Time capsules
from outer space

LIB: Mr Peters, do you remember your first contact with a meteorite?

Dr Stefan Peters: During my master’s studies in Amsterdam, I first heard about meteorites and planetary history in a lecture on extraterrestrial geochemistry that I attended. I was hooked immediately: the idea that natural laws known from Earth apply to other, much larger systems as well was fascinating. Later, I joined a research group in Cologne and started researching meteorites soon thereafter.
The subject continues to fascinate me even now. Meteorites enable us to understand fundamental processes of the solar system. I see them as far more than just random rocks fallen to Earth: they have the effect of time capsules that tell us about an early cosmos.

LIB: What exactly is a meteorite?

S. Peters: A meteorite is a piece of rock that originates from space and is found on the Earth’s surface. A characteristic fusion crust forms on it as it melts when entering the atmosphere. Most meteorites come from the asteroid belt.

LIB: Meteorites make many people think of science fiction or apocalyptic scenarios. What makes them interesting for scientific studies?

S. Peters: Meteorites are literally the building blocks of planets. Their mineralogy and chemistry tell us how planets formed, developed, and differentiated. We can learn why Earth has water and life when other planets do not.

LIB: Why should everyone learn about meteorites?

S. Peters: They show us where we come from. All the material that makes up the Earth—rocks, metals, water, organic compounds—originates from these early cosmic building blocks. Knowing their history helps us better understand the unique and precious elements of our planet. Even technologies for a sustainable future are based on materials originating in space: essential magnetic components in wind turbines and electric motors were formed in supernovae and are found in meteorites.

LIB: What have we learned about meteorites in the last twenty years?

S. Peters: About ten to fifteen years ago, we found out that there really are two groups of meteorites: some from the inner solar system, i.e., up to the orbit of Jupiter, and others from the outer solar system. The latter are often rich in water and organic matter. Understanding this has fundamentally changed our understanding of the early solar system.

LIB: One of your research areas pertains to the Elmshorn meteorite. How is it special?

S. Peters: The first thing that stands out is its composition: It is a breccia, a mixed rock that contains fragments of various asteroids. This proves that it comes from an asteroid destroyed by colliding with another one. Secondly, we have its unusually well-documented fall history: Its impact on 25 April 2023 was captured on video and audio alike. This is extremely rare. Visitors to our exhibition are particularly impressed by this as it makes them understand that a stone that is 4.5 billion years old, and thus predates our planet, can suddenly drop into their backyard. It makes for an immediate, tangible feeling of prehistoric times.

LIB: Meteorites are rare and expensive. How do you acquire your samples?

S. Peters: I don’t have a lot of issues with this. After all, I have access to the museum collection. (Laughs.) Many museums consider their collections resources for research and will readily provide small samples upon request. Online databases contain lists of all known meteorites. All you need is a specific research idea to contact museums directly. NASA works along the same lines. I’ve worked with material from an Apollo mission, for example—with samples that were simply mailed to me.

LIB: How does meteorite research fit into an institute that focuses on biodiversity change?

S. Peters: Life changes rocks, and rocks change life in turn. When rocks weather, minerals enter the oceans and atmosphere, shaping their chemistry. This influences which organisms thrive. Vice versa, life alters the geology of our planet. This interaction shapes biodiversity.

LIB: Has your research changed your ideas of our planet?

S. Peters: It has! My understanding of time was particularly affected. I have come to think in terms of millions and billions of years by now. Earth has changed throughout its history, as have its oceans, atmosphere, and life forms. The laws of nature, however, have not. That puts our everyday lives into perspective. At the same time, it makes clear just how fragile our current lives are. It makes you realise how closely systems like the atmosphere, rocks, water, and life are interconnected, and how pervasive the effects of even small changes to these systems can be on life as we know it.