Investigating the Dust Flux in the Meteoric Smoke Sampler (MESS) Instrument for Sampling Dust in the Mesosphere

We report and discuss the design of a rocket instrument to collect mesospheric dust particles that are composed of ice and include smaller refractory meteoric smoke particles (MSP). We expect that the ice components melt and that MSP are collected. The instrument consists of a collection device with an opening and closure mechanism and an attached conic funnel. Attaching the funnel increases the sampling area in comparison to the collection area which is kept small since this determines the size of the closure device which is a critical component to be designed for sea recovery. The instrument will collect primary particles that directly hit the collection area and secondary particles that form from mesospheric dust hitting the funnel. We simulate the entry and impact of dust onto the detector considering their trajectories in the airflow and the fragmentation at the funnel. We estimate the collection efficiency of the instrument and the impact energy of particles at the collecting area. The design considered has a sampling area of 5 cm diameter and a collection area of 1.8 cm diameter. To estimate the expected amount of collected dust we assume collection during rocket flight through a 0.5 to 4 km dust layer with dust number densities and dust sizes at 85 km as derived from lidar observations (Kiliani et al., 2015). Assuming the collected particles contain 3 % volume fraction of MSP, we find that the instrument would collect of the order of 1014 to 1015 amu of refractory MSP particles. The estimate basis on the assumption that the ice components are melting and the flow conditions in the instruments are for typical atmospheric pressures at 85 km.

Deep-sea search and recovery: with and without operating an underwater vehicle

Deep-sea search and recovery mainly refers to the search, recovery, and salvage of objects with high value that are lost on the deep-sea bottom. Deep-sea search and recovery objects include aircraft black boxes, underwater vehicles, and other types of objects. The recovery and salvage of objects involves accurately obtaining their underwater positions. Depending on whether or not the salvage object carries an acoustic beacon, two methods are available: onboard acoustic signal search and near-bottom sweep search and search. Once the underwater position of a salvage object is known, it can be recovered and salvaged with a remotely operated underwater vehicle (ROV) and/or human-occupied vehicle (HOV). However, there are many difficulties with the practical application of existing deep-sea recovery systems that are based on the deep-sea operation of ROVs and HOVs. Based on the design idea and working mode of TV-grab in oceanography, this paper proposes a new type of deep-sea recovery system that does not rely on operating underwater vehicles and presents its recovery process. The new deep-sea recovery system combines underwater optical imaging, mechanical docking/grasping, acoustic imaging and positioning, and propeller operating to provide low-cost and rapid deep-sea recovery. Compared to the deep-sea recovery system with a ROV and/or HOV, the new deep-sea recovery system without an operating underwater vehicle described in this paper is proposed to be used, but not tested yet.