PS Planetary and Solar System Sciences
The 2023 Division Outstanding Early Career Scientist Award is awarded to Tim Lichtenberg for outstanding research in cosmochemistry and planet formation, with emphasis on volatile cycling between atmospheres and planetary interiors, and especially with regard to magma oceans.
Tim Lichtenberg’s research is wide-ranging, and we begin this citation for what he is perhaps best known for: the development of sophisticated codes for dealing with self-gravitating fluid instabilities in protoplanetary disks. This work highlights the importance of short-lived radionuclides in desiccation of the planetary building blocks (termed planetesimals). The results are important because they indicate an important control on whether rocky planets are at the one extreme “born dry” or at the other born with a volatile inventory substantially in excess of what is known on Earth or Venus. This work also connects the volatile inventory with the galactic environment in which planets form, as a planet such as Earth may need to form in a disk quite near an object such as a supernova or Wolf-Rayet star in order to get an appreciable inventory of short-lived radionuclides such as 26Al to heat it in the first few million years. Lately, Lichtenberg’s work on this topic has extended to carbon species and H2O in the context of the chemical and thermodynamic structure of protoplanetary disks.
Lichtenberg has also investigated the bifurcation of planetary building blocks, by going significantly beyond earlier work on volatile delivery to tackle the role of the inhomogeneous cosmochemical environment in protoplanetary disks. He has taken on the long-standing ‘Big Question’ concerning an evident dichotomy in the reservoirs from which the planets are made and establishes him as one of the world’s key emerging players in the quest to understand what determines the volatile inventory of planets (a key aspect of habitability, among other things). An example is his 2021 Science paper that shows an outstanding ability to connect theoretical concepts of disk dynamics and planet formation with data on isotopic composition in the Solar System. Tim Lichtenberg is very productive, having published 30 or peer-reviewed articles and peer-reviewed book chapters thus far. His citation metrics are excellent for his stage of career and research field (Google scholar h = 12).
Magma oceans form an important determinant of subsequent planetary evolution, and Tim Lichtenberg’s two 2019 papers were significant in exploring the extent to which this stage of planetary evolution could be characterized by direct-imaging observations, and in the fluid mechanics of magma ascent, respectively. Furthermore, Lichtenberg has become conversant with the atmospheric modeling side of things, which he early recognized as crucial to his research programme since the blanketing affect of atmospheres determines how rapidly a planetesimal or young planet can cool off; atmospheres also exchange with planetary interiors, both during the magma ocean stage, and subsequently after the solidification of the melt. The 2021 Journal of Geophysical Research paper led by him, which coupled the state-of- the art Sun Planet Interactions Digital Environment on Request (SPIDER) magma ocean model to a radiative-convective atmosphere, involves coupling of interior dynamics to volatile cycling and atmospheric models. Other recent work has modelled redox hysteresis in magma oceans.
Beyond this remarkable research productivity, Tim Lichtenberg has also been dedicated to service to the planetary science community. In particular he is the lead organiser for the 2022 Rocky Worlds II conference, and is very active in advising of DPhil students. He is a rising star, and richly deserves the Planetary Sciences Division’s Outstanding Early Career Scientist Award.