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Project Reports

• Detectability of Life

  Detectability of Life investigates the detectability of chemical and biological signatures on the surface of icy worlds, with a focus on spectroscopic techniques, and on spectral bands that are not in some way connected to photosynthesis.Detectability of life investigation has three major objectives: Detection of Life in the Laboratory, Detection of Life in the Field, and Detection of Life from Orbit.

  ROADMAP OBJECTIVES: 1.2 2.1 2.2 4.1 5.3 6.1 6.2 7.1 7.2

• AIRFrame Technical Infrastructure and Visualization Software Evaluation

  We have analyzed over four thousand astrobiology articles from the scientific press, published over ten years to search for clues about their underlying connections. This information can be used to build tools and technologies that guide scientists quickly across vast, interdisciplinary libraries towards the diverse works of most relevance to them.

  ROADMAP OBJECTIVES: 1.1 1.2 2.1 2.2 3.1 3.2 3.3 3.4 4.1 4.2 4.3 5.1 5.2 5.3 6.1 6.2 7.1 7.2

• Astronomical Observations of Planetary Atmospheres and Exoplanets

  This task encompasses remote-sensing observations of Solar System and extrasolar planets made by the VPL team. These observations, while providing scientific exploration in its own right, also allow us to test our planetary models and help advance techniques to retrieve information from the astronomical data that we obtain. This can include improving our understanding of the accuracy of inputs into our models, such as spectral databases. This year we made and/or analyzed observations of Mars, Venus and Earth taken by ground-based and spaceborne observatories, to better understand how well we can determine planetary properties like surface temperature and atmospheric composition, when a terrestrial planet is observed only as a distant point of light.

  ROADMAP OBJECTIVES: 1.2 2.2 7.2

• Project 1: Looking Outward: Studies of the Physical and Chemical Evolution of Planetary Systems

  This project five main objectives focused broadly on understand the origin and early evolution of our solar system. First, we have employed a new planet finding spectrometer to aid in detecting planetary systems surrounding neighboring stars. Second, we have begun the Carnegie Astrometric Planet Search project to detect giant planets around nearby loss mass dwarf stars. Third, we focused on understanding of radial transport and mixing of matter in protoplanetary disks. Fourth, we have continued to survey of small planetary size objects in the Kuiper belt. Fifth, we have continued our studies of the composition, structure, and ages of circumstellar disks.

  ROADMAP OBJECTIVES: 1.1 1.2 2.2 3.1

• Disks and the Origins of Planetary Systems

  This task is concerned with understanding the evolution of complex habitable environments as primitive planetary bodies are forming in a developing protoplanetary disk. The planet formation process begins with the collapse of large molecular clouds into flattened disks. This disk is in many ways an astrochemical “primeval soup” in which cosmically abundant elements are assembled into increasingly complex hydrocarbons and mixed in the dust and gas envelope within the disk. Gravitational attraction among the myriad small bodies leads to planet formation. If the newly formed planet is a suitable distance from its star to support liquid water at the surface, it is in the so called “habitable zone.” The formation process and identification of such life-supporting bodies is the goal of this project.

  ROADMAP OBJECTIVES: 1.1 1.2 2.1 4.3

• Detectability of Biosignatures

  In this project VPL team members explore the nature and detectability of biosignatures, global signs of life in the atmosphere or on the surface of a planet. This year we completed and published our work on the build up and detectability of sulfur-based biosignatures in early Earth-like atmospheres, especially for planets orbiting stars cooler than our Sun. We also continued to explore the potential non-biological generation of oxygen and ozone in early Earth-like atmospheres, which could result in a “false positives” for photosynthetic life. In parallel, we worked with three simulators for telescopes that will one day be able to observe and determine the properties of extrasolar terrestrial planets, and used these simulators to calculate the relative detectability of gases produced by life.

  ROADMAP OBJECTIVES: 1.1 1.2 4.1 7.2

• Path to Flight

  Our technology investigation, Path to Flight for astrobiology, utilizes instrumentation built with non-NAI funding to carry out three science investigations namely habitability, survivability and detectability of life. The search for life requires instruments and techniques that can detect biosignatures from orbit and in-situ under harsh conditions. Advancing this capacity is the focus of our Technology Investigation.

  ROADMAP OBJECTIVES: 1.1 1.2 2.1 2.2 3.1 3.2 7.1 7.2

• Dynamical Effects on Planetary Habitability

  The Earth’s orbit is near-circular and has changed little since its formation. The Earth is also far enough away from the Sun, that the Sun’s gravity doesn’t seriously affect the Earth’s shape. However, exoplanets have been found to have orbits that are elliptical, rather than circular, and that evolve over time, changing shape and/or moving closer or further to the parent star. Many exoplanets have also been found sufficiently close to the parent star that the star can deform the planet’s shape and transfer energy to the planet in a process called tidal heating. In this VPL task we investigate how interactions between a planet’s orbit, spin axis, and tidal heating can influence our understanding of what makes a planet habitable. Scientific highlights include the finding that tidal effects could be strong enough to cause a planet to overheat and ultimately lose its ocean, that large changes in the direction of the spin-axis of a planet could potentially increase the range of distances from the star in which the planet could remain habitable, and that the Sun may have moved significant distances outward through the Galaxy during its lifetime, changing the rate of at which large bodies have hit the Earth.

  ROADMAP OBJECTIVES: 1.1 1.2 3.1 4.3

• Collisional Evolution of Planetesimal Systems and Debris Disk Patterns

  Marc Kuchner and his graduate student Erika Nesvold are working on a new tool for modeling the collisional evolution and 3-D distribution of planetesimals in planetary systems and debris disks. We plan to use this tool for interpreting images of planetary systems: modeling images and other data on circumstellar disks. We expect to be able to use this approach to locate hidden exoplanets via their dynamical influence on the shapes of the disks. We also expect to use our new models to understand the evolution of planetesimals in the solar system during the time when these planetesimals probably delivered the Earth’s ocean water.

  ROADMAP OBJECTIVES: 1.1 1.2 3.1

• Biosignatures in Extraterrestrial Settings

  The focus of this project is to explore indicators of life outside of Earth, both within the Solar System and on extrasolar planets. The work includes studies of the chemistry and composition of the Solar System, and the past history of conceivable sites for life in the Solar System. We also look for habitable planets outside the Solar System; work on developing new techniques to find and observe potentially habitable planets; and model the dynamics, evolution and current status of a variety of extrasolar planets.

  ROADMAP OBJECTIVES: 1.1 1.2 2.1 2.2 4.1 4.3 6.2 7.1 7.2

• Earth as an Extrasolar Planet

  Earth is the only known planet that can support life on its surface, and serves as our only example of what a habitable planet looks like. This task uses distant observations of the Earth taken from spacecraft combined with a sophisticated computer model of the Earth to understand the appearance and characteristics of a habitable planet. With our model, we can generate accurate simulations of the Earth’s brightness, color and spectrum, when viewed at different time-intervals, and from different vantage points. This year we used these simulations to understand how we might detect the presence of an ocean on an exoplanet using polarization, and the presence of a moon around a distant exoplanet using heat energy, rather than visible light.

  ROADMAP OBJECTIVES: 1.2 7.2

• Planetary Surface and Interior Models and SuperEarths

  We use computer models to simulate the evolution of the interior and the surface of real and hypothetical planets around other stars. Our goal is to work out what sorts of initial characteristics are most likely to contribute to making a planet habitable in the long run. Observations in our own Solar System show us that water and other essential materials are continuously consumed via weathering (and other processes) and must be replenished from the planet’s interior via volcanic activity to maintain a biosphere. The surface models we are developing will be used to predict how gases and other materials will be trapped through weathering over time. Our interior models are designed to predict how much and what sort of materials will come to a planet’s surface through volcanic activity throughout its history.

  ROADMAP OBJECTIVES: 1.1 1.2 4.1 5.2 6.1

• Modelling Planetary Albedo & Biomarkers in Rocky Planets’/moons Spectra

  Using data from Kepler and new ground-based detections, Lisa Kaltenegger and Dimitar Sasselov have identified which confirmed and candidate planets orbit within the Habitable Zone and could provide environments for basic and complex life to develop. They have also developed atmosphere models for extrasolar planetary environments for different geological cycles and varied environments for the advent of complex life. The team modeled detectable spectral features that identify such planetary environments for future NASA missions like the James Webb Space Telescope.

  ROADMAP OBJECTIVES: 1.1 1.2 4.1 4.2 6.2 7.2

• Formation and Prospect of the Detection of Habitable Super-Earths Around Low-Mass Stars

  In the quest for potentially habitable planets, the nearest stars are of special importance. These stars have accurate distances and precisely determined stellar parameters, and are the only stars for which follow-up by astrometry and direct imaging is possible. Within the Sun’s immediate neighborhood, M stars constitute the majority (72%) of nearby stars. The proximity, low surface temperatures, and small masses of these stars have made them unique targets for searching for terrestrial and habitable planets. During the past five years, team member N. Haghighipour has been actively involved in the detection of extrasolar planets around M stars both in theoretical and observational fronts.

  ROADMAP OBJECTIVES: 1.1 1.2

• Postdoctoral Fellow Report: Mark Claire

  I have studied how biology might have impacted Earth’s early atmosphere, and how the Sun’s light has changed with time. More specifically, I’ve modeled how enhanced release of biogenic sulfur gases in earlier periods of Earth history may have left clues in the geologic record, and compared these predictions to the data. Furthermore, I have made a model of what how the light from the Sun would appear at any planet or any time in the solar system.

  ROADMAP OBJECTIVES: 1.1 1.2 2.1 4.1 7.2

• Stellar Radiative Effects on Planetary Habitability

  Habitable environments are most likely to exist in close proximity to a star, and hence a detailed and comprehensive understanding of the effect of the star on planetary habitability is crucial in the pursuit of an inhabited world. We looked at how the Sun’s brightness would have changed with time. We used models to study the effect of one very big flare on a planet with a carbon dioxide dominated atmosphere, like the early Earth’s, and found that these types of planets are well protected from the UV flux from the flaring star. We have also looked at the first quarter of Kepler data to study flare activity on “ordinary” cool stars, that have not been preselected for their tendency to have large flares. We find that these cool stars fall into two categories: stars that have long duration flares of several hours, but flare less frequently overall, and stars that have short duration flares, but more of them. In future work we will explore the comparative effect on a habitable planet of these two patterns of flaring activity.

  ROADMAP OBJECTIVES: 1.1 1.2 2.1 4.1 4.3 7.2

• Ice Chemistry Beyond the Solar System

  The molecular inventory available on the prebiotic Earth was likely derived from both terrestrial and extraterrestrial sources. Many molecules of biological importance have their origins via chemical processing in the interstel-lar medium, the material between the stars. Polycyclic aromatic hydrocarbons (PAHs) and related species have been suggested to play a key role in the astrochemical evolution of the interstellar medium, but the formation mechanism of even their simplest building block, the aromatic ben¬zene molecule, has remained elusive for decades. Formamide represents the simplest molecule contain-ing the peptide bond. Conse¬quently, the formamide molecule is of high interest as it is considered as an important precursor in the abiotic synthesis of amino acids, and thus significant to further prebiotic chemistry, in more suitable environments. Ultra-high vacuum low-temperature ice chem-istry experiments have been conducted to understand the formation pathways in the ISM for many astrobiologcally important molecules.

  ROADMAP OBJECTIVES: 1.1 1.2 3.1 3.2 3.3 6.2 7.1

• NIR Spectroscopic Observations of Circumstellar Disks Around Young Stars

  As a research scientist in the Planetary Systems Laboratory at NASA GSFC, A. Mandell studies the formation and evolution of planetary systems and the structure and composition of the atmospheres of extra-solar planets utilizing near-infrared spectroscopy. Mandell’s current observing campaigns focus primarily on high-resolution ground-based spectroscopy of circumstellar disks and extrasolar planetary transits and secondary eclipses using instruments on the Keck II telescope and the Very Large Telescope. Additionally, Mandell assists as a co-investigator on computational studies of terrestrial planet formation and evolution using N-body simulations of planetary accretion.

  ROADMAP OBJECTIVES: 1.1 1.2 3.1

• Observations of the Water and Organic Content of Protoplanetary Disks and Comets

  The Blake group has been carrying out joint observational and laboratory program with NAI node scientists on the water and simple organic chemistry in the protoplanetary disk analogs of the solar nebula and in comets. It has been a highly productive year. The major overview papers outlining the results from our extensive (>100 disks) Spitzer IRS survey of the molecular emission from the terrestrial planet forming region are now published, and the initial follow-up work with GSFC scientists on the high spectral resolution ground based observations of such emission has just been submitted for publication. We have probed the outer disk’s water emission with the Herschel HIFI instrument, and also measured the D/H ratio in a Jupiter Family Comet for the first time with Herschel – finding a value consistent with that in the Earth’s oceans. Now that ALMA is ramping up toward operations, we look forward to high angular resolution observations of simple organics in the outer regions of disks and comets over the coming years. The full suite of results will permit the first detailed examination of the radial water and gas phase organic chemistry in planet-forming environments.

  ROADMAP OBJECTIVES: 1.1 1.2 3.1

• The VPL Life Modules

  The Life Modules team at VPL works on developing models of how biological processes – such as photosynthesis, breathing, and decay of organic materials – work on a planetary scale. When this is combined with the work of the atmospheric and planetary modeling teams, we are able simulate how these processes impact the atmosphere and climate of a planet. This information, then, helps us understand how might be able to detect whether or not a planet has life by looking at its atmosphere and surface. The Life Modules team has engaged in previous work coupling early Earth biogeochemistry and 1D models in the VPL’s suite of planetary models. Current work now focuses on biosphere models that simulate geographic distributions of life adapted to different climate zones and capable of coupling to 3D general circulation models (GCMs). Current project areas are: 1) development of a model of land-based ecosystem dynamics suitable for coupling with GCMs and generalizable for alternative planetary parameters, and 2) coupling of an ocean biogeochemistry model to GCMs.

  ROADMAP OBJECTIVES: 1.2 6.1 6.2 7.2

• Understanding Past Earth Environments

  For much of the history Earth, life on the planet existed in an environment dramatically different than that of modern-day Earth. Thus, the ancient Earth represents a planet with a biosphere that is both dramatically different than the one in which we live and is accessible to detailed study. As such, is serves as a model for what types of biospheres we may find on other planets. A particular focus of our work was on the “Early Earth” (formation through to about 500 million years ago), a timeframe poorly represented in the geological and fossil records but comprises the majority of Earth’s history. We have studied the composition of the ancient atmosphere, modeled the effects of clouds on such a planet, studied the sulfur, oxygen and nitrogen cycles, and the atmospheric formation of molecules that were likely important to the origins of life on Earth.

  ROADMAP OBJECTIVES: 1.1 1.2 4.1 4.2 5.1 5.2 6.1

• Remote Sensing of Organic Volatiles in Planetary and Cometary Atmospheres

  We developed state-of-the-art spectroscopic methods to analyze our extensive infrared database of Mars and cometary spectra. In the last two years, we acquired the deepest and most comprehensive search for biomarkers on Mars using powerful infrared high-resolution spectrometers (CRIRES, NIRSPEC, CSHELL) at high-altitude observatories (VLT, Keck-II, NASA-IRTF respectively). In order to analyze this unprecedented wealth of data, we developed highly automated and advanced processing techniques that correct for bad-pixels/cosmic-rays and perform spatial and spectral straightening of anarmophic optics data with milli-pixel precision. We also constructed line-by-line models of the ν7 band of ethane (C₂H₆), the ν₃ and ν₂ bands of methanol (CH₃OH), we compiled spectral information for H₂O and HDO using 5 databases (BT2, VTT, HITEMP, HITRAN and GEISA), and compiled spectral information NH₃ using 4 databases (BYT2, TROVE, HITRAN and GEISA). These great advancements have allowed us to understand the infrared spectrum of planetary bodies with unprecedented precision.

  ROADMAP OBJECTIVES: 1.1 1.2 2.1 2.2 4.1 7.1 7.2

• VPL Databases, Model Interfaces and the Community Tool

  The Virtual Planetary Laboratory (VPL) develops computer models of planetary environments, including planets orbiting other stars (exoplanets) and provides a collaborative framework for scientists from many disciplines to coordinate their research. As part of this framework, VPL develops easier to use interfaces to its models, so that they can be used by more researchers. We also collect and serve to the community the scientific data required as input to the models. These input data include spectra of stars, data files that tell us how atmospheric gases interact with incoming stellar radiation, and plant photosynthetic pigments. We also develop tools that allow users to search and manipulate the scientific input data.

  ROADMAP OBJECTIVES: 1.1 1.2

• VYSOS Construction

  The VYSOS project aims at surveying all the major star forming regions across the entire northern and southern sky for variable young stars.using two small telescopes and robotics.
  As instrument implementation continues, We are working with Timm Riesen and Karen Meech to study the evolution of comet tails and to improve data relating to comet-focused missions.

  ROADMAP OBJECTIVES: 1.2