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Project Reports

• 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 atmospheric and surface temperature and pressure, 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 integrates the work of Carnegie Institution Astronomers in the 1) the search for extrasolar planets, 2) understanding the flow of matter in protoplanetary disks around young stars, 3) understanding the origin of Near Earth Objects, in particular, their relationship with objects in the asteroid belt, and 4) understanding the composition of disks around young stars and the potential delivery of volatiles to terrestrial planets in other solar systems.

  ROADMAP OBJECTIVES: 1.1 1.2 2.2 3.1

• Delivery of Volatiles to Terrestrial Planets

  We are investigating the mechanisms by which terrestrial planets obtain water and organic compounds. By understanding how these crucial constituents for life came to Earth, we can determine whether these mechanisms also operate in exoplanetary systems. When an earth-like planet is finally discovered in an exoplanetary system, it will be difficult to directly measure the composition of that planet. However, VPL scientists will use the observable properties of the system to determine whether that planet has a history that allowed water and organics to have been transported to it. One of the important questions is the initial state of the organic compounds, which sets stringent limits on the ability of the earth-like planets to acquire carbon.

  ROADMAP OBJECTIVES: 1.1 1.2 3.1 4.1 4.3

• Biosignatures in Extraterrestrial Settings

  Exploring the prospects for biosignatures in extraterrestrial settings is a multi

  ROADMAP OBJECTIVES: 1.1 1.2 2.1 2.2 3.1 4.1 4.3 6.2 7.1 7.2

• Disks and the Origins of Planetary Systems

  This task is concerned with the formation and evolution of complex habitable environments. The planet formation process begins with fragmentation 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 organic compounds and mixed in the dust and gas within the disk. Gravitational attraction among the myriad small bodies leads to planet formation. If the newly formed planet is a distance from its star that is suitable to support liquid water at the surface, it is in the so-called “habitable zone” (HZ). 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 submitted for publication modeling work that explores the potential for 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

• 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

• Path to Flight

  The (Field Instrumentation and) Path to Flight investigation’s purpose is to enable in-situ measurements of organics and biological material with field instrumentation that have high potential for future flight instrumentation. The preceding three Investigations (Habitability, Survivability and Detectability) provide a variety of measurable goals that are used to modify or “tune” instrumentation that can be placed in the field. In addition the members involved with Investigation provide new measurement capabilities that have been developed with the specific goal of life-detection and organic detection using both non-contact/non-destructive means and ingestion based methods. The developments under this investigation (Inv 4) incorporate state-of-the-art laboratory instruments and next generation in-situ instrumentation that have been developed under programs that include NASA as well as NSF and DOD. These include mass-spectrometers, gas analyzers, and fluorescence/Raman spectrometry instruments.

  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 it 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 modeling of habitable planets around brown dwarfs, the first comprehensive analysis of exomoon habitability, the role of distant stellar companions on planetary system architecture, and an improved understanding of the origins of terrestrial planet composition.

  ROADMAP OBJECTIVES: 1.1 1.2 3.1 4.3

• Detection of Circumbinary Planets Using Kepler Space Telescope

  Observations of stars in our galaxy have indicated that more than 60% of stars are in binaries or clusters. Several of these binary systems have been found to host circumbinary debris disks, suggesting that planet formation may proceed successfully around the entire binary system. During the past year, the PI teamed up with the Kepler Science Team to look for circumbinary planets. Their search has resulted in the discovery of three of such planets in 2012.

  ROADMAP OBJECTIVES: 1.1 1.2

• Earth as an Extrasolar Planet

  Earth is the only known planet that can support life on its surface, and often serves as the typical example of what a habitable planet looks like. In anticipation of future discoveries of observable, potentially habitable worlds around other stars, this task seeks to understand how we would characterize and understand the distant Earth. To accomplish this, we have developed several tools and approaches for simulating and investigating the Pale Blue Dot. In particular, we have demonstrated how an airless moon can affect observations of a habitable planet, developed new metrics to measure atmospheric pressure, and modeled light reflected off liquid water surfaces.

  ROADMAP OBJECTIVES: 1.2 7.1 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

• Dynamical Evolution of Multiple Star Systems

  During the past year I have performed 200,000 numerical simulations of newborn triple systems embedded in their placental gas cores. This has led to a number of surprising results, primarily a new model for the formation of extremely wide binaries, which is now in press in Nature.

  ROADMAP OBJECTIVES: 1.1 1.2

• Evolution of Protoplanetary Disks

  Drs. Aki Roberge and Carol Grady are pursuing studies related to Theme 2 of the NASA GSFC Astrobiology Node, “From Molecular Cores to Planets: Our Interstellar Heritage.” Over the last year, they have continued work on two Open Time Key Projects for the Herschel Space Observatory, an ESA mission launched in May 2009. Herschel is spearheading the next big advances in our knowledge of planet formation, protoplanetary disk evolution, and debris disks. One project (GASPS) is illuminating the evolution of gas abundances and chemistry in protoplanetary disks over the planet-forming phase. The other (DUNES) has sensitively probed the Sun’s nearest neighbors for signs of cold debris disks associated with extrasolar Kuiper Belts.

  ROADMAP OBJECTIVES: 1.1 1.2

• Habitability of Extrasolar Planets

  We model if and under what conditions some of the recently detected Super-Earths – small, Earth-sized planets that have been discovered in in the classical Habitable Zone Sun-like stars – could be habitable. These models explore the underlying physics of planetary atmospheres and their remotely detectable features.

  ROADMAP OBJECTIVES: 1.1 1.2 4.1 4.2 6.2 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 providing wavelength-dependent scaling factors for solar flux anywhere in the solar system from 0.6 to 6.7Gyr. Extrasolar planetary systems can only be determined through studying the host star; therefore we have also worked on determining the ages of Kepler planet host stars. We have constructed far ultraviolet to mid-infrared stellar spectra for 44 stars for being used as input in climate and photochemical models that are applied for determining habitable zones and possible characteristics of habitable planets. We have looked into the effect of methane (CH₄) and hydrogen (H₂) on the outer edge of the habitable zone for F, G, and M stars. We have studied the effect of host star stellar energy distribution (SED) and ice-albedo feedback on the climate of extrasolar planets.

  ROADMAP OBJECTIVES: 1.1 1.2 2.1 4.1 4.3 7.2

• The VPL Life Modules

  The VPL Life Modules involve development of simulation 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 helps us understand how we 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 the development of a land biosphere model coupled with a previously developed ocean biogeochemistry model and a 3D general circulation model (GCM). This terrestrial biosphere model is designed to simulate geographic distributions of life adapted to different climate zones, surface albedo, and carbon dioxide exchange and other biogenic gases with the atmosphere. These coupled models are first tested against Earth ground and satellite observations. A large data mining effort is now under way for the model of land-based ecosystem dynamics to uncover vegetation adaptations to climate that may be generalizable for both the Earth and alternative planetary environments.

  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 very 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, but that is also accessible to detailed study. As such, it 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 and pressure of the ancient atmosphere; modeled the effects of clouds on such a planet; studied the sulfur, oxygen and nitrogen cycles; and explored 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

• Measuring Interdisciplinarity Within Astrobiology Research

  To integrate the work of the diverse scientists working on astrobiology, we have harvested and analyzed thousands of astrobiology documents to reveal areas of potential connection. This framework allows us to identify crossover documents that guide scientists quickly across vast interdisciplinary libraries, suggest productive interdisciplinary collaborations, and provide a metric of interdisciplinary science.

  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

• Progress Report From G. Blake – CIT

  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. Scientific results continue to flow at a rapid clip. We have followed up our major overview papers outlining the results from our extensive (>100 disks) Spitzer IRS survey of the molecular emission from the terrestrial planet forming region with follow-up work with GSFC scientists on the high spectral resolution ground-based observations of such emission and that from cometary comae (and possible non-transiting exoplanets) using the Keck telescope and the VLT. We have measured the angular scale of the disk emission, and discovered a new transitional disk class characterized by a wide angle molecular wind. We have probed the outer disk’s water emission with the Herschel HIFI instrument, and also measured the (D/H)water ratio in a Jupiter Family Comet for the first time with Herschel – finding a value consistent with that in the Earth’s oceans. Our first Cycle 0 ALMA data are now in hand, and beautifully demonstrate the high angular resolution observations of simple organics in the outer regions of disks and comets that will become possible 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 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, and provides model output datasets, 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. This year we provided Earth model datasets, new tools for searching the molecular spectroscopic database, and a new database of biological pigments. All of these products and others are published on the VPL Team Website at: http://depts.washington.edu/naivpl/content/models-spectra.

  ROADMAP OBJECTIVES: 1.1 1.2 3.2 4.1 6.1 7.1 7.2

• Remote Sensing of Organic Volatiles in Planetary and Cometary Atmospheres

  In the last year, we have greatly advanced our capabilities to model spectra of cometary and planetary atmospheres (Villanueva et al. 2012a, 2012b). Using these newly developed analytical methods, we derived the most comprehensive search for biomarkers on Mars (Villanueva et al. 2012, submitted) from our extensive database of high-quality Mars spectra. Furthermore, we retrieved molecular abundances of several comets (Villanueva et al. 2012c, Gibb et al. 2012, Paganini et al. 2012a/b), and of several young circumstellar disks (Mandell et al. 2012). These great advancements have allowed us to understand the infrared spectrum of planetary bodies and their composition with unprecedented precision.

  ROADMAP OBJECTIVES: 1.1 1.2 2.1 2.2 3.1 3.2 7.1 7.2

• Rings in Debris Disks: A Signature of Planets or of Volatiles?

  Marc Kuchner and his collaborator Wladimir Lyra at JPL have developed a new explanation for the origin of eccentric rings in debris disks—like the rings around Fomalhaut and HR 4796. A popular explanation for these rings is that they represent dust shepherded by extrasolar planets, which are often too faint to see. Instead of hidden planets, Kuchner and Lyra’s models invoke a hidden component of gas in these disks, which supports a thermal instability that causes the dust to clump together in narrow eccentric rings. The presence of this instability makes inferring the presence of exoplanets more difficult, but it may aid in planet formation and provide important clues to the history of volatiles in the solar system.

  ROADMAP OBJECTIVES: 1.1 1.2 3.1

• The VYSOS Project

  The VYSOS project aims at surveying all of the major star forming regions visible from Hawaii for variable young stars. A small survey telescope provides shallow observations over a large area of the sky, and a larger telescope enables deeper, more detailed observations of smaller regions. All observations are done robotically.

  ROADMAP OBJECTIVES: 1.2