Browsing by Author "Sanchez, Joan-Pau"
Now showing 1 - 11 of 11
Results Per Page
Sort Options
Item Open Access Asteroid flyby opportunities using semi-autonomous CubeSats: mission design and science opportunities(Elsevier, 2018-11-10) Machuca, Pablo; Sanchez, Joan-Pau; Greenland, S.CubeSat technology has recently attracted great interest from the scientific community, industry and space agencies, and represents today an exciting movement towards a more affordable and accessible space industry. In view of potential applications of CubeSat technology to small-body planetary exploration, this paper studies the feasibility of using autonomous CubeSats to flyby near-Earth asteroids. This work provides an overview of the current state of CubeSat technology and proposes a 3U CubeSat mission using primarily off-the-shelf components. The proposed mission considers a CubeSat is deployed by a larger spacecraft in a periodic orbit around the first (L1) or the second (L2) Sun-Earth Lagrange points (common destinations to observe the Sun and outer space), from where fuel-optimal impulsive trajectories are designed to flyby asteroids between 2019 and 2025. Navigation support and ground operations costs still represent a major challenge for interplanetary CubeSats. As such, Monte Carlo simulations are performed to determine the flyby accuracies that can be accomplished by a 3U CubeSat flying autonomously (i.e., using observations of the Sun during cruise and observations of the asteroid before the flyby to estimate its own trajectory, instead of using ground stations for navigation support). Asteroid flyby opportunities for an autonomous 3U CubeSat are identified between years 2019 and 2025. Flyby altitudes below 500 km are found possible with currently-available CubeSat components. Possible science payloads are also overviewed, and the potential scientific return of such a low-cost mission is discussed.Item Open Access Asteroid retrieval missions enabled by invariant manifold dynamics(Elsevier, 2016-06-16) Sanchez, Joan-Pau; Garcia Yárnoz, DanielNear Earth Asteroids are attractive targets for new space missions; firstly, because of their scientific importance, but also because of their impact threat and prospective resources. The asteroid retrieval mission concept has thus arisen as a synergistic approach to tackle these three facets of interest in one single mission. This paper reviews the methodology used by the authors (2013) in a previous search for objects that could be transported from accessible heliocentric orbits into the Earth's neighbourhood at affordable costs (or Easily Retrievable Objects, a.k.a. EROs). This methodology consisted of a heuristic pruning and an impulsive manoeuvre trajectory optimisation. Low thrust propulsion on the other hand clearly enables the transportation of much larger objects due to its much higher specific impulse. Hence, in this paper, low thrust retrieval transfers are sought using impulsive trajectories as first guesses to solve the optimal control problem. GPOPS-II is used to transcribe the continuous-time optimal control problem to a nonlinear programming problem (NLP). The latter is solved by IPOPT, an open source software package for large-scale NLPs. Finally, a natural continuation procedure that increases the asteroid mass allows to find out the largest objects that could be retrieved from a given asteroid orbit. If this retrievable mass is larger than the actual mass of the asteroid, the asteroid retrieval mission for this particular object is said to be feasible. The paper concludes with an updated list of 17 EROs, as of April 2016, with their maximum retrievable masses by means of low thrust propulsion. This ranges from 2,000 t for the easiest object to be retrieved to 300 t for the least accessible of them.Item Open Access An automatic process for sample return missions based on dynamic programming optimization(AIAA, 2021-12-29) Bellome, Andrea; Sanchez, Joan-Pau; Rico Álvarez, Jose Ignacio; Afsa, Hadrien; Kemble, Stephen; Felicetti, LeonardThis work describes a methodology to design sample return missions and rendezvous trajectories options towards cometary objects. These are visited through a succession of fly-bys with Solar System planets, on an overall Multiple Gravity Assist (MGA) transfer. The method is based upon dynamic programming in conjunction to a specific MGA trajectory optimization model to investigate sample return mission scenarios. The model implemented is based on evaluation of grids of transfers between successive planets. The grid is obtained with Lambert arc transfer for a range of departure dates at one planet and range of time of flight to the next planet. For each successive planet in the sequence, discontinuities between incoming and outgoing Lambert arcs arise, which are in part compensated by the fly-by of the planet and, if required, an additional Δv maneuver is added on the given leg of a planet-to-planet transfer. The solutions identified are validated by re-optimizing the complete MGA trajectories as sequences of swing-bys, Deep Space Maneuvers and Lambert arcs transfers. A procedure for discontinuities removal using position constraints is also presented. Mission scenarios towards Saturn are used to validate the accuracy of proposed methods. Trajectory design for novel sample return options and rendezvous are explored for objects among Jupiter Family Comets (JFCs), as well as for never explored targets and orbital regions, as highly inclined Centaurs objects.Item Open Access Autonomous optical navigation for small spacecraft in cislunar space(International Astronautical Federation (IAF), 2022-09-22) Wu, Christian Xianyang; Machuca, Pablo; Felicetti, Leonard; Sanchez, Joan-PauThe Earth-Moon system is expected to be increasingly populated especially due to large space missions like the Lunar Gateway. Communication constellations and small spacecraft are also expected to be deployed in the coming years. However, small spacecraft missions are heavily challenged by limited access and high costs of communicating with ground antennas, and constraints on on-board components. Hence, small spacecraft could greatly benefit from the development of autonomous optical navigation, allowing for higher levels of independence, flexibility, and lower operation costs in a complex environment like cislunar space. The scope of this study is to assess the optical navigation (OPNAV) accuracies achievable through horizon-based position estimation algorithms applied to synthetic images of the Moon. The simulation framework is implemented in Python+Vapory+OpenCV, and it simulates the image acquisition process at different solar phase angles and distances (including camera performance), and the processing of images (involving limb-fitting, centroiding and relative position estimation). A conventional ellipse fitting (EF) technique and the recently proposed Christian-Robinson (CR) approach are compared. Lastly, a Monte Carlo analysis allows to assess the effects of different sources of errors and uncertainties and to gain a better understanding of the navigation accuracies that may be obtained in future cislunar scenarios of interest. Preliminary results show that the CR algorithm consistently provides better performance than the EF technique, both in accuracy and computational time. The resulting errors in range estimation depend on distance, with values of approximately 22 km at a distance of 20, 000 km and up to 422 km at a distance of 150, 000 km. In terms of cross-axis distance estimation, the errors present values around 3.55 km (36 arcsec) at 20, 000 km, and 11.85 km (16 arcsec) at 150, 000 km. Furthermore, simulation outcomes show near normally distributed OPNAV performance with standard deviations around 0.68 km and 0.73 arcsec. A power law function is also provided to approximate the trend of OPNAV accuracies as a function of the distance relative to the observed body, is found based on the outcome of this study. Colour maps illustrating OPNAV accuracies as a function of observation geometry provide a comprehensive picture of the expected performance of OPNAV depending on distance and orientation relative to the observed object.Item Open Access CASTAway: An asteroid main belt tour and survey(Elsevier, 2017-11-01) Bowles, Neil E.; Snodgrass, Colin; Gibbings, Alison; Sanchez, Joan-Pau; Arnold, Jessica A.; Eccleston, Paul; Andert, Tom; Probst, A.; Naletto, Giampiero; Vandaele, A. C.; de Leon, J.; Nathues, A.; Thomas, Ian R.; Thomas, Nicholas; Jorda, Laurent; Da Deppo, Vania; Haack, H.; Green, Simon F.; Carry, Benoit; Donaldson Hanna, Kerri L.; Leif Jorgensen, J.; Kereszturi, Akos; DeMeo, F. E.; Patel, Manish R.; Davies, John K.; Clarke, Fraser; Kinch, K.; Guilbert-Lepoutre, A.; Agarwal, J.; Rivkin, Andy S.; Pravec, Petr; Fornasier, Sonia; Granvik, Mikael; Jones, Rhian H.; Murdoch, Naomi; Joy, Katherine H.; Pascale, Enzo; Tecza, Matthias; Barnes, Jenny M.; Licandro, J.; Greenhagen, Benjamin T.; Calcutt, Simon B.; Marriner, C. M.; Warren, Tristram; Tosh, IanCASTAway is a mission concept to explore our Solar System’s main asteroid belt. Asteroids and comets provide a window into the formation and evolution of our Solar System and the composition of these objects can be inferred from space-based remote sensing using spectroscopic techniques. Variations in composition across the asteroid populations provide a tracer for the dynamical evolution of the Solar System. The mission combines a long-range (point source) telescopic survey of over 10,000 objects, targeted close encounters with 10–20 asteroids and serendipitous searches to constrain the distribution of smaller (e.g. 10 m) size objects into a single concept. With a carefully targeted trajectory that loops through the asteroid belt, CASTAway would provide a comprehensive survey of the main belt at multiple scales. The scientific payload comprises a 50 cm diameter telescope that includes an integrated low-resolution (R = 30–100) spectrometer and visible context imager, a thermal (e.g. 6–16 µm) imager for use during the flybys, and modified star tracker cameras to detect small (∼10 m) asteroids. The CASTAway spacecraft and payload have high levels of technology readiness and are designed to fit within the programmatic and cost caps for a European Space Agency medium class mission, while delivering a significant increase in knowledge of our Solar System.Item Open Access Deterministic and stochastic exploration of long asteroid fly-by sequences exploiting tree-graph and optimal substructure properties(International Astronautical Federation (IAF), 2022-09-22) Sanchez, Joan-Pau; Bellome, Andrea; Carrillo, Maria; Del Ser, J.In the past, space trajectory design was limited to the optimal design of transfers to single destinations. However, a somewhat more daring approach is today making the space community to consider missions that visit, with one single spacecraft, a multitude of celestial objects; such as asteroid tour mission proposals CASTAway or MANTIS, which both proposed to visit 10 or more asteroids in a quick succession of asteroid fly-bys. The design of these so-called asteroid tours is complicated by the fact that the sequence of asteroids is not known a priori, but is the objective of the optimisation itself. This leads to a complex mixed-integer non-linear programming (MINLP) problem, on which the decision variables assume both continuous and discrete values. Beyond the obvious complexity of such problem formulation, preliminary mission design requires not only to locate the global optimum solution but, also, to map the ensemble of solutions that leads to feasible transfers. This paper analyses the complexity of such search space, which can be efficiently modelled as a tree-graph of interconnected Lambert arc solutions between two consecutive asteroids. This allows to exploit the optimal substructure of the problem and enables complete tree traverse explorations for limited asteroid catalogues. Nevertheless, the search space quickly grows in complexity for larger catalogues, featuring a labyrinthine multi-modal structure and extreme non-linearities. This underlying complexity ultimately renders common stochastic heuristics, such as Ant Colony Optimization, rather inefficient. Mostly, due to the fact that the metaheuristic processes are not able to gather any real understanding, or knowledge, such that it can efficiently guide the search. Instead, an astrodynamics-lead heuristic based on the distance between spacecraft and asteroid at the asteroid’s MOID-point crossing epoch, enables an efficient pruning of the asteroid catalogue. Then, deterministic processes based on dynamic programming and beam search can be efficiently applied, providing solutions to both the global optimum and the constraint satisfaction problems.Item Open Access High-fidelity trajectory design to flyby near-Earth asteroids using CubeSats(Elsevier, 2019-11-05) Machuca, Pablo; Sanchez, Joan-Pau; Masdemont, Josep J.; Gomez, GerardFast development of CubeSat technology now enables the first interplanetary missions. The potential application of CubeSats to flyby near-Earth asteroids is explored in this paper in consideration of CubeSats' limited propulsive capabilities and systems constraints. Low-energy asteroid flyby trajectories are designed assuming a CubeSat is initially parked around to the Sun-Earth Lagrange points. High-impulse and low-thrust trajectories with realistic thrusting models are computed first in the Circular Restricted Three-Body Problem (CR3BP), and then in a high-fidelity ephemeris model. Analysis in the ephemeris model is used to confirm that trajectories computed in the CR3BP model also exist in a more realistic dynamical model, and to verify the validity of the results obtained in CR3BP analysis. A catalogue of asteroid flyby opportunities between years 2019 and 2030 is provided, with 80 m/s of available ΔV and departure from halo orbits around the first and second Sun-Earth Lagrange points (of similar size to those typically used by scientific missions). Results show that the CR3BP model can serve as an effective tool to identify reachable asteroids and can provide an initial estimation of the ΔV cost in the ephemeris model (with ±15 m/s accuracy). An impulsive maneuver model can also provide an accurate estimation of the ΔV requirement for a CubeSat equipped with a high-impulse thruster (with 4 m/s accuracy), even if its thrust magnitude is small and requires duty cycling; low-thrust ΔV requirements, however, may differ significantly from the impulsive results (±15 m/s).Item Open Access Laplace plane and low inclination geosynchronous radar mission design(Springer, 2017-05-17) Hobbs, Stephen; Sanchez, Joan-PauThis study is inspired by the Laplace orbit plane property of requiring minimal station-keeping and therefore its potential use for long-term geosynchronous synthetic aperture radar (GEOSAR) imaging. A set of GEOSAR user requirements is presented and analysed to identify significant mission requirements. Imaging geometry and power demand are assessed as a function of relative satellite speed (which is determined largely by choice of orbit inclination). Estimates of the cost of station-keeping as a function of orbit inclination and right ascension are presented to compare the benefits of different orbit choices. The conclusion is that the Laplace plane (and more generally, orbits with inclinations up to 15°) are attractive choices for GEOSAR.Item Open Access Optimization of asteroid capture missions using Earth resonant encounters(Springer, 2018-02-11) Neves, Rita; Sanchez, Joan-PauThis paper describes a robust methodology to design Earth-resonant asteroid capture trajectories leading to Libration Point Orbits (LPOs). These trajectories consider two impulsive manoeuvres; one occurring before the first Earth encounter and a final one that inserts the asteroid into a stable hyperbolic manifold trajectory leading to an LPO of the Sun-Earth system. The first manoeuvre is key to exploit the chaotic perturbative effects of the Earth and obtain important reductions on the cost of inserting the asteroid into a manifold trajectory. The perturbative effects caused by the Earth are here modelled by means of a Keplerian Map approximation, and these are a posteriori compared with the dynamics of the Circular Restricted Three-Body Problem. Savings in the order of 50% of total Δv are computed for four different asteroids.Item Open Access Perception fields: analysing distributions of optical features as a proximity navigation tool for autonomous probes around asteroids(IEEE, 2021-08-19) Di Fraia, Marco Zaccaria; Feetham, Luke; Felicetti, Leonard; Sanchez, Joan-Pau; Chermak, LounisThis paper suggests a new way of interpreting visual information perceived by visible cameras in the proximity of small celestial bodies. At close ranges, camera-based perception processes generally rely on computational constructs known as features. Our hypothesis is that trends in the quantity of available optical features can be correlated to variations in the angular distance from the source of illumination. Indeed, the discussed approach is based on treating properties related to these detected optical features as readings of a field - the perception fields of the title, assumed induced by the coupling of the environmental conditions and the state of the sensing device. The extreme spectrum of shapes, surface properties and gravity fields of small celestial bodies heavily affects visual proximity operational procedures. Therefore, self-contained ancillary tools providing context and an evaluation of estimators' performance while using the least number of priors are extremely significant in these conditions. This preliminary study presents an analysis of the occurrences of optical feature observed around two asteroids, 101955 Bennu and (8567) 1996 HW1 in visual data simulated within Blender, a computer graphics engine. The comparison of three different feature detectors showed distinctive trends in the distribution of the detected optical features, directly correlated to the spacecraft-target-Sun angle, confirming our hypothesis.Item Open Access Trajectory design for asteroid retrieval missions: a short review(2018-10-02) Sanchez, Joan-Pau; Neves, Rita; Urrutxua, HodeiIn simple terms, an asteroid retrieval mission envisages a spacecraft that rendezvous with an asteroid, lassos it and hauls it back to the Earth's neighborhood. Speculative engineering studies for such an ambitious mission concept appeared in scientific literature at the beginning of the space age. This early work employed a two-body dynamical framework to estimate the Δv costs entailed with hauling an entire asteroid back to Earth. The concept however has experienced a revival in recent years, stimulated by the inclusion of a plan to retrieve a small asteroid in NASA's 2014 budget. This later batch of work is well aware of technological limitations, and thus envisages a much more level-headed space system, capable of delivering only the most minimal change of linear momentum to the asteroid. As a consequence, the design of retrieval trajectories has evolved into strategies to take full advantage of low energy transfer opportunities, which must carefully account for the simultaneous gravitational interactions of the Sun, Earth, and Moon. The paper reviews the published literature up to date, and provides a short literature survey on the historical evolution of the concept. This literature survey is particularly focused on the design of asteroid retrieval trajectories, and thus the paper provides a comprehensive account of: the endgame strategies considered so far, the different dynamical models and the trajectory design methodologies.