Dr. Pratik Joshi is an internationally recognized scientist with extraordinary ability and original scientific contributions in space science and remote sensing. Since joining my group as a Ph.D. student in August 2016, he has impressed me with his keen insight and ability to identify outstanding problems in space and planetary physics and his enthusiasm to tackle the hardest of them.

Over the years, he has proven that his ambition to conduct such impactful research is well matched by his solid work ethic, technical rigor, and personal and professional maturity.

For example, using a multidecade baseline of optical and radar data acquired at the National Science Foundation’s (NSF) Arecibo Observatory, he established a new community standard for the O-O⁺ charge-exchange cross section, a crucial parameter that governs the energetic and dynamic coupling between the thermosphere and ionosphere. He also made significant advances in understanding charge-exchange coupling involving thermospheric hydrogen (H) atoms, research that was supported by a NASA FINESST (Future Investigators in NASA Earth and Space Science and Technology) Fellowship. By combining data from three of the instruments on board NASA’s Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics (TIMED) mission, he established the first rigorous, data-driven analysis of the solar cycle climatology of atmospheric H density, its vertical flux, and its energetic partitioning among thermal and nonthermal (charge-exchange driven) gravitational escape pathways. This work led to his discovery that Earth’s H escape exhibits unexpectedly large spatial dependencies, seasonal and solar cycle periodicities, transient responses to geomagnetic storms, and secular evolution.

Extending his H density retrieval techniques to NASA’s MAVEN/IUVS (Mars Atmosphere and Volatile Evolution/Imaging Ultraviolet Spectrograph) data, Dr. Joshi also discovered that charge-exchange interactions involving H atoms in the Martian thermosphere strongly influence vertical H transport and escape, contradicting the long-standing assumption that such nonthermal effects are negligible. His work has been crucial for developing the instrument requirements, concept of operations, and data processing software for NASA’s Carruthers Geocorona Observatory mission, for which he is now serving as the Science Retrieval Algorithm Development Lead since his graduation in 2022.

Beyond these extraordinary research achievements, which span physics-based model development, multisensor data analysis, and geophysical inverse theory, Pratik is exceptionally personable, responsible, and conscientious. He has also proven himself to be a dedicated educator, twice receiving nominations for teaching excellence awards. His 11 years of research experience in space science and remote sensing have significantly contributed to space missions in NASA’s Heliophysics, Planetary Science, and Earth Science divisions and NSF’s radio and optical programs.

—Lara Waldrop, University of Illinois Urbana-Champaign

I dedicate this Fred L. Scarf Award to my beloved astrophysicist grandpa, Gajanan Joshi, for igniting in me a passion and love for the universe through his personally designed telescope, and my physicist parents, Prasad Joshi and Vrushali Joshi, and lovely grandmas, Mrunalini Joshi and Mangala Bhambe, for their inspiration, love, and support, and all my teachers and well-wishers in life for their wisdom and belief in me. I am indebted to Prof. Joseph Baker and Prof. Michael Ruohoniemi at Virginia Tech for introducing me to space physics as a young graduate student and honing my skills in ionospheric research through NSF’s SuperDARN radars and Prof. Randolph Wynne for training me in interdisciplinary GIS tools and field experience in Earth sciences and supervising my research in developing hyperspectral machine learning algorithms for NASA’s Landsat 8 mission. My deepest gratitude goes to my Ph.D. adviser, Prof. Lara Waldrop, at Electrical and Computer Engineering (ECE) Illinois, for her unwavering belief in me and for her time, support, and invaluable advice in every academic and research pursuit over the past 7 years with NASA’s TIMED and MAVEN missions and the upcoming NASA Carruthers Geocorona Observatory. The countless opportunities and insights she provided me in exospheric science, UV spectroscopy, ion-neutral charge exchange, planetary physics, and radiative transfer techniques have established my research and career direction. She is my scientific idol and shaped much of who I am today as a researcher. At ECE Illinois, Prof. Erhan Kudeki’s advice about remote sensing of ions using incoherent scatter radars, Prof. Jonathan Makela’s insights about neutral wind measurements by Fabry- Perot interferometers, and Prof. Gary Swenson’s guidance about mesospheric physics have been crucial to my research. Dr. Dolon Bhattacharyya and Dr. Michal Chaffin at the Laboratory for Atmospheric and Space Physics (LASP) guided my planetary research with their thorough advice about radiative transfer modeling and Martian physics. Special thanks to Dr. Alex Glocer for the dream research experience at NASA Goddard and for training me to use the Polar Wind Outflow Model (PWOM). Thanks to all my collaborators, Dr. Joseph Huba, Dr. Richard Hodges, Dr. Sonal Jain, Dr. Nick Schneider, and Dr. Christiano Brum, for supporting my research through models, data, and scientific discussions. I am grateful to NASA FINESST awards, the NASA Mars Data Analysis Program (MDAP), and NSF Atmospheric and Geospace Sciences grants for supporting my research. Thanks to the AGU Honors Committee for this distinguished recognition. “All time is all the time,” and this inspiring award marks the grateful epoch of my journey as a space scientist! —Pratik Joshi, University of Illinois Urbana-Champaign