The Scientific Context for Exploration of the Moon (2007)

The committee identified several related concepts (numbered 1R through 4R) pertaining to the optimal implementation of science in the Vision for Space Exploration (VSE). This effort was driven in large part by the stark realization that more than 30 years have passed since Apollo and that the nature of the VSE itself warrants a major reconsideration of the basic approach to conducting lunar science. In more than 30 years, robotic capability has increased dramatically, analytical instrumentation has advanced remarkably, and the very understanding of how to explore has evolved as scientists have learned about planetary formation and evolution. The VSE offers new opportunities: researchers are no longer limited to short-duration lunar stays of 2 or 3 days and “emplacement science”; scientists on the Moon can operate as scientists, doing analytical work and deciphering sample/source relationships; site revisit with follow-up science is possible (e.g., an outpost); robotic-capable equipment can be used between missions; geophysical equipment can be used in survey modes; time-consuming deep drilling is possible; lunar samples can be “high-graded” for return to Earth. These are but examples of how different the VSE exploration should be as compared with that of the Apollo program. Nurturing a new approach to lunar exploration must be fostered early in the program if we are to reap the potential of the VSE is to be reaped.

Successful implementation of science in a program of human exploration starts with and is highly dependent on a cooperative relationship among all of the involved communities. To acquire lessons learned from past experience, the Space Studies Board’s Committee on Human Exploration (CHEX) conducted a study of science prerequisites, science opportunities, and science management in the human exploration of space.¹ For science management, CHEX studied the Apollo, Skylab, Apollo-Soyuz, and Shuttle/Spacelab programs to determine what organizational relationships, roles, and responsibilities contributed to superior science outcomes.

CHEX found that human exploration offers a unique opportunity for science accomplishment and as such should be viewed as part and parcel of an integrated human exploration-science program. That committee developed three broad management principles, which, if implemented, would improve the probability of a successful synergy between science and human exploration:

1. Integrated Science Program—The scientific study of specific planetary bodies, such as the Moon and Mars, should be treated as an integral part of an overall solar system science program and not separated out simply because there may be concurrent interest in human exploration of those bodies. Thus, there should be a single NASA headquarters office responsible for conducting the scientific aspects of solar system exploration.

2. Clear Program Goals and Priorities—A program of human spaceflight will have political, engineering, and technological goals in addition to its scientific goals. To avoid confusion and misunderstandings, the objectives of each individual component project or mission that integrates space science and human spaceflight should be clearly specified and prioritized.²

3. Joint Spaceflight/Science Program Office—The offices responsible for human spaceflight and space science should jointly establish and staff a program office to collaboratively implement the scientific component of human exploration. As a model, that office should have responsibilities, functions, and reporting relationships similar to those that supported science in the Apollo, Skylab, and Apollo-Soyuz Test Project (ASTP) missions.

Consistent with the principles enunciated above, CHEX found a definitive correlation between successful science accomplishment and organizational roles and responsibilities. In particular, the quality of science was enhanced when the science office (NASA’s Science Mission Directorate [SMD] now) controlled the process of establishing science priorities, competitively selecting the science and participating scientists and ensuring proper attention to the end-to-end cycle ending in data analysis and the publication of results. This process extends to the selection of science contributions by international partners; competitive merit should prevail.

Finding 1R: The successful integration of science into programs of human exploration has historically been a challenge. It remains so for the VSE. Prior Space Studies Board reports by the Committee on Human Exploration (CHEX) examined how the different management approaches led to different degrees of success. CHEX developed principles for optimizing the integration of science into human exploration and recommended implementation of these principles in future programs.³ This committee adopts in Recommendation 1R the CHEX findings in a form appropriate for the early phase of VSE.

Apollo experience demonstrated both the complexity of planning lunar surface and orbital operations and the benefits of so doing. The challenge today is, if anything, greater, in that the more than 30 year hiatus since Apollo has seen a remarkable evolution of planetary exploration strategy and capability. One cannot start too

early: detailed Apollo planning started in the early 1960s, well before Apollo 11 landed on the Moon in 1969, and included robotic precursors, determination of science objectives, astronaut selection, selection of landing sites, astronaut science training, science team selection, traverse planning, sampling strategies, geophysical station development (the Apollo Lunar Surface Experiments Package [ALSEPs]), full-up mission simulations, and data-analysis preparations. A similar range of preparation is essential for implementation of the Vision for Space Exploration. The merit of including scientists in the astronaut corps has long been recognized and the benefits demonstrated on Apollo 17, Skylab, the Space Shuttle, Spacelab, and the International Space Station. Scientist-astronauts should be among all lunar mission crews.

Much of what was learned by hard experience on Apollo can now be efficiently incorporated into VSE planning. Obviously much of the detailed planning will have to, and should, await a date closer to mission implementation; however, many aspects can be initiated now with relatively low investment and high return. Two areas stand out as needing early planning and the involvement of the science community: (1) site selection and the related issue of sortie missions and/or a lunar outpost, and (2) surface mission planning and related requirements for mobility and the use of robotics.

1. Landing site selection. NASA’s plans to return humans to the Moon necessarily involve the selection of surface exploration sites. The site selection process becomes a matter of which sites best satisfy Exploration Systems Mission Directorate (ESMD) goals and priorities. Among the considerations are science, the buildup of an outpost or base, preparation for Mars exploration, the development of in situ resource utilization (ISRU), and commercial potential. Then will come the obvious overlay of budget and engineering limitations, site access, logistics, and safety. Successful accomplishment of many of the science goals elucidated in this report depends critically on getting to specific lunar landing sites. In contrast to site selection for the Apollo program, VSE site selection has to satisfy multiple goals of which science is but one, albeit an important one. The challenge becomes one of optimizing site selection to accomplish multiple goals. The committee notes that there are site selection considerations that are independent of human exploration sites: for example, robotic sample return from sites that may not be visited by humans and/or the global emplacement of geophysical networks. These science activities recognize that the VSE is advertised as not solely for human missions but that it is to involve an ongoing mix of human and robotic missions.

A dichotomy already exists regarding lunar landing sites. On the one hand, the sortie mode is preferred by most lunar scientists, who consider it necessary to visit many diverse lunar sites both for geologic studies and for instrument emplacement. The ESMD, on the other hand, has made a preliminary determination that a singular (tentatively polar region) outpost site best serves its higher-priority goals of “habitation” and “prepare for exploration.” Although a sortie capability is currently stated as continuing to be available, the cost of such a capability would be billed to the Science Mission Directorate (at about $2 billion). That cost must be traded off against accomplishing the science goals robotically and against competing nonlunar space science.

The attributes of the lunar outpost concept for purposes of scientific investigation deserve joint ESMD/SMD study. The potential advantages are increased time for detailed geologic study; deep drilling, core retrieval, and downhole instrument emplacement; geophysical instrument emplacements; traverse surveys; returned-sample selection (“high-grading”); follow-up on results obtained on earlier outpost missions; and utilization of logistics previously emplaced. An outpost would warrant a greater investment in terms of reusable resources—for example, a multimission rover with resuppliable onboard life support and sophisticated analytical instrumentation. Such a rover could be used in automated mode between outpost visits. Many of these attributes were being considered in the 1960s as follow-ons to the initial Apollo missions but were, obviously, never executed when missions after Apollo 17 were canceled. It is important to note that the precise location of an outpost site will determine the scientific return. It thus behooves the ESMD to incorporate scientific site criteria among its overall criteria.

2. Surface and orbital mission operational planning. Apollo experience demonstrated that the most valuable resource on the Moon is time. There is inevitably more to be done than time allows. For example, astronauts were constantly under pressure to “move on to the next station.” Many opportunities to examine discoveries in more detail were missed. Things that went wrong (e.g., a stuck drill or an instrument failing to operate) took time away from meeting the time lines. It is necessary to devise methods to conserve astronaut time, doing robotically

those things that do not take greatest advantage of the human capability to observe, to make decisions, and to use manual dexterity to advantage. NASA should undertake a reexamination of Apollo missions with an eye toward identifying time-saving opportunities. It should examine roles for the much-improved robotics capability available today, including consideration of robotic assistants.

Astronauts should be employed as an inherent on-site element in early surface science activities, when the unequaled human characteristics of adaptability, quick reaction, and discerning observation offer the best potential for achieving a science objective. In all considerations of on-the-surface human versus telepresence versus autonomous implementation, trade-offs will compare cost, capability, safety, probability of task success, and coincident activity. Mission planning and management tools for this specific purpose should be developed.

The typical Apollo-type sortie mission of 2 to 3 days is too short to accomplish the level of scientific investigation now merited by our improved understanding of lunar science. If, however, sortie missions are a selected mode for early exploration missions (currently, sortie capability of up to 7 days is under consideration), then planning is needed to increase their efficiency. A possible mode is to precede the human flight with robotic rover precursors: the rovers, possibly similar to the Mars Exploration Rovers (MERs) on Mars, would conduct reconnaissance and identify high-priority traverse locations for astronaut investigation. The Lunar Roving Vehicles on Apollo missions 15 to 17 demonstrated the benefit of mobility; their range was limited primarily by safety and life-support supply considerations. Analysis of the extent to which such constraints can be relieved on future missions is necessary. The desirability of increasing mobility range beyond the canonical walk-back distance (about 10 km) is supported by the general observation that the lunar geologic variety occurs on the scale of tens to hundreds of kilometers. Given the paramount consideration of safety and limited time, telerobotic operations during a human mission might add immeasurably to mission efficiency. Surface rovers capable of being either teleoperated or crewed, (so-called dual mode) should be developed and used on all surface missions. Outfitted with manipulators and observational/analytical instrumentation, these rovers would become telerobotic explorers when astronauts are not present. And with a capability for long-range travel, they potentially could be redeployed from one sortie science site to another, thus saving mission systems duplication. Such site-to-site traverses offer a great potential for geophysical profiling and geological observations of opportunity in a true discovery mode.

Finding 2R: Great strides and major advances in robotics, space and information technology, and exploration techniques have been made since Apollo. These changes are accompanied by a greatly evolved understanding of and approach to planetary science and improvements in use of remote sensing and field and laboratory sample analyses. Critical to achieving high science return in Apollo was the selection of the lunar landing sites and the involvement of the science community in that process. Similarly, the scientific community’s involvement in detailed mission planning and implementation resulted in efficient and productive surface traverses and instrument deployments.

The preceding section on Concept 2R discusses a number of operational concepts, equipment, instruments, and analytical tools that will enhance VSE lunar science. The eventual incorporation of many of these, and others not yet determined, into missions is dependent on the development of advanced technology and instrumentation.

Given the long lead time associated with advancing technology, it is imperative to start soon to fully identify, prioritize, and fund those enabling technologies. When such technologies are successfully developed through NASA strategic investments, they should have a clear path into flight development to meet either SMD or ESMD goals and requirements. Providing well-defined paths into flight development will make the best use of and leverage NASA technology development funds as well as provide an incentive for other technology providers (i.e., industrial, academic, governmental) to take their own risk of developing new technologies. To give a sense of the variety and magnitude of the needed developments, some of the most critical technologies are enumerated below.

1. Advanced technology. The combination of surface mobility and equipment and sample manipulation is a key requirement for conducting science on the Moon, during both precursor and sortie missions. For autonomous/ semi-autonomous robotic operations on the lunar surface, large gaps exist in current robotic capabilities. These gaps should be addressed to enable the achievement of science goals. The challenges include development of the following capabilities:

   • Long-distance traversing, navigation, and access:

     • Rovers (possibly dual-mode with crewed vehicles) with multiyear life, and day/night and permanent-shadow operational capability;

     • Rover capability to access and maneuver on all lunar terrain types, including disturbed lunar soil, steep slopes, craters, and basins; to traverse long distances; to carry/deploy payloads; and to cache samples for later retrieval;

     • Navigation in shadowed regions, such as those found in the polar craters;

     • Enhanced visualization and assessment of the environment for human supervision/telepresence; and

     • Communications infrastructure for full-time teleoperation of surface mobility.

   • Instrument placement and manipulation:

     • Dexterous placement of science instruments;

     • Interchange of end-effectors needed to achieve contact measurements;

     • Robust acquisition, manipulation, and analysis of multiple science samples and transport to a location of interest (e.g., to a sample cache site);

     • Manipulation of sensors for active experimentation such as seismic and electromagnetic sounding;

     • Subsurface data collection: drilling, core retrieval, and downhole emplacement of instruments;

     • Self-contained experiment packages (a la Shuttle Hitch-Hikers and Get Away Specials) requiring minimal crew resources for deployment; and

     • Geophysical probe delivery systems enabling orbital deployment at globally distributed locations.

2. Instrumentation. Some types of in situ and laboratory measurement technology have not yet achieved their potential to contribute to the accomplishment of scientific goals. For use on both robotic and human missions and for returned samples, development of the following instrumentation capabilities is needed:

   • In situ determination of the radiometric age of a crystalline igneous or impact melt;

   • In situ measurement of cosmic-ray exposure ages;

   • In situ routine microanalysis (major elements, mineralogy) and imaging at the 10 micron scale, for fields of view of a few millimeters;

   • In situ measurement of minor and trace elements for gram-sized samples;

   • High-resolution remote sensing, at the scale of tens of centimeters, to allow an assessment of local geology and precise targeting of samples, and to inform the crews and ground support of the types and distributions of materials present at the site;

   • Upgrading of analytical instrumentation for sample analyses in the curatorial facilities and in principal investigators’ laboratories (see also Concept 4R); and

   • Geophysical instrumentation capable of being deployed from orbit and surviving high-g impacts.

Finding 3R: The opportunity provided by the VSE to accomplish science, lunar and otherwise, is highly dependent for success on modernizing the technology and instrumentation available. The virtual lack of a lunar science program and no human exploration over the past 30 years have resulted in a severe lack of qualified instrumentation suitable for the lunar environment. Without such instrumentation, the full and promising potential of the VSE will not be realized.

The NASA system of sample documentation and curation established for the Apollo program has been remarkably successful in protecting samples from contamination, providing ample materials for scientific investigations, preserving materials for later studies, and maintaining configuration control of the collection so that analyses of subsamples can be reliably related to the samples from which they were derived or to other subsamples. It has also been the model on which the means of documentation, preservation, and subsampling of Antarctic meteorites, cosmic dust, and Stardust and Genesis samples were based. The Apollo lunar samples have always been treated as if they were the last samples that might be retrieved from the Moon. The Vision for Space Exploration offers the possibility of collecting many more samples from the Moon, from a much wider variety of locations. This potentially includes the collection of samples from much more extreme environments than was possible during Apollo: examples are cryogenic samples from shadowed polar craters, samples preserved in lunar vacuum conditions, or electrostatically levitated dust. There is also the potential to return additional samples of human-made materials exposed to the lunar environment, which will be of scientific interest (for astrobiology and planetary protection) as well as engineering interest. It is important to re-evaluate the curatorial functions for lunar samples in light of the new opportunities and capabilities of the Vision for Space Exploration. Historically NASA has successfully involved the broad science community—for example, the Curation and Analysis Planning Team for Extraterrestrial Materials (CAPTEM) to assist it in such evaluations and assessments.

It is well to remember the principal objectives of proper extraterrestrial sample preservation: (1) to preserve information on the relationship of the sample to its original environment on the planetary body; (2) to ensure that samples, once collected and returned to Earth, are both available to study and preserved for future scientific investigations, which may be more rigorous with regard to precision, scale, and degree of contamination; and (3) to protect samples from unfavorable contamination due to handling techniques or exposure to the terrestrial environment.

This preservation process must begin on the Moon, with the collection, documentation, and packaging of samples. Documentation of the original collection location must be accomplished by crewmembers on the surface, provided with adequate documentation tools. During Apollo, the orientation of some rocks proved important in some studies of the lunar radiation environment. It will be especially important to document any samples collected in situ, that is, from outcrops, rather than loose materials in the regolith. Several samples from the same outcrop might be collected to study its internal variations, which must be kept separate if their original relations (position, orientation) to the outcrop are to be preserved. It proved close to impossible to preserve Apollo samples in lunar vacuum conditions (although there were few, if any, vacuum chambers on Earth that could be used to study samples maintained at lunar vacuum), because of problems of dust on container seals. Documentation of the deployment and functioning of special sample collection and containment devices, which will undoubtedly be developed for particular samples (such as cryogenic samples from the poles), and provision for transferring these samples to Earth, will be needed. The consideration of these requirements should be incorporated into the design of surface exploration tools provided to lunar crews.

Curation of lunar samples has always aimed to avoid cross-contamination of samples. A major manifestation of this requirement is that samples from more than one location on the Moon have been handled in separate work areas (typically nitrogen-filled stainless steel cabinets) or in work areas that are thoroughly cleaned before samples from another area are introduced. The challenge of working with samples from a much wider variety of areas will be significant, and the procedures and facilities for doing that should be re-evaluated. For example, working with a large number of small samples from a diversity of areas might require smaller, more flexible, work areas.

Many of the large samples collected by Apollo proved to be needlessly redundant scientifically. When most analyses can be done on milligram to gram quantities of samples, 10 kg rock samples are likely to be too large. This may not be true of rock samples for which important internal relationships (e.g., contacts between matrix and clasts in complex breccias) require study. Large regolith samples (perhaps greater than 200 g) can prove to be cumbersome to handle and preserve, when only a few grams of material are designated for study. These types of considerations should be included in designing crew surface procedures, sampling tools, and containers.

The ability to return to a field area or to a central outpost will open some opportunities not available to the Apollo program. In particular, capability can be provided for storing larger pieces of rock on the Moon in a protected environment, in case there is a future call for study of those samples when something unusual is discovered during scientific investigations. As mentioned elsewhere, analytical capability on the Moon could be used to select portions of samples, such as fragments from a sieved regolith sample. In these cases, the residual materials, which may have future scientific value, should be isolated and preserved in some manner. The characteristics of a lunar curatorial facility and associated hardware and procedures should receive study.

Finding 4R: The NASA curatorial facilities and staff have provided an exemplary capability since the Apollo program to take advantage of the scientific information inherent in extraterrestrial samples. The VSE has the potential to add significant demands on the curatorial facilities. The existing facilities and techniques are not sufficient to accommodate that demand and the new requirements that will ensue. Similarly, there is a need for new approaches to the acquisition of samples on lunar missions.