Environmental Engineering Reference
In-Depth Information
comparison with the more common externally controlled constellation, can
have the following advantages:
1.
In locations not reachable in a timely manner through human contact:
(a)
Initiating and/or changing orders automatically.
(b)
Evaluating and summarizing global health status, and therefore,
being able to assess the constellation's ability to conduct a specific
exercise, and further, being able to engage in self-protection and self-
reconfiguration, among other self-
functions to ensure the survival
and viability of the entire constellation.
(c)
Providing summary status of the entire constellation.
∗
2.
On-the-job training or programming:
(a)
Provoking a new mode of behavior on the part of constituent satellites
by observing operators and the environment [
185
].
The role of autonomicity in constellations depends on the needs of the
satellites individually and collectively, and on the needs of mission control.
For example, how robust an autonomic function on any single satellite must
be would depend on such things as the proximity to standard tracking and
telecommunications facilities, the urgency of data and command access by the
ground, and for survey missions, the area of simultaneous coverage needed
by satellites in the constellation. Availability of communication channels is
another factor, whether it be the timing/accessibility and individual chan-
nel bandwidth capacity or, in close formation flying, frequency separation of
channels. Of course, there are various ways of getting around mutual inter-
ference constraints, such as limiting the individual contact events to a single
communications link at a time when in close formation, or by compressing
the bandwidth requirements, as was mentioned previously; a fully networked
inter-spacecraft communications architecture involving multihop packet rout-
ing also represents an alternative approach for some types of mission. But
providing an autonomic function that can address the constraints of a system
given the current situation in a mission provides a much more flexible and
reusable solution than can be solved by single-point solutions.
The autonomicity of constellation governance influences the spacecraft
inter-connectivity design and ground-connectivity design (i.e., human con-
trol) in much the same ways as does the individual satellite's subsystem con-
trol structure. However, the geometry, scale, and desired performance of the
constellation as an integral entity come into play adding additional design
complexity. As a basic consideration, the level of interdependency among con-
stellation members is a factor influenced strongly by mission class, e.g., what
type of payload is being carried.
In certain types of mission (for surveillance, analysis, monitoring, etc.), the
requirements for accuracy and speed of data or event notification are becoming
more demanding. In addition, the resolution requirements for imaging systems
require ever larger apertures, and hence, larger instrument sizes.
