The Greeley Early Career Award is named for pioneering planetary scientist Ronald Greeley. Ron was involved in nearly every major planetary mission from the 1970s until his death and was extraordinarily active in service to the planetary science community. Ron’s greatest legacies, however, are those he mentored through the decades, and it is young scientists whose work and promise we seek to recognize. This year’s Greeley Award winner is Brandon Johnson, an assistant professor at Brown University.
Brandon received his Ph.D. in physics from Purdue University in 2013 for fundamental work on the mechanisms by which impact spherules and melt droplets form in large cratering events. His work linked the size of ancient spherules to the size and velocity of the projectile that created them. He demonstrated that the impactor flux was much higher in the Archean than it is today.
Although his core area of expertise is impact cratering, Brandon has addressed a range of fundamental problems in planetary science. He revived the controversial idea of an impact origin of chondrules by developing models for impact jetting onto the surfaces of protoplanets. As the jetting model was debated among meteoriticists, Brandon linked CB chondrules to the high-energy impacts generated by Jupiter’s growth and migration. This work highlights Brandon’s talent in combining collision physics with planetary observations in the broader context of planet formation.
Brandon has also provided new insight into the physical properties of the Sputnik Planitia basin on Pluto. He showed that the positive gravity anomaly required the presence of a subsurface ocean, placing a key thermal constraint on the history of Pluto. With important contributions spanning the mechanics of impact basin formation to tectonics on icy satellites, Brandon’s work has consistently reframed our views on important planetary processes.
AGU congratulates Brandon Johnson for his diverse and creative contributions to planetary science.
—Sarah T. Stewart, University of California, Davis