Deeg H. and Ninkov Z.  "Deep CCD
Photometry and the Initial Mass Function of the Core of the OB Cluster
Berkeley 86", Astronomy and Astrophysics, vol. 119, 221
Corba M., Ninkov Z., Backer B., Wu M.  "Photon-counting system with intensified CID : Preliminary Results", SPIE Proceedings 2654, 35
Backer B., Ninkov Z., Corba M., Libonate S.  "Characterization of a CID-38 Charge Injection Device", SPIE Proceedings 2654, 2
Ninkov Z., Bretz D., Easton R.L. and Shure M.  "Imaging of the Central Region of IC 1805", Astronomical Journal 110, 2242
Dyar M.D., Treiman A., Beauchamp P., Blake D., Blaney D., Kim S., Klinelhoefer G., Mehall G., Morris R., Ninkov Z., Sprague A., Zolensky M., Pieters C.  Planetary Surface Instrument Workshop, LPI Technical Report 95-05, Lunar and Planetary Institute, Houston (also available at http://cass.jsc.nasa.gov/publications/psiw/psiw7.html)
Corba M. and Ninkov Z.  "Modular Architecture for Real-Time Astronomical Image Processing with FPGAs" , Lecture Notes in Computer Science Volume 975, Field Programmable Logic and Applications, ed. Moore & Luk, vol. 975, 362 (also submitted to I.E.E.E. Systems and Circuits)
Olson J., Jungquist R. and Ninkov Z.  "Tunable Multispectral Imaging System Technology for Airborne Applications", SPIE Proceedings 2480, 268
Backer B., Ninkov Z., and Cirillo W.  "First Order Image Correction using a CID Array", SPIE Proceedings 2416-14
Deeg H. and Ninkov Z.,  ''Characterization of a Large Format CCD Chip'', Optical Engineering, Vol. 34 (1), 43
Savakis A, Ninkov Z and Easton R. L.  " Screen-CCD Imaging System for Real-Time Mammography", Proceedings of the 2nd International Digital Mammography, York, England, Elsevier Press pp. 199-208
Ninkov Z. Tang C., Backer B., Easton R.L., and Carbone J. , " Charge Injection Devices for Use in Astronomy", SPIE Proceedings 2198, 868
Ninkov Z., Tang C., Easton R.L. , " Evaluation of a Charge Injection Device Array", SPIE Proceedings 2172, 15
Ninkov Z . , " A Near Stellar Occultation of P/Grigg-Skjellerup",  Astronomical Journal 107, 1182
Ninkov Z., Backer B., Bretz B. , " Performance of a 2K x 2K MPP CCD for Low Light Astronomical Imaging", SPIE Proceedings Vol. 1987, 2
Nadeau D., Yee H.K.C., Forrest W.J.,Garnett J.D., Ninkov Z., Pipher J.L., , " Infrared and Visible Photometry of the Gravitational Lens System 2237+030", Astrophysical Journal 376, 430
Forrest W., Pipher J., Ninkov Z., Garnett J., , "InSb DRO Array Characteristics", Proceedings of 3rd IR Detector Meeting, ed. C. McCreight, NASA Technical Memorandum 102209, 157
Forrest W.J., Ninkov Z., Garnett J.D., Skrutskie M.F., Shure M., , "Discovery of Low Mass Objects in Taurus", Proceedings of 3rd IR Detector Meeting, ed. C. Mcreight, NASA Technical Memorandum 102209, 221
Forrest, W. J., Garnett J. D., Ninkov Z., Skrutskie M., Shure M. , "Discovery of low-mass brown dwarfs in Taurus", P.A.S.P., 101, 877
Yang S., Ninkov Z., Hill G., Walker G.A.H.,, "New Emission Lines in the Spectra of O and Of Stars", Publications of the Astronomical Society of the Pacific 99, 284
Yang S., Ninkov Z., Walker G.A.H. , " Nonradial Oscillations of the Be Star Gamma Cassiopeiae", Publications of the Astronomical Society of the Pacific 100, 233
Ninkov Z., Walker G.A.H., Yang S., , " The Primary Orbit and Absorption Lines of HDE 226868 (Cygnus X-1) ", Astrophysical Journal 321, 425
Ninkov Z., Walker G.A.H., Yang S., , " The He II 4686 and H alpha Emission Lines of Cygnus X-1", 1987, Astrophysical Journal . 321, 438
Ninkov Z., Pipher J.L., Forrest W.J., , " Results of Testing 58 x 62 InSb Array Detectors ", in "Infrared Astronomy with Arrays", ed. C.G. Wynn-Williams and E.E. Becklin, page 37
Zealey W.J., Ninkov Z., Rice E., Hartley M., Tritton S.B., , "Cometary Globules in the Gum Vela Complex ", Astrophysical Letters 23, 119
Hickson P., Ninkov Z., Huchra J.P., Mamon G., , " The Structure of Compact Groups of Galaxies ", in ' Clusters and Groups of Galaxies ', Ed. F.Mardirossian, G. Giuricin, M. Messetti [Reidel]
Ninkov Z., Walker G.A.H., Yang S., , " Rapid Variations in Gamma Cas and Zeta Oph", 1983, Hvar Observatory Bulletin (Workshop on Rapid Variability of Stars) 7, 167
Hickson P., Fahlman G.G., Auman J.R., Walker G.A.H., Menon T.K., Ninkov Z., , "CCD Photometry of Markarian 421 and 501", Astrophysical Journal 258, 53
Brown R.D., Godfrey P.D., Crofts J., Ninkov Z., Vaccani S., , "Molecular Ion Fluorescence Excitation Spectrum from an Ion Beam ", Chem. Phys. Letters 62, 195
Invited Review Paper
"Absolute long term photometric stability of CCDs", Transits of Extrasolar Planets (TEP) Meeting, Paris, March 1995
"Large Format CCD Imaging at Mauna Kea", Astronomical Society of New York 25th Annual Meeting, Cornell University , April 25, 1992
"A Review of IR Array Detectors", 1988, International Astronomical Union (IAU) General Assembly, Baltimore, USA
Doyle L.R., Jenkins J.M., Deeg H.-J., Martin E., Schneider J., Chevreton M., Paleologou E., Kylafis N., Lee W. -B., Dunham E., Koch D., Blue E., Toublanc D., Ninkov Z., Sterken C.  " Observations for Extra Solar Planets", Division of Planetary Science Annual Meeting #28, Hawaii
Schneider J., Chevreton M., Deeg H., Doyle L., Lee W.B., Martin E., Paleologu E., Ninkov Z., Sterken C. , "The TEP (Transits of Extra-Solar Planets) Network", Conference on Detection and Study of Extra-Solar Planets, University of Colarado, Boulder, May 15-17, 1995
Bretz D., Ninkov Z.  " The Initial Mass Function of IC 1805", B.A.A.S 25, 3
Ninkov Z.  '' Results from a near Stellar Occultation by P/Grigg-Skjellerup'' BAAS 24, 1126
Meisel D., Schulitz F., Lacasse M., Ninkov Z.  '' More Observations of Hubble's Variable Nebula NGC 2261'', BAAS 24, 1246
Ninkov Z., Easton R.L., Enge J.  '' H3+ Imaging of Jupiter'', American Astronomical Society Meeting 179th Meeting, January 12-16 1992, Atlanta
Forrest W.J., Ninkov Z., Garnett J.D., Skrutskie M.F., and Shure M. , " Discovery of Low Mass Objects in Taurus", 1990 Proc. of the 24th Yamada Conference : Strongly Coupled Plasmas, ed. S. Ichimaru (Holland, Elsevier Science Publishers B.V.) p. 33
Nadeau D., Yee H.K.C., Forrest W.J., Garnett J.D., Ninkov Z., Pipher J.L. , " Imaging and Photometry of the Gravitational Lens 2237+030", NOAO/KPNO Conference on "Astrophysics with IR Arrays", Tucson, Arizona, February 1990
Nadeau D., Yee H.K.C., Forrest W.J., Garnett J.D., Ninkov Z., Pipher J.L., , " IR Imaging and the Light Curve of 2237+030", Toulouse Workshop on Gravitational Lensing (September 1989)
Forrest W, Ninkov Z., Garnett J., Skrutskie M., Shure M., June 1989, AAS 174th Meeting, Ann Arbor, " Discovery of Brown Dwarfs in Taurus "
Ninkov Z. and Forrest W.J.  " Material Science Limitations on IR Imaging", Meeting on Chemistry and Material Science Aspects of Imaging Science, American Chemical Society Meeting, November 1989, Rochester NY
Ninkov Z., " Observations of the Nucleus of NGC 2903", Proc. Astronomical Society of New York, 1986, vol II, number 10, 17
Walker G.A.H., Ninkov Z., Yang S., "On the Absence of Balmer Line Emission in Vega", 1984, Be Star Newsletter
Ninkov Z., Walker G.A.H., Mochnacki S.  " The Nucleus of NGC 2903", Canadian Astronomical Society Annual Meeting, May 1984
Vaccani, Brown R.D., Crofts J., Ninkov Z., Godfrey P.D. , ''Construction of an Ion Beam Spectrometer for Microwave Optical Double Resonance'', 11th Australian Spectroscopy Conference, Brisbane
Research featured in December 1993 issue of Laser Focus World.
Research documented in feature article in the New York Times June 16, 1989, Section IV (Science Reviews), page 16.
Papers in Preparation
Ninkov Z. "Shapes of O-star Multiple Systems", in preparation for the Astronomical Journal.
Ninkov Z. and Bretz D. ''Near-Infrared Colors of Early Type Main Sequence Stars'', in preparation for the Astronomical Journal.
Wu M.M. and Ninkov Z. ''Read-out Techniques for CID Arrays'', in preparation for Optical Engineering (paper held pending Patent submission).
Backer B. and Ninkov Z. " Tip-Tilt correction with CID arrays", in preparation for Publications of the Astronomical Society of the Pacific.
Kavaldjiev D. and Ninkov Z. "First measurements of the sensitivity within CCD Pixels", for Optical Engineering
Books in Preparation
Preparation of book provisionally entitled ''Solid State Imaging Principles''.
Deep CCD photometry and the initial mass function of the core of the OB cluster Berkeley 86
H.J. Deeg and Z. Ninkov
Rochester Institute of Technology, Center for Imaging Science, Rochester, NY 14623, U.S.A. Instituto de Astrofisica de Canarias, Via Lactea s/n, 38200 La Laguna, Tenerife, Spain email: firstname.lastname@example.org, email@example.com
Astronomy and Astrophysics Supplement Series, Vol. 119, October II 1996, 221-230
Based on photometry of deep CCD frames of the central region of the OB cluster Berkeley 86, we derive the cluster mass function. The absence of current star formation, and the cluster's young age of about 6 Myrs, leads to the conclusion that the initial mass function (IMF) and the current mass function are identical for stars with m < 10 . In the range of , an IMF with a slope of is found. This value agrees well with other recent determinations of young clusters IMFs which are close to the classical Salpeter IMF with . Sections of the IMF of Berkeley 86 that are significantly steeper, or flatter, are most likely the result of a dip in the star's mass distribution in the range of . Similar dips may have led to steep IMFs over narrow mass ranges, as reported in the literature for some other clusters. No sign for a low mass turn-over in the IMF of Berkeley 86 is found for masses extending down to 0.85 .
Preliminary results with a CID-based photon counting system
CORBA, MASSIMILIANO; NINKOV, ZORAN; BACKER, BRIAN; WU, MINMING; SLAWSON, BOB
(Rochester Institute of Technology)
Proc. SPIE Vol. 2654, p. 310-316, Solid State Sensor Arrays and CCD Cameras, Constantine N. Anagnostopoulos; Morley M. Blouke; Michael P. Lesser; Eds. Publication Date: 03/1996
A photon counting system, utilizing a CID as the imager sensor, is under development at RIT. The system integrates a programmable, DSP based driver system capable of generating fast readout and sub-array dynamic control sequences. A high speed event recognition and centroiding computation task is performed by a dedicated board, based on field programmable gate array technology, which provides the necessary spatial resolution while maintaining high data throughput capability. The system architecture is flexible and capable of handling different CID array architectures and sizes. Preliminary performance results are presented, and characteristics of CIDs, such as subarray injection, that impact the total possible throughput, and therefore, the dynamic range, are discussed.
Characterization of a CID-38 charge injection device
BACKER, BRIAN; NINKOV, ZORAN; CORBA, MASSIMILIANO
(Rochester Institute of Technology)
Proc. SPIE Vol. 2654, p. 11-19, Solid State Sensor Arrays and CCD Cameras, Constantine N. Anagnostopoulos; Morley M. Blouke; Michael P. Lesser; Eds.
Charge coupled devices have been the dominant solid state detector array in the visible due to their relatively simple design and easy implementation. With recent advances in lithographic techniques, arrays having smaller photosite dimensions and an increased number of pixels have become available. Further advances in large format CCDs have been limited by charge transfer efficiency (CTE) of photoelectrons to the readout amplifier. The increased number of pixel transfers in large arrays can degrade image quality and MTF unless even higher CTEs are achieved. Multiplexer designs that remove the need for thousands of charge transfers can bypass these CTE limitations. One such focal plane architecture is the CID or charge injection device. This paper presents results obtained with one particular CID based system. The array is housed in a dewar capable of liquid nitrogen operation. The output signal from the array is amplified with a nearby low noise preamplifier before digitization. Results on injection efficiency, readout noise, and other pertinent CID parameters, are presented obtained from this device preamplifier as well as specific experiments.
PLANETARY SURFACE INSTRUMENT WORKSHOP
Convened and Edited by Charles Meyer, NASA - Johnson Space Center Allan H. Treiman, Lunar and Planetary Institute Theodor Kostiuk, NASA Headquarters. Held at Houston, Texas May 12-13, 1995. Sponsored by the Lunar and Planetary Institute 3600 Bay Area Boulevard Houston, TX 77058-1113
LPI Technical Report Number 95-05 LPI/TR 95-05 This report may be cited as: Meyer C., Treiman A. H., and Kostiuk T., eds. (1995) Planetary Surface Instrument Workshop, LPI Tech. Rpt. 95-05, Lunar and Planetary Institute, Houston.
Table of Contents
I. Introduction to Report
II. Summary of Report
III. Precise Chemical Analyses
IV. Isotopic Analyses and Evolved Gases
V. Planetary Interiors
VI. Atmospheres from Within
VIII. Carbon-Based Compounds and Exobiology
IX. Regoliths in 3-D
X. Field Geology / Processes
Part 7. MINERALOGY
M. Darby Dyar, Allan Treiman, Patricia Beauchamp, David Blake, Diana Blaney, Sun S. Kim, Goestar Klingelhoefer, Greg Mehall, Richard Morris, Zoran Ninkov, Ann Sprague, Michael Zolensky, Carle Pieters
Lunar and Planetary Institute, Tech. Rep. 95-05
Minerals are described and defined not only by the elements they contain, but by the positions of the atoms relative to each other in their structures. Strictly speaking, minerals must be naturally occurring crystalline solids, since only crystalline materials can have stoichiometric elemental compositions and only crystalline materials can be phases in the thermodynamic sense, and can be placed on a stability diagram. The power of mineralogical analysis as a descriptive or predictive technique stems from the fact that only a few thousand minerals are known to occur in nature (as compared to several hundred thousand inorganic compounds), and all have specific stability ranges in pressure, temperature and composition (PTX) space. A specific knowledge of the mineralogy of a planet's surface or interior therefore allows one to characterize the present or past conditions under which the minerals were formed or have existed. Thus, mineralogical studies are extremely well suited for characterization of planetary histories. For the purposes of this chapter, we will choose to adopt a slightly broader definition of mineralogy by including not only crystalline materials found on planetary surfaces, but also ices and glasses that can benefit from in situ types of analyses.
Because minerals make up the small-scale constituents of rock, they can best be studied by using in-situ measurements. In situ mineralogical observations provide significant advantages over remote observations for several reasons. Perhaps the most important is that the variety of mineral-specific, mineral-sensitive techniques can be used. This permits better constraints on mineral identification and relative abundances than can be obtained from remote sensing. In situ measurements are made at spatial resolutions not obtainable from orbit. Mineral identification, abundance and spatial distribution are essential for understanding formation and weathering processes.
In keeping with the theme of this volume, this chapter addresses the instrumentation needs for planetary surface exploration through two avenues. In the first section, 13 analytical techniques for mineral analysis and identification are presented, including estimates of state of the art precision and current implementations of each method (Table 7.1a and Table 7.1b). A brief discussion of the scientific background for each technique is presented, along with a reference list for further information of the topics tabulated here. It is hoped that this section will provide a background reference for future mission planning and instrument development.
In the second section of this chapter, mineralogical problems that can be studied with these methods are addressed. The types of mineralogical questions that can be answered on different planetary surfaces vary widely according to the type of body being studied. Due to the need to customize instrumentation for various conditions, this section is subdivided according to three different body types: primitive bodies, differentiated bodies without atmospheres, and differentiated bodies with significant atmospheres (Table 7.2a, Table 7.2b, Table 7.3, and Table 7.4). Furthermore, the mineralogical questions are organized according to the types of planetary processes they address. Mineralogical studies can be used to constrain a number of planetary processes that are highlighted here: condensation, differentiation, volcanism, impact cratering, physical weathering, chemical weathering, and metamorphism. Tables in this section summarize which types of mineralogical instrumentation are needed to address which types of processes on each type of extraterrestrial body. Again, these tables are constructed to provide easy references to the instrumentation needed to address body-specific planetary processes from a mineralogical perspective.
1. Visual Imagery at Micro-Scales
Visual examination is among the most rapid and powerful tools for mineral identification, but is easily overlooked amid the plethora of "high-tech" spectroscopies available for robotic probes to planetary surfaces. Visual examination is the first step in mineral identification. It is taught to beginning geology students, used by professional mineralogists and petrologists in nearly all phases of investigation, and is almost always applied before more detailed or quantitative techniques (like electron microscopy, X-ray diffraction, etc.). Visual mineralogy has an honorable history in planetary exploration; it was the principal mineralogic tool on the Apollo missions and led directly to important discoveries, like "Genesis Rock" anorthosite found by the Apollo 15 astronauts. Unfortunately, robotic imaging instruments on past probes to planetary surfaces (Surveyor, Viking, Venera, VEGA) were not useful for mineralogy because their spatial resolution was too poor.
Visual examination as a mineral identification tool relies on the optical reflection properties of mineral surfaces. In effect, these properties are observed, and the observations compared with a huge database of similar observations on all known minerals (terrestrial, meteoritic, and lunar). The comparison can be broadened to include all inorganic and organic substances and glasses. Visual examination is usually performed with some magnification because most mineral grains in rocks are too small for naked-eye examination. In the laboratory, binocular microscopes are the visual instruments of choice. In the field where space, weight, and convenience are at a premium, a hand lens of 5X - 15X is the preferred tool for visual mineralogy.
The properties usually observed in visual examination are color, cleavage, fracture, luster, and habit. The property color is obvious; the human eye acts as an imaging three-color spectrometer, and can be trained to recognize subtle color differences that are strong indications of mineral identity. Fracture characterizes the morphology of broken mineral surfaces: smooth, irregular, conchoidal, etc. Many mineral species break along well-defined crystallographic directions; this property is cleavage. The number of cleavage planes, the ease with which the mineral breaks, and other structures revealed by cleavage can be indicative or conclusive mineral identifiers (e.g., the characteristic lamellar twinning in plagioclase feldspar is best observed by the orientations of cleavage surfaces on individual twin lamellae). Luster describes the reflective properties of the surface, e.g., dull, glassy, resinous, adamantine (diamond), etc. Habit refers to the shape of a mineral grain; in many geological settings, minerals grow in characteristic shapes or crystal forms, which can be useful in their identification. These properties alone, along with some sense of the regional geological setting, are usually enough to allow mineral identification to at least group level. Equally important, that the habits and relationships among mineral grains, their parageneses, can be characteristic of their conditions of formation and can constrain mineral identification. For instance, a white mineral associated with olivine could likely be plagioclase but would not likely be wollastonite.
A visual mineralogy system for a robotic probe to a planetary surface involves five elements: a source of illumination; a light input element, (e.g., lens or aperture); a mobility system which allows the input element to be positioned close to the target sample; a light transfer path from the input system to the imaging sensor; and an imaging sensor element, which converts the optical image to electrical signals for storage/transmission. Each of these elements can be implemented in many ways.
A functional implementation is the Mikrotel instrument, which has demonstrated the feasibility and usefulness of such imaging system (Jakes, 1992; Jakes and Wanke, 1993; see also Part 10 on Field Geology). The Mikrotel incorporates the whole system except the mobility element in a single hardware unit; mobility is provided by a robot arm or moving vehicle (e.g., Nanokhod, see Rieder et al., 1995) which positions the hardware unit over the surface of interest. The target scene is viewed through a magnifier lens group as the light input element; the choice of magnification depends on detail to be imaged (i.e., grain size of the soil or rock), and is adjustable to trade off depth of the focus and resolution. Light travels from the magnifier lens group to a commercial 3-color CCD television camera through ambient atmosphere. The Mikrotel system produces good, European TV-quality (PAL) images of rock and sand surfaces and allows identification of mm-sized mineral grains. The Mikrotel system offers great flexibility, allowing different magnifications, imaging sensor elements, and data recording devices. In addition, the Mikrotel could be used as an imaging spectrometer if it had sensors active into near-IR wavelengths and tunable monochromatic light sources.
It is not known if the Mikrotel system is the most advantageous for robotic planetary instruments, because there have been no trade studies on possible element implementations. However, the success of the Mikrotel system appears to validate the general concept of a robotic "hand lens" as a remote system for mineral identification.
A visual mineralogy system cannot answer all questions relating to the mineralogy of planetary surfaces, but will provide rapid identifications of common minerals, rapid constraints on less common minerals, and rapid guidance about which samples would yield the most return from analyses by more quantitative methods. Visual mineralogy also will supply critical constraints to assist in interpreting the results of more quantitative analytical methods (e.g., X-ray diffraction, IR reflection spectroscopy). A visual hand lens system is important or critical to field geology and regolith studies (see these respective chapters), and so appears to be among the highest priorities for development of planetary surface instruments.
2. X-ray Diffraction Analysis
Minerals can be characterized by a variety of analytical techniques, the most definitive and widely used (on Earth) being X-ray Diffraction, XRD (Klug and Alexander, 1974; Bertin, 1978; Brindley, 1980). X- ray diffraction utilizes two unique properties of X-rays: first, that they interact with atomic nuclei, and second, that their wavelengths are of the same order of magnitude as the distances between atoms in crystalline solids (~0.5-15 Angstroms). A significant proportion of X-ray photons that strike a solid are absorbed and re-emitted without energy loss as a spherical waves centered on individual atoms. Statistically large numbers of these X-rays constructively and destructively interfere, producing (for crystalline materials) maxima at specific angles relative to the incoming X-ray photons. A tabulation of the angles and intensities of all possible diffraction maxima in four directions specifies the structure of the crystalline solid. Because X-ray photons interact with the nuclei of sample atoms, the diffraction technique is independent of chemical bonding or valence effects. The analysis is characteristic of the bulk properties of the solid, since diffraction occurs throughout regions hundreds to thousands of cubic microns in volume. Some of the most powerful diffraction techniques, such as single crystal X-ray diffraction, are not amenable to a remote instrument due to sample preparation limitations or the extreme specificity of the result. However, the technique of powder X-ray diffraction is a valuable and general technique which can be used to characterize the complex mixtures typically found in the natural environment.
In X-ray diffraction, a collimated beam of monochromatic X-rays is directed at a sample of unknown material. Some of the incident X-rays are diffracted by the crystalline structure of the material; the diffractions' angles yield the interplanar spacings of the crystalline material are determined using Bragg's law, nl = 2dsinq, where l is the wavelength of the X-radiation, d is the interplanar spacing within the crystal, and q is the quarter-angle of the cone of diffracted beams emanating from the sample. The resulting list of d-values (interplanar spacings) and diffracted intensities can be compared to equivalent listings from standards (published in computerized data bases such as the ICDD powder diffraction file) to provide a definitive match. In cases where a mixture of minerals is analyzed, various methods are available to strip out maxima from individual minerals in sequence (Chung, 1974a,b; Bish and Chipera, 1988; O'Connor and Raven, 1988; Howard and Preston, 1989; Jones and Bish, 1991). It is even possible to obtain complete mineral structures (all atom positions) from powder XRD patterns (Bish and Howard, 1986, 1988; Snyder and Bish, 1989; Bish and Post, 1993).
Powder X-ray diffraction is limited as to sample type and geometry:
1. Many crystals must be exposed to the X-ray beam simultaneously. The X-ray beam (whether from a radioactive or electrical source) is typically less than about 1 mm in diameter, so the target crystals must be small. If the target material is fine grained (e.g., wind-blown dust, soil), it may be analyzed without preparation. If the target material is coarse-grained (> 50 micrometers), its grainsize must be reduced, e.g. by a a drill or grinder. Alternatively, a small single crystal can be precessed through a large number of random orientations relative to the beam. 2. Results of X-ray diffraction results may not be representative of a rock or rock unit. XRD analysis of a hand sample, even if finely polycrystalline, will characterize only its outermost hundred microns (approximately). Unless the sample is broken or abraded to expose fresh surfaces, the XRD analytical volume may thus include weathering rind and powdered soil. Preferred orientation of crystals within a rock may render a rock sample unsuitable for quantitative or even qualitative analysis.
3. Mössbauer spectroscopy
Mössbauer spectroscopy makes use of the resonance absorption of recoil-free emitted gamma-rays (the Mössbauer effect) by certain nuclei in a solid to investigate the splitting of nuclear levels that is produced by interaction with its surrounding electronic environment. Resonance absorption and emission take place only under certain favorable conditions, for instance when the absorbing (or emitting) atom is bound in a crystal lattice. In general, the nuclear energy levels of the source and absorber will be different because of different oxidation states and/or chemical environments. To achieve resonance conditions, the energy of the emitted gamma-quanta has to be modulated. This is done by using the Doppler effect by mounting the source on a velocity transducer and moving it with respect to the absorber. A Mössbauer spectrum thus is the measurement of the rate of resonance absorption as a function of the relative velocity between source and absorber.
The shape of a Mössbauer spectrum is determined by the hyperfine interaction of the Fe nucleus with its electronic environment. Three hyperfine parameters can be determined by Mössbauer spectroscopy:
isomer shift (IS)
quadrupole splitting (QS)
magnetic hyperfine field (Bhf).
These parameters are different for different minerals. Therefore each Fe-bearing phase has its own characteristic Mössbauer spectrum. The Mössbauer spectrum of a mixture of different Fe-bearing phases is simply the superposition of the spectra of the individual Fe-bearing compounds, with the relative intensities (or relative areas) of the individual mineral spectra directly proportional to the relative amount of mineral present in the mixture. The Mössbauer parameters for individual phases are also dependent on temperature. Therefore measurements made during day and night would supply additional information.
Mössbauer spectroscopy can be performed in either transmission or backscatter geometry. In transmission geometry, the sample is placed in between the source and radiation detector and an adsorption Mössbauer spectrum is obtained. A relatively thin and homogeneous sample is needed to avoid thickness effects. Rocks could not be analyzed in this transmission-mode geometry on planetary surfaces. However, in backscatter geometry, the source and radiation detector are on the same side of the sample, so an emission Mössbauer spectrum is obtained. Backscatter geometry has no restrictions on sample shape and thickness. No sample preparation is required because the active end of the instrument is simply placed in mechanical contact with the soil or rock sample that is to be analyzed.
a. Major instrument parameters:
Miniaturized Mossbauer instruments have been developed for use on the surfaces of the Moon or Mars (Agresti et al., 1992; Klingelhoefer et al., 1995). The major instrument parameters are very similar:
(I) 6 detector-channel version
Mass: < 500 g
Dimensions: about 600 cm^3
Power: about 4 Watt
Data: about 100 kb/sample analysis
Instruments of this class were included in 2 Discovery-class proposals for the Monn and as part of the Russian Mars-96/98 mission, installed on the Russian Mars-Rover 'Marsokhod'.
(II) 2 detector-channel version (MIMOS-II)
This version was developed for use in space missions with very limited power resources such as the Small Stations of the Russian Mars-96 mission;
Mass: < 300 g
Dimensions: about 150 cm^3
Power: about 0.5 Watt
Data: about 60 kb/sample analysis
This instrument is shown in Figure 7.1a and Figure 7.1b.
For all instruments described above a radioactive source of about 200- 300 mCi of Co-57 (at launch) in a rhodium matrix would be needed for a mission to Mars, because the half life of the source is 271 days. This life time has to be considered in each mission planning.
4. Visible to Near IR Spectroscopies
Diagnostic mineral absorption bands span the near-infrared, typically between 0.35 and 3.5 micrometers. There are two principal causes of diagnostic features in this part of the spectrum. The first are electronic transitions of d-orbital electrons of transition element ions in a well defined crystal field such as within an octahedral or tetrahedral site of a mineral. The energy (wavelength), strength, and width of these absorptions are a function of the ion (e.g., Fe+2, Fe+3, Cr+3, etc.) and the size, shape, and symmetry of the site. These properties characterize specific minerals, allowing them to be identified by the nature of the observed absorption bands. Such bands are often referred to as crystal field electronic transition absorptions and occur from 0.4 to 2.5 micrometers. The second type of absorption bands arise from fundamental molecular vibrational and rotational modes and their overtones and combinations (typically OH, H2O, and CO3). These molecular absorption bands occur from about 1.4 micrometers to longer wavelengths.
Visible and near-infrared spectrometers have a long heritage in their use for remote determination of mineralogy. The basic concept is simple: the spectral properties of light reflected from a surface is measured through a large number of contiguous spectral channels (typically a few hundred). This radiation has interacted with the surface, has been transmitted through several grains, and has obtained an imprint of absorption bands and other spectral features which are diagnostic of the minerals present. The technology developments over the last few decades have concentrated on making spectrometers more accurate, more flexible, and more capable. These trades are very important in selecting a specific design for a given application. Parallel progress has occurred in the analytical area in which tools for information extraction have been developed. These have concentrated on mineral identification, mineral abundance determination, and mineral composition determination.
Some of the most recent new technology advancements have been the development of high precision spectrometers (imaging spectrometers) which produce "image cubes" of data: three dimensions of 10-14 bit data numbers, each with several hundred elements. Two of the dimensions contain spatial elements and the third contains spectral elements or channels. The important scientific application is the ability to evaluate diagnostic spectral properties of individual surface elements in a spatial (geologic) context. There are several spectrometer designs which will obtain image cubes, each with its own strengths and weaknesses, depending on the application. Almost all use two dimensional arrays as the prime detector, with the third dimension derived through time sequential measurements. If the target of interest is not moving, then the two dimensions of spatial information can be recorded simultaneously and the spectral dimension obtained sequentially with a dispersive element or filters. Alternatively, one dimension of spatial information can be recorded simultaneously with one dimension of spectral information obtained with a dispersive element or an interferogram. The second dimension of spatial information is then built sequentially as the system scans across a field of view. A more simple design is a spectrometer which uses a dispersive element and a single or composite linear array to measure an individual spectrum; this design does require a more complex scanner to scan across two spatial dimensions.
5. Mid- / Thermal IR
Visible and near-infrared reflectance spectra are valuable in discriminating some elements and molecular groups in geologic materials, e.g., Fe, CO3, and H2O- and OH-bearing clays and other weathering products (McCord et al., 1982a,b; Singer, 1982; Goetz et al., 1982). However, many geologically important elements (like Si, Al, O, and Ca) do not absorb directly in the visible or near-infrared, although they can influence the shape and location of other absorption bands (Hunt and Salisbury, 1970). However, many of the major rock-forming elements and their complexes have fundamental vibration frequencies corresponding to mid and thermal IR wavelengths, 5-50 micrometers. Nearly all silicates, carbonates, sulfates, phosphates, oxides and hydroxides show mid-IR and thermal IR spectral signatures (e.g. Lyon, 1962; Hunt and Salisbury, 1974, 1975, 1976; Farmer, 1974).
The strong spectral activity in the mid-IR results from structural, chemical, and physical properties of silicate rocks and minerals (e.g., Lyon, 1962,1964; Hovis and Callahan, 1966; Goetz, 1967; Lazarev, 1972; Farmer, 1974; Hunt and Salisbury, 1974, 1975, 1976; Karr, 1975; Vincent et al., 1975; Salisbury and Walter, 1989; Walter and Salisbury, 1989; Hapke, 1993; Pieters and Englert, 1993). Nash et al. (1994) give a review of mid-IR spectoscopy of the Moon. Laboratory reflectance spectra of common rock- forming minerals on the Earth show strong spectral activity in the mid-infrared wavelengths. The spectral features are characteristic of photon interactions with the material in the `transition region' where absorption bands show up as troughs in reflectance and peaks in emission. Bands in the 4 - 7 micrometer region are mostly overtones and combination tones of the stretching and bending of Si-O and Al-O fundamentals with some lattice modes present. Also, carbonates have strong absorptions from CO3 internal vibrations in the 6-8 µm region; these bands are easily distinguished from silicate absorptions (Adler and Kerr, 1963; Hunt and Salisbury, 1975).
The 7 - 11 micrometer region is largely dominated by surface scattering except at the Christiansen frequency or feature (CF). The CF is a reflectance minimum (and corresponding emittance maximum), typically between 7 and 9 micrometers, representing the strongest molecular vibration absorption band in silicate rocks and minerals. The CF wavelength is a function of the polymerization of the silicate lattice, and so is diagnostic of rock type and the chemical compositions of minerals (Vincent and Thomson, 1972; Hunt and Salisbury, 1974; Hunt, 1980). Thus the emission maximum occurring in the 7 - 11 micrometer region can be interpreted in terms of chemical content. Glassy and powdery samples yield more subdued spectral features than crystalline or slab samples, at least in the laboratory, but the CF wavelength is independent of grain size or texture. Emission spectra obtained by telescope or method are approximately the 'complement' of reflectance spectra as given by Kirchhoff's Law: fractional absorptivity = 1 - the fractional reflectivity. Note also that, in strict thermodynamic equilibrium, fractional emissivity = fractional absorptivity.
IR spectral features at wavelengths longer than 11 micrometers are 'transparency features'; quartz and feldspar which have strong and unique features in this region. Several examples are given in the laboratory compendia of Salisbury and others (see reference list.). The features in the 12 to 40 micrometer range include Si, O, and Al stretching and bending modes. Hydroxide-bearing minerals (clays) also have characteristic mid-IR spectra (van der Marel and Beutelspacher, 1976), with spectral features from the fundamental bending modes of OH attached to various metal ions, such as an H-O-Al bending mode near 11 micrometer in kaolinite (Hunt, 1980). Phosphates and sulfates also have diagnostic absorption bands associated with their anion complexes (PO4 and SO4), as do oxides, nitrites, and nitrates. Sulfides and halogenide salts are also readily distinguished (Hunt and Salisbury, 1975).
For natural surfaces, thermal emission spectra are modified by scattering of the outgoing energy within the surface. Thus, physical properties such as particle size and packing can affect emission spectra (Logan et al., 1973, Salisbury and Estes, 1985; Salisbury and Walter, 1989). These effects only become significant as the particle size becomes small (< ~100 micrometer) and are most important as the size approaches the wavelength being observed (Lyon, 1964; Hunt and Vincent, 1968; Hunt and Logan, 1972; Salisbury and Walter, 1989). To deal with the effects of scattering, the thermal emission data can be modeled using radiative transfer techniques that incorporate Mie scattering theory (Conel, 1969; Moersch and Christensen, 1991), and Chandrasekhar scattering theory (Hapke, 1981).
For airless body studies like Mercury, asteroids and the Moon, the diagnostic utility of the mid-infrared spectral regions benefits from the vacuum environment surrounding the surface materials which enhances spectral contrast over that obtained in laboratory spectra most commonly obtained at ambient 1 bar pressure. For Mars, the atmospheric emission spectrum will mix with that from the surface materials. Mars Observer carried the Thermal Emission Spectrometer (TES) on board for planned surface and atmospheric studies.
One thermal emission spectrometer design is flight-qualified, flew on Mars Observer, and is slated for the Mars Global Surveyor mission (Christensen et al., 1992). That instrument, the TES, weighs 14.4 kg and consumes 14.5W average. Individual mineral species were clearly distinct in its thermal emission spectra, such that a grain of olivine could confidently be distinguished from pyroxene. Mineral mixtures could also be discriminated. Sulfates were detectable at a few weight percent (Christensen et al., 1992), but it is not clear how well silicate mixtures could be discriminated.
6a. Electron Paramagnetic Resonance (EPR)
Electron Paramagnetic Resonance (EPR) or Electron Spin Resonance (ESR) spectroscopy studies atoms, ions or molecules with unpaired electron(s) in an applied magnetic field (e.g., 1~6 kGauss) by irradiation of microwaves (~9 GHz for X-band EPR) to induce transitions between electronic spin states. The electronic states and their energy levels are modified through various interactions, such as interaction with nuclear spin(s) (within the same atom, molecule or neighboring ones), molecular environment, amorphous or crystalline matrix. Magnitudes of such interactions can be deduced through EPR spectra and used to obtain information about molecular structures of radicals, oxidation states of ions, electronic structures, symmetry of ionic sites and the surroundings. Samples of all phases, gas, liquid, or solid, can be studied by EPR. In conventional EPR experiments, the microwave frequency is fixed at a tuned value, and resonance condition is searched by scanning the applied magnetic field through an electromagnet.
EPR has been extensively applied for the study of geologic materials of all phases, including crystalline, powder and amorphous samples. The analysis can be carried out with little disruption of surface structures or chemical equilibria, and requires little sample preparation, with mg to g size samples.
Specific applications of EPR for planetary exploration include:
Nature of oxidant (radicals) in Martian soil Oxidation state of paramagnetic ions in soil (mineralogy) Characterization of volatiles (carbonates, sulfates, nitrates) Color centers in icy samples (Impurity level chemicals in ice, inorganics, organics, carbonates) Detection of possible organics from subsoil.
6b. Ferromagnetic Resonance (FMR)
Compared with the paramagnetic samples in which individual electron spins are isolated or weakly interacting, the spins in ferromagnetic samples, e.g., metals of iron, cobalt and nickel and some rare-earth elements, are strongly coupled and possess a spontaneous magnetic moment even in the absence of an applied magnetic field. Spectroscopic principles and instruments are the same as EPR, except that in the interpretation of spectra, the ferromagnetic nature of the samples must be considered. Detection and characterization of ferromagnetic particles are the most important applications of FMR for planetary exploration.
7. Nuclear Magnetic Resonance (NMR)
Nuclear Magnetic Resonance (NMR) studies atoms or molecules with nuclear spin(s); in most other aspects, its principles of operation are similar to those of EPR. NMR exploits the fact that many of isotopes in molecules possess unique nuclear gyromagnetic ratios. Through interactions with electrons and neighboring nuclei, NMR spectra of molecules show unique lineshapes or chemical shifts, and such information is utilized for characterization purposes. Through NMR spectroscopy, one can obtain information about the constituent nuclei and chemical structure of molecules. From the time of inception, the proton has been the most frequently studied nucleus and thus proton magnetic resonance has become almost synonymous with NMR. Using proton-NMR, one can accurately determine the quantity and physical and chemical nature of water, i.e., H2O, OH, in geologic samples. Proton NMR is operated with samples (0.1-1 g) in an applied magnetic field by irradiation of radiofrequency (e.g., ~ 13 MHz at ~ 3 kGauss) to induce transitions between proton spin states.
NMR can be obtained by scanning a magnetic field at a fixed radiofrequency or by scanning radiofrequency at a fixed magnetic field. Like EPR, the method is non-destructive, and requires little sample preparation. A miniature magnetic resonance spectrometer (< 500 g, < 5 W) with combined capabilities of EPR and NMR is being developed at JPL (Kim and Bradley, 1994). A permanent magnet assembly (Nd-B-Fe) is used for the spectrometer.
Specific applications of NMR for planetary exploration include: presence of water in the soil, minerals and rocks; free water in rock pores; adsorbed water on surface; and chemically bound water.
8. X-ray Fluorescence Analysis (XRF)
XRF is principally a bulk chemical analysis method, and is described in the chapter on chemical compositions. However, bulk chemistry of single mineral grains can provide important clues to their identity; when coupled with other structural data, identification is almost assured. One proposed instrument which uses XRF primarily as a mineralogic tool is under development. It is designed to analyze powder samples in a transmitted, forward reflection geometry either as-received (e.g., wind-blown dust) or as the result of grinding or drilling operations (David Blake, personal communication). This instrument would yield bulk composition and X-ray diffraction data simultaneously. This instrument is proposed for inclusion on the Champollion lander and the Mars '98 missions. Its principal engineering parameters are:
Energy range, eV 150 - 8050
Diffraction range, 2-theta 5 - 50
X-ray source Copper anode x-ray tube (Or radioactive source, where appropriate)
Detector CCD, 1024 x 1024, 18 µm pixels
Size, cm 11 x 11 x 8
Mass, g 800
Power (operating), w 3
Energy per sample, W-h 6
A scanning electron microscope with chemical analytical capability using energy dispersive analysis (SEM/EDX) could be useful in mineralogy as a source of morphological and compositional data on individual mineral grains. SEM/EDX is briefly discussed in Part 3 on Precise Chemical Analyses.
10. Raman Spectroscopy
Laser Raman spectroscopy is an optical scattering technique which can provide molecular and crystal- structural information about solid materials (McMillan and Hawthorne, 1988; T. Wdowiak, pers. comm). Raman spectroscopy is an established laboratory method for identification and characterization of organic/hydrocarbon and inorganic/mineral substances (e.g., Wang et al., 1994). When light interacts with a material, a small portion of the incident photons (one photon per 10^8 - 10^12) is scattered inelastically, with energy loss/gain to/from the material; this is the Raman effect. The energy losses or gains associated with Raman scattering are characteristic of molecular and lattice vibrational modes (fundamental, combination, and overtone) of the target material, and can be used to identify and characterize the target material.
The spectral frequency shifts of Raman scattering are related to molecular structures in essentially the same way as the absorption/emission transitions in infrared absorption, reflectance, and emission spectroscopy; however, different transitions are observed by the two techniques, as the quantum selection rules are different for absorption and Raman scattering. Additionally, many of the common difficulties in interpreting infrared spectra such as particle size effects, transparency peaks, volume scattering, and thermal gradients are not problems in Raman. Instead of the broad absorption bands of visible and infrared spectra, Raman spectra record discrete, sharp emission peaks. Laser light induced fluorescence of some species can be an interference, but techniques are available for minimizing its effect. These include algorithms for extraction of the narrower Raman features, long wavelength lasers that induce less fluorescence, and time gating of the detector that excludes fluorescence because of its longer duration.
Raman spectra are taken by illuminating the sample with a monochromatic light source, and obtaining spectra at wavelengths longer (and shorter) than that of the source. In the laboratory, Raman spectra of solids are usually obtained on prepared powders, although spectra can also be obtained on individual mineral grains through an optical microscope ('micro-Raman' spectroscopy). The analytical depth is effectively the depth of light penetration into the solid.
The Raman spectrometer consists of five components: laser light source, absorption filter (notch) at the light source wavelength, monochrometer, optical coupling, and detection (CCD) system. The light source must be monochromatic, and laser diodes are suitable. Single mode laser diodes with efficiencies of 23- 40%, power draws of 3-500 mW, and wavelengths of 630 nm or longer are suitable sources for Raman spectroscopy. Light can be conducted to the sample by a fiber optic cable. The filter and monochrometer prevent all light with wavelengths near that of the incident light from hitting the detector. Holographic notch filters at laser wavelengths of sufficient absorption efficiency are available for this purpose commercially. Light scattered from the target material must be conducted to the detector. The monochrometer and detector can be at the site of analysis, or the light can be conducted by fiber optic cable from a remote sample to the monochromator/detector system. Cables of sufficient clarity and length (up to 1 km) are available commercially (Schoen 1994); temperatures as low as 77 K can be tolerated. Finally, the monochrometer must be able to disperse light by wavelength and the detector must record a spectrum of sufficiently signal/noise. Available CCD spectrometer systems of small size and weight are apparently adequate for this task.
While Raman spectroscopy is a powerful laboratory technique, its value in robotic sensing of planetary surfaces (Wdowiak et al., 1995) remains to be validated through actual testing. The low efficiency of Raman excitation implies low signal/noise in the detector, and requires either long analysis times, high- power light sources, or both. Stimulated Raman spectroscopy (McMillan and Hofmeister, 1988) permits much higher excitation efficiencies, but at the cost of large power flux and sample heating. Once a Raman spectrum is obtained, it is not clear how well spectra of mineral mixtures can be deconvolved to yield species or abundances of the constituent minerals; and what the minimum detectable mineral abundance is. The answer may lie in the use of microscopic Raman spectroscopy on single mineral grains, a standard laboratory technique. However, Raman spectra can readily distinguish crystalline and glassy materials, a task difficult to most methods. These questions are obvious points for future research in this promising technique.
11. Optical Luminescence Spectroscopy
Optical luminescence is emission of non-thermal optical photons (near-UV through IR) as a response to energy input (Barnes, 1958; Geake and Walker, 1975; Marfunin, 1975; Waychunas, 1988). On absorption of energy, an atom (or ion) will enter an excited state; the most probable decay mechanism of many such excited states involving valence-band electrons is emission of an optical photon.
Fluorescence is prompt emission of in response to high-energy photons, and can be useful in determinative mineralogy, especially of ionic salts (e.g., carbonates, sulfates). Fluorescence can arise from essential elements (or ions), trace element substituents (activators), or defects. Common activators in salts of alkali and alkaline earth elements include Mn2+(VI), other transition metals, the rare earths, and the actinides (Waychunas, 1988). Trace substituents of other species can enhance fluorescence (e.g., Pb2+), while other species (e.g., Fe3+) quench it effectively. Fluorescence can also arise from defects in crystal structures, including those caused by radiation and shock.
Minerals may also luminesce on heating, thermoluminescence (TL), as structural defects like radiation damage anneal out. Thermoluminescence can be readily related to radiation exposure, and a suitable heating chamber (like a differential scanning calorimeter [DSC]) may be available on the lander.
Optical luminescence may be particularly useful for surface investigations on Mars, as atmosphere-surface interactions may have produced ionic salts of the alkali and alkaline earth elements (Gooding, 1978, 1992; Sidorov and Zolotov, 1986; Fegley and Treiman, 1992; Treiman, 1992; Treiman et al., 1993). One possible Mars surface mineral, scapolite, has distinctive optical luminescence, and should be readily detectable [Clark et al., 1990; Treiman, 1992].
Instrumentation to permit fluorescence spectroscopy is simple: a vis-NIR spectrometer and a short- wavelength light source. The former is likely to be manifested for reflection spectroscopy, and the latter might be manifested for other purposes (e.g. a laser range finder, atmosphere sounder, or chemical analytical tool). However, fluorescence spectroscopy has severe limitations, and cannot be considered a mature analytical method. In most cases, fluorescence spectroscopy cannot provide mineral proportions or compositions, as luminescence response of a mineral depends on many aspects of its trace element composition and structural state. Also, there has been little systematic investigation of luminescence at infrared wavelengths or of faint luminescences (that interfere with Raman spectroscopy). This is a field with considerable potential, as many common minerals that do not luminesce at visible wavelengths may do so in the infrared.
12. Thermal Analyses
Many minerals transform or react during heating, and the thermal effects of those transformations can be characteristic of particular minerals, and nearly unequivocal for mineral indentification. These thermal effects are the basis for the standard thermal methods, which include differential thermal analysis (DTA) and differential scanning calorimetry (DSC). In both methods, an unknown sample is introduced into a heating chamber in close proximity to a reference sample, and both sample and reference are heated. In DTA, sample and reference are heated at a constant rate (usually linear with time); and the temperature difference between the sample and reference is recorded. In DSC, sample and unknown are heated separately so that both stay at the same temperature; the recorded quantity is the difference in heats added as a function of reference temperature. DSC can be more quantitative that DTA with respect to the abundances of phases (the heats absorbed or evolved); this quantification, however, requires accurate masses of the analyzed samples. DSC also is currently limited to thermal effects below 700oC (Wendlandt, 1986). DTA is semiquantitative with respect to mineral abundances, but is easier to implement than DSC and is limited only to temperatures below 1200oC (Wendlandt, 1986).
Thermal analysis (DSC or DTA) by itself can detect the heat effects associated with crystalline phase changes, magnetic order/disorder transition, chemical reactions such as devolatilizaton, and melting. However, thermal analysis techniques are especially powerful when coupled with a method of analyzing the gas (if any) emitted during a thermal event. There are many available methods for analyzing the gases evolved during heating. Mass spectrometric methods are discussed in Part 4 of this report. Gas chromatography (GC), also discussed briefly in Part 4, involves passing the evolved gas in an inert carrier through a long column of porous, chemically adsorbing material. As they pass through the column, the evolved gas species become separated according to how well they bind to the column material. Properly calibrated, GC can be nearly definitive for presence and abundance of some species. For samples which contain only a few known volatile species, or for applications where concentrations of only a few species are needed, gas- specific chemical sensors are favored. Most compound-specific sensors are designed so the compound of interest sets up an electrochemical potential (voltage) across the sensor, the potential is a calibrated function of the compound abundance. Many compound-specific electrodes respond (to varying degrees) to non-target compounds, so sensors for a number of specific compounds may be required to yield unambiguous analyses. For water, other types sensors can measure relative humidity or dew point. Sensors for H2O and CO2 were available in 1994 (Boynton et al., 1994; Gooding;, 1994), and development of other compound-specific sensors is in progress.
This combination of methods, thermal and evolved gas, can provide significant mineralogical information about unknown samples, including mixtures and complex soil samples (Wendlandt 1986). Thermal/evolved-gas methods are particularly powerful for volatile-rich materials, such as terrestrial soils. Their analytical values presumably extend to Martian soils, regoliths of primitive asteroids, and regoliths of comets. Thermal analysis is a bulk technique for the sample collected; it is not sensitive to surface coatings and weathering rinds (Schwartz et al., 1995), except as the coatings and rinds become a significant portion of the sample mass. With thermal analysis and evolved gas analysis, it is relatively straightforward to distinguish among clays, silicates, feldspars, zeolites, glasses, and evaporites as well as to determine if organics are present, even for some phases to the 0.02% wt level (Boynton et al., 1994). Thermal and evolved gas methods are also discussed in Partss 4 and 8 of this report as they relate to trapped/implanted gases and carbon-based chemistry / exobiology.
No thermal analysis instruments are currently flight qualified, but a number are at brassboard stage, and are competing for inclusion in the Mars Surveyor Lander. Current concepts couple thermal analyses with evolved gas analysis: Mancinelli et al. (1994) proposed a DTA with a evolved gas analysis by chromatography; Boynton et al. (1994) and Gooding et al. (1994) have proposed DSCs with evolved gas analysis by compound-specific sensors. Gooding et al's instrument (TAPS) has a mass near 1 kg, including a sampling device, and consumes ~5W-hr per analysis of a 20-50 mg sample. Minerals with thermal effects alone (e.g., quartz) are detectable at near 1% of the sample. Minerals which evolve gas may be detectable at much lower levels (e.g., carbonate detectable at the 0.02% level).
A remarkable result from the Viking missions was the discovery that the Martian soil is highly magnetic, in the sense that the soil is attracted by a small permanent magnet. The soil was found to adhere almost equally to a strong and a weak Sm-Co magnet attached to the Viking lander backhoe at both landing sites. The strong magnet had a surface field and a surface field gradient of 0.25 T and 100 T/m respectively (2500 gauss, 10000 gauss/cm). The corresponding numbers for the weak magnet were 0.07 T and 30 T/m (700 gauss, 3000 gauss/cm). Based on the returned pictures of the amount of soil clinging to the magnets, it was estimated that the particles in the Martian dust contain between 1% and 7% of a strongly magnetic phase, most probably a ferrimagnetic ferric oxide intimately dispersed throughout the soil.
Appropriate limits for the spontaneous magnetization (ss) were advanced:
1 Am2(kg soil)-1 < ss < 7 Am2(kg soil)-1
The essential difference between Permanent Magnet Arrays for coming landers and the Viking Magnetic Properties Experiment is that arrays on future landers should include magnets of lower strengths than the weakest Viking magnets. The reason for this is that both the strong and weak magnets on the Viking Landers were saturated with dust throughout the mission. The proposed Magnet Array contains 5 magnets of different strengths, total mass is about 70 g. The outer diameter of the magnets is 18 mm each. The center and ring magnets are magnetized parallel to their axes, but in opposite directions. When mounted the magnets are completely immersed in a thin magnesium plate. The magnets are of equal strengths, but mounted at different depths below the surface of the magnesium plate. Discrete (single phase) particles of the strongly magnetic minerals (g-Fe2O3, Fe3O4) will stick to all five magnets, while composite (multiphase) particles will stick only to the strongest magnets. The two strongest magnets have the same strengths as the backhoe magnets on the Viking landers. The plate with the magnets will be placed on the surface of the lander. The Magnet Array will be periodically viewed by the onboard camera and the returned pictures are the data on which conclusion will be based. If the Magnet Array is placed on the surface of the lander, it will be possible to perform X-ray fluorescence and Mössbauer analysis of the dust on the magnets.
III. PRIMITIVE BODIES
The many different types of undifferentiated bodies in the solar system share a collection of surficial and interior processes that be profitably studied by determining the mineralogy of reactant and resultant phases. The types of processes and the unique instrumentation required to address them are presented in Table 7.2a and Table 7.2b. Specific issues for each type of body are further (briefly) summarized here. First, the reader should recognize that the basic types of undifferentiated bodies are somewhat arbitrarily divided into (1) asteroids and (2) comets and Kuiper Belt objects. While the latter are assumed to be the more primitive, in reality there is a complete gradation between these objects and their effective discrimination hinges on presence or absence of an ephmeral atmosphere. The analysis concerns with regards to mineralogy are similar for all primitive bodies.
The key questions for primitive bodies focus on the recognition and identification of interstellar, nebular and protoplanetary minerals, and the phases resulting from oxidation, sulfidation, heating (and further crystallization of amorphous materials), carburization, aqueous alteration state of the primary materials. Some primitive phases are known to be amorphous, and subsequent heating and annealing will produce materials with a varying degree of crystallinity. For this reason, techniques which can probe atomic structure (X-ray diffraction, Mössbauer, optical spectroscopy, differential scanning calorimetry) will be critical tools. The oxidation state of minerals and bulk samples is also critical information, and this can be analyzed by Mössbauer, electron magnetic resonance, and visible-NIR spectroscopic techniques. Major element compositions can be probed using SEM/EDX and XRF instruments. Mineral textures are important records of formation processes, and these can be studies using SEM or visual imaging techniques.
IV. DIFFERENTIATED BODIES WITH NO (OR NEGLIGIBLE) ATMOSPHERES
The many different types of differentiated bodies in the solar system that lack significant atmospheres share a collection of surficial and interior processes that can be studied using mineralogy. The types of processes and the unique instrumentation required to address them are presented in Table 7.3. Specific issues for each type of body are further (briefly) summarized here.
On Mercury, key mineralogical questions focus on the oxidation state of the surface mineralogy and the composition of the polar deposits. In the former case, mineralogy (which is dependent on knowledge of oxidation state) of surface sulfides may give significant insight into the oxidation state of the planet at the time of formation and core formation. Related to this is the Mg/(Fe+Mg) ratio, a parameter that places important constraints on petrology but cannot be evaluated because the oxidation state is not known. In the latter case, knowledge of the composition of the polar deposits on Mercury can yield important insight into volatiles and differentiation on the planet. Finally, knowledge of the Na content of feldspar on Mercury‚s surface could provide constraints on surface evolution.
On the Moon, we note that the Apollo program, ground-based observations, and Clementine have been effective in studying the composition of the lunar surface. Thus, these authors believe that more emphasis should be placed on other airless bodies in this document. However, key issues that have not been explored to date include knowledge of the composition of polar deposits, and sampling of xenoliths or deep craters to attempt to sample the lunar mantle.
For differentiated asteroids, mineralogy could provide knowledge of the surficial evolution by determining the presence or absence of hydrated minerals, the elemental abundances at the surfaces, and any mantle signatures that might be present. Finally, for Galilean and Saturnian satellites, the surface mineralogy and bulk composition are again important. For these bodies, such information could provide insight in the fractional amount of water on the surfaces, other imbedded gases, dimers, molecules, and the rates of sputtering, outgassing, and accretionary processes present.
V. DIFFERENTIATED PLANETS WITH ATMOSPHERES
The surface mineralogy of differentiated planets with atmospheres (i.e., Venus and Mars) differs dramatically from that found on primitive bodies and differentiated planets which lack an atmosphere, and therefore deserves more extensive discussion herein. The types of processes and the unique instrumentation required to address them are presented in Table 7.4.
Rock-atmosphere-hydrosphere interaction on Mars and rock-atmosphere interactions on Venus have undoubtedly led to a wide variety of minerals that reflect specific processes that have occurred. These interactions are broadly called "chemical weathering" because the initial mineralogy of the source rock has been changed. Because mineral phases are stable only for specific ranges of pressure, temperature and composition, the mineralogy of the alteration products and their spatial and petrologic associations provide insight into the environments in which they formed. In this context, it is important to note that minerals, once formed, can persist metastably for extended periods of time.
In the case of Mars, for example, hydrated minerals formed early in its history could persist to the present time under the cold dry conditions which prevail now. Surface mineralogy can also provide
information critical to the exobiological exploration of Mars.
There are two principal reasons for this; First, life as we know it requires liquid water, and a knowledge of surface mineralogy provides insight into the activity of water. Second, the biogenic elements H, C, N, O, and S are also the principal volatiles elements comprising the present and past atmospheres of mars. In this section, we attempt to present a sampling of the critical questions that can be answered if surface mineralogy is known.
1. Chemical Weathering
Throughout the last four billion years the atmospheres of Mars and Venus has been interacting with the surface to alter initially igneous material. Minerals are a permanent reservoir of carbon dioxide and sulfur for both Venus and Mars and for water on Mars. Elemental abundances, such as those measured by the Viking XRF experiment, can constrain the present state and allow inference of the starting composition of the source material but not reveal the processes which have occurred. The mineralogy of the alteration products is a sensitive indicator of formation conditions such as oxidation state, pH, abundance and phase of water, atmospheric chemistry, temperature, and surface pressure. This knowledge is critical in understanding the Mars and Venus volatile cycles during the present epoch and throughout the planet's history.
Types of secondary minerals which are especially important are sulfates, carbonates, iron oxides, and on Mars where water has been involved in weathering environment-hydrates. In addition to determining the mineralogy of the weathering product, the mineralogy of unaltered material needs to be determined. We need to know the mafic mineralogy of the source rock (e.g. olivine and pyroxene composition and abundance) in order to separate weathering products derived locally under current conditions from material formed under other conditions. Contextual information such as the composition of any weathering rinds on rocks and how it differs from soil mineralogy and the mineralogy of any duricrusts is needed to derive an integrated picture of what processes have occurred and when.
For instance, consider weathering under current Martian conditions. Two weathering paths may be occurring. The first is gas-solid reactions at 240oK while the second assumes that occasional films of liquid water are present at 273oK (applicable in the equatorial regions). Using mineral reaction diagrams, the thermodynamically stable alteration products for each reaction path can be determined (Gooding, 1978; Gooding and Keil, 1978; and Gooding et al., 1992). For gas-solid reactions at 240oK the dominant weathering products are clays (including the smectite Ca-beidellite) and the carbonates magnesite (MgCO3), dolomite (CaMg(CO3)2), or calcite (CaCO3).
With liquid-solid reactions at 273 K in addition to the minerals mentioned for solid-vapor interactions, Mg-phyllosilicates (talc, saponite, and montmorillonite) and (Na,K) beidellites would be present. The composition and abundance of currently formed alteration products provides a mechanism to estimate the rate at which water and carbon dioxide are being removed from the Martian atmosphere-cap regolith cycle today.
Another Martian example, is that the mineralogy of weathered materials formed during an early clement period on Mars where liquid water was abundant would be rich in carbonates. Dissolved CO2 in water would react quickly to form massive carbonate deposits (e.g., Fanale and Cannon 1979, Pollack et al., 1987). The abundance and mobility of water during this period would determine the mineralogy of the clays based on the solubility of different ions.
Sulfur is fairly abundant on the Martian surface; soils analyzed by both Viking Lander XRF instruments contained 5-9 wt% SO3. The elemental analyses of the red fine-grained material that dominated the surface at both sites were nearly identical for most elements, except sulfur whose concentration was variable in the different soil samples collected at the two sites (Clark et al., 1982). The oxidation state of the surface and the concentration of sulfur in clods was interpreted as a sulfate duricrust formed by the upward migration of water containing the sulfate anion (Toulmin et al., 1977; Burns 1988) or alternatively deposited from volcanic aerosols (Settle, 1979). Knowledge of the mineralogy and distribution of Martian sulfates is critical in determining how the duricrust formed.
Understanding the nature of chemical weathering on Mars cannot be done without knowing the mineralogy of iron. This is the case because it is abundant on the Martian surface (~12% Fe according to Clark et al., 1982), it forms stable compounds in both divalent and trivalent oxidation states, and changes oxidation state in response to external conditions. Arguments developed by Morris et al (1989) and Morris and Lauer (1990) suggest that well-crystalline hematite (alpha-Fe2O3) is present as an optically important constituent on Mars. This may imply that the surface of Mars is anhydrous and/or that formation process were at high enough temperatures to form hematite relative to ferric oxyhydroxide phases. It is also important to establish the size distribution of iron oxide particles. Small particles (nanophase ferric oxides) are formed during low temperature processes like palagonitization and well-crystalline ferric oxides are formed by higher temperature hydrothermal processes.
On Mars, the alteration of material in impact ejecta blankets or volcanic geothermal regions would also have a distinctive geochemical signature due to the circulation of hydrothermal fluids interacting with impact glasses and breccias. Calculations based on minimizing the Gibbs free energy of the chemical system by Zolensky et al. (1988) show that gibbsite (Al(OH)3), kaolinite (an Al-rich clay, and nontronite (an Fe-rich smectite clay) would be present. The abundance of each clay would depend on the amount of rock which has reacted and the initial composition of the rock. If only a small percentage of the rock reacts, carbonates would not form.
2. The Importance of Mineralogy for the Exobiological Exploration of Mars
According to a recent study document (Carr et al., 1995; "An Exobiological Strategy for Mars Exploration"), three scenarios exist which are of high exobiological interest:
I. Prebiotic organic chemistry occurred but life never developed, II. Life developed in some form during an earlier clement period but is now extinct, III. Life exists, perhaps in "clement" niches in or below the surface.
Unless one assumes that life forms were delivered to Mars from elsewhere, (1) above is required for (2) and (3), and evidence of (2) is likely to exist in the rock record if (3) is true. The Viking life detection experiments revealed the presence of a strong oxidant in the Mars soil which could have destroyed any evidence of organic materials. It appears that, until much more is known about the geology, mineralogy, and surface chemistry of Mars, exobiological investigations should be undertaken which have the broadest possible scope.
3. The Early History of Martian Volatiles
Mars is a dry eolian planet with a tenous atmosphere of ~7 millibars pressure, composed mostly of CO2. However ancient surface morphological features such as stream channels and other fluvial and lacustrine features provide compelling evidence that liquid water once existed on the surface of Mars in large quantity. This abundance of liquid water implies that early Mars was once wetter and warmer, and had a dense atmosphere, perhaps of a greenhouse gas such as CO2 (Clifford et al., 1988). The ultimate fate of atmospheric CO2 is of exobiological interest because this compound figures prominently in prebiotic organic chemistry, and because a full inventory of the CO2 sinks is required to provide a balanced volatile budget for the planet. A major reservoir for the carbon dioxide could be in the form of carbonates deposited as chemical sediments or as hydrothermal precipitates.
Alternatively (or additionally), CO2 could be stored in the form of clathrate hydrates beneath the surface or in the polar caps (Miller, 1973), or as solid carbon dioxide at the poles. Each of these phases can be unequivocally distinguished and characterized by mineralogical techniques. In the case of carbonates, the crystal symmetry (rhombohedral or orthorhombic), the extent of cation solid solution (Ca, Mg, Fe, Mn, etc.), cation order/disorder and cation stoichiometry can all be determined through mineralogical analysis.
Each of these distinguishing characteristics provides information about the specific origin of the mineral phase and its environment of formation. The total quantity of water which apparently existed on the surface of Mars early in its history cannot be accounted for by the polar caps alone. It is likely that hydrated phases exist either as a consequence of their direct deposition from aqueous solution or as products of the reaction of anhydrous igneous minerals with water. The quantity, type and degree of crystallinity of clays, micas and other hydrated phases can be determined by mineralogical analysis and their known stability relationships can constrain the conditions under which they were formed.
4. The Presence and Lateral Extent of Hydrothermal Systems
Abundant morphological evidence exists for early and extensive volcanic activity on the surface of Mars, and for the presence of liquid water. The juxtaposition of these features is permissive if not compelling evidence that hydrothermal systems once (or have always) existed on Mars. Isotopic data from the SNC meteorites also suggests that there was an exchange of hydrogen and oxygen between the crust and the atmosphere. The depletion of volatiles such as sulfur and carbon is puzzling and these elements may now be contained within minerals precipitated in hydrothermal systems. A knowledge of the presence and distribution of sulfur and carbon containing mineral phases is important first because they are biogenic elements, and second because compounds containing them could have been utilized by autotrophic organisms as energy sources. Ancient hydrothermal systems could have been eroded or exhumed, exposing minerals and mineral assemblages at the surface which were formed at depths inaccessible in presently active systems. The mineralogical characterization of such a system could provide an evaluation of the role hydrothermal processing has played in modifying the early Martian atmosphere and in altering deep-seated volcanic rocks. Hydrothermally altered rocks, dissected and exposed at the surface by erosion, could contain fossil evidence of the nature of the early Mars atmosphere and of the fate of its volatiles.
5. Evidence of Prebiotic Organic Chemistry
On the Earth, all evidence of prebiotic organic chemistry has been erased. In the earliest terrestrial rocks for which conditions of metamorphism would permit it, evidence of life is present. Therefore, even if life never originated on Mars, it would be exceedingly valuable to find some evidence in the geologic record of Martian prebiotic organic chemistry. This would be possible on Mars more than on the Earth, since extensive regions of ancient terrain exist on Mars which have not been subject to metamorphism. The current notions of prebiotic organic chemistry are that many important reactions may have occurred in hydrothermal systems where energy could have been provided by mineral hydration reactions. Hydrothermal systems also provide a means for gas exchange with the atmosphere and transport of reactants to the sites of reactions. Ancient hydrothermal systems exhumed by erosion could provide surface material that contains distinctive mineral assemblages. It is often the case that hydrated minerals and their anhydrous counterparts are compositionally very similar. Thus, elemental analyses would not easily distinguish one from the other. Mineralogical analysis, comprising both compositional and structural information, can provide a definitive answer.
6. Evidence of Extinct Life
Evidence of life on the Earth occurs in the earliest rocks which could have preserved signs of its presence ~3.5 billion years ago. However, much of the geologic record from the earliest sedimentary sequences has either been heated to the extent that metamorphism would have removed evidence of life, or has simply been destroyed by subduction. Due to the apparent lack of tectonic activity on Mars, a great deal of the sediment deposited on the ancient Martian surface still exists and was probably not heated to the extent of equivalent sediments on the early Earth. Therefore, it is likely that if life originated early in Mars history, some record of its existence would be manifest in the earliest geologic record.
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LIST OF TABLES
Table 1. Reference Table for Analytical Techniques for Mineralogy
Table 2. Methods for the Study of Primitive Bodies
Table 3. Methods for the Study of Differentiated Bodies with No or Negligible Atmospheres
Table 4. Methods for the Study of Differentiated Bodies with Atmospheres
Appendix 7.1: A Tunable Diode Laser (TDL) Spectrometer as a Planetary Surface Instrument
Albert Yen and Randy May
Tunable diode lasers (TDLs) are high resolution (0.0005 cm^-1), near- to mid-IR sources which have been used for over 15 years in balloon and aircraft instruments to make absorption measurements of trace atmospheric constituents (Webster et al., 1994). Traditional lead-salt TDLs operate between 3 and 30 micrometers but require cryogenic cooling (liquid helium and nitrogen temperatures) and are, therefore, not practical for planetary surface experiments. Recent advances in semiconductor laser technology, however, allow operation at room temperature for wavelengths between 1.1 and 2.06 micrometers (Forouhar, 1986). These new InGaAsP lasers are well suited for in situ evolved gas analyses of planetary surface samples and offer greater sensitivity (measurable absorptance of 0.001%) than existing mass spectrometry techniques for many species. Within the next year, GaSb based TDLs operating between 2 and 5 micrometers will become available and will provide additional flexibility in selection of molecular transitions.
A planetary surface instrument for evolved gas analysis based on a TDL would consist of a laser, a detector for the operating wavelength (e.g., InGaAs), a thermoelectric cooler for temperature stabilization of the laser, control and data processing electronics, a sample collection mechanism, a heat source for volatilizing constituents in the sample, and an optical path between the laser and detector through the evolved gases. The wavelength scan range of a TDL is a few reciprocal centimeters and is typically achieved by applying a current ramp across the diode. Since temperature variations also affect the output wavelength of the laser, a thermoelectric cooler is necessary to maintain the TDL within approximately 0.1 K of a pre-selected set point. If the output of the TDL is modulated at a high frequency (typically kHz), then absorption sensitivities of 0.001% can be achieved by harmonic detection techniques using integration times of less than one second (May and Webster, 1993). Recent development work at JPL indicate that the TDL and its associated electronics can fit into a volume of less than 10 cm3 and consume less than 1 W. The mass and volume of the overall instrument will be dominated by the design of the soil collector, optical chamber, heat source, etc. The power requirements will increase if electrical heating is used.
As a specific example, consider an evolved water analysis experiment for a Mars lander. A TDL operating at 7294 cm^-1 would only need a 2.5 cm path from the laser to the detector to detect 15 ppmv of water vapor. If desired, a multipass (e.g. Herriott) cell could be used to increase the path length and lower the detection limit within a similar volume. Taking measurements every few seconds as the soil sample is heated would provide an evolved water signature. Additional TDLs scanning over different wavelengths could be used to quantify other evolved molecular species of interest (e.g., the isotopes of CO2).
Webster, C.R., et. al. "Aircraft Laser Infrared Absorption Spectrometer (ALIAS) for Polar Ozone Chemistry on the ER-2." Appl. Optics, Vol. 33, No. 3, pp. 454-472. 1994.
Forouhar, S. (JPL Microdevices Laboratory) personal communications. Also see: Agrawal, G.P. and N.K. Dutta. Long-wavelength Semiconductor Lasers. Van Nostrand Reinhold, 1986.
May, R.D. and C.R. Webster. "Data Processing and Calibration for Tunable Diode Laser Harmonic Absorption Spectrometers." J. Quant. Spectrosc. Radiat. Transfer, Vol. 49, No. 4, pp. 335-347, 1993.
Imaging of the Central Region of IC 1805
NINKOV, ZORAN; BRETZ, DAVID R.; EASTON, ROGER L., JR.; SHURE, MARK
Astronomical Journal v.110, p.2242
Tunable multispectral imaging system technology for airborne applications
OLSON, JAMES; JUNGQUIST, ROBERT; NINKOV, ZORAN Affiliation:
(Eastman Kodak Co.) (Rochester Institute of Technology)
Proc. SPIE Vol. 2480, p. 268-279, Imaging Spectrometry, Michael R. Descour; Jonathan M. Mooney; David L. Perry; Luanna R. Illing; Eds. Publication Date:
The measurement of the spectral distibution of radiation from individual points on the earth's surface provides important information of the material composition of those points. To collect data over large areas, it is necessary to use either airborne or spaceborne platforms. In this paper, different approaches to collecting such spectral information from a lightweight airborne platform will be reviewed. The use of spectral tuning technologies such as acousto-optical filters, liquid crystal filters, and linearly variable filters, as well as slit spectrometer systems, will be rebiewed. Features and benefits of each tuning technology and their limitations are presented. Various system configurations are also reviewed as well as constraints placed on system level performance parameters. In particular, trade studies of system level parameters, such as field of view and optical throughput, which are directly constrained by tunable filter technologies, are presented.
Title: Detection of Habitable-Sized Planets: A Progress Report Authors:
DOYLE, L. R.; DEEG, H. -J.; MARTIN, E.; JENKINS, J. M.; SCHNEIDER, J.; CHEVRETON, M.; LEE, W. -B.; KIM, H. -I.; NINKOV, Z.; BLUE, J. E.; STONE, R.; TOUBLANC, D.; PALEOLOGOU, E.; PAPAMASTORAKIS, J.; KOZHEVNIKOV, V. P.; ZAKHAVOVA, P. E.; DOYLE, M. Affiliation:
AA(SETI Inst.), AB(Inst. de Canarias), AD(SETI Inst.), AE(Obs. de Meudon), AG(Korean Astron. Obs.), AI(Rochester Inst. Tech.), AJ(SRI Internatl.), AK(U.C. Lick Obs.), AL(Obs. de Bordeaux), AM(U. of Crete), AQ(FIDM) Journal:
Bull. American Astron. Soc., DPS meeting #28, #12.02 Publication Date: 1996
Planets forming around close binary systems should form in the binary orbital plane (varying precession periods of protoplanetary material should provide strong collisional damping; Schneider and Doyle 1995). Planets around eclipsing binaries may then be expected to have formed in the binary orbital plane and thus to be detected by their transits across the line of sight. It has been demonstrated that 1-meter ground based observations of the smallest eclipsing binaries could detect such transits with reasonably precise ground-based photometry using a matched filter analysis (cross-correlating all possible transit signatures with the light curves derived from aperture photometry on CCD images; Jenkins, Doyle, and Cullers 1996). Incidentlly, precise (GPS) timing of the eclipses of the binaries themselves will provide sufficient precision to allow the detection of any gas giant planets around dozens of small mass systems; the drift in timing being produced by the offset of the binary barycenter by the gas giant planet). The TEP (transit of extrasolar planets) observing network has now completed over 1000 hours of observations on the CM Draconis system with a consequent dozen candidate (i.e. terrestrial sized planet) transit events that are in the process of being verified. This system also shows a drift in eclipse minima epoch indicative of a possible larger, gas giant planetary third body also awaiting confirmation. Finally, 11 additional small-mass eclipsing binary systems have been added to our program beginning this year at U.C. Lick Observatory. We hope to begin to be able to say something observationally useful about habitable-sized planets around small, close binary systems soon. 1) J. Schneider, L.R. Doyle, 1995, Earth, Moon, Planets 71, 153-173. 2) J.M. Jenkins, L.R. Doyle, D.K. Cullers, 1996, Icarus 119, 244-260. 3) L.R. Doyle, E.T. Dunham, H.-J. Deeg, J.E. Blue, J.M. Jenkins, J. Geophy. Res. Planets 101, 14823-14829.back