Life is based on organic matter. Understanding the processes responsible for its formation is thus crucial to shed light on the emergence of life on Earth. Evidence suggests that organic molecules can form in space, as indicated by their presence in meteorites, extraterrestrial samples that provide insights into the chemical processes going on at the dawn of the solar system. Astronomical observations and space mission data show that organics are widespread in the solar system, with detections in pristine bodies that have likely preserved the composition of the material available in the protoplanetary disk, such as comets, asteroids, and icy trans-Neptunian objects (TNOs). Many questions remain regarding the origins of organics in these bodies, the chemical pathways involved, the time and location of their formation, and their present distribution.

This seminar will focus on one particular pathway for the formation of organic matter and its precursors in space: the interaction of simple carbon-bearing ices with energetic radiation. In particular, we will see how laboratory experiments help us understand the role of low-energy cosmic rays and solar particles in the formation of organics in pristine carbon-bearing ices from which primitive small bodies formed. Experiments also help us to explore how energetic radiation can alter the organic matter after its formation, a process at work on the surface of various celestial objects that lack protective atmospheres or magnetospheres, typically comets, asteroids, and TNOs where we look for traces of pristine organic matter.

The studies help us understand how the composition of the pristine ices, the timescale of exposure to radiation, the type of radiation, and subsequent processing in pristine bodies affect the properties of organic matter in space.