Thermal Infrared Imaging of Exoplanets around the Closest Stars
Dr. Daniel Apai (Space Telescope Science Institute)
Direct imaging of exoplanetary systems is - although conceptually simple - an observationally challenging method. Yet, it remains the only way to assess the planet mass distribution at larger separations and to directly study the atmospheres of weakly-irradiated giant exoplanets. In the near future, direct imaging is also expected to play a key role in searching for Earth twins and study their atmospheric properties. We present an overview of several ongoing, adaptive optics high-contrast imaging surveys of nearby stars with the VLT and MMT telescopes. We show a new high-contrast imaging technique that reaches uniquely high sensitivities to planets at spatial scales smaller than our inner Solar System. We show how these surveys can be used to assess the frequency of massive giant planets in debris disks, Jupiter-analogs at larger separations, and massive planets on orbits as small as Jupiter's.
Enceladus as a Potential Abode for Life: Evidence from Cassini VIMS
Dr. Bonnie Buratti (Jet Propulsion Laboratory)
Enceladus, a medium-sized icy satellite of Saturn, exhibits active cryovolcanism that is likely driven by a liquid ocean. During several targeted encounters (one with a closest approach of only 26 km) during the nominal and extended missions, the Cassini Visual Infrared Mapping Spectrometer (VIMS) obtained spectral maps of the satellite from 0.35-5.2 microns. The spectra show evidence for light organics (Brown et al., 2006), and a tentative identification of hydrogen peroxide has been made (Newman et al., 2007). Most of the heat emitted from the satellite comes from the south polar region, which is the location of the “tiger stripes”. These active geologic features are the source of the water ice plumes that in turn feed the E-ring of Saturn. Medium spatial resolution (250m-2km) VIMS spectra of this region show no thermal signature, which suggests the radiating area is small and thus hot, perhaps as high as 200K.
Astrobiology Teaching and Emerging Meteorite Studies at the University of Chile
Prof. Luis Campusano (University of Chile)
"Life in the Universe through Science" has been offered since 2006 as a general course on science to students of all disciplines of the Universidad de Chile. An introductory course in Astrobiology saw light in 2009 at the Faculty of Physical and Mathematical Sciences (FCFM), addressed to more advanced and analytically literate students, and thus possibly preparing the initial potential manpower that will develop this science in Chile. The lecturers are a mix of astronomers, geophysicists, geologists, biologists and technologists. We analyze our experience with this course offered in two flavors, its perspectives and significance, and their role to familiarize the university community and the general public to this new science, and also to generate research initiatives. In fact, Millarca Valenzuela, a geologist and the the most junior member of the teaching team, is leading and pioneering a research effort to study meteorites collected in the Atacama desert. The best places in the world to find meteorites are deserts. In these arid regions (both hot deserts and the cold desert of Antarctica) weathering occurs at slower rates than in temperate or tropical areas and therefore accumulations of meteorites may occur. In this context, the Atacama Desert in northern Chile, one of the driest deserts of the world, has became a prolific meteorite recovery areas in the last five years, that has increased the number of chilean ordinary chondrites from 20 to 43. It represents an extreme habitat for life on Earth and serves as an analogue for dry conditions on Mars, reason why NASA routinely has been using for robotic mission simulations as well as many other astrobiologist investigating these analogues to the environment of the early Earth and Mars. One specific aim of this research initiative is to study the diversity of meteorites and micrometeorites, for information on the sources of material now falling to Earth, especially from the collection of the Atacama Desert meteorites.
MOMA-LDMS: Instrument Concept and Results
Dr. Kittisak Chaicharoen (JHU)
The Mars Organic Molecule Analyzer (MOMA) is a powerful multi-source mass spectrometer-based instrument suite for investigation of potential life on Mars. MOMA has been selected as a core element of the Pasteur payload on the ESA ExoMars mission. The MOMA instrument is the next generation design for in situ life detection instrumentation. A key element of MOMA is the laser desorption mass spectrometer (LDMS) that incorporates several methods of volatilizing and ionizing chemical compounds from intact samples without further processing or manipulation. State-of-the-art laser desorption coupled to an ion trap mass spectrometer provides enhanced mass resolution over a broad dynamic range and detailed structural information on key organic molecules and compounds. In this poster we present our current MOMA-LDMS prototype design and some preliminary results on organic compounds of interest and several Martian analog samples.
Spontaneous Assembly of Cell-Like Structures From Likely Prebiotic Materials
Dr. Henderson Cleaves (Carnegie Institution of Washington)
It has been suggested by a number of theoreticians that cellularity is a precondition for a living system. Over the years many researchers have sought to synthesize structures morphologically resembling cells under prebiotic conditions. Many of these structures clearly contain no lipid and are thus perhaps not “cells”. Conversely, likely prebiotic organic amphiphiles such as fatty acids only produce micelles or vesicles under select conditions: high ionic strength and divalent cations inhibit the self-assembly of cell-like structures such as vesicles. During investigations of the chemistry of HCN we have discovered cell like-structures of extremely homogeneous size distribution which are produced robustly from these simple reactions. The chemical and morphological structure of these and their interactions with amphiphilic species have been investigated. These are potentially important as intermediates in cellular development on the primitive Earth, and may have implications for life-detection on other planets and in the geological record.
Benefits of Ground-Based Photometric Follow-Up for Potentially Habitable Transiting Planets Discovered with Kepler and CoRoT
Ms. Knicole Colón (University of Florida)
Currently, over forty transiting planets have been discovered by ground-based photometric surveys, and space-based missions like Kepler and CoRoT are expected to detect hundreds more. Follow-up photometric observations from the ground will play an important role in constraining both orbital and physical parameters for newly discovered planets, especially those with small radii (approximately less than 4 Earth radii) and/or intermediate to long orbital periods (i.e., greater than ~30 days). Here, we simulate transit light curves from Kepler-like photometry and ground-based observations in the near-infrared (NIR) to determine how jointly modeling ground-based and space-based light curves can improve measurements of the transit duration and planet-star radius ratio. Assuming a relatively modest ground-based precision of 1.7 mmag each minute, we find that adding observations of at least one ground-based transit to space-based observations can significantly improve the accuracy for measuring the transit duration and planet-star radius ratio of small planets (with radii less than ~4 Earth radii) in long-period (~1 year) orbits, largely thanks to the reduced effect of limb darkening in the NIR. We also demonstrate that multiple (low-precision) ground-based observations are needed to gain a substantial improvement in the measurement accuracy for small planets with short orbital periods (~3 days). We find that recent improvements in ground-based photometric precisions will enable even greater improvements in measurement accuracy for small planets. Furthermore, measurements of larger planets (those with radii greater than ~4 Earth radii) begin to improve as higher ground-based precision is assumed, particularly for increasing orbital periods. Our results can help inform the priorities of transit follow-up programs (including both primary and secondary transit of planets discovered with Kepler and CoRoT), leading to improved constraints for planet sizes, transit durations, and orbital eccentricities. These constraints can then help characterize the equilibrium temperatures, atmospheres, and even potential habitability of transiting extrasolar planets.
Mass Spectral Signatures of Intact Microorganisms in the Search for Life on Mars
Dr. Timothy Cornish (JHU Applied Physics Lab.)
The observation of discrete spatial and temporal methane plume releases on Mars has provided further arguments for the existence of life on that planet. Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) has become an established tool for rapid characterization of intact microorganisms. Here we demonstrate its applicability to detect live organisms that might mimic life on Mars. Methanococcus jannaschii - a methanotrophic extremophile that thrive in deep sea volcanoes at temperatures around 110 °C - is one of the first microorganisms whose genome has been sequenced. M. jamnaschii may be a good first approximation for an anaerobic methane-generating organism that may exist on Mars. Both positive and negative ion MALDI mass spectra from intact M. jamnaschii have been obtained for the first time and will be discussed here. A home-built miniaturized time-of-flight (TOF) and commercial TOF and tandem TOF instruments are used for biomarker signature acquisition and individual biomarker identification. Experimental mass spectra are further matched to spectra generated in silico from sequences in a genome database.
The ITASEL project : Italian Search for Extraterrestrial Life
Prof. Cristiano Cosmovici (IFSI-INAF)
The ITASEL project, financed by the Italian Space Agency (ASI), started 1994 after the unique detection of the water MASER 22 GHz emission in the Jovian atmosphere caused by the catastrophic impact of comet Shoemaker/Levy9 with Jupiter (Cosmovici et al. Planet.Space Sci.,44,735,1996). It was then decided to use this discovery as a powerful diagnostic tool for water search in exoplanetary systems. We investigated 32 targets up to 60 LY, where planets were indirectly detected, by using new powerful multichannel spectrometers coupled to the 32 m Medicina radiotelescope (Cosmovici et al., APS Conference series, 398, 33, 2008). Moreover we searched for the MASER line in sun-grazing and bright comets (Cosmovici et al. Planet. Space. Sci. ,46,467,1998) and in the Saturnian system (Pogrebenko et al., A&A 494, L1-L4, 2009)in order to test also the feasibility of the "borderline" project. Contemporaneously we participated in the international SETI program by using a 24 million channel Serendip IV high-resolution spectrometer (Montebugnoli et al., Acta Astronautica,58,222,2006). Here we'll present the results achieved up to now in the different topics of the ITASEL project.
Enrichment of L-isovaline by Aqueous Alteration on CI and CM Chondrite Parent Bodies: Implications for the Origin and Search for Life
Dr. Jason Dworkin (NASA Goddard)
The distribution and enantiomeric composition of the five-carbon (C5) amino acids found in six CI, CM, and CR type carbonaceous meteorites were investigated using LCMS. A large L-enantiomeric excess of the α-methyl amino acid isovaline was found in the CM meteorite Murchison and the CI meteorite Orgueil. Interference from all other C5 amino acid isomers, analytical biases, and terrestrial amino acid contamination were eliminated. We observed no L-isovaline enrichment for the CR meteorites EET92042 and QUE99177. The large asymmetry in isovaline and other α-dialkyl amino acids found in altered CI and CM meteorites suggests that amino acids delivered by asteroids, comets, and their fragments would have biased the Earth’s (and other solar system bodies’) prebiotic organic inventory with left-handed molecules prior to the origin of life. This both increases the chances of independent origins of life in the solar system and makes distinguishing it from terrestrial contamination more complex.
Carbon Isotopic Measurements of Amino Acids in Stardust-Returned Samples
Dr. Jamie Elsila (NASA Goddard Space Flight Center)
NASA’s Stardust spacecraft returned to Earth samples from comet 81P/Wild 2 in January 2006. Preliminary examinations revealed the presence of a suite of organic compounds including several amines and amino acids, but the origin of these compounds could not be identified. Here, we present the carbon isotopic ratios of glycine and e-aminocaproic acid (EACA), the two most abundant amino acids, in Stardust-returned foil samples measured by gas chromatography-combustion-isotope ratio mass spectrometry coupled with quadrupole mass spectrometry (GC-QMS/IRMS).
IR Doppler Techniques for Detecting Habitable Earth like Planets Around M Dwarfs
Prof. Jian Ge (University of Florida)
At University of Florida, we are developing two infrared Doppler techniques for detecting and characterizing extrasolar planets around M dwarfs aiming at detecting habitable Earth like planets. One IR Doppler technique is based on a cross-dispersed echelle spectrometer using a silicon immersion grating called Florida IR Silicon immersion grating spectromeTer (FIRST), and the other IR technique is based on a dispersed fixed-delay interferometer, called IR ET. FIRST is designed to have a spectral resolution of R=55,000 and cover 1.15-1.8 microns with a 2kx2k H2RG array in a single exposure. IR ET consists of a monolithic Michelson type fixed-delay interferometer and an R=18,000 cross-dispersed echelle spectrograph. The same 2kx2k H2RG array covers 0.8-1.35 microns for IR ET in a single exposure. Our initial goal is to reach ~3 m/s photon noise limited Doppler precision in 15 min exposures for a M2V star with the Apache Point Observatory (APO) 3.5m telescope. Current plan is to deploy prototypes at the APO 3.5m in August 2009 and conduct science demonstration in the fall. The prototypes will be replaced with science instruments in 2010.
From Prebiotic Chemistry to Biology: Modeling the Emergence of Protocells in Early Earth
Prof. Marcelo Gleiser (Dartmouth College)
The activation-polymerization-epimerization-depolymerization (APED) model of Plasson et al. has recently been proposed as a mechanism for the evolution of homochirality on prebiotic Earth. The dynamics of the APED model in two-dimensional spatially-extended systems is investigated for various realistic reaction parameters. It is found that the APED system allows for the formation of isolated homochiral proto-domains surrounded by a racemate. A diffusive slowdown of the APED network induced, for example, through tidal motion or evaporating pools and lagoons leads to the stabilization of homochiral bounded structures as expected in the first self-assembled protocells.
Living with a Red Dwarf: On the Suitability of Red Dwarf Stars to Support Life on Nearby Hosted Planets
Prof. Edward Guinan (Villanova University)
Red Dwarf (late dK & dM) stars are the most numerous stars in our Galaxy. These faint, cool, long-lived, and low mass stars make up over ~80% of all stars. Determining the number of red dwarfs with planets and assessing planetary habitability (a planet’s potential to develop and sustain life) are critically important because such studies would indicate how common life is in the universe. Our "Living with a Red Dwarf" program addresses these questions. We are investigating the long-term nuclear evolution and magnetic-dynamo generated coronal and chromospheric X-ray to ultraviolet properties of red dwarf stars with ages from <50 Myr to ~12 Gyr. We discuss how the stellar XUV emissions, flares & stellar winds affect hosted planets and impact their habitability. Also ee have developed age-rotation-activity relations for determining accurate ages from rotation or magnetic activity. As part of this program we also are determining XUV irradiances for dK5 - dM7 type stars from youth to old age. These irradiances can be used to study the effects of XUV radiation and winds on planetary atmospheres and on possible life on nearby hosted planets. Despite the earlier pessimistic view that red dwarfs stars may not be suitable host stars for habitable planets - mainly because their low luminosities require a hosted planet to orbit quite close (r <0.3 AU) to be sufficiently warm to support life. Thus a planet orbiting that close would become tidally-locked as well as being exposed to high levels of XUV radiation from flares. However, our initial results indicate that the warmer red dwarf stars can indeed be suitable hosts for habitable planets capable of sustaining life for hundreds of billion years. Some examples of red dwarf stars currently known to host planets are given along with astrobiological assessments of their habitability. This research is supported by grants from NASA/FUSE (NNX-06AD38G), and NSF/RUI (AST-0507542 & AST-0507536) which we gratefully acknowledge.
The Case for Solar System SETI
Jacob Haqq-Misra (Penn State University)
Given the old age of our galaxy, if the evolution of life and subsequent development of intelligence is common, then extraterrestrial intelligence (ETI) could have colonized the Milky Way several times over by now. Known as the Fermi paradox, the lack of ETI observation leads some to conclude that humans have formed the only advanced civilization in this galaxy, either because life is rare or because intelligent civilizations inevitably destroy themselves. There are many resolutions to the so-called paradox including the "Sustainability Solution", which proposes that faster (e.g. exponential) growth may not be sustainable on a galactic scale. If this is the case, then we may never observe a galactic-scale ETI civilization, for such an empire would have grown and collapsed quickly relative to geologic and astronomic timescales. The Search for Extraterrestrial Intelligence (SETI) should therefore focus on ETI that grow within the limits of their carrying capacity, thereby avoiding collapse. In addition to radio broadcasts, extant slower-growth ETI may possess the technological capacity for remote interstellar exploration. ETI interstellar probes may have already reached the Solar System, residing in the asteroid belt, Lagrange points, or other stable orbits. Such probes with a limiting size of only ~1-10 meters may have so far eluded observation, so SETI may be more successful if it is expanded to include a search of our Solar System for small, unmanned extraterrestrial artifacts.
Ecliptic-Plane SETI with the Allen Telescope Array
Prof. Richard Conn Henry (Johns Hopkins University)
The successful launch of NASA’s Kepler Mission to find Earthlike exoplanets refocuses attention on the important inverse problem, that of detecting radio signals from civilizations in our galaxy that know of our existence because they detected transits of our Earth across the face of our Sun. If any such civilizations exist, they must of course be located in or near the ecliptic plane (Filippova & Strelnitskij 1988, Filippova 1990, Shostak & Villard 2002, Kilston, Shostak, & Henry 2008, Henry, Kilston, & Shostak 2008). Furthermore, they should be easy to find, if they exist, because we know where to look, and because they are expected to be targeting us because they have detected water, and free oxygen, in our atmosphere. These, together, strongly suggest the presence of life to those carbon-based beings that have a similar biochemistry. Our proposal to search for such civilizations by using the Allen Telescope Array was accepted in 2008 July; we were awarded 32 hours of observing time. Our observing is expected to begin as soon as in a few months’ time––we hope to be able to observe a few nights per month. The hypothesis that we are testing is optimal, because we observe at night, thus avoiding the problem of solar interference. We are tentatively planning to do a series of 100-second observations stepping down a vertical line, centered in the anti-solar direction. This, of course, only samples a small part (beam size is a few arc minutes) of the 0.5 degree band in which others could see us transit the Sun, but it is perhaps as reasonable as any other approach. We will do two beams simultaneously, as this will allow us to compare them for common signals, which can then be ruled out as terrestrial interference. Since we would need only 3 observations per vertical stripe, our sampling along the ecliptic would be complete for the centerline stripes. After all, it takes ~2 hours for the Sun to move 5 arcminutes. So, either we could have very long integrations, or we could use shorter ones, and do adjacent, vertical stripes. We can do one band at a time. 21 cm is an obvious choice, but Gerry Harp suggests that, for example π ?1.420 MHz would be “practically virgin territory” for SETI. Filippova, L. N.; Strelnitskij, V. S.; “Ecliptic as an Attractor for SETI.” Astronomicheskii Tsirkulyar No. 1531, Sept. 1988 Filippova, L. N.; “A List of Near Ecliptical Sun like Stars for the Zodiac SETI Program,” Astronomicheskii Tsirkulyar No. 1544, Sept. 1990 Henry, R.C., Kilston, S., & Shostak, S. 2008, “SETI in the Ecliptic Plane,” poster at the American Astronomical Society meeting, St. Louis, MO Kilston, S., Shostak, S., & Henry, R.C. 2008, “Who’s Looking at You, Kid?”: SETI Advantages near the Ecliptic Plane, Astrobiology Science Conference, Santa Clara, CA. Shostak, S., & Villard, R. 2002, “A Scheme for Targeting Optical SETI Observations,” in Bioastronomy 2002: Life Among the Stars, IAU Symposium No. 213, ed. R. P. Norris and F. H. Stootman (ASP, San Francisco), p. 409
Circular Polarization in Comets: Does it Manifest the Presence of Homochiral Organics?
Dr. Ludmilla Kolokolova (University of Maryland)
A unique characteristic of life is the homochirality of biological molecules, i.e. predominance of one of the mirror form of the molecules. This characteristic may be manifested on a macroscopic scale through the optical activity of the chiral molecules and, hence, the presence of circular polarization in the light they scatter. Due to recent work by the authors, a unique set of the data on circular polarization in comets has been accumulated. It has been confirmed that all comets with a significant value of circular polarization show predominantly left-handed circularly polarized light. There are three main mechanisms that may produce circular polarization in the light scattered by comet dust grains: multiple scattering, alignment of particles, and excess of L-enantiomeric molecules in cometary organics. We consider all three mechanisms and show that neither multiple scattering nor alignment of dust particles can explain the observed circular polarization in comets. Our computer and laboratory simulations of the light-scattering by optically-active particles support the idea that cometary dust can include optically active materials which may be prebiological homochiral organics The results of this study can be applied to search of molecules of prebilogoical and biological origin in astronomical objects other than comets, such as planets, extrasolar planets, and protoplanetary nebulae.
Organics in Galaxies, as Traced by the Diffuse Interstellar Bands
Dr. Brandon Lawton (STScI)
Organic molecules, as probed by the diffuse interstellar bands (DIBs), are commonly observed in our Galaxy and to a lesser degree in the Magellanic Clouds. The carriers of these absorption bands, which are possibly polycyclic aromatic hydrocarbons, carbon chains, and/or fullerenes, may have played a role in prebiotic chemistry after seeding early Earth. Understanding the abundances of these organics in the ISM of galaxies allow for us to determine the conditions conducive for their existence. Our work complements the DIB studies done locally by observing DIB strengths in seven gas-rich galaxies known as damped Lyman-alpha galaxies (DLAs) and in 18 heavily starbursting galaxies. In the sample of seven low to moderate redshift DLAs, we provide conservative equivalent width limits of six DIBs observed to have large strengths in our Galaxy. DIBs were detected in only one of the seven DLAs, that which has the highest reddening and metallicity. If similar to the Milky Way, these galaxies are expected to have strong DIB absorption based solely from their large neutral hydrogen abundance; however, the fact that most do not exhibit DIBs could be caused from effects due to metallicity, ionizing radiation, and dust content. The one detected DIB within a DLA galaxy is evidence that the galaxy's relatively high metallicity is partially responsible. In the sample of 18 low to moderate redshift starburst galaxies, we tentatively identify DIB detections in 14 of the starbursts. Starbursts are kinematically violent galaxies with large gas outflow velocities. The most commonly observed DIB in our sample is the 5780 Angstrom DIB, thus, we perform Kendall-tau correlations for the 5780 DIB equivalent widths and velocities with all compiled galaxy properties, including the large neutral sodium (NaI) gas outflow velocities. There is a weak trend indicating the 5780 DIB absorbing gas is outflowing, but it lags behind the higher velocity of the NaI outflowing gas. If this trend holds true, then it indicates that organics can survive in relatively turbulent gas. The higher success rate of DIB detections in starbursting galaxies may be attributable to their larger metallicities and dust abundances, relative to DLAs.
The Transmission Spectrum of a Habitable Planet
Prof. Eduardo Martin (University of Central Florida)
The optical-infrared transmission spectrum of planet Earth has been obtained during the total lunar eclipse of August 2008. It is compared with the reflected spectrum from Earth and it is found that key biomarkers are easier to detect with transmission spectroscopy than with reflected spectroscopy. This result could have an impact on future strategies to characterize the spectra of rocky exoplanets in the habitable regions of nearby stars.
Resources for Life in Solar Nebulae
Prof. Michael Mautner (Virginia Commonwealth University)
Solar nebulae may allow the formation, growth and dispersion of microbial life. In particular, asteroids during aqueous alteration could originate and sustain early microorganisms. This hypothesis may be tested using nebula materials preserved in meteorites. For this purpose, water-soluble nutrients in carbonaceous chondrites, and microbial growth on these meteorite materials, were tested. Based on the soluble meteorite contents, fluids in early aqueous asteroids contained high concentrations (several moles/liter) of organics and electrolytes, including the macronutrient elements C, N, P and K. These solutions, trapped in asteroid/meteorite pores with mineral catalysts, could allow complex reactions leading to biomolecules. Similar reactions could occur in the pores of meteorites on aqueous planets. Microbial tests suggest that these solutions can also sustain microorganisms that originated in or colonized these objects. For example, we found that oligotrophic bacteria such as Nocardia asteroides, hydrocarbon-degrading bacteria, complex communities of bacteria and fungi, and algae and plant cultures all grow well on these materials. Soil fertility tests suggest that similar materials in carbonaceous asteroids can provide resources for human settlements in space. As for the past roles, the results suggest that microorganisms can originate and survive in early aqueous asteroids, and disperse by collisions in solar nebulae. For these reasons, solar nebulae may be suitable targets to search for life, and may be also useful targets for directed panspermia to seed new solar systems. References Links to the references are available at www.astroecology.com Mautner, M. N. “Planetary Resources and Astroecology. Planetary Microcosm Models of Asteroid and Meteorite Interiors: Electrolyte Solutions and Microbial Growth.” Astrobiology 2002, 2, 59-76. Mautner, M. N. “Directed Panspermia. 3. Strategies and Motivation for Seeding Star-Forming Clouds.” J. British Interplanetary Soc. 1997, 50, 93.
Quantitative Potentials for Life in Predicted Periods of Cosmology
Prof. Michael Mautner (Virginia Commonwealth University)
Astrobiology investigates the origins, prevalence, and future of life in the universe. As to future potentials, conditions for life about various types of stars in predicted ages of cosmology were considered by Adams and Laughlin (1999). A quantitative assessment these potentials is of interest. The amounts of life in habitats of finite duration may be quantified in terms of time-integrated biomass (measured in kg-years, where terrestrial life to date amounts to about 1024 kg-years). In the Solar System, carbonaceous asteroids may provide accessible resources. Water-soluble elements in carbonaceous meteorites suggest that 1022 kg carbonaceous asteroids may sustain 1028 kg-years, while their total elemental contents may sustain 1030 kg-years of time-integrated biomass about the main-sequence Sun. Considering energy-limited conditions about other stars and biomass power requirements of 100Watts/kg, Red Giants may sustain on the order of 1034; White Dwarfs, 1033; Red Dwarfs, 1034; and Brown Dwarfs, 1028 kg-years of time-integrated biomass, per star, during their predicted lifetimes (multiplied by about 1011 – 1012 stars for potential time-integrated biomass in the future galaxy). Finally, the upper limits of life in the galaxy and in the universe may be also quantified. An estimated 1041 kg baryonic matter in the galaxy and 1052 kg in the universe, fully converted to biomass and to sustaining energy, would yield on the order of 1048 kg-years of time-integrated biomass in the galaxy and 1059 kg-years in the universe. This extensive potential for life can allow substantial biological advancements. References Links to the references are available at www.astroecology.com Mautner, M. N. “Life in the Cosmological Future: Resources, Biomass and Populations.” J. British Interplanetary Soc. 2005, 58, 167 – 180. Adams, F. and Laughlin, G. “The Five Ages of the Universe”. Touchstone Books, New York, 1999.
Asteroid 1 Ceres: Evidence for Water Beneath its Surface
Dr. Lucy McFadden (U. Maryland)
Assuming that the presence of water is an indicator of possible life, we present both experimental and theoretical evidence for the existence of water below the surface of the dwarf planet, 1 Ceres, the largest and most massive body in the main asteroid belt of our solar system. NASA’s Dawn mission is on its way to study both Vesta and Ceres, and will contribute additional knowledge related to the question of the existence of life elsewhere in our solar system. Spectral evidence of water of hydration on asteroid 1 Ceres was first recognized by Lebofsky in 1978. Further analysis and laboratory spectral studies of carbonaceous meteorites and clay minerals lead to the interpretation of structural water in clay minerals (Lebofsky et al. 1980). Higher resolution spectra suggested the presence of water frost at 3.07 µm (Lebofsky et al. 1981). King et al. (1992) reinterpreted the narrow and weak absorption band at 3.07 µm as due to ammoniated saponite, a low temperature alteration product of a clay mineral. Renewed interest in large asteroids, which are arguably protoplanets (e.g. McCord et al. 2006) has motivated both theoretical models and additional astronomical observations. McCord and Sotin (2005) developed thermal models for Ceres’s internal evolution, to explore the nature of large (1000’s km diameter), water-bearing protoplanets. Their analysis indicates that the heat generated by radioactive decay melted the interior of water-rich Ceres, and that its interior may contain water at temperatures above the melting point of ice. They predict a surface undergoing planetary processes and a chemically complex interior (Castillo-Rogez & McCord, 2009). In December 2003 and January 2004, Hubble Space Telescope observed Ceres during a full rotation (Parker et al 2004). Thomas et al. (2005) using these images, inferred from its shape and density that Ceres has a differentiated interior. This is consistent with the thermal modeling of McCord and Sotin. Albedo maps derived by Li et al. (2006) using Hubble images show terrain of variable albedo and color in the visible and ultraviolet. Li et al. concludes that the degree to which albedo is uniform, together with the mean density determined by Thomas et al. (2005) suggests that Ceres could have been resurfaced by liquid water. Observations by the Dawn spacecraft will address some of the outstanding questions related to the possibility of life supporting conditions at Ceres.
Origin of Life on Earth: the Role of Doublet Codons in the Primordial Genetic Code
Dermott Mullan (University of Delaware)
In the prebiotic Earth, during an interval of time of order 0.1 Gyr, a finite number N of chemical reactions occurred between the monomers which were available, including amino acids and nucleosides. The number N enabled the sampling of the genomic phase space of a cell of a certain size. In a cell which relies on single-strand RNA for its genetic material, the size of phase space F is a function only of the number of genes p and the number T of bases in a codon. Plausible estimates of N are not sufficient to allow dense sampling of the phase space of any viable cell if T has its current value (T=3). However, if T=2, i.e. if proteins operate with a slightly reduced set (16) of amino acids, dense sampling of phase space becomes possible for a cell with p as large as 15. Such a cell may be viable.
The New SETI Projects in Korea
Dr. Myung-Hyun Rhee (Yonsei University Observatory, Yonsei University)
We have recently launched a couple of SETI projects as parts of main events for the 2009 International Year of Astronomy (IYA2009) in Korea. We report early results from the projects. The 7m public radio telescope has been constructed at the Gwacheon National Science Museum. It is equipped with one million channel SETI spectrometer. It will be used for 22GHz all-sky SETI survey and for targeting SETI observations of the selected stars with known planets. We are also developing new education programs for radio astronomy and SETI. We have developed an algorithm to detect very short time scale transient events from Very Long Baseline Interferometer (VLBI) raw data. We have produced 100,000 work units from our artificial VLBI raw data sets with artificial ExtraTerrestrial Intelligence (ETI) signals used for simulations of detection efficiency. These work units are to be used for a test run with the distributed computing platform, Korea@Home. We report in this paper some results from these Monte Carlo simulations. The 3-day workshop focusing mainly on SETI science for SF writers was held at the Sobaeksan Observatory and KVN-Yonsei Radio Observatory. More workshops for animation artists and tale writers are planned. We will soon launch an organized public campaign for creating new Arecibo and Voyager-type messages to ETI. Parts of the results will be displayed in Daejeon Art Gallery as a part of the Science-Art exhibition.
Transiting Exoplanet Survey Satellite (TESS)
Dr. George Ricker (MIT)
The Transiting Exoplanet Survey Satellite (TESS) is a low cost, SMEX-class planet finder. In a two year all-sky survey, TESS will search more than two million bright, nearby stars for planetary transits. TESS is expected to detect more than 1000 transiting exoplanets, including a sample of ~100 small rock-and-ice “Super Earths” orbiting stars with spectral types spanning a broad range, including F, G, K, and M dwarfs. No ground-based survey can achieve this feat. TESS’s "wide-shallow" survey complements the "narrow–deep" Corot and Kepler surveys. The TESS Transit Catalog of bright, nearby stars will constitute a unique legacy for followup observations. TESS will identify Super Earths orbiting IR-bright stars, ideal for JWST searches for planetary water and carbon dioxide. TESS is currently completing a NASA-funded Phase A study, and is proposed for launch in December 2012.
Which Radial Velocity Exoplanets Have Undetected Outer Companions?
Mr. Timothy Rodigas (Steward Observatory, University of Arizona)
The observed radial velocity (RV) eccentricity distribution for extrasolar planets in single-planet systems shows that a significant fraction of planets are eccentric (e > 0.1). However an RV planet's eccentricity, which comes from the Keplerian fitting, can be biased by low signal-to-noise and poor sampling. Here we investigate the effects on eccentricity produced by undetected outer companions. We have carried out Monte Carlo simulations of mock RV data to understand this effect and predict its impact on the observed distribution. We first quantify the statistical bias of known RV planets’ eccentricities produced by undetected zero-eccentricity wide-separation companions and show that this effect alone cannot explain the observed distribution. We then modify the simulations to consist of two populations, one of zero-eccentricity planets in double-planet systems and the other of single planets drawn from an eccentric distribution. Our simulations show that a good fit to the observed distribution is obtained with 45% zero-eccentricity double-planets and 55% single eccentric planets. Matching the observed distribution allows us to determine the probability that a known RV planet's orbital eccentricity has been biased by an undetected wide-separation companion. Averaged over eccentricity we calculate this probability to be ~ 4%, suggesting that a small fraction of systems have a yet to be discovered outer companion. For low eccentricity orbits, in particular 0.1 < e < 0.3 and 0.1 < e < 0.2, the probability is ~ 13% and ~ 19%, respectively. We therefore encourage both high-contrast direct imaging and RV follow-up surveys of known RV planets with eccentricities in these ranges to look for potential wide-separation companions.
SAGE-Spec Infrared Spectra of Organic Molecules around Young Stellar Object Candidates in the Large Magellanic Cloud
Dr. Benjamin Sargent (STScI)
Infrared spectra taken by the Infrared Spectrograph (IRS) on board the Spitzer Space Telescope of four objects proposed from previous studies to be Young Stellar Objects are consistent with the hypothesis that these stellar systems are young. The spectra were obtained as part of the SAGE-Spec Spitzer Legacy program (PIs: Kemper, Tielens), a spectroscopic follow-up program to the Spitzer Legacy program SAGE (Surveying the Agents of a Galaxy's Evolution; PI: Meixner). SAGE observed millions of sources at infrared wavelengths in the Large Magellanic Cloud (LMC), one of the nearest galaxies to our own Milky Way, and SAGE-Spec followed up by obtaining IRS spectra (5-37 microns wavelength) of 196 targets observed by SAGE. All four candidate YSO spectra discussed here show emission from silicate dust grains, consistent with spectra of local YSOs in the Milky Way. The spectra and Spectral Energy Distributions (SEDs) of these candidate YSOs are further consistent with spectra and SEDs of local YSOs in that the circumstellar material around each of these stars is probably orbiting as a disk around the star. However, only two of the spectra show strong Unidentified Infrared (UIR) emission associated with organic molecules like Polycyclic Aromatic Hydrocarbons (PAHs). The other two spectra show weak or nonexistent UIR emission. Spectra of young stars of early spectral type (A, B), like the four LMC candidate YSOs discussed here, local to the Sun typically show UIR emission. That two of the four candidate YSOs discussed here do not show strong UIR emission is interesting and will be investigated further.
Planetary System, Star Formation, and Black Hole Science with Non-Redundant Masking on Space Telescopes
Dr. Anand Sivaramakrishnan (American Museum of Natural History)
Non-redundant masking (NRM) is a high contrast, high resolution technique relevant to future space missions concerned with extrasolar planetary system and star formation, as well as general high angular resolution galactic and extragalactic astronomy. NRM enables the highest angular resolution science possible given the telescope's diameter and operating wavelength. It also provides precise information on a telescope's optical state. NRM relies on its high quality self-calibration properties and the robustness of interferometric techniques, whereas coronagraphy requires exquisite wavefront quality. Stability during an observation sets fundamental NRM contrast limits. A non-redundant mask was recently added to JWST's Fine Guidance Sensor Tunable Filter Imager (FGS-TFI) instrument, bringing a no-cost, no-impact boost in angular resolution that complements JWST's coronagraphs. The JWST NRM search space lies between 50 and 400 mas at 3.8 to 5um, even if the telescope's image quality does not meet requirements. JWST's NRM will produce 10 magnitudes of contrast in a 10~ks exposure on an M=7 star, placing Taurus protoplanets and nearby Jovians younger than 300 Myr within JWST's reach. Future space telescopes can improve vastly on JWST's NRM by utilizing more refined observing methods, and instrumentation designed to take full advantage of NRM's high dynamic range. The ATLAST 16m design can deliver 10 to 12 magnitudes of contrast between 0.7 to 6 mas at 0.1 um On an 8m telescope at 0.1um. NRM resolution is almost ten times finer than ALMA's finest resolution. Polarization with space-based NRM opens new vistas of astrophysics in planetary system and star formation as well as AGNs and structure around galactic black hole candidates. Space NRM explores areas inaccessible to both JWST coronagraphs and future 30-m class ground-based telescopes. Ground-based NRM is limited by atmospheric variability. Optimization of space-based NRM requires consideration of flat fielding accuracy, target placement repeatability, charge diffusion, intrapixel sensitivity, image persistence, charge transfer efficiency, guiding, wavefront stability, pupil wander, and other details. We must assess NRM contrast limits realistically to understand the science yield of NRM in space, and, simultaneously, develop NRM science for planet and star formation and extragalactic science in the UV-NIR, to help steer high resolution space-based astronomy in the coming decade.
The Frequency of Young Ultracool Dwarfs in the Solar Neighborhood and Their Flare Rate
Mr. Ramarao Tata (University of Central Florida)
Ultracool dwarfs(UCDs) are excellent targets for planets searches (even for possible super-Earths in the habitable zone) as they have relatively smaller masses and radii. A census of UCDs in the solar neighborhood is needed. We present our discovery of 38 new UCDs (Spectral types M6 to L4) in the solar neighborhood. We find 6/71 (~8.5%) young (<100 Myr) UCD's in our sample of field objects. 4/6 of these young UCD's have H-alpha emission. We did not detect any obvious flares in our observations. Absence of flaring in UCDs (even young UCDs) provide an evolutionary advantage for the atmospheres of any possible terrestrial planets around them.
Formation, Survival, and Detectability of Planets Beyond 100 AU
Dr. Dimitri Veras (University of Florida)
Direct imaging searches have begun to detect planetary and brown dwarf companions and to place constraints on the presence of giant planets at large separations from their host star. This work helps to motivate such planet searches by predicting a population of young giant planets that could be detectable by direct imaging campaigns. Both the classical core accretion and the gravitational instability model for planet formation are hard-pressed to form long-period planets in situ. Here, we show that dynamical instabilities among planetary systems that originally formed multiple giant planets much closer to the host star could produce a population of giant planets at large (~100 AU - 100000 AU) separations. We estimate the limits within which these planets may survive, quantify the efficiency of gravitational scattering into both stable and unstable wide orbits, and demonstrate that population analyses must take into account the age of the system. We predict that planet scattering creates a population of detectable giant planets on wide orbits that decreases in number on timescales of ~10 Myr. We demonstrate that several members of such populations should be detectable with current technology, quantify the prospects for future instruments, and suggest how they could place interesting constraints on planet formation models.
The Chirality of Life: From Phase Transitions to Astrobiology
Mrs. Sara Walker (Dartmouth College)
Our understanding of the likelihood of life elsewhere in the universe hinges on our knowledge of its emergence on Earth. A key-missing piece is the origin of biomolecular homochirality: permeating almost every life-form on Earth is the presence of exclusively levorotary amino acids and dextrorotary sugars. The mechanism behind this fundamental asymmetry of life remains unknown. Coupling the spatiotemporal evolution of a general autocatalytic reaction network to external environmental effects, we show through a detailed statistical analysis that life’s homochirality resulted from sequential chiral symmetry breaking triggered by environmental events in a mechanism we refer to as punctuated chirality. Applying these arguments to other potentially life-bearing planetary platforms has significant implications for the search for extraterrestrial life: we predict that a statistically representative sampling of extraterrestrial stereochemistry will be racemic on average.
Exploring New Parameter Space with the Anglo-Australian Telescope
Dr. Rob Wittenmyer (University of New South Wales)
With more than 300 extrasolar planets now known to orbit Sun-like stars, the time has come to extend our efforts into new regions of parameter space. Two new projects are now being undertaken at the Anglo-Australian Telescope: (1) the search for terrestrial-mass planets, and (2) the characterisation of planets orbiting stars more massive than our Sun. These are critical investigations for understanding the planet formation process, and for quantifying the population of potentially habitable planets. I present results from a 48-night radial-velocity campaign which achieved a detection sensitivity of a few Earth masses for planets in short-period orbits. I also describe our efforts to complete an all-sky survey of evolved, high-mass stars with the goals of determining the dependence of planetary system properties on host-star mass, and disentangling the origin of the planet-metallicity correlation.
First Light with Project 1640, an Integral Field Spectrograph for Exoplanetary Science
Mr. Neil Zimmerman (Columbia University)
In October 2008 the Project 1640 team began a high contrast survey of the environments of nearby stars from Palomar Observatory. We demonstrate our first results and describe the data processing methods we have devised for our novel instrument.