International peer review of MoonLite

The NASA-BNSC Joint Working Group (JWG) identified the Moon Lightweight Interior and Telecoms Experiment (MoonLITE) mission as an important element of potential collaboration between these two space agencies. Subsequently a six member MoonLITE international peer review committee (the Panel) was formed to evaluate the science merits of this proposed mission and to provide advice on several aspects of the mission.

A pre-phase A "Preliminary Science and Payload Definition Document (SPDD)" was prepared and distributed to the panel along with abstracts of science presentations presented at the 2008 LPSC in Houston and the JWG report on lunar cooperation.

The Panel met with the MoonLITE pre-phase A team in London July 9, 2008 for a very full day of presentations and discussion on MoonLITE science objectives and the mission concept. The Panel spent the next two days discussing the science merits of MoonLITE based on interactions with the MoonLITE team and materials available. This letter and attachment are the result of the Panel's deliberations.

The context of the MoonLITE mission is an invigorated and highly exciting decade of international lunar exploration. Five major remote sensing missions to the Moon have been or will be launched between 2007 and 2011 from Japan, China, India, and the US, most with a one to two year nominal lifetime and a typical one-year data release policy.

Figure 1
MoonLITE science configuration through Phase A with potential descopes

In the 2012-2014 timeframe the first serious global assessment of the Moon (topography, morphology, gravity, mineralogy, elemental abundance, thermal emittance, regolith sounding) will be accomplished with modern remote sensors. The international science community will harvest these data to understand much about the geologic evolution of this small differentiated planetary body that shares the environment with Earth at 1 AU. The exploration community will use these advanced sensor data to plan the next phases of human exploration.

However, a key science element left undone by this international armada is probing the interior of the Moon to learn the present internal structure and thermal state, which is essential to constrain the early history of this small planetary body and neighbor of Earth. This characterization of the internal structure can only be accomplished by distributed "network" science, a series of coordinated landed instruments that will measure properties of the interior (see discussion below). Furthermore, by 2014 the question of the origin of the hydrogen detected in the extreme cold regions of the permanently shadowed regions at the lunar poles could remain unresolved since only remote sensing techniques have probed these areas.

The possible presence of water ice in these regions has long term implications for human exploration. Both of these fundamental science issues are well suited to be addressed by an approach that uses a distributed network of instrumented penetrators across the Moon. This is the unique capability potentially provided by the MoonLITE concept.

Several aspects of the lunar science proposed by MoonLITE stand out as scientifically compelling. The Panel considered the most important to be those associated with a geophysical network and in-situ investigation of polar volatiles. Both, or either, of these provide extremely valuable information about the Moon that is not accomplished by any of the current missions flown or in preparation. Both, or either, provide information that feed directly into long term planning of human activities. Both, or either, allow a clear pathway for training the next generation of scientists who are cognizant about planetary science processes and issues.

The Panel found the scientific potential of the MoonLITE penetrator network concept to be exceptionally high in the context of the international exploration activities. This exciting mission would provide a stand-alone cornerstone to the proposed International Lunar Network and is a particularly valuable contribution to the early phases of a broader Global Exploration Strategy (GES).

It is recognized that the status of the MoonLITE mission is in pre-Phase-A. A detailed technical assessment of the straw-man instruments proposed was beyond the scope of the Panel's terms of reference, as was evaluation of the technical aspects of mission architecture, complexity, and implementation. The scientific success nevertheless depends on the capabilities of the instruments, the actual lifetime of key components, and the data downlink and telecommunications mission constraints and these must be scrutinized during a phase-A study.

The Panel considers the multifaceted MoonLITE mission as currently conceived to have the greatest scientific merit because it potentially could address both the geophysical as well as volatile and compositional science objectives. Such a combined mission is well worth serious consideration during a Phase A study. However, we recognize this may prove to be a serious and complex challenge to implement within reasonable cost constraints.

Possible post-Phase A configurations of a MoonLITE network are discussed below in order of currently perceived scientific merit and rational descope options. Figure 1 illustrates the relation of possible MoonLITE configurations that result from a Phase-A study with various descopes as determined from technical evaluation and/or cost constraints. Descope options involve removal of one or more of the scientific packages on each penetrator, but not a reduction in the number of penetrators, since the Panel considered the proposed network of four penetrators to be essential to the scientific return.

Attached are more detailed discussions of (A) the Panel's assessment of Scientific rationale for MoonLITE instruments (PDF - 22kB) (link opens in a new window) and (B) the Panel's recommendations for issues to be addressed (PDF - 33kB) (link opens in a new window) during Phase-A Study.