The success of all missions is ultimately critically dependent on an end-to-end partnership between the science team and the engineering team to ensure that an iterative process emerges that continuously balances all of a mission’s constraints, both technical and programmatic. Instead of a process that starts with gathering science requirements and then determining the resulting cost of a derived mission, those with science, engineering, systems engineering, and cost expertise should all be involved from the beginning. By understanding the source of various requirements, their relative priorities, and the consequences of designing to satisfy the requirements, engineers are better able to push back if incremental science requirements will drive up a mission design’s cost or risk, identifying the “knees in the curves,” and interacting with the science stakeholder community in a productive and iterative fashion toward development of a truly optimized design.9 By fully sensitizing all involved to the factors associated with implementing and costing a mission, this interaction can help minimize the “sticker shock” associated with individual missions when they are handed off from the broader science community to the mission implementers.
Early establishment of cost and schedule constraints would allow an iterative process to emerge that could continuously balance all of the mission constraints within a known and achievable funding envelope, leading to a more robust yet affordable implementation. This way, the team can be focused on maximizing science return on investment rather than attempting to craft a “perfect” yet unaffordable mission. The committee found that process transparency is essential to ensure that the implementation of the decadal survey is regarded as a community-driven effort and not one driven by local or vested interests, and thus offers the following recommendation:
• NASA’s Earth Science Division (ESD) should implement its missions via a cost-constrained approach, requiring that cost partially or fully constrain the scope of each mission such that realistic science and applications objectives can be accomplished within a reasonable and achievable future budget scenario.
Further, recognizing that survey-derived cost estimates are by necessity very approximate and that subsequent, more detailed analyses may determine that all of the desired science objectives of a particular mission cannot be achieved at the estimated cost,
• NASA’s ESD should interpret the 2007 decadal survey’s estimates of mission costs as an expression of the relative level of investment that the survey’s authoring committee believed appropriate to advance the intended science and should apportion funds accordingly, even if all desired science objectives for the mission might not be achieved.
To coordinate decisions regarding mission technical capabilities, cost, and schedule in the context of overarching Earth system science and applications objectives, the committee also recommends that
• NASA’s ESD should establish a cross-mission Earth system science and engineering team to advise NASA on execution of the broad suite of decadal survey missions within the interdisciplinary context advocated by the decadal survey. The advisory team would assist NASA in coordinating
9End-to-end system simulations performed prior to Preliminary Design Review can help to quantitatively identify the cost/benefit ratios for the baseline design, as well as a range of alternatives.