Dust Next Generation Sensor : Innovative instrument and sensors for measuring dynamical parameters of dust in extraterrestrial environment.

Abstract:

The study of the characteristics of refractory and icy particles in the space environment has become crucial to the understanding of many phenomena in which dust plays a fundamental role. 

Dust instruments play a crucial role in analyzing the icy and potentially refractory plumes emanating from moons of giant planets like Jupiter and Saturn.By measuring the dynamical parameters of dust and ice particles within these plumes,  vital insights into the subsurface environments can be retrieved. This analysis helps determine the presence of water, organic molecules, salts, and silicate materials, providing clues about the potential habitability of these ocean worlds and the geological processes occurring within them.

The Dust Next Generation Sensor  aims to develop next-gen sensors based on optical detection and piezoelectric transducers to retrieve size,  mass, velocity, trajectory, and spatial distribution of particles. The sensors will be capable of measuring particles ejected within plumes driven by gas or ejected by different processes (e.g. electrostatic charging), moving in atmospheres and levitating on airless bodies. The measurement system is formed by an optical detector coupled with an impact sensor, that is able to determine the dynamical parameters of the particles that cross its sensitive area.

The 2 subsystems are development of the GIADA (Grain Impact Analyzer and Dust Accumulator) instrument (on board Rosetta Esa mission) measurement subsystems: 

• ISC (Impact Sensor and Counter) which working principle is similar to GIADA-Impact sensor, for measuring the momentum of dust particles hitting its sensing surface.
• Optical Stage formed coupling fiber-coupled lasers and highly sensitive sensors Silicon PhotoMultipliers (SiPMs) to measure the speed, trajectory and optical cross section evolution of the GDS (Grain Detection System) GIADA subsystem.

ISC (Impact Sensor and Counter)

The Impact Sensor and Counter is a further improvement of DISC (Figure 1)  selected for Comet Interceptor  and is able to measure momentum of impinging particles on its sensing surface. A similar sensor was used on Rosetta ESA mission to measures particles with low speed (<300 m/s) and the same configuration demonstrated the capability to measures particles impacting in hypervelocity regime. The sensing element is formed by piezoelectric sensors (PZT) connected to a mechanical element: the sensing plate. The PZTs detect the acoustic bending Lamb waves (Lamb, 1, generated by the dust impact, propagating across the aluminium plate and convert the elastic deformation of the plate into an electrical signal whose amplitude is linked to the momentum of the impacting particle. These elastic waves are generated both by low speed and hypervelocity impacts and the same sensor configuration shall be applicable.                                                                        

Optical Stage

The Optical Stage (OS) is the development of the Grain Detection System (GDS) on board GIADA. It will measure the light scattered by dust grain when crosses in a illuminated area. The primary objective of Optical Stage, shown in draft drawing (Figure 2), is to measure the scattered light by dust with size in a range 1-100 micrometers. It foreseen 2 optical plane (X,Y) each equipped with 10 laser coupling to fiber and 2 arrey of next-generation optical sensors Silicon Photo Multipliers (SiPMs). SiPMs (Figure 3) are advanced devices that utilize solid-state technology to detect single photons. They consist of an array of Single Photon Avalanche Diodes (SPADs), named microcells or micro-pixels, that operate independently in parallel. The OS will be coupled with the DISC in a cascade configuration and the measurements from the 2 subsystems can be cobined to retrieve additional information on particles crossing their sensing areas:

• Optical Cross Section
• Velocity
• Direction
• Partcle mass

Figure 1 : DISC

                                    Figure 2 : Draft drawing of the Optical Stage

 

Acknowledgement: This work has been funded by the ASI-INAF agreement N. 2024-19-HH.0