"swarm" or loose constellation of satellites that act as one large antenna or optical
array, even though they are separate and their positions are neither constant nor lie
along a parabola or plane in space. The individual satellites can be as simple as one­
element flying chips or as complex as today's self-contained sensing spacecraft of
various sizes.
The advantage of coherently cooperating distributed systems is that they can form
sparse RF antennas and optica l sensors with diameters so large that they would be
impossible to implement with filled apertures even if formed with adaptive membranes;
and have orders of magnitude smaller mass. The relative locations of individual
spacecraft in the swarm can be controlled by MEMS FEEP propulsion, tethers, or by
cleverly conceived orbits in which the elements of the array appear to orbit a common
center within it, thus eliminating the need to use propulsion at least for first order
station keeping.
UNCLASSIFIED,<,<FOA QFFISIAL HSI!! 8HLY
36