Q. I know that ship and vessel names are italicized, but what is your criterion for determining what is a ship or vessel? I thought the idea was that the thing could carry people, but I must be wrong, because you set the Phoenix Mars lander in italics in your example. Are artificial satellites such as Sputnik set in italics? How about things like the International Space Station or the James Webb Telescope?
A. For every guideline in CMOS, at some point we have to stop narrowing our criteria and examples and just trust readers to use their own best judgment and record their decisions in their style sheets. Depending on the context, you might want to style gray-area terms consistently with other terms that you confidently styled per CMOS.