2020 Leonard Medal for Michael Zolensky
Citation by Don Brownlee (University of Washington, Seattle)
President Mini Wadhwa and members of the Meteoritical Society, it is a genuine pleasure to present Michael Ewing Zolensky as the 55th recipient of Leonard Medal. Mike has made many remarkable contributions to meteoritics and allied fields; his discoveries, innovative science, enthusiastic sharing of his encyclopedic meteoritic and mineralogical knowledge as well as tireless curatorial service to the sample analysis community have profoundly enriched our field.
Mike is a renowned expert on the mineralogy, petrology and geochemistry of meteoritic materials. He has been a vital intellectual resource to our community as well as a person who has instigated many fruitful collaborative and innovative studies that have involved hundreds of colleagues around the world and produced an impressive list of publications. His broad range of endeavors has included the historic study and curation of the first asteroid and comet samples collected by spacecraft. With Japanese colleagues, he participated in identification and the study of the asteroid Itokawa samples collected by Hayabusa. Work on these samples led to a direct link between S-type asteroids and ordinary chondrites and provided unique evidence on space-weathering. He led the large international Mineralogy-Petrology Team on the Stardust mission that produced the first characterization of samples collected from a comet. This effort led to the unexpected discovery of high temperature materials such as chondrule and CAI fragments in comets providing direct evidence of large-scale mixing of solids between the hottest and coldest regions of the early solar system. He also found that aqueous alteration products, a major focus of his meteorite studies, were surprisingly rare in an ice-rich body from the outer solar system.
In addition to mission samples, he also worked on naturally delivered “sample returns” including cosmic dust on Earth and in its atmosphere as well as meteoroids captured in space. Mike has played major roles in the study of many meteorites including exceptional ones such as Tagish Lake, Kaidun and the astronomically observed asteroid 2008 TC3 that produced cogenetic but perplexing samples in the Almahata Sitta fall. He has long been intrigued by foreign inclusions in meteorites that, that essentially are tiny asteroid fragments collected by other asteroids. He has been centrally involved in organized searches for meteorites and tektites on at least four continents.
A common theme in Zolensky’s research over the years has been aqueous alteration. This work has included processes and alteration products in chondrites, Martian meteorites and hydrated interplanetary dust particles. Using electron microscopy on the fine-grained materials, Mike and Ian Mackinnon, identified the prominent but mysterious phase in CMs that had formerly been called PCP for Poorly Characterized Phase. By linking it to the rare terrestrial mineral Tochilinite, they gave PCP a name and provided new constraints on the asteroidal environments needed to produce it. Related to these efforts is his spectacular work on fluid inclusions found in rare, miraculously preserved, meteoritic halite. These inclusions are the only extraterrestrial water samples that have been directly studied in the laboratory and they retain organics that were in early parent body water. In my opinion, his work on these ancient blue salt crystals has been a heroic endeavor with astounding results. I was first shown these in Monahans in Mike’s office. Mike asked if I wanted to taste one, lick one of the spectacular tiny amethyst-like crystals. I didn’t but I have always secretly wished that I had committed such a sacrilegious act. At the time it was not yet known that these odd salt crystals had old 129I ages and provided unique information on the early solar system.
In his curatorial functions, Mike has made crucial contributions to the managing, processing and analysis of extraterrestrial samples. He played a major role in the study of impact craters on space-exposed materials including those from the LDEF spacecraft and he was the Cosmic Dust curator that led the collection, handling, initial characterization and allocation of NASA JSC collected interplanetary dust in the stratosphere. He was in charge curation of the both the comet and interstellar samples collected by the Stardust mission. He, along with Scott Sandford at NASA Ames, were the “doomsday squad” that would have used flashlights, tongs and other gadgets to gather loose aerogel and comet dust from the Utah desert if the Stardust sample capsule popped open during a hard landing. This was to be done at 3 AM in a remote region containing 50 years of unexploded military ordinance. In another noteworthy feat, Mike and colleagues, were successful in using a Dremel tool to legally excavate tiny fragments of the Stardust mission collector, while on permanent display at the Smithsonian Air & Space museum. The composition of these materials was needed to understand the nature of secondary impact debris in the part of the collector used for collecting interstellar particles.
In addition to scientific prowess, Mike is just a lot of fun to work with. When publishing with a group, Mike, with a grin, always suggests alphabetical author order, starting with Z. When we had our first Stardust meeting at the Timbercove Inn we all drove so far on the winding coast road north of San Francisco that we seemed be at the end of the known world. When Mike reached our isolated outpost, he established an instant friendship with the Inn’s owner. They both just happened to be good friends of the person who found the best samples of Taglish Lake and soon all three were on the phone together talking about the recovery. At the Second Timbercove conference, Mike arrived late at night. He had had actually come early so he could visit the type locality of Deerite, Howieite, and Zussmanite and he gave some of us samples of these rare but famous minerals. As a final fun story, I have to mention how I ended up, in the middle of a dark night, at the century old (and reportedly haunted) long abandoned Baby Head Cemetery in the Texas hill country. I was traveling with family and wanted to see some of the marvelous chatoyant blue quartz that Mike had mentioned. I found them nearby and later discovered that Mike had written the definitive paper on them. He used the full power of microanalysis methods to show that the odd color was due to Rayleigh scattering from submicron ilmenite inclusions.
Mike Zolensky has been ubiquitous in our field and I don’t believe that I have ever been part of or heard of a sample-related committee or group that he wasn’t part of. His curatorial and scientific efforts have benefited a great number of people and he has been a great facilitator of collaborations between scientists working in different countries. This strong interaction between cultures has enriched the remarkable world-wide cross fertilization within cosmochemistry. Many people will agree with the following comment from one of the many supporting nomination letters: “I view Dr. Zolensky as one of living legends in the golden age of astromaterial sample return missions in the post-Apollo era”.