No abstract

Multiple autonomous Unmanned Aerial Vehicles (UAVs) can be used to complement human teams. This paper presents the results of an exploratory study to investigate gesture/speech interfaces for interaction with robots in a situated manner and the development of three iterations of a prototype command set. A command set was compiled from observing users interacting with a simulated interface in a virtual reality environment. We discovered that users find this type of interface intuitive and their commands tend to naturally group into both 'High-Level' and 'Low-Level' instructions. However, as the robots moved further away, the loss of depth perception and direct feedback was inimical to the interaction. In a second experiment we found that using simple heads up display elements could mitigate these issues.

Jupiter has the most complex and energetic radiation belts in our Solar System and one of the most challenging space environments to measure and characterize in-depth. Their hazardous environment is also a reason why so many spacecraft avoid flying directly through their most intense regions, thus explaining how Jupiter’s radiation belts have kept many of their secrets so well hidden, despite having been studied for decades. In this paper we argue why these secrets are worth unveiling. Jupiter’s radiation belts and the vast magnetosphere that encloses them constitute an unprecedented physical laboratory, suitable for interdisciplinary and novel scientific investigations: from studying fundamental high energy plasma physics processes which operate throughout the Universe, such as adiabatic charged particle acceleration and nonlinear wave-particle interactions, to exploiting the astrobiological consequences of energetic particle radiation. The in-situ exploration of the uninviting environment of Jupiter’s radiation belts presents us with many challenges in mission design, science planning, instrumentation, and technology. We address these challenges by reviewing the different options that exist for direct and indirect observations of this unique system. We stress the need for new instruments, the value of synergistic Earth and Jupiter-based remote sensing and in-situ investigations, and the vital importance of multi-spacecraft in-situ measurements. While simultaneous, multi-point in-situ observations have long become the standard for exploring electromagnetic interactions in the inner Solar System, they have never taken place at Jupiter or any strongly magnetized planet besides Earth. We conclude that a dedicated multi-spacecraft mission to Jupiter is an essential and obvious way forward for exploring the planet’s radiation belts. Besides guaranteeing numerous discoveries and huge leaps in our understanding of radiation belt systems, such a mission would also enable us to view Jupiter, its extended magnetosphere, moons, and rings under new light, with great benefits for space, planetary, and astrophysical sciences. For all these reasons, in-situ investigations of Jupiter’s radiation belts deserve to be given a high priority in the future exploration of our Solar System. This article is based on a White Paper submitted in response to the European Space Agency’s call for science themes for its Voyage 2050 programme.

A significant but unexpected result of the Cassini mission was the discovery of heavy organic negative ions in Titan’s ionosphere at altitudes between about 950 and 1400 km by the CAPS Electron Spectrometer (ELS). The heaviest ions were observed during the T16 fly-by with masses over 13 000 u/q. This is significantly higher than the maximum masses observed during other fly-bys. We study T16 CAPS-ELS observations and examine the evolution of mass spectra at different altitudes. We also study maximum mass trends using a large data set from all available CAPS-ELS observations of the Cassini mission in order to investigate the conditions necessary to allow negative ions to grow to the highest masses. For the first time, we are able to investigate the relationship between the highest mass particles and seasonal effects. We find that the combination of high latitude and winter conditions, resulting in long-term restricted solar flux, create an environment in which ion growth can reach the highest masses, as observed during T16. Restricting solar flux long term, and hence photodestruction reactions such as photodetachment, appears to be essential for negative ions to grow beyond 10 000 u/q.

Saturn’s main ring system is associated with a set of small moons that either are embedded within it or interact with the rings to alter their shape and composition. Five close flybys of the moons Pan, Daphnis, Atlas, Pandora, and Epimetheus were performed between December 2016 and April 2017 during the ring-grazing orbits of the Cassini mission. Data on the moons’ morphology, structure, particle environment, and composition were returned, along with images in the ultraviolet and thermal infrared. We find that the optical properties of the moons’ surfaces are determined by two competing processes: contamination by a red material formed in Saturn’s main ring system and accretion of bright icy particles or water vapor from volcanic plumes originating on the moon Enceladus.