The Tromsø programme of in situ and sample return studies of mesospheric nanoparticles

We review some of the work performed over the past two decades with rocket-borne detectors to study mesospheric dust or nanoparticles, including meteoric smoke particles (MSPs) and water ice particles in the mesosphere. We focus on regions in which noctilucent clouds (NLCs) and polar summer mesospheric echoes (PMSEs) occur. Our primary emphasis is on several detectors designed, built and used by the Tromsø group and collaborators, and results obtained with them. These include the DUSTY, MUDD and ICON probes, the latter for which the results of laboratory tests are presented. However, we also mention, but do not address in detail, some of the investigations conducted by others and describe very briefly our preparations for sample return measurements. We consider the importance of accounting for the secondary charging occurring in detectors as nanoparticles strike them, evidence that MSPs fill up to several per cent of the volume in icy particles and measurements of the size distribution of the MSPs.