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Project Reports

• Project 2: Processing of Precometary Ices in the Early Solar System

  The discovery of numerous planetary systems still in the process of formation gives us a unique opportunity to glimpse how our own solar system may have formed 5 billion years ago. We use computers to simulate events called shock waves which are common in young planetary systems. These shock waves “light up” the gas and dust in young planetary systems, making it possible to observe molecules that would not be visible otherwise. Our goal is to determine whether some of the essential building blocks of life can be detected by exploiting this effect.

  ROADMAP OBJECTIVES: 1.1 3.1 3.2

• Project 7: Prebiotic Chemical Catalysis on Early Earth and Mars

  The “RNA World” hypothesis is the current paradigm for the origins of terrestrial life. This hypothesis proposes that the first life on Earth was based on RNA, and that RNA subsequently catalyzed life based on DNA. Our research is aimed at testing a key component of the paradigm, i.e., the efficiency with which RNA molecules form and grow under realistic conditions. We are investigating abiotic production and polymerization of RNA by catalysis on montmorillonite clays. We find that RNA chains some 50 units long can be formed in the laboratory from activated RNA monomers with montmorillonite as a catalyst, and that 12 of the 22 montmorillonites we tested are catalytic. A correlation is found between catalytic activity and charge: montmorillonites with a low negative charge are catalytic, those with a high negative charge are not.

  ROADMAP OBJECTIVES: 3.1 3.2

• Project 6: The Environment of the Early Earth

  Our project entitled “Environment of the Early Earth” involves the development of capabilities that will allow scientists to obtain information about the conditions on early Earth (3.0 to 4.5 billion years ago) by performing chemical analyses of crystals (minerals) that have survived since that time. When they grow, minerals incorporate trace concentrations of ions and gaseous molecules from the local environment. We are conducting experiments to calibrate the uptake of these “impurities” that we hope will serve as indicators of temperature, moisture, oxidation state and atmosphere composition. To date, our focus has been mainly on zircon (ZrSiO₄), but we have recently turned our attention to quartz as well.

  ROADMAP OBJECTIVES: 1.1 4.1 4.3

• Project 4: Impact History in the Earth-Moon System

  The influx of interplanetary debris onto the early Earth represents a major hazard to the emergence of life. Large crater-forming bodies must have been common in the early solar system, as craters are seen on all ancient solid surfaces from Mercury to the moons of the outer planets. Impact craters are few in number on the Earth today only because geologic activity and erosion gradually erase them. The Earth’s nearest neighbor, the Moon, lacks an atmosphere and significant tectonic activity, and therefore retains a record of past impacts. The goal of our research is to reconstruct the bombardment history of the Moon, and by proxy the Earth, to establish when the flux of sterilizing impacts declined sufficiently for the Earth to became habitable.

  ROADMAP OBJECTIVES: 4.3

• Project 1: Interstellar Origins of Preplanetary Matter

  Astronomers have found interstellar space to be rich in the raw materials required for planets and life, including the essential chemical elements (C, N, O, Mg, Si, Fe, etc.) and compounds (water, organic molecules, and planet-building minerals). Our research is aimed at characterizing the composition and structure of these materials and the chemical pathways by which they form and evolve. The ultimate goal is to determine the inventories of protoplanetary disks around young sun-like stars, leading to a clear understanding of the processes that led to our own origins and insight into the probability of life-supporting environments emerging around other stars.

  ROADMAP OBJECTIVES: 1.1 3.1

• Project 3: Pathways for Exogenous Organic Matter to the Early Earth and Mars

  Comets are rich in ices and organic molecules and were almost certainly important sources of biogenic elements to early Earth and Mars. However, because of their relatively high encounter speeds (averaging some 50 km/s), comets may be relatively inefficient sources of organic compounds to these planets. In contrast asteroids, although less rich in organics, may have been more important because their much lower encounter speeds (15 – 20 km/s) allow significant quantities of unaltered material to reach the surfaces of the terrestrial planets. A major question we propose to investigate is the relative contributions of the thermally-altered asteroidal organics versus relatively pristine cometary organics to early Earth and Mars.

  ROADMAP OBJECTIVES: 1.1 3.1

• Project 5: Vistas of Early Mars: In Preparation for Sample Return

  To understand the history of life in the solar system requires knowledge of how hydrous minerals form on planetary surfaces, and the role these minerals play in the development of potential life forms. One hydrous mineral found on Earth and inferred from in situ measurements on Mars, is the mineral Jarosite, KFe₃(SO₄)₂(OH)₆. We are investigating whether radiometric ages, specifically ⁴⁰Ar/³⁹Ar ages on jarosite can be interpreted to accurately record climate change events on Mars. This project not only requires understanding the conditions required for jarosite formation and preservation on planetary surfaces, but also assessing under what conditions its “radiometric clock” can be reset (e.g., during changes in environmental conditions such as temperature). By studying jarosites formed by a variety of processes on Earth, we will be prepared to analyze and properly interpret ages measured from jarosite obtained from future Mars sample return missions.

  ROADMAP OBJECTIVES: 1.1 2.1 7.1