MSR Campaign Science Group (MCSG) et al. (>10)
Meteoritics & Planetary Science (in Press) Open Access link to Article [doi: 10.1111/maps.139811]
Published by arrangement with John Wiley & Sons

The Mars 2020/Mars Sample Return (MSR) Sample Depot Science CommunityWorkshop was held on September 28 and 30, 2022, to assess the Scientifically-ReturnWorthy (SRW) value of the full collection of samples acquired by the rover Perseverance atJezero Crater, and of a proposed subset of samples to be left as a First Depot at a location within Jezero Crater called Three Forks. The primary outcome of the workshop was thatthe community is in consensus on the following statement: The proposed set of ten sampletubes that includes seven rock samples, one regolith sample, one atmospheric sample, andone witness tube constitutes a SRW collection that: (1) represents the diversity of theexplored region around the landing site, (2) covers partially or fully, in a balanced way, allof the International MSR Objectives and Samples Team scientific objectives that areapplicable to Jezero Crater, and (3) the analyses of samples in this First Depot on Earthwould be of fundamental importance, providing a substantial improvement in ourunderstanding of Mars. At the conclusion of the meeting, there was overall communitysupport for forming the First Depot as described at the workshop and placing it at theThree Forks site. The community also recognized that the diversity of the Rover Cache (thesample collection that remains on the rover after placing the First Depot) will significantlyimprove with the samples that are planned to be obtained in the future by the Perseverancerover and that the Rover Cache is the primary target for MSR to return to Earth.

¹Y. O. CHETVERIKOV,^1,2V. F. EZHOV,^3,4M. S. GLUKHOV,^5,6E. M. IVANKOVA,²A. S. LOSHACHENKO,²V. D. KALGANOV,^2,7O. V. YAKUBOVICH
Meteoritics & Planetary Science (in Press) Link to Article [doi: 10.1111/maps.13991]
¹Petersburg Nuclear Physics Institute named by B. P. Konstantinov of National Research Center “Kurchatov Institute”,Gatchina, Russia
²Saint Petersburg State University, St. Petersburg, Russia
³Kazan Federal University, Kazan, Russia
⁴Zavaritsky Institute of Geology and Geochemistry, Ural Branch of the Russian Academy of Sciences, Yekaterinburg, Russia
⁵Institute of Macromolecular Compounds, Russian Academy of Sciences, St. Petersburg, Russia
⁶Kirov Military Medical Academy, St. Petersburg, Russia7Institute of Precambrian Geology and Geochronology, Russian Academy of Sciences, St. Petersburg, Russia
Published by arrangement with John Wiley & Sons

Dust particles obtained by filtering fresh snow collected from May to September2017 in the vicinity of Vostok station in Antarctica were examined using a scanning electronmicroscope. The collection of dust particles contains 197 spherules ranging from 0.5 to 117μmin diameter, the most abundant ones (n=188) by far being iron oxide spherules. Analyses ofmeteorological and human activity data suggest an extraterrestrial origin of most of thespherical particles. The particle size distribution histogram showed a smooth increase in theirnumber with decreasing size and a dramatic drop at sizes smaller than 3μm. The number ofspherical particles has an uneven distribution over time, with an intense peak in July 27–28,2017 which correlates by dates with the peak of the Southern Delta Aquariids meteor shower.The size distribution of the particles collected during the same period indicates the presenceof a mechanism that accelerates their fall to the Earth. We propose that they are effectivecenters of condensation of ice crystals in stratospheric clouds. Our data indicate thatcollection of micrometeorites with sizes of several microns from the fresh snow is possible,opening a new way for sampling micrometeorites, including separate meteor showers.