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This review discusses the unsolved problem of the detection of interstellar particles in the Earth's atmosphere and the presence of interstellar meteors in meteor databases. Owing to the difficulties in obtaining accurate meteor measurements and, consequently, the meteoroids' orbital parameters, the identification of interstellar meteors based on their hyperbolic excess velocities is extremely challenging. Moreover, it has to be verified whether the orbit's hyperbolicity was not produced in the Solar System. Searches for interstellar meteors have been carried out using different observational techniques for more than a quarter of a century and, although they have produced many valuable results, not a single case of a meteor claimed to be produced by an interstellar particle has proven satisfactorily convincing. The reason rests in the constraints of the meteor observations, which we outline here, using meteor datasets obtained by various techniques. • We have shown how challenging the identification of interstellar particles is. • The interstellar meteoroids reported to date have been put into doubt owing to the constraints of the accuracy of current meteor measurements. • The only dependable measured interstellar particles in our Solar System which we have to date are the detections of dust instruments. • The Local Interstellar Cloud is, to date, the only confirmed source of interstellar particles. • Improvements in astrometric accuracy, in meteor trajectory estimations, and in orbital parameter determinations are needed. [ABSTRACT FROM AUTHOR]

The DESTINY + spacecraft will be launched to the active asteroid (3200) Phaethon in 2025. The spacecraft will be equipped with the DESTINY + Dust Analyzer (DDA) which will be a time-of-flight impact ionization mass spectrometer. In addition to the composition of impacting dust particles, the instrument will measure the particle mass, velocity vector, and surface charge. Here, we study the detection conditions of DDA for interstellar dust during the DESTINY + mission. We use the interstellar dust module of the Interplanetary Meteoroid environment for EXploration model (IMEX Sterken et al., 2013; Strub et al., 2019) to simulate the flow of interstellar dust through the Solar System. Extending earlier work by Krüger et al. (2019b) we consider the entire DESTINY + mission, i.e. the Earth-orbiting phase of the spacecraft during the initial approximately 1.5 years after launch, the nominal interplanetary mission phase up to the Phaethon flyby, and a four-years mission extension beyond the Phaethon flyby. The latter may include additional asteroid flybys. For predicting dust fluxes and fluences we take into account a technical constraint for DDA not to point closer than 90 ° towards the Sun direction for health and safety reasons of the instrument and in order to avoid electrical noise generated by photoelectrons. For the Earth orbiting phase after launch of DESTINY + our simulations predict that up to 28 interstellar particles will be detectable with DDA in 2026. In the following years the interplanetary magnetic field changes to a focussing configuration for small (≲ 0. 1 μ m) interstellar dust particles. This increases the total number of detectable particles to 50 during the interplanetary mission of DESTINY + in 2027. In 2028 and 2029/30 approximately 160 and 190 particles will be detectable, respectively, followed by about 500 in 2030/31. We also make predictions for the detectability of organic compounds contained in the interstellar particles which is a strong function of the particle impact speed onto the detector. While organic compounds will be measurable only in a negligible number of particles during the Earth orbiting and the nominal interplanetary mission phases, a few 10s of interstellar particle detections with measurable organic compounds are predicted for the extended mission from 2028 to 2031. • The DESTINY+ spacecraft will be launched to the active asteroid (3200) Phaethon in 2025. The spacecraft will be equipped with the DESTINY+ Dust Analyzer (DDA) which will be a time-of-flight impact ionization mass spectrometer. • We use the interstellar dust module of the Interplanetary Meteoroid environment for EXploration model (IMEX) to simulate the detection conditions for interstellar dust with DDA. • Our results show that DDA will be able to detect and analyze several hundred interstellar dust particles during its nominal and extended interplanetary mission. [ABSTRACT FROM AUTHOR]

The JAXA/ISAS spacecraft DESTINY+ will be launched to the active asteroid (3200) Phaethon in 2022. Among the proposed core payload is the DESTINY+ Dust Analyzer (DDA) which is an upgrade of the Cosmic Dust Analyzer flown on the Cassini spacecraft to Saturn (Srama et al., 2011). We use two up-to-date computer models, the ESA Interplanetary Meteoroid Engineering Model (IMEM, Dikarev et al., 2005a, c), and the interstellar dust module of the Interplanetary Meteoroid environment for EXploration model (IMEX;Sterken et al. 2013; Strub et al., 2019) to study the detection conditions and fluences of interplanetary and interstellar dust with DDA. Our results show that a statistically significant number of interplanetary and interstellar dust particles will be detectable with DDA during the 4-years interplanetary cruise of DESTINY+. The particle impact direction and speed can be used to descriminate between interstellar and interplanetary particles and likely also to distinguish between cometary and asteroidal particles. [ABSTRACT FROM AUTHOR]

Europa is the closest and probably the most promising target to search for extant life in the Solar System, based on complementary evidence that it may fulfil the key criteria for habitability: the Galileo discovery of a sub-surface ocean; the many indications that the ice shell is active and may be partly permeable to transfer of chemical species, biomolecules and elementary forms of life; the identification of candidate thermal and chemical energy sources necessary to drive a metabolic activity near the ocean floor. In this article we are proposing that ESA collaborates with NASA to design and fly jointly an ambitious and exciting planetary mission, which we call the Joint Europa Mission (JEM), to reach two objectives: perform a full characterization of Europa's habitability with the capabilities of a Europa orbiter, and search for bio-signatures in the environment of Europa (surface, subsurface and exosphere) by the combination of an orbiter and a lander. JEM can build on the advanced understanding of this system which the missions preceding JEM will provide: Juno, JUICE and Europa Clipper, and on the Europa lander concept currently designed by NASA (Maize, report to OPAG, 2019). We propose the following overarching goals for our Joint Europa Mission (JEM): Understand Europa as a complex system responding to Jupiter system forcing, characterize the habitability of its potential biosphere, and search for life at its surface and in its sub-surface and exosphere. We address these goals by a combination of five Priority Scientific Objectives, each with focused measurement objectives providing detailed constraints on the science payloads and on the platforms used by the mission. The JEM observation strategy will combine three types of scientific measurement sequences: measurements on a high-latitude, low-altitude Europan orbit; in-situ measurements to be performed at the surface, using a soft lander; and measurements during the final descent to Europa's surface. The implementation of these three observation sequences will rest on the combination of two science platforms: a soft lander to perform all scientific measurements at the surface and sub-surface at a selected landing site, and an orbiter to perform the orbital survey and descent sequences. We describe a science payload for the lander and orbiter that will meet our science objectives. We propose an innovative distribution of roles for NASA and ESA; while NASA would provide an SLS launcher, the lander stack and most of the mission operations, ESA would provide the carrier-orbiter-relay platform and a stand-alone astrobiology module for the characterization of life at Europa's surface: the Astrobiology Wet Laboratory (AWL). Following this approach, JEM will be a major exciting joint venture to the outer Solar System of NASA and ESA, working together toward one of the most exciting scientific endeavours of the 21st century: to search for life beyond our own planet. • In this article we are proposing that ESA collaborates with NASA to design and fly jointly an ambitious planetary mission: the Joint Europa Mission (JEM). • The JEM observation strategy will combine three types of scientific measurement sequences. • The implementation of these three observation sequences will rest on the combination of two science platforms. • We describe a science payload for the lander and orbiter that will meet our science objectives. • We propose an innovative distribution of roles for NASA and ESA. [ABSTRACT FROM AUTHOR]