3 items with the tag “earth

  • Origin of Earth’s Water
    NAI 2013 University of Hawaii, Manoa Annual Report

    Understanding the sources and delivery mechanisms of water to the Earth and the other terrestrial planets allows for the validation of planetary accretion models. This information can help us establish at what time the Earth contained sufficient water for the development of life. A key parameter in determining the source(s) of terrestrial planetary water is the hydrogen isotope composition of this water. However, hydrogen fractionation during surface and atmospheric processes on terrestrial planets such as Earth and Mars may have significantly changed the Deuterium/Hydrogen (D/H) ratio in the various water reservoirs. Therefore, to determine the primordial D/H ratio of these planets water we must find reservoirs that has been unaffected by surface processes. Plate tectonics is known to drag surface water down into the crust and the upper mantle, but the transition zone and lower mantle are thought to be uncontaminated by surface water. Therefore, we aimed to sample terrestrial hydrous minerals and melt inclusions sourced from these uncontaminated regions, such as deep mantle plume samples from Iceland and Baffin Island, along with possible deep mantle diamond inclusions. As plate tectonics never developed on Mars, the primary igneous hydrous minerals in martian meteroites were assumed to be isolated from martian surface processes. We analyzed the D/H ratio of these samples using the Cameca ims 1280 ionmicroprobe at the University of Hawaii to produce a dataset that establishes the primordial D/H ratio of Earth and Mars.

    To gain insights into the amount of water present in terrestrial planetary mantle material we synthesized samples of high-pressure mineral phases that are likely hosts for H, and thus water, in planetary interiors. We measured the physical properties of these minerals, including crystal structure, density, elasticity, and electrical conductivity, to investigate the degree to which water may be incorporated into these minerals in the Earth’s mantle.

    Models of terrestrial planet formation have been successful in producing terrestrial-class planets with sizes in the range of Venus and Earth. However, these models have generally failed to produce Mars-sized objects. The body that is usually formed around Mars’ semimajor axis is, in general, much more massive than Mars. We have developed new model for the formation of Mars in which a local depletion in the density of the protosolar nebula results in a non-uniform formation of embryos and ultimately the formation of Mars-sized planets.

    ROADMAP OBJECTIVES: 1.1 4.1
  • Earth as an Extrasolar Planet
    NAI 2013 VPL at University of Washington Annual Report

    Earth is our only example of a habitable planet, or a planet capable of maintaining liquid water on its surface. As a result, Earth serves as the archetypal habitable world in conceptual studies of future exoplanet characterization missions, or in studies of techniques for the remote characterization of potentially habitable exoplanets. We seek to accurately simulate the time-, phase-, and wavelength-dependent appearance of the Pale Blue Dot, and to use these models to understand how to best recognize and characterize potentially Earth-like exoplanets.

    ROADMAP OBJECTIVES: 1.2 7.2
  • Exoplanet Detection and Characterization: Observations
    NAI 2013 VPL at University of Washington Annual Report

    In this task, VPL researchers use astronomical instrumentation to detect and measure the properties of exoplanets. They also study terrestrial planets in our Solar System that can serve as practice targets for exoplanet observational techniques. These observations help us to develop and understand the techniques and measurements required to learn about planetary environments. Although many of these observations are now made on planets that are too large, or too close to their stars to be habitable, once proven, these techniques can then be adapted to help characterize the smaller, cooler planets that may be habitable.

    ROADMAP OBJECTIVES: 1.2 2.2 7.2