Field geological research, as traditionally practiced on Earth, is an extremely flexible science. Although field geologists plan their traverses ahead of time—nowadays with the advantage of remote-sensing data—initial plans are continually modified in response to observations, such that traverses evolve over time. This research modality differs from that utilized in extreme environments on Earth (e.g., on the ocean floor), on the Martian surface by the mobile laboratories Spirit and Opportunity , and by the Apollo astronauts during their explorations of the Moon. Harsh and alien conditions, time constraints, and resource limitations have led to the development of operational modes that provide a constrained and usually lower science return than traditional field geology. However, emerging plans for renewed human exploration of the Moon, Mars, and near-Earth asteroids serve as an opportunity to invent a new paradigm for advanced planetary field geology that embraces coordinated human and robotic research activities. This approach will introduce an operational flexibility that is more like that of traditional field geology on Earth. In addition, human and robotic collaborations, combined with the integration of new “smart” tools, should provide an augmented reality that leads to even greater science return than traditional field geology. In order to take full advantage of these opportunities when planetary field geology again becomes practical, it is imperative for field geologists on Earth to begin right now to learn how best to incorporate advanced technologies into their research. Geologic studies of analog sites on Earth that employ new technology-enabled strategies rather than traditional research methods provide ideal opportunities to test and refine emerging designs for advanced planetary field geologic studies, as well as to gain new insights into terrestrial geologic processes. These operational experiments will be most informative if they embrace the entire geologic research process—including problem definition, field observation, and laboratory analysis—and not simply field work. The results of such comprehensive research can be used to inform the design of a maximally effective training regimen for future astronaut explorers.

Since the beginning of the U.S. space program, the National Aeronautics and Space Administration (NASA) has trained astronauts in basic earth science topics to support their observations of Earth's surface from low Earth orbit. From its roots in the Apollo geology training campaigns, we describe the evolution of astronaut Earth observation training across human spaceflight programs, with a focus on the training for space shuttle and International Space Station (ISS) missions. Astronauts' Earth observation experiences—both preflight training and interactions with scientists on the ground during spaceflight missions—provide relevant information for defining training requirements for future astronaut exploration missions on other planetary surfaces.

The operational and logistical burden associated with putting a team of four scientists in a hostile environment was investigated as part of the Antarctic Search for Meteorites (ANSMET) Project during the austral summer of 2002–2003. Operational time data, when compared with similar data from the Apollo J-series missions, suggest that crew time available to science on future exploration missions will be no more than 20% of the total available surface time, due to the time demands associated with operating in a hostile environment. A comparison of time-distance statistics derived from ANSMET meteorite search traverses to similar traverses from Apollo was inconclusive—there was no clear pattern of similarity or dissimilarity between the two data sets. However, both data sets reinforce the benefits of robust rover capability over simple walking because rovers allow exploration of a wider area for a given period of time when compared to walking. Lastly, mass data for equipment and supplies for a four-person team on the Antarctic polar plateau suggest that supplying a Mars or lunar mission with the necessary supplies for nominal surface operations would take up a significant amount of the mass-to-orbit prior to initiating trans-Mars or lunar injection.

As humans venture back to the Moon, or onward to near-Earth objects and Mars, it is expected that the rigors of this exploration will far exceed those of Apollo . Terrestrial analogs can play a key role in our preparations for these complex voyages, since in addition to their scientific value, analogs afford the exploration community a means to safely prepare and test exploration strategies for future robotic and human planetary missions. Many relevant analog studies exist, and each is focused on a particular aspect of strategic development. Some analog programs such as the Pavilion Lake Research Project (PLRP) present the opportunity to investigate both real scientific and real exploration scenarios in tandem. The activities of this research program demand the use of techniques, tools, and strategies for underwater scientific exploration, and the challenges associated with the scientific exploration of Pavilion Lake are analogous to those human explorers will encounter on other planetary and small solar system bodies. The goal of this paper is to provide a historical synopsis of the PLRP's objectives, milestones, and contributions to both the scientific and exploration community. Here, we focus on detailing the development and deployment of an integrated science and exploration program with analog application to our understanding of early Earth systems and the preparation for future human space exploration. Over a decade of exploration and discovery is chronicled herein.

We compared the morphology of gully sedimentary fans on Svalbard as possible analogs to gullies on Mars in order to constrain whether fluvial and/or debris-flow processes are predominantly responsible for the formation of Martian gullies. Our analysis is based on high-resolution imagery (High Resolution Stereo Camera [HRSC-AX], ~20 cm/pixel) acquired through a flight campaign in summer 2008 and ground truth during two expeditions in the summers of 2008 and 2009 in Svalbard, compared to high-resolution satellite imagery (High Resolution Imaging Science Experiment [HiRISE], ~25 cm/pixel) from Mars. On Svalbard, fluvial and debris-flow processes are evident in the formation of gullies, but the morphological characteristics clearly show that the transport and sedimentation of eroded material are predominated by debris flows. Most investigated gullies on Mars lack clear evidence for debris-flow processes. The Martian gully fan morphology is more consistent with the deposition of small overlapping fans by multiple fluvial flow events. Clear evidence for debris flows on Mars was only found in one new location, in addition to a few previously published examples. The occurrence of debris-flow processes in the formation of Martian gullies seems to be rare and locally limited. If predominantly fluvial processes caused the formation of gullies on Mars, then large amounts of water would have been required for their formation because of the relatively low sediment supply in stream and/or hyperconcentrated flows. Repeated seasonal or episodic snow deposition and melting during periods of higher obliquity in the recent past on Mars can best explain the formation of the gullies.

We present landforms on Svalbard (Norway) as terrestrial analogs for possible Martian periglacial surface features. While there are closer climatic analogs for Mars, e.g., the Antarctic Dry Valleys, Svalbard has unique advantages that make it a very useful study area. Svalbard is easily accessible and offers a periglacial landscape where many different landforms can be encountered in close spatial proximity. These landforms include thermal contraction cracks, slope stripes, rock glaciers, protalus ramparts, and pingos, all of which have close morphological analogs on Mars. The combination of remote-sensing data, in particular images and digital elevation models, with field work is a promising approach in analog studies and facilitates acquisition of first-hand experience with permafrost environments. Based on the morphological ambiguity of certain landforms such as pingos, we recommend that Martian cold-climate landforms should not be investigated in isolation, but as part of a landscape system in a geological context.

The Jurassic Todilto Formation of NW New Mexico and SW Colorado, USA, has utility as an analog of Martian flood evaporites. The Todilto Formation is a concentrically and vertically zoned carbonate (calcite with minor late dolomite) to sulfate (gypsum) evaporite deposit that developed over a short time span (10 4 –10 5 yr) after rapid flooding of the vast dune field of the Entrada Formation. Within the limits of the very different hydrogeologic environments of Mars and Earth, the Todilto setting of short-lived brine evolution in a largely eolian environment, with terminal formation of a salt hydrate common to both planets (gypsum), provides a useful field area for descriptive and petrogenetic studies of evaporite evolution and interaction with a porous, sandy substrate. The Todilto Formation has an added feature of interest in its association with bituminous materials that have likely microbial precursors, providing a brine-microorganism association that may represent a potential setting for primitive life as might be found on Mars.

Thermal spring deposits are features of considerable interest to Mars scientists because of their potential as astrobiological oases and as records of the paleohydrology of the planet. Terrestrial counterparts can assist in recognizing such features on Mars and in developing technologies for their study and sampling. In this paper, we describe one such analog, the Dalhousie Springs complex in central Australia. The Dalhousie Springs complex is one of largest groundwater discharge landforms known on Earth. It is a carbonate-limited precipitation system due to the non-supersaturated ascending water. Spring carbonates are deposited as discrete mounds and outflow channels resting unconformably on older units. Although subject to postformation geomorphic modification, the spring deposits persist in the landscape and are recognizable long after the parental spring has shut down. We identify 14 specific microfacies belonging to seven facies, which form three environmental associations related to specific depositional environments. Diagenesis has occurred in several stages, as evidenced by distinctive textures on the deposits. Spring deposits on Mars would potentially be recognized by similar textures (although compositions may be quite different) and similar geomorphic relationships. However, in satellite images, spring deposits may be difficult to differentiate from deposits resulting from other processes that produce similar geomorphic features, including mud volcanoes, pingos, and rootless cones. Mineralogical data may assist, but ultimately ground truth will be required.

Recent orbital and rover missions to Mars have returned high-resolution images that show complex surface landforms in unprecedented detail. In addition, the spectral data sets from mission instruments reveal the presence of a wide array of mineral species on the surface of Mars. These discoveries are changing the analog science requirements of projects targeting exploration missions to Mars. Mission managers now expect field deployments to include complementary investigations of surface processes, rock types, mineral species, and microbial habitats. Earth-based analog sites are selected according to their potential for integrated geological and biological studies, wherein a central theme is the search for life. Geological field studies on Axel Heiberg Island, in the Canadian Arctic, demonstrate that the Isachsen Formation represents a high-fidelity analog for comparative studies of volcanic terrain on Mars. The two sites of interest are located in structurally complex zones (chaotic terrain) where basaltic lava flows, mafic dikes, and sandstone beds of Early Cretaceous age intersect evaporite outliers at the periphery of the diapirs. At the North Agate Fiord diapir and Junction diapir, remnant blocks of basaltic rock are pervasively altered and contain copper and iron sulfides, as well as the secondary sulfates copiapite, fibroferrite, and jarosite (North Agate Fiord diapir). Alteration zones within poorly consolidated quartzitic sandstone consist of thin layers of goethite, hematite, illite, and jarosite. The sites are morphologically different from Martian patera, but they provide access to volcanic successions and evaporites in areas of permafrost, i.e., conditions that are invoked in conceptual models for hydrothermal systems and groundwater flow on Mars.

Martian meteorites provide our only samples for laboratory investigations of Mars, yet the lack of geologic context severely limits their utility. Strong petrologic similarities between the pyroxenitic layer of a 120-m-thick, mafic Archean lava flow in Ontario, Canada, called Theo's Flow, and the nakhlite meteorite group may elucidate geologic processes that operated on Mars. Theo's Flow is in the Abitibi greenstone belt, an area that is well known as a komatiite location. The type locality, and best outcrop, of Theo's Flow is an upturned (~70°) section stretching east-west for ~500 m. Theo's Flow can be divided into distinct lithologic units: a thin basal peridotite (0–9 m), a thick pyroxenite (50–60 m), a gabbro (35–40 m), and a hyaloclastic, brecciated top (8–10 m). It is the thick pyroxenitic layer that bears a striking textural similarity to the Martian nakhlites. Serpentinization of olivine, chloritization of orthopyroxene, and alteration (e.g., pseudomorphic replacement) of plagioclase and minor phases have transformed the original mineral assemblage, though augites remain largely unaltered, and textural relationships are well preserved throughout the flow. Variations in iron and minor-element abundances in augite cores exhibit typical trends for an evolving melt. Bulk rock analyses exhibit elemental trends consistent with an evolving melt, though they exhibit evidence of elemental remobilization by later metamorphism. An average of the peridotite, pyroxenite, and gabbro compositions compares well to that of the quenched top hyaloclastite, suggesting it is a single flow that was differentiated by crystal settling. The lithologic diversity within Theo's Flow suggests that nakhlites may also have complementary lithologies that remain unsampled.

Sulfate-rich mineral deposits have been discovered in many locations on Mars through observations by orbiters, landers, and roving spacecraft. It appears that in most cases, these minerals are produced by acid-sulfate weathering of igneous rocks, which may have been a widespread process for the first billion years on Mars. The origin of life on Earth may have occurred in iron-sulfur hydrothermal settings, and early Mars likely had similar environmental conditions. An excellent terrestrial analog for acid-sulfate weathering of Mars-like basalts exists at Cerro Negro, Nicaragua, where acidic sulfur-bearing gases interact with recently erupted basaltic ash in numerous active fumaroles. We investigated the chemistry and mineralogy of the pristine basalts and their chemically weathered products, and we studied the associated microbiological communities as an analog for potential early life on Mars. Measured pH values of condensed volcanic vapors range from −1 to 5, and near-surface temperatures in the fumaroles range from 40 to 400 °C. In a few years, fresh basalt can weather to amorphous silica and gypsum, along with lesser amounts of other sulfates (natroalunite and jarosite), Fe-hydroxides, and clays. Altered rocks have up to 35 wt% SO 3 equivalent, similar to the amounts of sulfur reported for Meridiani Planum bedrocks and inferred in other sulfate-bearing bedrock on Mars. Heavily weathered rocks have silica contents up to 80 wt%, similar to silica-rich soils at Gusev crater that possibly formed in hydrothermal environments. Here, we provide preliminary results of our studies and outline the logistics for a field excursion to this Mars analog system.

Analysis of geologic materials at the microscale—where we use the term “microscale” to refer to features resolved approximately by a hand lens—has proven to be a powerful strategy to maximize the information gleaned from limited samples, such as on Mars. However, discrimination between processes that leave behind similar traces requires enlightened comparisons to well-characterized analogs. We characterized and imaged several terrestrial analogs of materials produced by volcanic, hydrovolcanic, or cryovolcanic Martian processes at the hand lens scale, and then we produced a convenient tool for the community to access those data for comparisons. We report on the preparation of this Mars-focused image atlas (the Mars Analog Handlens-Scale Image Database), using as an example analog studies of particles deposited by the 1996 Skeiđarársandur jökulhlaup (a jökulhlaup is a subglacially generated outwash flood resulting in a sandur, or sheet of outwash sands and gravel). We imaged unconsolidated sediment particles in situ at about hand lens scale and documented their characteristics at six sites along the sandur. Average particle size and number of angular, very angular, and subangular particles decreased with distance from the source; the average sphericity of particles increased slightly; and the range of sphericity values present narrowed with distance. If observed in a region on Mars, this combination of characteristics would be one indicator that subglacially generated outwash flooding was the process responsible for deposition of sediment. The Mars Analog Handlens-Scale Image Database is searchable and can be found on the Geosciences Node of the Planetary Data System at http://an.rsl.wustl.edu/marsanalog/ .

Utah offers spectacular geologic features and valuable analog environments and processes for Mars studies. Horizontal strata of the Colorado Plateau are analogous to Mars because the overprint of plate tectonics is minimal, yet the effects of strong ground motion from earthquakes or impacts are preserved in the sedimentary record. The close proximity of analog environments and lack of vegetative cover are advantages for field and remote-sensing studies. Dry, desert climate and modern wind processes of Utah are comparable to Mars and its current surface. Analogs in Utah include eolian, sabkha and saline bodies, glacial, lacustrine, spring, alluvial, fluvial, delta, and outflow channel depositional environments, as well as volcanic landforms and impact craters. Analogous secondary processes producing modification features include: diagenetic concretions, weathering and soils, sinkholes, sapping, knobs and pinnacles, crusts and varnish, and patterned grounds. Utah's physical and chemical environments are analogous to conditions on Mars where water existed and could support microorganisms. The development of Mars includes: ancient and modern depositional records, burial and diagenesis, uplift and tectonic alteration, and modern sculpting or weathering of the surface exposures. Recent satellite images are providing unprecedented details that rival the outcrop scale. Analogs in Utah are prime field localities that can be utilized in planning future robotic and human missions to Mars, and for teaching the next generation of planetary explorers.

The Big Island of Hawai‘i presents ample opportunities for young planetary volcanologists to gain firsthand field experience in the analysis of analogs to landforms seen on Mercury, Venus, the Moon, Mars, and Io. In this contribution, we focus on a subset of the specific features that are included in the planetary volcanology field workshops described in the previous chapter in this volume. In particular, we discuss how remote-sensing data and field localities in Hawai‘i can help a planetary geologist to gain expertise in the analysis of lava flows and lava flow fields, to understand the best sensor for a specific application, to recognize the ways in which different data sets can be used synergistically for remote interpretations of lava flows, and to gain a deeper appreciation for the spatial scale of features that might be imaged in the planetary context.

The Pinacate volcanic field is ~330 km SSW of Phoenix, and it is a popular destination for volcanology and planetary geology field trips. The volcanic field, located on the Pinacate Biosphere Reserve in Sonora, Mexico, is a 1500 km 2 basaltic field including a shield volcano, lava tubes, maars, a tuff cone, cinder cones, pāhoehoe and ‘a‘ā lava flows as young as 12 ka, and phreatomagmatic constructs as young as 32 ka. We developed an image-based set of exercises for a 2 day field trip focusing on (1) Crater Elegante, a maar crater, (2) pāhoehoe and ‘a‘ā flows near Tecolote Cone campground, (3) the complex eruptive history of Mayo (cinder) Cone, and (4) Cerro Colorado tuff cone. This paper discusses exercises to teach concepts in visible and radar image interpretation and planetary volcanology, and provides an overview of the field trip.

A critical factor required to unravel processes that have shaped other planets is a solid understanding of geologic processes as they operate on Earth, and a logical way to understand those processes is to go into the field and view them. We provide a field guide to three locations: (1) Cima volcanic field, south of Baker, California; (2) Rainbow Basin, north of Barstow, California; and (3) Red Rock Canyon and vicinity in Nevada and California, all within the Mojave Desert of the southwestern United States. These locations highlight three processes that have affected Earth and other planets: volcanism, sedimentation, and tectonism. Volcanism is explored by looking at the basaltic cinder cones, lava flows, lava tube, and xenoliths of the later Tertiary and Quaternary Cima volcanic field. Felsic ash and volcaniclastic material interbedded with lacustrine, siliciclastic sedimentary rocks are examined in Rainbow Basin, a Tertiary strike-slip basin. The interplay between volcanic and sedimentary processes is examined at this locality, while deformation of the basin makes it ideal for examining structural and tectonic aspects. Broader-scale tectonism is observed in the hanging wall (Ordovician carbonates) and footwall (Jurassic sandstone) rocks to the Keystone thrust fault. The fault is visible given the color contrast between the lower (white and red) and upper (gray) plates. In Red Rock Canyon, Nevada, exposures of the Jurassic Aztec Sandstone display excellent examples of large-scale cross-stratification from eolian dune deposition. Each locale holds lessons pertinent for the study of processes that have operated on other planets in the solar system.

Multiple cemented channel-fill deposits from the Late Jurassic and Early Cretaceous, once buried beneath 2400 m of sediment, are now exposed at the surface in arid east-central Utah due to erosion of the less resistant surrounding material. This field guide focuses on examples near the town of Green River where there is public access to several different types of exhumed paleochannels within a small geographic region. We describe the geologic setting of these landforms based on previous work, discuss the relevance to analogous sinuous ridges that are interpreted to be inverted paleochannels on Mars, and present a detailed road log with descriptive stops in Emery County, Utah.

In response to the need to develop science-conducive architectures for future human exploration of particularly interesting targets on lunar and planetary surfaces, we have developed scenarios for a geological expedition to Marius Hills within current constraints of week-long sortie missions. This area has a dense nest of volcano-tectonic features representing the range of mare volcanic structures, which is one of the reasons why it is so compelling. Two distinct episodes of flood basaltic volcanism are represented, along with volcanic shields, domes, cones, rilles, wrinkle ridges, floor fractures, and a magnetic swirl anomaly. We found two potential landing sites (constrained to 10 km radius) in the southwestern portion of Marius Hills that would allow access to examples of most of the features of interest. We describe the geological context, resulting investigations, daily traverses, and survey/sample sites along those routes, in detail, as well as the required tools, instruments, and surface activities. The resulting science requirements, for a minimum of two rovers plus a few hundred kilograms of science payload, along with implications for a science-conducive architecture, are considered.