Longevity is the least interesting quality of a re-usable spacecraft. We have six decades' experience keeping spacecraft on long orbital, and even trans-planeta

Longevity is the least interesting quality of a re-usable spacecraft. We have six decades' experience keeping spacecraft on long orbital, and even trans-planetary, flights working. If testing longevity is any significant use of X-37B, that is another way of saying it is useless.