Macalester College
At Macalester College, three undergraduate research projects in Geology were supported with MnSGC funds in 1994. Erin Beutel ('95) worked with John Craddock on a structural and geochemical study of mafic dikes in Northern Wisconsin. The dikes are sub-vertical and planar bodies of rock that were intruded as igneous melts more than 1,100 million years ago. Previous studies suggested that these dikes were related to the formation of the midcontinent rift about 1,100 million years ago. However, the results of Beutel and Craddock suggest that the dikes are unrelated to the rift and are much older, perhaps 1,600 to 2,100 million years old. The research, which began as a field study in summer 1994, was continued as an senior honors project by E. Beutel. The results of the project will be presented by John Craddock at the Third International Dike Conference to held in Jerusalem in September 1995.

A second research project involved Christine Ronnback ('96) and Gerald Webers in a number of paleontological studies. These studies involved field collection of fossil marine invertebrates (primarily Cambrian trilobites) and fossil fish of Eocene age (about 50 million years) throughout the western U.S. Preliminary laboratory study of these fossils was conducted at Macalester College. Another study involved laboratory investigation and illustration of a fossil Cambrian mollusk called Paleaeacmaea. This project is nearing completion and a preliminary manuscript has been written.

Stephanie Grotta ('96), who worked with Karl Wirth on developing Macalester's courses for the ACTC minor, also worked on a research project with Karl. Stephanie worked in the field on a study of lava flows and associated sediments from the midcontinent rift. The field work was conducted on the Chengwatana lavas, which are exposed in the Taylors Falls-St. Croix Falls area, this is a relatively unstudied region that includes the southern-most exposed lavas in the rift. Stephanie is a coauthor of a paper that will be presented at the International Field Conference and Symposium on the Petrology and Metallogeny of Volcanic and Intrusive Rocks of the Midcontinent Rift System to be held in Duluth in August 1995. Her research on the interflow sediments of the rift will be continued as a independent research project during 1995-96.

Bethel College
In 1994, Bethel College senior Jason Sheard worked on the use of optical fibers as (expensive) thermometers. He measured phase shifts as a length of single-mode fiber which was transmitting a laser beam when heated. The paper he produced from this research won first prize at the spring meeting of the Minnesota Area Association of Physics Teachers. Two other students conducting research as part of Bethel's Space Grant Program won prizes at the meeting as well. They are: Chad Hoyt, who made holographic measurements in real time of changing refractivity in gases; and R. Jason Jones, who made and analyzed holographic "lenses" called zone plates. Additional research projects worked on by undergraduates involved the measurement of optical activity (the change of polarization of light as it goes through some materials) in real time and the construction and preliminary testing of a diode laser.

Bemidji State University
In the past year, with help from NASA, the MnSGC and support from other universities, BSU was able to sponsor and support two students at other institutions for summer research projects. First, John Dahl spent a summer at the Johnson Space Flight Center working on the scanning electron microscope (SEM) studying the aqueous alteration of cosmic dust particles. His work was presented at the Lunar and Planetary Science Conference in March 1995, and he received an honorable mention award for the best student paper. Jason will continue this work as part of his Space Studies Minor mini-thesis.

Second, David Kobilka is presently working as a summer research assistant at Washington University in St. Louis, Department of Earth and Planetary Sciences. His research is on the location and magnitude of earthquakes centered in the Tonga Trench, Western Pacific. This work will for the basis for David's Space Studies Minor thesis.

Beginning this summer, the MnSGC will sponsor two students for general field investigation of the Leech Lake/Beltrami County area in Northern Minnesota. This is part of a larger effort involving faculty and students in a cooperative effort with Purdue University (see faculty research for more details).

College of St. Catherine
Last summer, Hitomi Arimitsu and Terry Flower joined a group from the University of Minnesota Astronomy Department at the O'Brien Observatory near Marine, Minnesota, to participate in IR photometry of the Jupiter/SL9 Comet collision. They attempted to determine the increase in total brightness due to the fireball and estimate some characteristics of the depth of penetration of one fragment of the coment. Although bad weather interfered with the project, the students learned a considerable amount about what is involved in observing and recording such an event. This summer and continuing into the fall, another student will assist in CCD Photometry of star fields to detect dwarf novae.

University of Minnesota-Duluth
With support from the MnSGC, several space-science research projects are underway at the University of Minnesota-Duluth (UMD), under the direction of Dr. Gregory Ojakangas. First, geology/physics undergraduate student Bradley Sickler and Greg have developed a computer model which generates synthetic tidal rhythmites. These remarkable sedimentary rocks, composed of rhythmically alternating layers of mudstone and siltstone deposited under the influence of tidal currents, hold clues to the ancient orbit of the moon at their time of formation. In the figure below, given a hypothetical ancient lunar orbit and rotation rate for the Earth, the program computes ocean tide heights (top of figure) as functions of time, translates them into current speeds in a hypothetical tidal channel (middle of figure), and finally produces a rhythmic sequence of silt and mud lamina thicknesses (bottom of figure) deposited by the synthetic tidal currents. With such synthetic data, Ojakangas and Physics graduate student Haichuan Tan are investigating the degree to which the input lunar orbit can be retrieved through spectral analysis of the lamina sequence. With such knowledge, our understanding of the information encoded in actual tidal rhythmites will be improved.

In another research project partially supported by the MnSGC, the orbital and thermal histories of Saturn's icy moons, Enceladus and Dione, are being modeled by numerical integration. These moons are locked in an orbital resonance which transfers energy from their orbits to their interiors via tidal heating. The goal is to explain Enceladus's long history of volcanic activity (as recorded in its cratered surface), as well as the fact that it is probably volcanically active today.