Validation (not just verification) of deep space missions

Verification & validation (V&V) is a widely recognized and critical systems engineering function. However, the often used definition "verification proves the design is right; validation proves it is the right design" is rather vague. And while verification is a reasonably well standardized systems engineering process, validation is a far more abstract concept and the rigor and scope applied to it varies widely between organizations and individuals. This is reflected in the findings in recent mishap reports for several NASA missions, in which shortfalls in validation (not just verification) were cited as root- or contributing-factors in catastrophic mission loss. Furthermore, although there is strong agreement in the community that test is the preferred method for V&V, many people equate "V&V" with "test", such that analysis and modeling aren\´t given comparable attention. Another strong motivator is a realization that the rapid growth in complexity of deep-space missions (particularly planetary landers and space observatories given their inherent unknowns) is placing greater demands on systems engineers to "get it right" with validation