Environmental Engineering Reference
In-Depth Information
communications-margins evaluations, etc. Often the work in question has
been iterative and highly manually intensive. Some progress has been made
toward further automating of at least portions of these tasks, yielding reduced
production costs. It appears at this time to be less significant, from a purely
cost basis, as to whether this functionality is performed onboard or on the
ground.
2.1.12 Science Data Processing/Calibration
Science data processing and calibration have been nearly exclusively a ground
system responsibility for two reasons. First, the low computing power of radia-
tion hardened onboard computers (OBCs) relative to that available in ground
systems has limited the degree to which science data processing can be per-
formed onboard. Second, the science community generally has insisted that all
the science data be brought to the ground. Their position arises from a con-
cern that the data might not be processed as thoroughly onboard as it might
be on the ground, and that the science data users often process the same data
multiple times using different algorithms, calibrations, etc., sometimes years
after the data were originally collected.
Given the science customers' strong views on this subject, independent
of potential future advances in radiation hardened processing capabilities, it
would be ill-advised to devise a mission concept that relies exclusively on such
onboard autonomy features. A more appropriate approach would be to offer
these features as options to users, thereby allowing them to take advantage
of cost-saving opportunities as they deem appropriate. One can envision a
dual scenario where missions not only would send back the raw data for the
science community, but also would process it onboard to permit the exercise of
onboard autonomy through which the spacecraft might spot potential TOOs
and take unplanned science observations without having to wait for possibly
(likely) untimely instructions from ground control.
2.2 Flight Software
Although highly specialized to serve very precise (and often mission-unique)
functions, FSW must simultaneously satisfy a broad range of competing needs.
First, it is the FSW that provides the ground system an interface with the
flight hardware, both engineering and science. Since spacecraft hardware com-
ponents (including SIs) are constantly being upgraded as their technologies
continue to advance, the FSW elements that communicate to the hardware
components must regularly be updated as well. Fortunately, as the interface
with the ground system has largely been standardized, the FSW elements that
communicate to the ground remain largely intact from mission to mission. It is
in fact the ability of the FSW to mask changes in flight hardware input/output
