The Department of Terrestrial Magnetism was founded in 1904 to map the geomagnetic field of the Earth. Over the years the research direction shifted, but the historic goal to understand the Earth and its place in the universe has remained the same. Today the department is home to an interdisciplinary team of astronomers and astrophysicists, geophysicists and geochemists, cosmochemists and planetary scientists. These Carnegie researchers are discovering planets outside our solar system, determining the age and structure of the universe, and studying the causes of earthquakes and volcanoes. With colleagues from the Geophysical Laboratory, these investigators are also helping to define the new and exciting field of astrobiology.

The multidisciplinary program at DTM is unhampered by the constraints typically found in university departments. Current research spans the disciplines of astronomy, astrophysics, geophysics, geochemistry, cosmochemistry, and planetary science. Department faculty investigate their topics in a variety of ways that include field projects, astronomical and spacecraft observations, and advanced laboratory analysis. They also develop and improve specialized instrumentation to accomplish their scientific goals.

Investigators at the department participate in a variety of collaborative efforts with other institutions around the world in addition to undertaking smaller projects tailored to individual interests. In one large collaboration, DTM, in conjunction with scientists from Carnegie's Geophysical Laboratory, is a lead member of the NASA Astrobiology Institute. The effort demands a diverse complement of researchers who are looking into the synthesis of organic materials and potential habitats for life beneath the Earth's land surface and seafloor, on other bodies in the solar system, and on extrasolar planets. As part of this program, Carnegie scientists are analyzing organic chemical synthesis in water-rock systems under varying conditions of temperature, pressure, and chemistry to mimic environments that may be encountered in terrestrial and extraterrestrial settings. In related work, Carnegie scientists are investigating the physical and chemical environments of circumstellar disks around young stars and the nature of early organic compounds in extraterrestrial materials, such as meteorites.

Geophysicists, geochemists, and seismologists in the department coordinate with other researchers internationally on many projects, most recently including the PLUME (Plume-Lithosphere Undersea Melt Experiment) project. In addition, DTM staff are undertaking individual investigations to examine a number of fundamental problems in the fields of igneous geochemistry, geochronology, crustal evolution, seismology, volcano geophysics and geochemistry, and comparative planetary science.

Sean Solomon, director of the department, is the lead investigator of another large effort-a NASA mission that will teach us more about our solar system's innermost planet, Mercury. Understanding the unusual characteristics of Mercury, and the forces that have shaped it, is fundamental to understanding all of the terrestrial planets and their evolution. This mission, called MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging), was launched on 3 August 2004 and will orbit Mercury for one Earth year in 2011 after making three flybys of that planet in 2008 and 2009.

Astrophysicists in the department are leaders in the discovery of extrasolar planets, the study of their birthplaces, and the development of theories about their formation. A group co-led at DTM has found most of the approximately 140 currently known extrasolar planets in our galaxy using a technique called precision Doppler velocity. The method detects the subtle wobbles a star exhibits in response to the gravitational tug exerted by a large orbiting object. Other DTM scientists are using the characteristics of known planets and their environments to refine theories for how stars and planets form and evolve. DTM researchers actively use Carnegie's state-of-the-art telescope facilities at the Las Campanas Observatory in Chile to search for extrasolar planets and the disks from which they form and to study the large-scale motion of galaxies.