ESA F-Class Comet Interceptor: Trajectory design to intercept a yet-to-be-discovered comet

Comet Interceptor (Comet-I) was selected in June 2019 as the first ESA F-Class mission. In 2029+, Comet-I will hitch a ride to a Sun-Earth L2 quasi-halo orbit, as a co-passenger of ESA's M4 ARIEL mission. It will then remain idle at the L2 point until the right departure conditions are met to intercept a yet-to-be-discovered long period comet (or interstellar body). The fact that Comet-I target is thus unidentified becomes a key aspect of the trajectory and mission design. The paper first analyses the long period comet population and concludes that 2 to 3 feasible targets a year should be expected. Yet, Comet-I will only be able to access some of these, depending mostly on the angular distance between the Earth and the closest nodal point to the Earth's orbit radius. A preliminary analysis of the transfer trajectories has been performed to assess the trade-off between the accessible region and the transfer time for a given spacecraft design, including a fully chemical, a fully electric and a hybrid propulsion system. The different Earth escape options also play a paramount role to enhance Comet-I capability to reach possible long period comet targets. Particularly, Earth-leading intercept configurations have the potential to benefit the most from lunar swing-by departures. Finally, a preliminary Monte Carlo analysis shows that Comet-I has a 95–99% likelihood of successfully visit a pristine newly-discovered long period comet in less than 6 years of mission timespan

RC-SIM: Radiocomm Signals for Retrieval of Planetary Geophysical Parameters

The RC-SIM project aimed at the analysis of existing and new techniques for the exploitation of radio-communication signals from interplanetary probes for remote sensing of the surface and other geophysical parameters of planets and moons. Main objectives of the project have been to investigate the physical parameters which can be obtained from the use, as a remote sensing instrument, of the radio-communication systems on-board interplanetary probes; to analyse the added value provided by this approach compared to other types of instruments also supplying surface and other geophysical parameters; to develop a prototype simulator generating quantitative results of the different aspects involved in the radio communication link. After reviewing the previous and foreseen experiments on this field and the state-of-the-art of radio-communication systems, three target scenarios were considered: * Titan scenario, defining an orbiter around Titan and a balloon overflying its surface in different configurations for the realization of bistatic radar experiments to retrieve the dielectric constant and the root-mean-square (r.m.s.) surface slope. * Martian lander, to determine the Martian rotational state by using the Radio Frequencies (RF) signal coming from a lander on Mars to an Earth station. * Moon interferometric mission: this scenario involves a network of 3-4 widely spaced landers on the Moon and aims to accurate determination (to 0.2 mm) of lunar tides and librations. The most relevant models selected to simulate these scenarios have been: accurate Mars and Moon rotational state models; Titan surface model of interaction and reflection of RF signal; error models (atmospheric, solar plasma, transponder ageing \u2026); retrieval models. The simulator has been developed according to pre-selected scientific requirements that may come from future planetary missions to assess the potential benefits of the use of telecom links for geophysical investigation. The results show that state-of-the-art architecture of radio-communication systems may provide significant improvements in the knowledge of several geophysical parameters. The flexible simulator setup allows analysing different configurations and models, as well as performing sensitivity analyses in future missions\u2019 context