of these missions to the results obtained from past missions; and the incompletely articulated links between these missions and the priorities enunciated by the SSE decadal survey and MEPAG.

The committee offers the following recommendations to NASA:

• Recommendation: Include the Mars Long-Lived Lander Network in the mix of options for the 2016 launch opportunity.

• Recommendation: Consider delaying the launch of the Astrobiology Field Laboratory until 2018 to permit an informed decision of its merits and the selection of an appropriate instrument complement in the context of a mature consideration of the results from the Mars Science Laboratory and other prior missions.

• Recommendation: Establish science and technology definition teams for the Astrobiology Field Laboratory, the Mars Science and Telecommunications Orbiter, the Mid Rovers, and the Mars Long-Lived Lander Network as soon as possible to optimize science and mission design in concert with each other. (This model has been employed successfully by the heliospheric community.)

• Recommendation: Devise a strategy to implement the Mars Sample Return mission, and ensure that a program is started at the earliest possible opportunity to develop the technology necessary to enable this mission.

2. Does the revised Mars architecture address the goals of NASA’s Mars Exploration Program and optimize the science return, given the current fiscal posture of the program? The committee finds that it cannot definitively say whether or not the revised Mars architecture addresses the goals of NASA’s Mars Exploration Program because the architecture lacks sufficient detail with respect to the science and the cost to allow a complete evaluation. The various mission options are, as stated above, incompletely defined, and the strategic approach to, and the selection criteria to distinguish among, various mission options are lacking. The presence of Mars Scout missions in the architecture is welcomed because they help to optimize the science return and provide balance. Nevertheless, the Mars architecture as a whole is not optimized, because the importance of foundational strategic elements—for example, research and analysis programs and technology development—is not articulated.

In response to this finding, the committee offers the following recommendations to NASA:

• Recommendation: Develop and articulate criteria for distinguishing between the three options for missions to launch in 2016. Similarly, define a strategy that addresses the short lead time between science results obtained from the Mars Science Laboratory and selection of the mission to fly in 2016.

• Recommendation: Clarify how trade-offs involving mission costs versus science were made for the various launch opportunities to justify the rationale behind the proposed sequence of specific missions and the exclusion of others.

• Recommendation: Maintain the Mars Scouts as entities distinct from the core missions of the Mars Exploration Program. Scout missions should not be restricted by the planning for core missions, and the core missions should not depend on selecting particular types of Scout missions.

• Recommendation: Immediately initiate appropriate technology development activities to support all of the missions considered for the period 2013-2016 and to support the Mars Sample Return mission as soon as possible thereafter.

• Recommendation: Ensure a vigorous research and analysis (R&A) program to maintain the scientific and technical infrastructure and expertise necessary to implement the Mars architecture, and encourage collaboration on international missions.

3. Does the Mars architecture represent a reasonably balanced mission portfolio? The committee finds that in the context of the basic types of missions, the Mars architecture is a reasonably well balanced one: both landed and orbital missions are included in an appropriate mix, given the current state of Mars exploration.