As sigstoat said, Kepler is a fairly recent spacecraft. And yeah, it's interesting that they don't treat spacecraft like this as small-batch production runs. Th

As sigstoat said, Kepler is a fairly recent spacecraft. And yeah, it's interesting that they don't treat spacecraft like this as small-batch production runs. The incremental cost of producing 5 Kepler replicas and keeping equipment and processes documented at the time of initial production seems very small compared to doing the same project all over again a decade later. Even if they have to do some major changes, I imagine having a ready to go spacecraft helps. On the flipside, I guess the arguments for componentization apply. If off-the-shelf components are improving all the time, integrating them into a full spacecraft should be getting cheaper and easier over time. What I really wonder about is, given how troublesome and relatively lightweight gyros are, why didn't they have more spares?