The ground beneath our feet may seem unexceptional, but it has a profound impact on the mechanics of landslides, earthquakes, and even Mars rovers. That is why civil and mechanical engineer Jose Andrade studies soils as well as other granular materials. Andrade creates computational models that capture the behavior of these materials—simulating a landslide or the interaction of a rover wheel and Martian soil, for instance. Though modeling a few grains of sand may be simple, predicting their action as a bulk material is very complex. "This dichotomy…leads to some really cool work," says Andrade. "The challenge is to capture the essence of the physics without the complexity of applying it to each grain in order to devise models that work at the landslide level."
Geobiologist Victoria Orphan looks deep into the ocean to learn how microbes influence carbon, nitrogen, and sulfur cycling. For more than 20 years, her lab has been studying methane-breathing marine microorganisms that inhabit rocky mounds on the ocean floor. "Methane is a much more powerful greenhouse gas than carbon dioxide, so tracing its flow through the environment is really a priority for climate models and for understanding the carbon cycle," says Orphan. Her team recently discovered a significantly wider habitat for these microbes than was previously known. The microbes, she thinks, could be preventing large volumes of the potent greenhouse gas from entering the oceans and reaching the atmosphere.
Researchers know that aerosols—tiny particles in the atmosphere—scatter and absorb incoming sunlight, affecting the formation and properties of clouds. But it is not well understood how these effects might influence climate change. Enter chemical engineer John Seinfeld. His team conducted a global survey of the impact of changing aerosol levels on low-level marine clouds—clouds with the largest impact on the amount of incoming sunlight Earth reflects back into space—and found that varying aerosol levels altered both the quantity of atmospheric clouds and the clouds' internal properties. These results offer climatologists "unique guidance on how warm cloud processes should be incorporated in climate models with changing aerosol levels," Seinfeld says.
Credit: Yan Hu/Aroian Lab/UC San Diego
Tiny parasitic worms infect nearly half a billion people worldwide, causing gastrointestinal issues, cognitive impairment, and other health problems. Biologist Paul Sternberg is on the case. His lab recently analyzed the entire 313-million-nucleotide genome of the hookworm Ancylostoma ceylanicum to determine which genes turn on when the worm infects its host. A new family of proteins unique to parasitic worms and related to the early infection process was identified; the discovery could lead to new treatments targeting those genes. "A parasitic infection is a balance between the parasites trying to suppress the immune system and the host trying to attack the parasite," Sternberg observes, "and by analyzing the genome, we can uncover clues that might help us alter that balance in favor of the host."
Earth is special, not least because our solar system has a unique (as far as we know) orbital architecture: its rocky planets have relatively low masses compared to those around other sun-like stars. Planetary scientist Konstantin Batygin has an explanation. Using computer simulations to describe the solar system's early evolution, he and his colleagues showed that Jupiter's primordial wandering initiated a collisional cascade that ultimately destroyed the first generation population of more massive planets once residing in Earth's current orbital neighborhood. This process wiped the inner solar system's slate clean and set the stage for the formation of the planets that exist today. "Ultimately, what this means," says Batygin, "is that planets truly like Earth are intrinsically not very common."
Credit: Nicolás Wey-Gόmez/Caltech
Human understanding of the world has evolved over centuries, anchored to scientific and technological advancements and our ability to map uncharted territories. Historian Nicolás Wey-Gόmez traces this evolution and how the age of discovery helped shape culture and politics in the modern era. Using primary sources such as letters and diaries, he examines the assumptions behind Europe's encounter with the Americas, focusing on early portrayals of native peoples by Europeans. "The science and technology that early modern Europeans recovered from antiquity by way of the Arab world enabled them to imagine lands far beyond their own," says Wey-Gómez. "This knowledge provided them with an essential framework to begin to comprehend the peoples they encountered around the globe."
At Caltech, researchers study the Earth from many angles—from investigating its origins and evolution to exploring its geology and inner workings to examining its biological systems. Taken together, their findings enable a more nuanced understanding of our planet in all its complexity, helping to ensure that it—and we—endure. This slideshow highlights just a few of the Earth-centered projects happening right now at Caltech.
PhD candidate Mohamad Abedi has received a Paul & Daisy Soros Fellowship for New Americans. Abedi and 29 other fellows were selected "for their potential to make significant contributions to US society, culture, or their academic field."
Finding an anti-AIDS vaccine remains an elusive goal—partly because the HIV virus quickly mutates to evade the vaccine's antibodies. In a Watson Lecture on April 1, Caltech's Pamela J. Bjorkman will describe ways to neutralize that mutational advantage.