I consider myself to be an astrobiologist, or one who studies the the Origins of Life. This is a booming multidisciplinary, collaborative, worldwide effort to get scientists from widely different fields (biology, geology, astronomy, chemistry, physics, etc) talking together to get a big picture understanding of the development/emergence/evolution of life.

By furthering our understanding of the complicated interactions between  solid and gas phase chemistry in the interstellar medium, we may begin to understand what materials were available for forming planetary bodies in young star systems.  My research investigates one small piece of the puzzle  of how life began on Earth and may begin on other worlds in our galaxy. See my research pages for more information.

Organic Volatiles Toward Star Forming Regions and in Comets

Between the stars are large areas of vacuum with very little in the way of dust or gas.  On average, the density of this material is 19 orders of magnitude less than that of Earth's atmosphere at sea level!  There are  regions of much higher density (which are still better than the best vacuums on Earth) which we call dark molecular clouds.  The image above is one example of such a dark cloud.  Even though the number of dust particles per cubic meter is incredibly small by earthly standards, there is still enough dust in these objects to block the light from the stars behind the cloud, making the sky in that region appear dark.  Fortunately, these submicron (< one millionth of a meter) dust particles are relatively transparent to long wavelengths like infrared and radio, and we can use observations at these wavelengths to investigate the interiors of these dark clouds.  These clouds aren't made of just dust, however.  In fact, dust only makes up about 1% of the mass.  The rest of it is gas, primarily hydrogen.

In these very cold (as cold as only 10 Kelvin above absolute zero!), dark clouds, dust grains composed of silicate cores, with perhaps an organic refractory mantle or other refractory carbon component (such as graphite), accrete ices on their surfaces. Essentially, the grains are so cold that anything other than hydrogen and helium will stick when it collides with a grain.  Molecules will stick, but just as important (or perhaps moreso) are the atoms that collide and stick, such as carbon and oxygen.  A light atom like hydrogen can collide with a dust grain and then move around the surface for a while before escaping from the grain. If it happens to hit an oxygen atom, it could bond to it.  If a second hydrogen atom comes along, a water molecule can be formed. This is the process by which most of the water is believed to be formed in the interstellar medium. Likewise, CH4 (methane) may be formed by adding H atoms to carbon. Other molecules, like CO, form primarily in the gas phase. When the temperatures are cold enough, these ices will stick to grains as well.  Essentially, a silicate core with a layer of "polar" (water-rich) ice and a layer of "apolar" or "nonpolar" ice (rich in CO2 and CO) is formed.  Note that at this point, with cold temperatures, neutral chemical species, and relatively few collisions we have primarily very simple molecules.

When a core in a dark cloud gets to a certain density, known as the critical density, collapse can begin.  The gravitational attraction pulls matter inward.  By conservation of energy, we know that the initial potential energy of the cloud is converted into kinetic energy.  As the dust and gas fall inward, they collide with other particles, transferring their energy and raising the temperature of the infalling material.  The extended matter far away from the collapsing core stays cold, below 50 K or so, while the core can reach temperatures much higher, say above 150 K or so.  During collapse, a complex chemistry occurs both in the gas phase and on the grain that leads to the formation of many "large" molecules (astrophysically speaking), including such organics as methanol, formaldehyde, and many nitriles.  The interactions between solid and gas phase chemistry are still being studied by observers and experimenters.  If these species survive the star formation process, they could be incorporated into the excess material in the disk around the young star and possibly eventually into planets and comets.  This is one way to provide an early earth with sufficient organics to begin the complicated chemical processes that eventually led to the origin of life.

That's the big picture--how did life form on Earth, and, by extension, how could it happen on other planetary bodies?

Interested in an Undergraduate Research Experience?

I often have undergraduate students working with me on various research projects.  This involves learning how to reduce and analyze spectroscopic data.  Opportunities are limited to UMSL students.  Interested students must be physics majors and should have taken their basic introductory physics and math courses (PHYS 2111 & 2112, College Algebra and Calculus are required). Students are also encouraged to take AST 1050 and 1051 concurrent with research (these courses are also required for the astrophysics emphasis option of the physics degree). Students may request to do research during the semester for credit (usually 1 credit of PHYS 3390) or a summer research project.  Students are encouraged to present their results at the UMSL Undergraduate Research Symposium held each spring.  There may also be opportunities to present at professional meetings.

Current sources of Stipends:

NASA Space Grant, NSF Planetary Astronomy Program: Information is available in mygateway under Physics Majors