Windows of opportunity in the NASA Johnson Space Center cosmic dust collection

Non‐spherical chondritic interplanetary dust particles (IDPs) have been routinely collected in the stratosphere at ∼17–19 km altitude since May 1981 by the NASA Cosmic Dust Program. These IDPs show distinct morphological subtypes, viz. chondritic porous (CP) and chondritic filled (CF) aggregate particles, glazed CP and CF IDPs with ‘softened’ contours, and non‐aggregate chondritic smooth and rough‐textured (CR) IDPs. The distributions of these IDP subtypes show distinct abundance maxima as a function of collection time. Albeit conservatively at this time, these distributions support systematic intra‐ and inter‐annual variations. Rigorous statistical treatment of the data is disabled by gaps in the collection periods and uncertainties in collection and curation. This study recommends monthly sampling of the lower stratosphere during a two year period to quantify these temporal variations in the non‐spherical chondritic IDP subtypes. With frequent and systematic collection we will be able to combine temporal variations in IDP subtype distributions with their petrologic and chemical properties. It will then also be possible to correlate the temporal variations sampled in the lower stratosphere with events that deliver chondritic IDPs to the Earth’s atmosphere. Hence, the study of micrometeorites collected in the stratosphere might substitute for in‐situ sampling of asteroids and comet nuclei.