Before a robotic spacecraft launches to another planet seeking evidence of life, mission planners must establish a clear and direct relationship between the types of measurements needed to achieve the mission goal(s), the instrumentation required to perform those measurements, and the type and quantity of data that must be obtained. For example, the difference between ancient and presently living life may require focusing the search on (at least some) significantly different molecular markers. Such markers might in general, though not universally, be expected to be found in different locations for ancient vs. existing life. While these situations have not been treated as distinct within the LDKB, a mission planner should consider how their goals and objectives, along with practical limits on what is detectable, should drive the particular types and families of molecular markers being searched for as the “best set” in order to attain a given science goal or to prove/disprove a particular hypothesis regarding the existence of extraterrestrial life.

In robotic spaceflight projects, the increasing detail in the requirement flow-down, from goals to data, is captured in the form of a science traceability matrix (STM) [1]. The STM is a required NASA proposal element that shows how science goals and objectives “trace” (flow down) to instrument and mission requirements. The STM is pivotal to proposal success because it answers the questions:

Does the science address NASA goals?
Does the investigation address the science?
Does the instrument/mission implement the investigation robustly?

The Science Traceability Tool has been developed to help with the initial stages of design and construction of a STM for life detection missions. The tool is not intended to generate a final, competition-ready STM, which typically requires months of iterations, but to help understand how an STM is built and to help visualize how different life detection strategies may be captured in a science traceability format. The contents prescribed by the Science Traceability Tool are intended for guidance purposes only. The final wording and information presented in the different sections of the STM are the responsibility of the mission team. For example, Science Objectives may be defined more broadly or more specifically than prescribed by the Science Traceability Tool. Examples of variations are available in the Europa Lander and Enceladus Orbilander mission concept study reports. The initial contents of the STM generated with this tool can be exported as ‘.csv’ files so they can be further developed and optimized with a spreadsheet editor.

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