Dust Science with the DESTINY+ Dust Analyzer

<p>The DESTINY+<br />spacecraft (Demonstration and Experiment of Space Technology for<br />INterplanetary voYage with Phaethon fLyby and dUst Science) will be launched to the<br />active asteroid (3200) Phaethon by the Japanese Space Agency JAXA in 2024. The main<br />mission target will be Phaethon with a close flyby in 2028. Together with two cameras, the<br />DESTINY+ Dust Analyzer (DDA) on board will perform close observations of this rockcomet type object to solve essential questions related to the evolution of our inner Solar<br />System, especially the heating processes of small bodies. Phaethon is believed to be the<br />parent body of the Geminids meteor shower and is considered to be a comet-asteroid<br />transition object. Such objects likely play a major role to better understand the nature and<br />origin of mass accreted on to Earth. The DDA dust analyzer is an upgrade of the Cassini<br />Cosmic Dust Analyzer (CDA) which very successfully investigated the dust environment of<br />the Saturnian system. The DDA instrument is an impact ionization time-of-flight mass<br />spectrometer with integrated trajectory sensor, which will analyse sub-micrometer and<br />micrometer sized dust particles. The instrument will measure the particle composition (mass<br />resolution m/Δm ≈ 100-150), mass, electrical charge, impact velocity (about 10% accuracy),<br />and impact direction (about 10° accuracy). In addition to dust analysis in the vicinity of<br />Phaethon during the close flyby at this small asteroid, DDA will continuously measure dust<br />in interplanetary space in the spatial region between 0.9 and 1.1 AU during the<br />approximately four years spanning cruise phase from Earth to Phaethon. We give a progress<br />report of the instrument development together with an update on the preparation of the<br />scientific measurements planned during the DESTINY+ mission.</p>

Juventas Cubesat for the Hera mision

<p>The Juventas CubeSat, will be delivered to the Didymos binary asteroid system by ESA's Hera mission within the context of the Asteroid Impact and Deflection Assessment (AIDA) international collaboration. AIDA is a technology demonstration of the kinetic impactor concept to deflect a small asteroid and to characterize its physical properties. Due to launch in 2024, Hera would travel to the binary asteroid system Didymos. It will explore the binary asteroid and the crater formed by the kinetic impact the NASA’s Double Asteroid Redirection Test (DART). HERA will carry two 6U CubeSats, one of which is the Juventas CubeSat developed by GomSpace Luxembourg with the Royal Observatory of Belgium as principal investigator. The spacecraft will attempt to characterize the internal structure of Didymos’ secondary body, Dimorphos, over a period of roughly 2 months using a low-frequency radar, JuRa. During this period, Juventas will also perform radio science measurements using its Inter-Satellite-Link to characterize the mass and mass distribution of Dimorphos. Afterwards, Juventas will attempt to land on Dimorphos, during which the spacecraft is expected to perform several bounces. Once landed, Juventas will use its gravimeter GRASS to obtain measurements of the surface acceleration on Dimorphos for a nominal duration of two orbits. Through the monitoring of dynamics for landing and bouncing impacts as well as measurements from the GRASS gravimeter payload while on the surface, Juventas will determine surface mechanical properties and provide further information on subsurface structure and dynamical properties of Dimorphos.</p>

An N-body approach to modeling debris and ejecta off small bodies: Implementation and application

We introduce here our new approach to modeling particle cloud evolution off surface of small bodies (asteroids and comets), following the evolution of ejected particles requires dealing with various time and spatial scales, in an efficient, accurate and modular way. In order to improve computational efficiency and accuracy of such calculations, we created an N-body modeling package as an extension to the increasingly popular orbital dynamics N-body integrator Rebound. Our code is currently a stand-alone variant of the Rebound code and is aimed at advancing a comprehensive understanding of individual particle trajectories, external forcing, and interactions, at the scale which is otherwise overlooked by other modeling approaches. The package we developed – Rebound Ejecta Dynamics (RED) – is a Python-based implementation with no additional dependencies. It incorporates several major mechanisms that affect the evolution of particles in low-gravity environments and enables a more straightforward simulation of combined effects. We include variable size and velocity distributions, solar radiation pressure, ellipsoidal gravitational potential, binary or triple asteroid systems, and particle-particle interactions. In this paper, we present a sample of the RED package capabilities. These are applied to a small asteroid binary system (characterized following the Didymos/Dimorphos system, which is the target for NASA’s Double Asteroid Redirection Test mission).

Characterization of the June epsilon Ophiuchids meteoroid stream and the comet 300P/Catalina

Aims. Prior to 2019, the June epsilon Ophiuchids (JEO) were known as a minor unconfirmed meteor shower with activity that was considered typically moderate for bright fireballs. An unexpected bout of enhanced activity was observed in June 2019, which even raised the possibility that it was linked to the impact of the small asteroid 2019 MO near Puerto Rico. Early reports also point out the similarity of the shower to the orbit of the comet 300P/Catalina. We aim to analyze the orbits, emission spectra, and material strengths of JEO meteoroids to provide a characterization of this stream, identify its parent object, and evaluate its link to the impacting asteroid 2019 MO. Methods. Our analysis is based on a sample of 22 JEO meteor orbits and four emission spectra observed by the AMOS network at the Canary Islands and in Chile. The meteoroid composition was studied by spectral classification based on relative intensity ratios of Na, Mg, and Fe. Heliocentric orbits, trajectory parameters, and material strengths were determined for each meteor and the mean orbit and radiant of the stream were calculated. The link to potential parent objects was evaluated using a combination of orbital-similarity D-criteria and backwards integration of the orbit of comet 300P and the JEO stream. Results. We confirm the reports of an unexpected swarm of meteoroids originating in the JEO stream. JEO meteoroids have low material strengths characteristic for fragile cometary bodies, and they exhibit signs of a porous structure. The emission spectra reveal slightly increased iron content compared to all other measured cometary streams, but they are generally consistent with a primitive chondritic composition. Further dynamical analysis suggests that the JEO stream is likely to originate from comet 300P/Catalina and that it was formed within the last 1000 yr. Over longer timescales, the meteoroids in the stream move to chaotic orbits due to the turbulent orbital evolution of the comet. Our results also suggest that the impact of the small asteroid 2019 MO on June 22 was not connected to the JEO activity.

An artificial impact on the asteroid (162173) Ryugu formed a crater in the gravity-dominated regime

The Hayabusa2 spacecraft investigated the small asteroid Ryugu, which has a rubble-pile structure. We describe an impact experiment on Ryugu using Hayabusa2’s Small Carry-on Impactor. The impact produced an artificial crater with a diameter >10 meters, which has a semicircular shape, an elevated rim, and a central pit. Images of the impact and resulting ejecta were recorded by the Deployable CAMera 3 for >8 minutes, showing the growth of an ejecta curtain (the outer edge of the ejecta) and deposition of ejecta onto the surface. The ejecta curtain was asymmetric and heterogeneous and it never fully detached from the surface. The crater formed in the gravity-dominated regime; in other words, crater growth was limited by gravity not surface strength. We discuss implications for Ryugu’s surface age.