When is a satellite not a toaster? [satellite repair costs]

It is pointed out that automobiles are typically repaired, but inexpensive appliances are discarded at the first sign of trouble: they `cost too much to fix.´ Comparing $50 M satellites with toasters may seem odd, but the analogy can be appropriate. It is suggested that the too-much-to-fix argument can be used in deciding whether to replace or to repair satellites. The authors investigate when cost considerations dictate using constellations of expendable satellites to be routinely replaced and discarded on failure, and when circumstances indicate using constellations of satellites to be repaired on-orbit by exchanging failed modules