SmallSat exploration of Near-Earth and co-orbital asteroids

Abstract

<p><strong>Project Overview:</strong> Interest in Near-Earth Asteroids (NEAs) has rapidly grown in recent decades. The motivation is threefold: first, their proximity allows us to discover and investigate small bodies down to the metre-size, thus enhancing our understanding of the mechanisms underlying planetary formation; second, such information is also critical to mitigate their threat of collision with the Earth; third, their near-future exploitation can exponentially expand the natural resources available to humankind.</p><p>Ground-based observations of thousands of NEAs have revealed the striking diversity existing within this population in terms of physical properties. So far, only a handful of NEAs have been visited by space missions: each of them provided unexpected discoveries and huge steps forward in our understanding of planetary sciences.</p><p>Following the Near-Earth Space Trekker (NEST) proposal selected by ESA for the Phase 2 of the 2018 Call for a Fast mission, and the Asteroid Nodal Intersection Multiple Encounters (ANIME) proposal which passed the technical and financial screenings of the 2020 ASI Call for future CubeSat missions, here we propose to develop a flexible and modular concept, making use of smallsats and high-TRL available technology for the space exploration of several NEAs. Potential targets include Earth Trojan and other co-orbital asteroids, which are particularly appealing due to the low energetic cost to reach them. In particular, Earth Trojans represent a major gap in our inventory of near-Earth small bodies. Tracking their population size would put strong constraints on the dynamical and cosmochemical theories for the formation and evolution of the inner solar system.</p><p><strong>International Context:</strong> Deep-space smallsats represent a new frontier for the solar system exploration. After the success of the NASA/JPL Mars Cube One (MarCO) mission in 2018 and the launch of ASI LICIACube in November 2021 (currently hosted as piggyback of the NASA DART spacecraft, which will impact the binary NEA Didymos in September 2022), several further deep-space smallsat missions will take place in the next few years, e.g. in the framework of ESA HERA and NASA ARTEMIS I projects.</p><p><strong>Reference Scenario:</strong> Both CubeSat and larger SmallSat platforms are considered, which perfectly address the modularity and flexibility of the proposed mission concept. Multiple identical smallsats (to maximize mission return while minimizing costs and risks) can be launched profiting of the same or separate mission opportunities, and then reach their respective targets using electric propulsion and optimized interplanetary trajectories. Each smallsat will flyby and/or rendezvous multiple NEAs, with encounters at the nodal points.</p><p>A preliminary selection of the targets has been performed assuming a 12U platform and mission durations capped at 2-3 years, with total ΔV < 3 km/s. We stress that the existence of a large number of sequences with similar performances outlines the strong implementation flexibility of our concept. Indeed, the definitive choice of target NEAs can be easily updated even at relatively late project phases, also considering the exponential growth of NEA discoveries. This gives us a huge flexibility in terms of mission scenarios, which can be adapted to varying constraints in terms of, e.g., launch date, propulsion specifics, mission architecture and duration.</p><p>Example reference solutions that have been identified include the possibility to reach the Earth’s L4-L5 Lagrange points, using the smallsat payload for the discovery and characterization of Earth Trojan and co-orbital asteroids (especially those with a long synodic period relative to our planet, which are impossible to detect from Earth-based surveys), and to flyby already discovered Earth Trojan asteroids.</p><p>Considered scientific payload (whose final selection will depend upon the choice of the platform) includes an optical camera, a near-infrared spectrometer, a mass spectrometer and a neutral particle camera, while the onboard transponder will be used to acquire radio science data.</p><p><strong>Technology Readiness:</strong> Mission architecture will rely on flight-proven (TRL 9) COTS and in-house components and scientific payload, using heritage from a number of ongoing (e.g., BepiColombo, LICIACube, …) or under development (e.g., Hera) space missions.</p><p>Potentially selected components that have flown in the Earth orbital environment only will be appropriately shielded to ensure radiation tolerance to deep-space environment for the whole mission duration.</p><p><strong>Science and Technology Ambition:</strong> We aim to provide new insights into planetary science by characterizing several NEAs presenting peculiar and yet unexplored dynamical and physical properties. Noteworthy, such information will be also relevant for planetary protection purposes, as well as to assess a potential near-future exploitation of asteroid resources.</p><p>We also aim to validate critical technologies for the exploitation of smallsats in solar system exploration, benefiting from the deep knowhow already gained by our team in designing and managing space missions to NEAs.</p><p>Our mission concept relies on significant payload heritage and high-TRL available technology, based on our established consortium. Nevertheless, we will consider possible complementary contributions from further national and/or international partners willingly.</p>