Cosmic Dust News
Marc Fries, Cosmic Dust Curator
Volume 4 No. 1 • March 2022
This year is shaping up to be a busy year for the Cosmic Dust Collections as we continue to push for additions to the collections, improvements to collection operations, and expand interaction with the Cosmic Dust community. Here is a current summary of activities.
Interstellar Cosmic Dust Collection Working GroupOne item brought forward in the Cosmic Dust workshop during LPSC last year was to investigate the feasibility of collecting interstellar particles. Previous research indicates there is a temporal window where collection might be possible, but exploration is needed into when this window exists, how to collect interstellar particles using existing cosmic dust collecting methods, and how to identify interstellar particles. We will announce a call for a community working group to discuss these issues at the Spring 2022 ExMAG meeting, and participation is encouraged for all interested parties. Watch for the announcement at ExMAG.
Flights for 2022This year's flights will focus on testing "dry collection" technologies for the Aircraft Collected Particle (ACP) collection. ER-2 flights are scheduled for May-June with an emphasis on collecting as many hours as possible without regard to meteor shower flux. Collectors will include a pair of silicone oil-coated collectors as control samples, polyurethane and perfluorinated closed-cell foams, and honeycomb-faced collectors with two different geometries. Post-flight analysis will analyze the collection efficiencies of each collector type for future "dry collection" operations and degradation of the foam substrates. Particles collected in these flights will be made available for request in future issues of the Astromaterials Newsletter.
Upcoming Sample AnnouncementsTwo sets of new samples will be available soon, from a timed collection of the Geminids meteor shower in 2020 and a re-examination of a "dry" foam collector (W7262) flown in 2005. For the Geminids timed collection, six particles have been identified as cosmic and will be released in an upcoming issue of the Astromaterials Newsletter. Also, collector W7262 from an oil-free, "dry" foam collection in 2005 was re-examined to identify and remove additional cosmic dust. The foam was found to have degraded and is now sticky, frustrating efforts to remove samples. Raman spectroscopy indicates that the sticky material is a breakdown product of the foam itself, potentially from exposure to UV light at altitude or from residual monomer extrusion over time. Kathleen McBride found and removed a "new" cluster particle from W7262. This material was removed from the sticky foam with a hexane wash and has disaggregated into many small particles. Rather than issue a very small catalog with only the six timed-collection particles, the new catalog will also include the W7262 particles in a future issue of the Astromaterials Newsletter, possibly before the Fall 2022 Issue, so stay tuned. Going forward, foam-collected particles will be removed immediately after flight before the foam degrades, and new technologies to defeat this problem will be evaluated.
Cosmic Dust Flux Figures for all ACP CollectorsTo support efforts to identify cosmic dust particles from given meteor showers, Kathleen McBride has assembled a flux estimate figure for every ACP collector as shown below. This figure was assembled with community assistance and with permission to use a figure from Moorhead et al. (2019) as its basis (thank you!). This example is for collector W7321, which was part of the timed collection during the Geminids meteor shower in 2021. The figure shows estimated flux at LEO throughout the calendar year for four different infall masses (curved, colored lines) along with the time when the collector was exposed (at bottom). At a glance, you can now visualize which (if any) meteor showers were active at the time the collector was exposed. These figures will be viewable on the Cosmic Dust sample database pending a future update, and until then please contact the Curator for copies. Also, an LPSC abstract submitted this year includes a listing of all ACP collectors which coincide with meteor showers, either intentionally or not, as well as a listing of "control" collectors that do not coincide with any major meteor shower. (Abstract #2627, LPSC 2022).
Figure 1: Moorhead, A.V., Egal, A., Brown, P.G., Moser, D.E., and Cooke, W.J. (2019) Meteor Shower Forecasting in Near-Earth Space. Journal of Spacecraft and Rockets, 56, 1531-1545.