Some 40 thousand tons of extraterrestrial material fall on Earth every year. This cosmic debris provides cosmochemist Conel Alexander with information about the formation of the Solar System, our galaxy, and perhaps the origin of life.
Alexander studies meteorites to determine what went on before and during the formation of our Solar System. Meteorites are fragments of asteroids—small bodies that originated between Mars and Jupiter—and are likely the last remnants of objects that gave rise to the terrestrial planets. He is particularly interested in the analysis of chondrules, millimeter-size spherical objects that are the dominant constituent of the most primitive types of meteorites. Chondrules formed as molten droplets prior to the formation of the asteroids.
Alexander develops techniques to measure precisely the different isotopes, atoms of the same element with different numbers of neutrons, of potassium, iron, magnesium, and oxygen in meteorite samples. Depending on the conditions, these elements may have evaporated and recondensed during chondrule formation. The isotopic compositions can indicate the extent of evaporation and recondensation, which can reveal the conditions under which the chondrules formed.
Alexander's other major interest is presolar materials preserved in meteorites. These include the tiny grains that emerged around dying stars and interstellar organic matter. By deciphering these relics, he hopes to understand the processes of galaxy evolution, the formation of the elements inside stars via nucleosynthesis, and stellar evolution.
In recent years, evidence has mounted that meteorites may have played a role in the origin of life on Earth. Alexander studies this possibility as part of his work on the origin of interstellar organic matter in meteorites. In addition, a small number of meteorites come from Mars. They have a wide age range and contain water-bearing minerals. By studying the hydrogen isotopes of this water, Alexander hopes to test ideas about what happened to the water that was originally on that planet.
Alexander received his B.S. Geology from Imperial College, University of London and his Ph.D. in experimental physics from the University of Essex. For more information see http://www.dtm.ciw.edu/people/conel-m-od-alexander