In the years since publication of the NRC’s 1997 report Mars Sample Return: Issues and Recommendations,²² there have been numerous proposals for alternative approaches to handling sample return. For example, there has been debate about whether there should be multiple sample-receiving laboratories, rather than a single SRF; the advisability of transporting pristine subsamples to facilities outside the SRF to use special instruments or expertise for testing and sample characterization (see Chapter 6); and whether to site the SRF at a NASA center or in association with an existing BSL-4 containment facility. Discussions have also continued about the requirement to maintain all samples in containment until a full battery of biohazard tests have been completed—and how to accommodate the transport of sample materials to facilities outside the SRF for analysis using specialized instruments. In addition, prospects for international mission partnerships and shared responsibilities for the testing of returned materials have further complicated these discussions.

Clearly, a detailed discussion of these and other issues is beyond the scope of the present report. Suffice it to say that whatever decisions are made about containment and handling, the following planetary protection objectives should be given priority for implementation:

• Maintain the prescribed and appropriate levels of containment for pristine sample materials until a requisite battery of rigorous tests have been completed; and