CAST 2019

Systems designed to be operated in space have a few unique problems to must be addressed.
First, they cost a large amount of money. A “black box”, or in other words, a unit that performs a specific
task and is part of a larger system, can range up to several million dollars for one. Considering that
redundancy is used to increase the reliability of space systems, these costs can easily double. A small
communications satellite, which includes many units, runs into the tens of millions of dollars. A more
complicated satellite, such a radar imaging satellite can cost a few hundred million dollars. A constellation
of satellites, such as those proposed for worldwide communications are in the range of a few billion
dollars. This is just the cost of the hardware that is in space. Hidden costs include development and
qualification, launch costs, and operation costs. Worse yet, you cannot go up there and fix it if things
break.
These reasons alone is enough to justify a rigorous design, build and test philosophy. This
lecture will expand on these ideas, but concentrate on the testing aspects. Verification and testing is
different for manned systems compared to unmanned systems. Human life is precious, so manned
systems undergo more stringent testing. This lecture will concentrate on unmanned systems, and how
they are verified and tested. Specifying how one will verify and test starts from the top down.
However, during the build process, testing is done from the bottom up. What is being tested and
verified varies with each level of integration. These differences will be explained. Specific examples of
testing and verification at the different levels will be shown.