Mineralogy of the Mars Pathfinder Landing Site James F. Bell III, Cornell University Abstract: The proposed investigation will focus on using the results of the IMP experiment to map the distribution of climatically-diagnostic ferric- (Fe3+) and ferrous- (Fe2+) bearing minerals at the Mars Pathfinder landing site. Particular emphasis will be placed on determining the origin of the heavily-weathered ferric soils: that is, determining whether they are of local origin and using information on the original unweathered ferrous materials from which the soils were formed to infer the physical and chemical weathering history of the surface and to make inferences on Mars climatic variability in general. In addition, this investigation will incorporate the results of simultaneous visible through mid-IR groundbased and HST observations of the Pathfinder landing site and its surroundings, thus extending the local information from the lander into a more regional and global context. The proposed investigation is divided into four primary tasks: (1) Assisting the IMP team in developing optimized multispectral observation sequences that maximize the amount of mineralogic and compositional information obtained by the imager and the APXS within the severe data downlink constraints that exist for the mission; (2) Becoming actively involved in the reduction, calibration, and archiving of the IMP multispectral imaging data, using the PI's previous experience with the reduction, calibration, and archiving of spacecraft and telescopic CCD multispectral imaging data sets to assess and help refine the techniques and results of the IMP team's calibration pipeline; (3) Searching for and mapping the distribution of specific minerals at the landing site, including but not limited to hematite, goethite, and pyroxene; and (4) Assisting the IMP team in the interpretation of the mineralogic results with particular emphasis on determining the weathering and alteration history of the Pathfinder landing site. Data to be used in this investigation include multispectral images from IMP using up to 12 "geology" filters, pre-flight and in-flight IMP test and calibration data, imaging and other results from the IMP Magnetic Properties Experiment, and possibly data from the Sojourner rover 3- color aft imaging camera. In addition, the Pathfinder results will be augmented by previous and contemporaneous imaging and spectroscopic measurements from HST and groundbased observations in which the PI is heavily involved. This investigation cannot be performed simply by access to post-mission data because it relies heavily on the PI's involvement in the development of a "survey mode" IMP sequencing capability. This capability acknowledges the severe data downlink constraints of the mission and will allow IMP images obtained in only a few key mineralogy wavelengths to identify interesting and enigmatic regions where full 12-color mineralogic imaging could produce the greatest scientific gain. 1. Description of the Proposed Investigation I am proposing to conduct an investigation of the mineralogy of the Mars Pathfinder landing site using a combination of data to be obtained by the Imager for Mars Pathfinder (IMP) multispectral imaging and magnetic properties experiments. The ultimate goals of this investigation are to determine the physical and chemical weathering history of this part of the Martian surface, and through correlated observations from groundbased telescopes and the Hubble Space Telescope (HST), to interpret the Pathfinder results within the context of the global-scale weathering, alteration, and climate history of Mars. During this investigation, I propose to perform the following tasks: 1) Assist the IMP team in developing optimized multispectral observation sequences that maximize the amount of mineralogic and compositional information obtained by the imager and the APXS within the severe data downlink constraints that exist for the mission. 2) Become actively involved in the reduction, calibration, and archiving of the IMP multispectral imaging data, relying on my previous experience with the reduction, calibration, and archiving of spacecraft and telescopic CCD multispectral imaging data sets to assess and help refine the techniques and results of the team's calibration pipeline. 3) Produce maps of the distribution of mineralogy at the landing site. The IMP filters have the potential for detecting or constraining the abundances of ferric (Fe3+) oxides/oxyhydrox-ides, certain ferric- bearing clays, carbonates, and sulfates, as well as ferrous (Fe2+) bearing primary silicates like pyroxene and olivine (Figure 1). In addition, the results of the magnetic properties experiment will be used to help discriminate between certain important ferric phases, like magnetite and maghemite, that are difficult to uniquely identify using IMP data alone. 4) Assist the IMP team in the interpretation of the mineralogic results with particular emphasis on determining the weathering and alteration history of the Pathfinder landing site. This investigation will also help to place the mineralogy and climate/weathering history of the Pathfinder landing site into a global context by comparing the IMP data with groundbased and HST visible to near-IR imaging and spectroscopic data obtained before, during, and after the Pathfinder primary mission. These tasks are focused on producing the best possible set of IMP primary and nominal mission data products. They will assist the IMP team in maximizing the scientific return of the IMP investigation through the rapid analysis and interpretation of early mission data and the subsequent refinement and optimization of IMP observations based on the initial results. I have a deep scientific interest in the new information about Mars that will be provided by the Pathfinder mission, but I am also very aware that the first steps are to design and conduct the best possible set of investigations, to deliver properly reduced and calibrated data to the scientific community, and to communicate these results to the general public. I propose to help carry out these first steps as a Participating Scientist in the Mars Pathfinder program. 2. Scientific Justification The abundance, form, and distribution of Martian surface minerals provide important constraints on the history of weathering and climate on Mars. Because they are often formed under unique environmental conditions, the most diagnostic minerals that can be used to assess the duration and magnitude of past climatic changes are ferric oxides/oxyhydroxides, sulfates, carbonates, and hydrates (e.g., Bell, 1996). Equally important in making climatic assessments from surface mineralogy is the ability to characterize the mineralogy of primary, unaltered crustal materials. The IMP CCD imaging experiment on the Mars Pathfinder mission will be able to detect, map, and quantify the abundances of many primary and secondary climatically-diagnostic mineral phases. This is because the IMP uses an optimized set of 12 narrowband "geologic" filters to obtain data at near-UV to near-IR wavelengths chosen to sample a wide array of mineral absorption features (Fig. 1) (Smith et al., 1996). For mineralogic studies, the IMP experiment is considerably more powerful than any of the experiments performed by Viking, and the "grab bag" nature of the Pathfinder landing site will allow for the sampling of a wider diversity of mineralogies, possibly including ancient Martian highlands materials, than either of the Viking lander sites. This section provides a brief background on the important scientific issues that can be addressed from measurements of Martian surface mineralogy, and provides a general overview of how IMP measurements could contribute towards tackling these issues. A more detailed description of the specific methods to be used in this investigation is presented in Section 3. Iron is the most spectrally active cation on Mars. The Martian crust and mantle have relatively high iron contents (e.g., Toulmin et al., 1977; Dreibus and WŠnke, 1985), and Fe-bearing minerals and alteration products exist in enough abundance to be detectable using remote sensing techniques. Almost all of the absorption features that have been detected on Mars and identified with specific mineralogies are due to electronic transitions within Fe3+ cations and charge transfers between these cations and O2- anions (e.g., Sherman et al., 1982; Sherman and Waite, 1985; Morris et al., 1985), or to electronic transitions within Fe2+ cations and charge transfers between these cations and Fe3+ (e.g., Burns, 1970; Adams, 1974). The center wavelength positions and bandpasses of the 12 IMP geology filters will allow for the detection of, and in many cases discrimination between, most of the major crystalline ferric oxides/oxyhydroxides, primary among which are hematite (a-Fe2O3) and goethite (a-FeOOH). As well, these filters provide the capability of discriminating between the well-crystallized ferric oxide/oxyhydroxide phases and the poorly crystalline or amorphous ferric materials like nanophase ferric oxide and ferrihydrite, materials that have been shown to be responsible for much of the visible to near-IR spectral character of terrestrial Mars analog materials like palagonite [e.g., Singer, 1982; Morris et al., 1990; Bell et al., 1993]. Examples of the spectra of well- and poorly-crystalline ferric oxides/oxyhydroxides are shown in Figure 1 at full resolution and convolved over the 12 IMP geology filter bandpasses. These two powerful capabilities (assessment of degree of crystallinity of surface minerals, and identification of specific, crystalline ferric minerals) provide the possibility of using the IMP data to place stringent constraints on the environments in which these minerals were formed and subsequently modified (Bell, 1992), depending on which specific minerals are found to occur in this region of the Martian surface. As an example, perhaps one of the most important mineralogic measurements that can be made by IMP is the ratio of hematite to goethite in the Martian surface materials. Hematite has been definitively identified in a wide range of particle sizes in groundbased and Phobos-2 Martian surface spectra (e.g., Bell et al., 1990a; Murchie et al., 1993), and goethite has possibly been detected, but only in Phobos-2 spectroscopic measurements at the highest-available spatial resolution (e.g., Geissler et al., 1993). On Earth, hematite is a thermodynamically stable end product in many different low- temperature weathering and higher-temperature thermal alteration environments [see, for example, Gooding, 1978; Schwertmann and Taylor, 1989]. The terrestrial hematite to goethite ratio is strongly influenced by climate, and there is little reason to suspect otherwise for Mars. Schwertmann and Taylor [1989] conclude that hematite and goethite form via two mutually competitive processes, and they identify the factors that control these processes: the rate of Fe cation release from various sources, the presence or absence of organic matter, soil pH and Eh, soil temperature, and soil water content. Hematite formation is favored over goethite under conditions of higher temperatures, lower water content, and lower organic matter content. In the current Martian environment of low temperature, low water content, high CO2 partial pressure, and low O2 partial pressure, hematite and maghemite (g-Fe2O3) are the thermodynamically stable Fe3+-bearing gas-solid surface weathering products rather than goethite or ferric-rich clays [O'Connor, 1968; Gooding, 1978; Gooding et al., 1992]. However, the oxyhydroxide or clay phases may be thermodynamically stable in the Martian subsurface [Pollack et al., 1970], and thus may be detectable from high resolution IMP imaging of regions disturbed by the lander or the Sojourner rover. If past climatic conditions on Mars included a warmer, wetter epoch, then ferric oxyhydroxides like goethite may have formed and been thermodynamically stable [e.g., Posey-Dowty et al. 1986]. However, such minerals and any ferric-bearing clays would not be stable under current Martian climatic conditions [Gooding, 1978; Gooding et al., 1992], and should decompose/dehydrate to hematite or maghemite where exposed at the surface. Thus, the water vapor partial pressure and/or the liquid water abundance control the hematite to goethite ratio on Mars. Detection and mapping of the spatial distribution of hematite and goethite is therefore an important way to assess whether Martian surface weathering products have reached thermodynamic equilibrium or possibly whether a past warm, wet epoch may have existed. The IMP filters will permit a thorough examination of this issue among the various units sampled at the outflow of the Ares/Tiu Valles. The existence, form, and distribution of other Fe3+-bearing phases on the Martian surface would also have significant implications for the history of climate and weathering (Bell, 1992). For example, the poorly-ordered Fe3+-oxide ferrihydrite (variously described as 5Fe2O3„9H2O, Fe5(O4H3)3, and Fe2O3„2FeOOH„2.6H2O; Schwertmann and Taylor, 1989) is an important precursor in the formation of hematite. It occurs in nature as small spherical aggregates (3-7 nm in size) and is basically a structural isomorph of hematite, except for minor c-axis variations, some substitution of O and OH by H2O, and some vacant Fe positions [Towe and Bradley, 1967; Schwertmann and Taylor, 1989]. Aggregation, dehydration, and structural rearrangement of ferrihydrite particles forms hematite. Ferrihydrite has a fairly distinct visible to near-IR spectrum, and IMP measurements should provide important constraints on its presence and abundance. Another poorly-ordered ferric phase considered as a possible Mars surface material is palagonite (Toulmin et al., 1977; Evans and Adams, 1979; Singer, 1982), a field name for a poorly crystalline mineraloid assemblage that forms from the weathering of basaltic glass. Recent laboratory studies of terrestrial palagonites have shown that their visible to near-IR spectral similarities to Mars arise from the presence of nanophase ferric oxide minerals in palagonite (e.g., Morris et al., 1989; Bell et al., 1993; Morris et al., 1993), and that palagonite itself is even more mineralogically diverse that originally thought, containing a wide variety of possibly spectrally- active phases like phyllosilicates, sulfates, and carbonates (e.g., Golden et al., 1993; Morris et al., 1996). Adams et al. (1986) and Guinness et al. (1987) analyzed Viking Lander multicolor reflectance data and noted that most of the soils are redder than most palagonites, suggesting that the soils may have a greater degree of ferric iron crystallinity. The IMP filters will provide substantially better spectral sampling of the 400 to 750 nm absorption edge in Mars surface spectra, and will allow for a direct assessment of the presence, relative abundances, and possibly identifications of poorly- and well- crystalline ferric phases. Magnetic measurements performed on the Martian surface by the Viking Landers led Hargraves et al. (1977) to conclude that the surface contained from 1-7% of a highly magnetic mineral, interpreted as fine-grained possibly slightly ferroan maghemite dispersed as a pigment throughout all surface particles. In a contemporaneous study using Viking Lander aerosol imaging data, Pollack et al. (1977) found that fine-grained magnetite (Fe3O4 as Fe2+Fe3+2O4) best match their derived imaginary index of refraction values. These authors also claimed that magnetite could explain the surface magnetic data of Hargraves et al. (1977). Resolving this controversy on the origin and form of the magnetic phase(s) in the Martian soils is one of the primary goals of the IMP Magnetic Properties Experiment (MPE) (Smith et al., 1996). In addition to specific magnetic measurements at higher precision than those performed by Viking, IMP multispectral imaging will be able to contribute substantially to the resolution of this issue. There are many additional ferric minerals that could be detected and characterized by IMP and which have important implications for the study of the origin and evolution of the Pathfinder landing site region and the Martian surface in general (e.g., Bell, 1992). Spectra of many of these materials are shown in Figure 1. Proposal length limits prevent a detailed discussion of all of these additional materials, but briefly they include: (a) nontronite and Fe3+-substituted montmorillonite clays, inferred to occur on Mars from normative calculations based on Viking XRFS soil chemical composition (Toulmin et al., 1977). These minerals have diagnostic (but non- unique) 400 to 1000 nm spectral features and are known to contain structural and/or adsorbed water and thus are potentially critical for the understanding of surface-atmosphere volatile interactions on Mars; (b) ferric sulfates like jarosite [KFe3(SO4)2(OH)6] or ferric carbonates like ankerite [Ca(Fe,Mn,Mg)(CO3)2] or siderite (FeCO3) which exhibit potentially-diagnostic 400 to 1000 nm spectral features and which could be important indicators of acidic groundwater systems, hydrothermal regimes, and/or sequestering of atmospheric volatiles (e.g., Burns, 1987; Burns and Fisher, 1990); (c) other less common ferric oxide/oxyhydroxide minerals, often having exotic and unique formation conditions and/or having unique spectral signatures. Examples include feroxyhyte (d'-FeOOH) (Burns, 1980), lepidocrocite (g-FeOOH) (Fuller and Hargraves, 1978; Posey- Dowty et al., 1986), and akaganeite (b-FeOOH) (Sherman et al., 1982); and (d) ferric-bearing silicates like actinolite, antigorite, and epidote that exhibit Fe3+ absorption features resulting from electronic transitions of Fe3+ cations or impurities in the mineral structure. Finally, it is critical to obtain high quality measurements of primary, unaltered surface materials in order to understand the starting materials upon which all subsequent weathering and alteration processes have acted. For Mars, these are the dark materials that have been shown to be basaltic in composition based on groundbased and Phobos-2 ISM spectroscopy and on inferences from Viking XRFS data (e.g., Toulmin et al., 1977; Singer et al., 1979; Mustard et al., 1993). Many of the dark volcanics measured by Phobos-2 were found by Mustard and Sunshine (1995) to be two-pyroxene basalts (high- and low-Ca, likely pigeonite and augite; Fig. 1) analogous to basaltic compositions found in several of the SNC meteorites, with the modal mineralogy of these pyroxenes varying across the surface regions measured. This observed variability further strengthens the need for detailed IMP measurements of the mineralogy of the unaltered volcanics in the vicinity of the landing site, not only in order to understand how the observed secondary minerals and other weathering products may have formed, but in order to gain a deeper understanding of the evolution of magma composition over Martian geologic time. 3. Methodology This section provides a detailed description of how the tasks described in Section 1 will be performed during this investigation: 3.1. Task 1: Optimizing IMP Sequences The IMP data rate and data set volume will depend critically on the performance and pointing accuracy of the high gain antenna, the actual amount of power available during mission operations, and on the availability, visibility, and performance of the 70 m or 35 m Deep Space Network stations. Many of these factors will of course not be known until operations begin from the Martian surface. Nonetheless, the IMP team has already developed an estimate of the best-case daily data volume of 69 Mbits per day (PIP Table 1 and Smith et al., 1996), which corresponds to 90 uncompressed 248“256 ("one eye") IMP images or only Å7 twelve-color image cubes per day. Given the 14.4”“14.0” field of view of IMP and the need to obtain panoramic images covering all azimuths and a wide range of elevations, it is clear that multispectral imaging using all of the geology filters at all times will not be possible. Thus, it will be necessary to prioritize the filters and to devise a set of observational sequences using the most diagnostic subset of the 12 geology filters for "survey mode" mineralogic investigations that can be later followed up by detailed imaging of selected areas in possibly all 12 filters. As a Participating Scientist, I will assist the IMP team in defining the nature of the initial survey-mode mineralogic measurements. The decision of which filters to be used first and in what order can be made based on our current knowledge of the Martian reflectance spectrum and on laboratory spectra of rocks and minerals that have either already been detected on Mars or that have a reasonable chance of being detected by IMP (Fig. 1). For example, it has been previously mentioned that determination of the Martian hematite to goethite ratio would provide useful data on the climate and weathering history of the surface. Examination of laboratory spectra of hematite and goethite (e.g., Morris et al., 1985; Fig. 1 upper left) reveals that the most diagnostic wavelength regions in which to make this comparison are from 500 to 600 nm, where the reflectance of hematite drops off more quickly than that of goethite, and from 750 to 950 nm, where the broad 6A1®4T1(4G) ligand field transition absorption band is centered near 860 nm in hematite and near 900 nm in goethite. Convolving a number of ferric and ferrous mineral spectra over the bandpasses of the IMP geology filters as in Figure 1 allows the filters to be ranked by sensitivity to spectral variations between minerals of interest. A preliminary ranking of the filters is presented in Table 1. There are likely CCD sensitivity and S/N issues, other engineering or operational constraints, and science issues (e.g., true-color imaging goals versus mineralogic mapping) that influence the order of priority of these filters, and as a Participating Scientist I will work with IMP team members to try to understand these constraints and fold them into the best possible filter prioritization scheme. The ultimate goal is to be able to say that if a scene can be imaged in only N < 12 filters, the N filters chosen (likely in the range 3 ² N ² 6) provide the maximum discriminability of surface mineralogy. This choice also applies to the selection of which filters from the initial 12-color stowed-position full panorama images, stored into memory early in the mission, are actually transmitted back to Earth. The process of making this choice is also relevant to the planned investigation of the mineralogy of Phobos and Deimos using IMP, although the specific choice of filters to use would likely be different than for Martian surface mineralogy, given the substantial differences between the spectra of Phobos and Deimos and that of Mars itself (Thomas et al., 1992). 3.2. Task 2: Reduction, Calibration, and Archiving of IMP Data Due to the large total volume of IMP imaging data anticipated for the primary and nominal missions, there will be a need to develop automated data reduction and calibration routines to take the raw data through a well-defined "pipeline" to yield calibrated, spatially- registered radiances. As a Participating Scientist, I propose to assist the IMP team in developing this calibration pipeline, testing it on pre- flight and early in-flight IMP data, applying it to the IMP data, and producing final data products and documentation in a form suitable to be archived in the PDS. The reduction pipeline will include corrections for bias and dark current, flatfield variations (from pre- flight and in-flight flatfield target measurements), stray light modeling/removal, a correction for electronic shuttering "smear", and correction for geometric distortions. The calibration pipeline uses the reduced data as input and will include determination of absolute responsivity values using pre-flight and in-flight calibration coefficients derived from radiance, reflectance, and color standards, corrections for temperature-sensitive spectral response variations, mapping of pixels onto a standard projection grid so that mosaics can be generated and the photometric geometry of each pixel can be determined, and (optionally) application of photometric corrections using simple surface models (Lambert, Minnaert, Hapke). I have considerable experience dealing with similar data reduction and calibration exercises from groundbased and HST telescopic imaging (Bell and Crisp, 1993; Bell and Hawke, 1995; James et al., 1996; Bell et al., 1990b, 1992, 1996a,b) as well as most recently with the reduction and calibration of imaging data from the NEAR mission (Veverka et al., 1996). Some of the algorithms and routines that I have designed to perform image reductions and calibrations may prove useful to the IMP team, although I suspect that much of the pipeline described above is already in place at this late date, and so most of my effort on this task will likely involve testing and refinement of the team's existing reduction/calibration software. It is worth noting that the 3-color aft camera on the Sojourner rover may be able to provide unique data complementary to the IMP measurements. While the rover color camera bandpasses are not optimized for mineralogy, its three green (540 nm), red (650 nm), and "infrared" (750 nm) filters will allow for the gross characterization of visible spectral slope, and thus degree of crystallinity and possibly hematite/goethite discrimination (Fig. 1), at a spatial scale exceeding that of the IMP. The ability to accurately calibrate the rover color camera images is not discussed in the PIP, although it is noted that the infrared response is quite low. I think it would be worthwhile investigating whether or not IMP observations, or rover observations of IMP calibration targets, can be used to derive a calibration of the rover color camera and thus enhance the amount of useful mineralogic information obtained by the mission as a whole. 3.3. Task 3: Mapping Mineralogy at the Landing Site It will be critical to carry out "quick-look" analysis and interpretation of the early IMP results in order to (a) refine IMP data collection sequences to take advantage of the specific geology and mineralogy of the Pathfinder landing site; (b) provide input to the rover APXS investigation as to the location of the most promising sites to explore in greater detail; and (c) effectively communicate the early mission results to scientific colleagues and the general public. As part of this quick-look effort, I propose to generate maps of the distribution and abundance of a number of key surface materials that will be sought by the IMP experiment. Materials mapped will include hematite, goethite, pyroxene (possibly in a range of Ca contents), and nanophase ferric oxide. It may also be possible to produce maps of olivine, ferric sulfates, ferric carbonates, or any of the less common iron oxide/oxyhydroxide phases (Fig. 1) depending on the nature of the landing site. Careful observations of the IMP magnetic targets may provide a way to also produce a "magnetic map" of the landing site based on the spectral character of the magnetic phases that adhere to the test magnets. All of these maps will be produced using a subset of the initial reduced and calibrated data discussed above and a combination of analysis techniques, including: color ratio, curvature index, and relative band depth generation (Guinness et al., 1987; Bell and Crisp, 1993), correlation plots and principle components analysis (Arvidson et al., 1982; Bell, 1992), spectral mixture modeling (Adams et al., 1986; Bell, 1992, Bell and Hawke, 1995), as well as traditional and modern band-fitting and other spectrum analysis tools (e.g., Clark and Roush, 1984; Lucey et al., 1986; Sunshine et al., 1990). 3.4. Task 4: Initial Interpretation of IMP Mineralogic Results Along with the quick-look data products described above, it will be important for the IMP team to provide a fairly rapid initial interpretation of many of the results that are obtained. While it is generally more prudent to adopt a careful, methodical approach to data interpretation in science, there is a good reason in this case why a rapid initial interpretation of the IMP data would be useful: this is the desire to be able to react to surprises or unique observational opportunities during the relatively short lifetime of the mission. Initial interpretations of the data will likely quickly converge on a number on controversies, many of which may be testable with additional IMP or other lander/rover instrument measurements or operations. As a Participating Scientist I will provide input to the IMP team on initial interpretations of the data. Examples of specific contributions might include assessment of the geologic and/or climatic history of the Ares/Tiu Valles landing site based on the observed mineralogy of this grab-bag site (see Section 2 above), and extension of the IMP results to a more regional and global context using comparisons with previous and contemporaneous groundbased and HST imaging and spectroscopic observations in the visible and near-IR as well as (during the nominal mission) MGS MOC and TES data of the Pathfinder landing site region. For example, IMP investigations of atmospheric aerosol opacity could be substantially enhanced by folding in global synoptic observations of atmospheric dust and clouds obtained prior to and during the primary and nominal missions, as part of the Marswatch monitoring program. The geologic/climatic history of the Pathfinder landing site may be easier to understand when compared with visible through mid- IR high resolution HST, MOC, and TES mineralogic/compositional measurements of the regions surrounding the landing site. 4. Data Required for the Investigation This investigation will require access to the multispectral imaging data from the IMP experiment, including the results of the magnetic properties experiment part of IMP. This investigation will also require access to the pre-flight IMP calibration results, both at the instrument integration level (thermal vacuum testing) and piece-part component level. As outlined above, this investigation involves a close collaboration with the IMP team in the generation of the best possible data products. It is also possible that access to the Sojourner rover aft color camera data may provide additional unique data to assist in this investigation, depending on the ultimate ability to calibrate the rover camera data and to effectively use the infrared channel. The data required for placing the IMP measurements into a more global context will come from ongoing HST and groundbased observations. I am a Co-Investigator on two ongoing HST Mars imaging investigations (P.B. James, D. Crisp, PI's), and am thus involved with the production of the calibrated HST data required for this proposal. I have also been granted telescope time on the NASA IRTF to obtain the near-IR (1500-4200 nm) imaging spectroscopic data mentioned above, and will be participating in planned groundbased CCD imaging of Mars from Lowell Observatory during the course of the Pathfinder mission. Finally, the PI is the organizer of the "Marswatch" amateur-professional collaboration project (http://astrosun.tn.cornell.edu/marsnet/mnhome.html), and as such will have access to public-domain images and other data obtained by professionals and highly-skilled amateurs that may prove relevant to this proposed investigation. 5. Justification of Proposed PS Role 5.1. Operational Roles I propose to get deep into the nuts and bolts operation of the IMP experiment in order to use my previous experiences with groundbased and spacecraft imaging investigations to provide real-time operational advice and input to the IMP team. I anticipate spending a substantial amount of time at JPL during the primary and nominal missions as part of this interaction. I am proficient and comfortable with computers and laboratory test/calibration equipment, and I have some relevant (ongoing) experience with mission operations, management, and sequencing tasks. 5.2. Data Products to be Produced and Archived I am proposing to assist the IMP team at whatever level is possible/practical/desired in the reduction and calibration of all of the primary and nominal mission data with relevance to geology and surface mineralogy. In this proposal I describe only one set of specific data products for which I am prepared to assume personal responsibility for their production and archiving: maps of the distribution and abundances of specific minerals and other materials as outlined in Section 3.3. 5.3. Why can't this investigation just rely on postmission data access? The key to this investigation is generating the initial "survey mode" IMP multispectral observations in just a few (likely 3 ² N ² 6) well- chosen filters, because there is simply not enough downlink capacity to image all regions in all 12 geology filters. I would provide my experience in spectroscopy of ferric and ferrous minerals to the IMP team in their efforts to generate observing sequences using a small number of filters that provide the maximum ability to discriminate among a wide variety of potential minerals. These initial survey observations would be quickly reduced, calibrated, and interpreted, allowing more detailed follow-on imaging observations (possibly using all 12 filters) of specific regions exhibiting interesting or enigmatic spectral variability. The initial survey mode observations could also prove extremely useful to other Pathfinder experiments, such as the APXS, which will want to make the best possible use of a limited number of measurement opportunities. 6. Existing Facilities and Equipment The PI is a member of the research staff in the Cornell Center for Radiophysics and Space Research (CRSR), in the Department of Astronomy. CRSR is housed in the Space Sciences Building, with close access to the physics and chemistry buildings and to the Cornell National Supercomputer Facility. The Space Sciences Building is well-appointed with numerous laboratories and computer work rooms. It has its own computer network consisting of desktop workstations connected to two central servers, and houses a number of work spaces designated for NASA-sponsored projects, including several managed by the PI and devoted to planetary image and spectral processing. Major image processing efforts are currently ongoing in CRSR dealing with the Magellan, Galileo, Mars Global Surveyor, and NEAR missions, as well as with numerous HST data sets. These projects involve use of about a dozen powerful graphics workstations, including DEC VaxStations, IBM RS/6000 workstations, HP Workstations, and Sun SPARC 2, SPARC 20, and Ultra workstations. Several devices are available for publication-quality production of image hardcopies. CRSR administrative offices assuring personnel, budget, accounting, and purchasing support are also located in the building. The in-house administrative facilities are connected to a network of administrative organizations typical of a large research university. Table 1. Example "Mineralogy Oriented" Prioritization Scheme for IMP Geology Filters Rank Center (nm) Justification 1 530 Edge of deep near-UV absorption in hematite, d-FeOOH 2 480 Edge of deep near-UV absorption in goethite, lepidocrocite 3 750 Local maximum/continuum point for ferric oxides/oxyhydroxides 4 860 Near center of 6A1®4T1(4G) Fe3+ electronic transition in hematite 5 900 Near center of 6A1®4T1(4G) Fe3+ electronic transition in goethite 6 670 Near center of 6A1®4T2(4G) Fe3+ electronic transition in oxides 7 930 Center of "1-µm" Fe2+ band in low-Ca clinopyroxene (e.g., pigeonite) 8 965 Refinement of 1-µm Fe2+ band shape, ferric/ferrous band unmixing 9 1000 Center of "1-µm" Fe2+ band in high-Ca clinopyroxene; olivine detection? 10 440 Near center of 6A1®4E,4A1(4G) Fe3+ electronic transition in oxides 11 800 Refinement of 6A1®4T1(4G) Fe3+ electronic transition band shape 12 600 Local maximum.continuum point for 6A1®4T2(4G) Fe3+ band References Adams J.B. 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