Bio


Laura joined the department of Geological Sciences in January 2019 as an Assistant Professor. Laura received her Bachelor's from Washington University in St. Louis in 2002. She remained for several years at Washington University as a research assistant in Earth and Planetary Sciences, where she studied planetary atmospheres and their formation. In 2011, Laura began graduate school at the Harvard-Smithsonian Center for Astrophysics and received her PhD in Astronomy in 2016. Her thesis work focused on volatile cycles on rocky exoplanets, metal-silicate differentiation and atmosphere formation. In fall of 2016, Laura joined the School of Earth and Space Exploration at Arizona State University as a postdoctoral scholar where she worked on projects related to the evolution of mantle oxidation state and magma ocean evolution, as well as volatile cycles on planetesimals as a member of the NASA Psyche team.

Academic Appointments


Honors & Awards


  • Gabilan Faculty Fellow, Stanford University (2020-2021)

Professional Education


  • PhD, Harvard University, Astronomy & Astrophysics (2016)
  • B.A., Washington University in St. Louis, Earth and Planetary Science (2002)

Current Research and Scholarly Interests


I study atmosphere-interior exchange on rocky planets, both within our Solar System and beyond. I'm interested in the initial outgassed atmospheres of rocky planets and their evolution with time due to external factors and due to interaction with the solid planet. During planet formation, all the materials that make a planet are intimately mixed together, so the physical and chemical processes of accretion and differentiation can have long term effects on the composition of both the atmosphere and the interior. I study these early processes using a combination of magma ocean, atmospheric and internal structure models. The presence of extant magma oceans on some hot rocky exoplanets provide a window into the early planet differentiation processes of the Solar System.

In the Solar System, I have particular interest in understanding the atmospheric evolution of Venus and Jupiter's moon Io, which both may have experienced significant volatile loss, likely through very different mechanisms. These planets are excellent proxies for the rocky exoplanets that will be observable in the near-term with new telescopes like the James Webb Space Telescope.

I am also interested in understanding the conditions of early atmospheric formation that may help or hinder the origins of life both within the Solar System and on exoplanets. Long-term interactions of atmosphere and interior will also influence the stability of habitable conditions on rocky exoplanets and are therefore vital to understand as astronomical observations of these planets become more feasible.

2020-21 Courses


Stanford Advisees


All Publications


  • Atmosphere Origins for Exoplanet Sub-Neptunes ASTROPHYSICAL JOURNAL Kite, E. S., Fegley, B., Schaefer, L., Ford, E. B. 2020; 891 (2)
  • Superabundance of Exoplanet Sub-Neptunes Explained by Fugacity Crisis ASTROPHYSICAL JOURNAL LETTERS Kite, E. S., Fegley, B., Schaefer, L., Ford, E. B. 2019; 887 (2)
  • Hydrogen isotopic evidence for early oxidation of silicate Earth EARTH AND PLANETARY SCIENCE LETTERS Pahlevan, K., Schaefer, L., Hirschmann, M. M. 2019; 526
  • Water on rocky planets: Atmospheres, oceans, and deep interiors Schaefer, L. AMER CHEMICAL SOC. 2019
  • Absence of a thick atmosphere on the terrestrial exoplanet LHS 3844b. Nature Kreidberg, L., Koll, D. D., Morley, C., Hu, R., Schaefer, L., Deming, D., Stevenson, K. B., Dittmann, J., Vanderburg, A., Berardo, D., Guo, X., Stassun, K., Crossfield, I., Charbonneau, D., Latham, D. W., Loeb, A., Ricker, G., Seager, S., Vanderspek, R. 2019

    Abstract

    Most known terrestrial planets orbit small stars with radii less than 60 per cent of that of the Sun1,2. Theoretical models predict that these planets are more vulnerable to atmospheric loss than their counterparts orbiting Sun-like stars3-6. To determine whether a thick atmosphere has survived on a small planet, one approach is to search for signatures of atmospheric heat redistribution in its thermal phase curve7-10. Previous phase curve observations of the super-Earth 55 Cancri e (1.9 Earth radii) showed that its peak brightness is offset from the substellar point (latitude and longitude of 0 degrees)-possibly indicative of atmospheric circulation11. Here we report a phase curve measurement for the smaller, cooler exoplanet LHS 3844b, a 1.3-Earth-radii world in an 11-hour orbit around the small nearby star LHS 3844. The observed phase variation is symmetric and has a large amplitude, implying a dayside brightness temperature of 1,040 ± 40 kelvin and a nightside temperature consistent with zero kelvin (at one standard deviation). Thick atmospheres with surface pressures above 10 bar are ruled out by the data (at three standard deviations), and less-massive atmospheres are susceptible to erosion by stellar wind. The data are well fitted by a bare-rock model with a low Bond albedo (lower than 0.2 at two standard deviations). These results support theoretical predictions that hot terrestrial planets orbiting small stars may not retain substantial atmospheres.

    View details for DOI 10.1038/s41586-019-1497-4

    View details for PubMedID 31427764

  • Magma oceans as a critical stage in the tectonic development of rocky planets PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES Schaefer, L., Elkins-Tanton, L. T. 2018; 376 (2132)

    Abstract

    Magma oceans are a common result of the high degree of heating that occurs during planet formation. It is thought that almost all of the large rocky bodies in the Solar System went through at least one magma ocean phase. In this paper, we review some of the ways in which magma ocean models for the Earth, Moon and Mars match present-day observations of mantle reservoirs, internal structure and primordial crusts, and then we present new calculations for the oxidation state of the mantle produced during the magma ocean phase. The crystallization of magma oceans probably leads to a massive mantle overturn that may set up a stably stratified mantle. This may lead to significant delays or total prevention of plate tectonics on some planets. We review recent models that may help alleviate the mantle stability issue and lead to earlier onset of plate tectonics.This article is part of a discussion meeting issue 'Earth dynamics and the development of plate tectonics'.

    View details for DOI 10.1098/rsta.2018.0109

    View details for Web of Science ID 000446261300012

    View details for PubMedID 30275166

    View details for PubMedCentralID PMC6189560

  • Origin of Earth's Water: Chondritic Inheritance Plus Nebular Ingassing and Storage of Hydrogen in the Core JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS Wu, J., Desch, S. J., Schaefer, L., Elkins-Tanton, L. T., Pahlevan, K., Buseck, P. R. 2018; 123 (10): 2691–2712
  • Redox Evolution via Gravitational Differentiation on Low-mass Planets: Implications for Abiotic Oxygen, Water Loss, and Habitability ASTRONOMICAL JOURNAL Wordsworth, R. D., Schaefer, L. K., Fischer, R. A. 2018; 155 (5)
  • PLANETARY SCIENCE A steamy proposal for Martian clays NATURE Schaefer, L. 2017; 552 (7683): 37–38

    View details for Web of Science ID 000417560500036

    View details for PubMedID 32080510

  • Thermodynamic Constraints on the Lower Atmosphere of Venus ACS EARTH AND SPACE CHEMISTRY Jacobson, N. S., Kulis, M., Radoman-Shaw, B., Harvey, R., Myers, D. L., Schaefer, L., Fegley, B. 2017; 1 (7): 422–30
  • Redox States of Initial Atmospheres Outgassed on Rocky Planets and Planetesimals ASTROPHYSICAL JOURNAL Schaefer, L., Fegley, B. 2017; 843 (2)
  • Metal-silicate Partitioning and Its Role in Core Formation and Composition on Super-Earths ASTROPHYSICAL JOURNAL Schaefer, L., Jacobsen, S. B., Remo, J. L., Petaev, M. I., Sasselov, D. D. 2017; 835 (2)
  • PREDICTIONS OF THE ATMOSPHERIC COMPOSITION OF GJ 1132b ASTROPHYSICAL JOURNAL Schaefer, L., Wordsworth, R. D., Berta-Thompson, Z., Sasselov, D. 2016; 829 (2)
  • ATMOSPHERE-INTERIOR EXCHANGE ON HOT, ROCKY EXOPLANETS ASTROPHYSICAL JOURNAL Kite, E. S., Fegley, B., Schaefer, L., Gaidos, E. 2016; 828 (2)
  • SOLUBILITY OF ROCK IN STEAM ATMOSPHERES OF PLANETS ASTROPHYSICAL JOURNAL Fegley, B., Jacobson, N. S., Williams, K. B., Plane, J. C., Schaefer, L., Lodders, K. 2016; 824 (2)
  • A disintegrating minor planet transiting a white dwarf NATURE Vanderburg, A., Johnson, J., Rappaport, S., Bieryla, A., Irwin, J., Lewis, J., Kipping, D., Brown, W. R., Dufour, P., Ciardi, D. R., Angus, R., Schaefer, L., Latham, D. W., Charbonneau, D., Beichman, C., Eastman, J., McCrady, N., Wittenmyer, R. A., Wright, J. T. 2015; 526 (7574): 546–49

    Abstract

    Most stars become white dwarfs after they have exhausted their nuclear fuel (the Sun will be one such). Between one-quarter and one-half of white dwarfs have elements heavier than helium in their atmospheres, even though these elements ought to sink rapidly into the stellar interiors (unless they are occasionally replenished). The abundance ratios of heavy elements in the atmospheres of white dwarfs are similar to the ratios in rocky bodies in the Solar System. This fact, together with the existence of warm, dusty debris disks surrounding about four per cent of white dwarfs, suggests that rocky debris from the planetary systems of white-dwarf progenitors occasionally pollutes the atmospheres of the stars. The total accreted mass of this debris is sometimes comparable to the mass of large asteroids in the Solar System. However, rocky, disintegrating bodies around a white dwarf have not yet been observed. Here we report observations of a white dwarf--WD 1145+017--being transited by at least one, and probably several, disintegrating planetesimals, with periods ranging from 4.5 hours to 4.9 hours. The strongest transit signals occur every 4.5 hours and exhibit varying depths (blocking up to 40 per cent of the star's brightness) and asymmetric profiles, indicative of a small object with a cometary tail of dusty effluent material. The star has a dusty debris disk, and the star's spectrum shows prominent lines from heavy elements such as magnesium, aluminium, silicon, calcium, iron, and nickel. This system provides further evidence that the pollution of white dwarfs by heavy elements might originate from disrupted rocky bodies such as asteroids and minor planets.

    View details for DOI 10.1038/nature15527

    View details for Web of Science ID 000364026100044

    View details for PubMedID 26490620

  • THE PERSISTENCE OF OCEANS ON EARTH-LIKE PLANETS: INSIGHTS FROM THE DEEP-WATER CYCLE ASTROPHYSICAL JOURNAL Schaefer, L., Sasselov, D. 2015; 801 (1)
  • THE ATMOSPHERES OF EARTHLIKE PLANETS AFTER GIANT IMPACT EVENTS ASTROPHYSICAL JOURNAL Lupu, R. E., Zahnle, K., Marley, M. S., Schaefer, L., Fegley, B., Morley, C., Cahoy, K., Freedman, R., Fortney, J. J. 2014; 784 (1)
  • Atmospheric composition of Hadean-early Archean Earth: The importance of CO: Comment Schaefer, L., Fegley, B., Shaw, G. H. GEOLOGICAL SOC AMER INC. 2014: 29–31
  • VAPORIZATION OF THE EARTH: APPLICATION TO EXOPLANET ATMOSPHERES ASTROPHYSICAL JOURNAL Schaefer, L., Lodders, K., Fegley, B. 2012; 755 (1)
  • COMPOSITIONS OF HOT SUPER-EARTH ATMOSPHERES: EXPLORING KEPLER CANDIDATES ASTROPHYSICAL JOURNAL LETTERS Miguel, Y., Kaltenegger, L., Fegley, B., Schaefer, L. 2011; 742 (2)
  • The extreme physical properties of the CoRoT-7b super-Earth ICARUS Leger, A., Grasset, O., Fegley, B., Codron, F., Albarede, F., Barge, P., Barnes, R., Cance, P., Carpy, S., Catalano, F., Cavarroc, C., Demangeon, O., Ferraz-Mello, S., Gabor, P., Griessmeier, J., Leibacher, J., Libourel, G., Maurin, A., Raymond, S. N., Rouan, D., Samuel, B., Schaefer, L., Schneider, J., Schuller, P. A., Selsis, F., Sotin, C. 2011; 213 (1): 1–11
  • ATMOSPHERIC CHEMISTRY OF VENUS-LIKE EXOPLANETS ASTROPHYSICAL JOURNAL Schaefer, L., Fegley, B. 2011; 729 (1)
  • Earth's Earliest Atmospheres COLD SPRING HARBOR PERSPECTIVES IN BIOLOGY Zahnle, K., Schaefer, L., Fegley, B. 2010; 2 (10): a004895

    Abstract

    Earth is the one known example of an inhabited planet and to current knowledge the likeliest site of the one known origin of life. Here we discuss the origin of Earth's atmosphere and ocean and some of the environmental conditions of the early Earth as they may relate to the origin of life. A key punctuating event in the narrative is the Moon-forming impact, partly because it made Earth for a short time absolutely uninhabitable, and partly because it sets the boundary conditions for Earth's subsequent evolution. If life began on Earth, as opposed to having migrated here, it would have done so after the Moon-forming impact. What took place before the Moon formed determined the bulk properties of the Earth and probably determined the overall compositions and sizes of its atmospheres and oceans. What took place afterward animated these materials. One interesting consequence of the Moon-forming impact is that the mantle is devolatized, so that the volatiles subsequently fell out in a kind of condensation sequence. This ensures that the volatiles were concentrated toward the surface so that, for example, the oceans were likely salty from the start. We also point out that an atmosphere generated by impact degassing would tend to have a composition reflective of the impacting bodies (rather than the mantle), and these are almost without exception strongly reducing and volatile-rich. A consequence is that, although CO- or methane-rich atmospheres are not necessarily stable as steady states, they are quite likely to have existed as long-lived transients, many times. With CO comes abundant chemical energy in a metastable package, and with methane comes hydrogen cyanide and ammonia as important albeit less abundant gases.

    View details for DOI 10.1101/cshperspect.a004895

    View details for Web of Science ID 000282451000012

    View details for PubMedID 20573713

    View details for PubMedCentralID PMC2944365

  • Chemistry of atmospheres formed during accretion of the Earth and other terrestrial planets ICARUS Schaefer, L., Fegley, B. 2010; 208 (1): 438–48
  • Volatile element chemistry during metamorphism of ordinary chondritic material and some of its implications for the composition of asteroids ICARUS Schaefer, L., Fegley, B. 2010; 205 (2): 483–96
  • Cosmochemistry Fegley, B., Schaefer, L., Goswami, A., Reddy, B. E. SPRINGER. 2010: 347–77
  • CHEMISTRY OF SILICATE ATMOSPHERES OF EVAPORATING SUPER-EARTHS ASTROPHYSICAL JOURNAL LETTERS Schaefer, L., Fegley, B. 2009; 703 (2): L113–L117
  • Chemistry during accretion of the earth. II. Rockforming elements in the "steam" atmosphere Schaefer, L., Fegley, B. METEORITICAL SOC. 2008: A138
  • Chemistry during accretion of the Earth. I. volatiles in the "steam" atmosphere Fegley, B., Schaefer, L. METEORITICAL SOC. 2008: A42
  • Chemistry and Composition of Planetary Atmospheres Schaefer, L., Fegley, B., Zaikowski, L., Friedrich, J. M. AMER CHEMICAL SOC. 2008: 187–207
  • Outgassing of ordinary chondritic material and some of its implications for the chemistry of asteroids, planets, and satellites ICARUS Schaefer, L., Fegley, B. 2007; 186 (2): 462–83
  • Application of an equilibrium vaporization model to the ablation of chondritic and achondritic meteoroids Schaefer, L., Fegley, B. SPRINGER. 2005: 413–23
  • Silicon tetrafluoride on Io ICARUS Schaefer, L., Fegley, B. 2005; 179 (1): 252–58
  • Alkali and halogen chemistry in volcanic gases on Io ICARUS Schaefer, L., Fegley, B. 2005; 173 (2): 454–68
  • Predicted abundances of carbon compounds in volcanic gases on Io ASTROPHYSICAL JOURNAL Schaefer, L., Fegley, B. 2005; 618 (2): 1079–85

    View details for DOI 10.1086/426113

    View details for Web of Science ID 000226293800051

  • A thermodynamic model of high temperature lava vaporization on Io ICARUS Schaefer, L., Fegley, B. 2004; 169 (1): 216–41
  • Heavy metal frost on Venus ICARUS Schaefer, L., Fegley, B. 2004; 168 (1): 215–19