Caltech Division of Geological and Planetary Sciences

About Caltech Division of Geological and Planetary Sciences

Founded in 1926, the Division of Geological and Planetary Sciences (GPS) at the California Institute of Technology represents one of the most distinguished Earth and planetary science programs in the world. As a division within Caltech, it benefits from the institute's legendary focus on intensive, small-scale science education while contributing significantly to humanity's understanding of Earth, other planets, and the broader universe. The division operates within Caltech's broader framework, an institution consistently ranked among the top five universities globally by major ranking systems including QS and Times Higher Education. The GPS division has produced numerous groundbreaking discoveries in seismology, geochemistry, planetary science, and climate research. Notable alumni and faculty have included Charles Richter, who developed the Richter magnitude scale for measuring earthquakes, and Harrison Brown, whose pioneering work in nuclear geochemistry helped establish the age of the Earth. More recently, GPS scientists have been instrumental in Mars exploration missions and understanding climate change mechanisms. The division maintains approximately 25-30 faculty members and around 100 graduate students, creating an exceptionally low student-to-faculty ratio that enables intensive mentorship. The culture at GPS emphasizes collaborative research across traditional disciplinary boundaries. Graduate students regularly work with faculty from multiple research groups, and the division's location in Pasadena provides proximity to NASA's Jet Propulsion Laboratory, with which Caltech maintains a management relationship. This connection offers unparalleled opportunities for involvement in active space missions and planetary exploration research.

Admission to GPS graduate programs is highly competitive, with the division typically receiving over 300 applications annually for roughly 20-25 available positions. The acceptance rate hovers around 7-10%, making it one of the most selective Earth science programs globally. Applications are evaluated holistically, with research experience weighing heavily alongside academic credentials. The application deadline falls in mid-December for admission the following fall; GPS does not offer spring admission. Required materials include transcripts, GRE General Test scores (though policies have evolved, check current requirements), three letters of recommendation, a statement of purpose, and TOEFL or IELTS scores for international applicants whose primary language is not English. The TOEFL minimum typically stands at 100 (internet-based), while IELTS requires a 7.0. Applicants should have strong backgrounds in mathematics, physics, and chemistry in addition to geology or related fields. Successful applicants typically present undergraduate GPAs above 3.7, GRE scores in the 90th percentile or higher, and meaningful research experience demonstrated through publications, conference presentations, or detailed descriptions of independent projects. Letters from research supervisors carry particular weight. In the statement of purpose, admissions committees look for clear articulation of research interests aligned with faculty expertise, evidence of scientific creativity, and realistic understanding of graduate research demands. To strengthen an application, prospective students should: first, identify specific faculty members whose research genuinely interests them and reference this in application materials; second, gain substantive research experience rather than superficial exposure; and third, demonstrate quantitative sophistication through coursework and research projects. Reaching out to faculty before applying can be valuable but should demonstrate genuine engagement with their research rather than generic interest.

The Division of Geological and Planetary Sciences offers graduate programs leading to Ph.D. degrees in geological and planetary sciences, with students typically choosing focus areas in geobiology, geochemistry, geology, geophysics, or planetary science. The division does not offer a terminal master's degree; instead, the M.S. is awarded as students progress toward their doctoral degree. Undergraduate students at Caltech can pursue geological and planetary sciences through options (Caltech's term for majors) that integrate coursework from across the division's research areas. Research at GPS spans from the deep interior of the Earth to the outer reaches of the solar system. The geobiology group investigates the co-evolution of life and planetary environments, while geochemistry researchers study elemental and isotopic distributions to understand Earth's formation and evolution. The geophysics group maintains world-leading seismology programs, operating monitoring networks and developing new techniques for earthquake prediction and hazard assessment. Planetary science research connects directly to active NASA missions, with faculty and students analyzing data from Mars rovers, orbital observatories, and upcoming missions to ocean worlds like Europa. Teaching follows Caltech's signature approach of small classes emphasizing deep understanding over broad coverage. Graduate courses typically enroll fewer than 15 students, enabling seminar-style discussions with leading researchers. First-year graduate students complete core courses establishing fundamentals before moving into specialized research. The division emphasizes quantitative approaches, expecting students to develop strong foundations in mathematics, physics, and chemistry alongside geological expertise. Field work remains integral, with regular trips to classic geological localities and active research sites. The academic calendar follows Caltech's quarter system, allowing intensive focus on fewer subjects at a time.

Student Life & Environment

Graduate students in GPS join a tight-knit community within Caltech's already intimate campus environment. With approximately 100 graduate students across all research areas, the division feels more like an extended research family than a large academic department. Students typically spend their first two years completing coursework and teaching assistant responsibilities while beginning research, then transition to full-time dissertation work. The majority of graduate students live off-campus in Pasadena apartments, though Caltech provides housing resources and maintains some graduate housing options. Social life within GPS centers around the division's physical spaces, including the South Mudd and Geological Sciences buildings, where daily coffee gatherings and weekly seminars provide regular interaction opportunities. The division sponsors social events throughout the year, and students frequently organize hiking trips, sports teams, and informal gatherings. The broader Caltech community, while small by university standards with roughly 2,300 students total, offers additional social outlets through graduate student council events, intramural sports, and campus traditions. Diversity within GPS reflects broader challenges in the geosciences, though active efforts aim to increase representation of underrepresented groups. The division participates in recruitment programs targeting diverse applicants and supports student organizations promoting inclusive communities. International students comprise a significant portion of the graduate population, bringing perspectives from geological research traditions worldwide. Mental health resources include Caltech's counseling center and peer support networks, important given the intensive nature of doctoral research. One common challenge students note involves the high-pressure academic environment and relatively limited social scene in Pasadena compared to larger cities, though proximity to Los Angeles offers escape when needed.

Location & Surroundings

The GPS division is located on Caltech's main campus in Pasadena, California, a city of approximately 140,000 residents situated at the base of the San Gabriel Mountains. Pasadena offers a distinctive blend of small-city charm and metropolitan access, sitting just 11 miles northeast of downtown Los Angeles. The campus itself spans 124 acres in a suburban setting with tree-lined streets and Spanish colonial architecture creating an aesthetically pleasing environment. Southern California's Mediterranean climate provides year-round mild weather, with average temperatures ranging from the mid-50s Fahrenheit in winter to the mid-80s in summer. Rain falls primarily between November and March, with summers remaining essentially dry. This climate enables outdoor activities throughout the year, and the proximity to mountains offers hiking, skiing, and field work opportunities within an hour's drive. The San Gabriel Mountains themselves serve as a geological laboratory for many GPS research projects. Transportation in Pasadena presents typical Southern California challenges. While the Metro Gold Line connects Pasadena to downtown Los Angeles and extends toward eastern Los Angeles County, a car significantly expands mobility options. Cycling works for campus commuting, though the broader region requires automotive transportation. Los Angeles International Airport (LAX) sits approximately 30 miles southwest, while the smaller Bob Hope Airport in Burbank offers a closer alternative 15 miles away. Cost of living in Pasadena runs significantly above national averages, with graduate student stipends covering basic expenses but leaving limited discretionary income in this expensive region.

Costs & Career Outcomes

Graduate students in GPS receive full financial support throughout their doctoral studies, including tuition coverage, health insurance, and a competitive stipend currently around $42,000-$45,000 annually. This package eliminates tuition costs for students, though the high cost of living in Pasadena means budgeting remains important. Typical monthly expenses for housing, food, and transportation in the area run $2,000-$2,500, leaving modest savings possible on the stipend. The division maintains several named fellowships providing enhanced support for exceptional students. Additionally, students often receive funding through NASA grants, NSF awards, and other external sources supporting their research. Teaching assistantships provide stipend support during the first two years, while research assistantships funded by faculty grants typically support later years. Some students pursue external fellowships such as NSF Graduate Research Fellowships, which provide additional funding and prestige. Career outcomes for GPS graduates span academia, government research, and industry. Approximately 60% of graduates pursue academic careers, with alumni holding faculty positions at leading universities worldwide including MIT, Stanford, Berkeley, Columbia, and international institutions. Government agencies including NASA, USGS, NOAA, and national laboratories employ significant numbers of graduates. The petroleum and mining industries have historically hired GPS graduates, though clean energy companies increasingly recruit geoscientists. Average starting salaries vary widely by sector, ranging from $60,000-$70,000 for academic postdocs to $90,000-$120,000 for industry positions. The division's JPL connection creates unique pathways into space science careers, with many graduates joining mission teams as scientists and engineers. Career services at Caltech provide counseling, interview preparation, and networking events, though the tight-knit GPS community itself serves as the primary career network. Alumni engagement remains strong, with graduates frequently returning for seminars and recruiting visits. The six-year graduation rate exceeds 85%, reflecting strong student support and realistic project scoping.