The cosmochemist studying the 'seeds' of the solar system

Every year, Yale’s Faculty of Arts and Sciences welcomes exceptional scholars across the sciences, humanities, and social sciences. This series profiles six of the faculty joining the FAS in the 2025–26 academic year, highlighting their academic achievements, research ambitions, and the teaching they hope to do at Yale. Learn more about the faculty who recently joined the FAS. 

A scientist with the heart of a philosopher, Damanveer Singh Grewal studies space to grapple with some of humanity’s biggest questions. 

“Why,” he asks, “are we here on this particular planet? Why are we alone in this universe?” A cosmochemist, Grewal finds answers to these questions by exploring how solar systems and planets form.

Grewal joined the FAS in July 2025 as Assistant Professor of Earth and Planetary Sciences. Head of the CosmoGeo lab, he arrived eager to continue his research to understand the earliest days of our solar system.

Grewal is specifically interested in the formation of habitable, rocky planets like Earth. How do these planets take shape and form metallic cores? How did Earth obtain elements and compounds that are essential to the existence of life, like carbon, nitrogen, and water? And why is Earth habitable, while other planets are not?

To answer these questions, he turns not to planets themselves, but to other cosmic objects: meteorites.

Planetesimals and iron meteorites: Seeds of our solar system

Before our solar system had planets, it was a giant molecular cloud. 

Inside that cloud, gas, dust, ice, and other debris mixed, stuck together, and began to accumulate into small bodies. These bodies, called planetesimals, began to generate their own gravity and collide with each other—during which critical elements were deposited on these proto-planets.

Planetesimals are the “seeds” of rocky planets, Grewal says, and they are key to understanding how planets form. Iron meteorites, most of which form in the cores of planetesimals, offer glimpses of these early rocky bodies—and help scientists better understand the processes that formed the rocky planets in our solar system and beyond.

With a combination of high-pressure, high-temperature (HPHT) experiments and meteorite analysis, Grewal’s lab simulates the conditions of the early solar system in order to understand how planets were formed. By compressing materials at very high pressures and temperatures, they can recreate the cosmochemical and geochemical processes that melted early planetesimals and caused them to form metallic cores. 

While he was trained as an HPHT experimentalist, Grewal became “hooked on meteorites,” as he puts it, during the isolation period of the COVID-19 pandemic. He couldn’t go to the lab to do experiments, so he started to examine and reinterpret data on iron meteorites that had been previously collected. 

Grewal’s findings informed one of his recent studies, which hypothesized that high-energy collisions between planetesimals began earlier than scientists previously thought—and that metal-rich cores in some planetesimals formed, shattered apart, and were reassembled as new planets.

“Far from being made of pristine material, planets—including Earth—were built from recycled fragments of shattered and rebuilt bodies,” Grewal told Yale News about the study’s findings. 

The fact that some metallic cores were destroyed and re-integrated into other planets helps explain the unexpected chemical signatures in some planetesimals. 

“These events determined which elements and minerals young worlds carried into the next stage of planet formation,” Grewal told Yale News. “Our findings show that the pathway to planetary formation was far more dynamic and complex than previously thought.”

Now, Grewal is interested not only in how planets take shape, but how they obtain the building blocks of life—a question meteorites can also help answer.

A new era of experimentation 

Grewal has recently become fascinated by how Earth obtained nitrogen, carbon, and hydrogen—three key ingredients for life. All three are highly volatile—i.e., easily evaporated.

“I’ve really become intrigued by the [idea that the] most important processes that were establishing the nitrogen, carbon and water inventory of Earth did not take place when Earth was much bigger, but actually took place in those seeds,” he explains. “We have real rocks—meteorites—that come from these first planetesimals. And if I can do experiments, then I can really understand what happens in these seeds. A planet like Earth is more complicated, but the seeds are much simpler.”

Grewal analyzes the nitrogen and carbon present in iron meteorites to understand how much of these volatile elements were present in our solar system’s first planetesimals. His experiments have yielded some surprising results—including that the planetesimals that became Earth were comparatively rich in the elements for life, while the Earth is not.

“The first planetesimals in the inner solar system—where Earth was forming—they actually had nitrogen and carbon,” he points out. This means that the planetesimals that eventually became Earth had nitrogen, carbon, and hydrogen “right from the very beginning” —but somehow lost them.

This raises another question: if those volatile elements were present, “why is Earth depleted in nitrogen, carbon, and water by a factor of one hundred? We had everything, but we were losing that at a very early stage. What were the processes controlling that loss?”

Grewal’s novel approaches to this kind of question place him at the forefront of a new era in planetary science research. “I think it’s the perfect time to develop this kind of program, and Yale giving me the opportunity to help develop this program from scratch was one of the most exciting parts.” 

In the fall, Grewal taught a graduate course on cosmochemistry, in which students learned exactly how a cloud of gas and dust can eventually create a rocky planet like Earth.

The subject reminds Grewal of one of his favorite parts about being a scientist: participating in a centuries-old tradition of exploration, rigor, and progress—one that will continue until long after he’s gone. “When you leave science, you want to leave it in a better place. Being part of the collective, moving things forward, and talking about science—that really motivates me.”

“People like Plato and Aristotle started thinking about this problem thousands of years ago,” he says. He’s happy to continue shedding light on our place in the cosmos. 

“I feel very grateful. I think it's very deeply motivating and deeply humbling experience to do science.”