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Let $P: {\mathbb C} \to {\mathbb C}$ be a polynomial map with disconnected filled Julia set $K_P$ and let $z_0$ be a repelling or parabolic periodic point of $P$. We show that if the connected component of $K_P$ containing $z_0$ is non-degenerate, then $z_0$ is the landing point of at least one {\it smooth} external ray. The statement is optimal in the sense that all but one ray landing at $z_0$ may be broken., Comment: 10 pages, 3 figures

The complex problem of constructing the return trajectories of a spacecraft (SC) from a circumlunar orbit before entering the Earth’s atmosphere for subsequent landing on the southern territory of the Russian Federation is considered. The problem includes two components: the choice of the conditions for the optimal impulse maneuver for the Moon–Earth flight and the determination of the descent distance from the point of entry into the Earth’s atmosphere to the given landing point. The magnitude of the impulse required and the sufficient descent distance to return on any date are estimated.

A three-impulse point return orbit design method is proposed for the manned lunar high-latitude exploration mission. First, considering the restrictions of the reentry corridor and the landing point simultaneously, the constraint conditions of the point return orbit are analyzed. Second, a serial orbit design strategy is presented. In the initial calculation, by decoupling the three-impulse transfer and the lunar escape, a two-segment patched method based on the pseudo-perilune parameters is proposed to determine the three-impulse point return orbit. The three-impulse transfer segment is backward designed by combining maneuvering at the special points with the Lambert problem in the hybrid orbit model, while the lunar escape segment is forward solved by introducing a comprehensive conic method. In the accurate solution, the result of the initial calculation serves as the initial value to perform the backward and forward integration for two segments in the high-fidelity model, respectively. The simulation examples verify the effectiveness and feasibility of this strategy, and show the advantages of high accuracy of the initial calculation and low velocity increment consumption. Finally, a large amount of simulations are conducted by applying this strategy, and the orbit characteristics are discussed. The research conclusions can provide a reference for the design of the point return orbit scheme for the manned lunar exploration mission.

The state of emergency that is being experienced has generated a sort of dynamic disorder of complex systematic re-elaboration within the framework of the legal system of the state. We appreciate a permanent tension between the rule of law and the discipline of emergency which manages to find a problematic landing point in the prefiguration of the existence of an emergency legal system, based on a different Grundnorm and parallel to the one that sustains the whole establishment of the legal system of the sources of the state legal order

Aiming at the problem that the traditional error corridor guidance method has poor adaptability in lateral guidance of predictor-corrector guidance, an algorithm of reentry guidance based on the vehicle lateral maneuverability prediction is proposed without increasing the calculation too much. The lateral component mean value of lift at reentry is calculated by using the bank angle magnitude function obtained from longitudinal guidance. According to the above-mentioned, a crossrange corridor with dynamic boundary constraint is designed to control bank angle reversal timing. Online parameters estimation is introduced to suppress the influence of the atmospheric density and aerodynamic parameters disturbance on the predictor model. The CAV-L, a kind of hypersonic vehicle, is used as an object to carry out reentry guidance simulation. The results show that the guidance algorithm can effectively guide vehicle to target for reentry missions of different range, the landing point error are small and the guidance effect is stable. The simulated results via Monte Carlo method verify that the guidance algorithm has a good adaptability and robustness to initial state deviations and process disturbances.

In the UAV parachute recovery process, the UAV and the parachute have always been in the state of dynamic balance, so it is difficult to deal with the constraint between them. In order to solve this problem, the UAV parachute recovery system was divided into three parts:the parachute, riser and UAV. The extension length of riser was obtained by the velocity relationships of the riser connection points. The riser tension was obtained by the product of the elastic coefficient and the extension length of the riser. And it was applied to the parachute and UAV systems respectively. Finally, based on the Newton-Euler equation, the 12-DOF model of UAV parachute recovery system was established, in which the unsteady aerodynamic model of the UAV from the forward flight to the steady descents was established based on the ONERA equation. The simulation and test results shows:the 12-DOF model is consistent with the results of the experimental data, which verifies the accuracy of the 12-DOF model. The 12-DOF model is more accurate than the past 6-DOF model. This model established in this paper can provide reference for the selection of parachute in the UAV parachute recovery system and the determination of the landing point of the UAV.

On December 8, 2018, China launched the Chang’E-4 lunar probe and implemented soft landing and patrol exploration on the lunar farside for the first time. Fast and high-precision positioning of the landing point is a critical step of the mission, and also an important prerequisite for surface operations of the lander and rover. Based on the high-precision image matching and geometric transformation methods, and considering the engineering requirements, the landing point location of the Chang’E-4 lander was initially determined using the near real-time high compression ratio descent sequence images. Then, the position was refined using the replayed low compression ratio descent images, and the landing point position was calculated to be (177.5884°E, 45.4565°S). The landing point localization method and result have been successfully applied to actual engineering tasks for the first time in China, thus providing important support to the topographic analysis of the landing area and mission planning of the follow-up teleoperations.

Considéré comme une véritable source d’espoir pour promouvoir la pêche artisanale en Côte d’Ivoire, le débarcadère de Locodro baptisé « Point de débarquement Mohammed VI » reste encore loin de répondre à cette attente après son ouverture en juin 2018. Cette situation suscite plusieurs interrogations sur les difficultés auxquelles il est confronté vu les commodités qu’il comporte pour être un excellent centre d’approvisionnement en produits halieutiques. Cette étude permet donc d’identifier ces difficultés, de montrer leurs conséquences sur la vie socio-économique des acteurs et de faire des recommandations pour la bonne marche dudit débarcadère. Pour la collecte des données, des documents traitant des thèmes en rapport avec la pêche ont été consultés. En plus, une enquête a été réalisée par le biais d’un questionnaire et des entretiens. Les résultats ont montré que les difficultés qui entravent le bon fonctionnement du débarcadère sont principalement liées à sa délocalisation d’Abobo-Doumé à Locodjro. Ces difficultés impactent négativement la vie socio-économique des acteurs. Cette situation qui suscite des inquiétudes recommande que des mesures correctives soient prises avec l’implication de toutes les parties concernées pour une rentabilité durable du débarcadère au profit de tous. Considered as a real source of hope to promote artisanal fishing in Côte d'Ivoire, the landing stage of Locodro named "Mohammed VI Landing Point" is still far from meeting this expectation after its opening in June 2018. This situation raises several questions about the difficulties it faces given the amenities it has to be an excellent supply centre for fishery products. This study therefore makes it possible to identify these difficulties, to show their consequences on the socio-economic life of the actors and to make recommendations for the good functioning of the said landing stage. For the collection of data, documents dealing with themes related to fishing were consulted. In addition, a survey was carried out by means of a questionnaire and interviews. The results showed that the difficulties hindering the proper functioning of the landing stage are mainly related to its relocation from Abobo-Doumé to Locodjro. These difficulties have a negative impact on the socio-economic life of the stakeholders. This situation, which gives rise to concern, recommends that corrective measures be taken with the involvement of all the parties concerned for a sustainable profitability of the landing stage for the benefit of all. Article visualizations

This paper takes selective badminton students of Shenyang Sport University as experimental objects, with methods of experiment, literature, questionnaire and mathematical statistics. It studies the physiological and physical features, badminton technical levels and sport skill rules of these students. Combined with the characteristics of multi-shuttlecock teaching, it sets a series of teaching content more suitable to their development needs at the present stage. The experimental results show that the multi-shuttlecock practice has a good effect on the improvement of students' badminton skills. This improves not only their special qualities, but also their special qualities of badminton and learning interests. Besides, it has a good effect on mastering badminton basic technology, actual combat ability, accuracy of landing point, reaction speed and lower limb movement speed. Fixed-point multi-shuttlecock practice is more effective in improving students' special qualities and skills.

In this study, three-dimensional baseball kinematics are described including spin characteristics batted toward the left field (same field), center field, and right field (opposite field) in baseball. The study also discusses the effects of these kinematics on the flight distance. Six collegiate male baseball players performed free-batting and were instructed to hit the ball as far as possible. The balls just before, at, and after bat–ball impact were recorded with three high-speed video cameras. Eighty-one trials (same field: 25 trials, center field: 30 trials, and opposite field: 26 trials) were analyzed, and the ball kinematics among the three hitting directions were compared. Although there were no significant differences in the initial velocities and launch angles along the vertical plane of batted balls for the three hitting directions, the flight distance for the opposite field was significantly shorter than that for the other fields. The magnitude of the side spin components for the opposite field was significantly greater than that for the other fields. We conjecture that the balls batted toward the opposite field experienced a larger Magnus force along the horizontal direction; moreover, the trajectories were relatively more curved than in the cases towards the other fields. Therefore, a straight-line distance to the batted ball landing point in the opposite field tended to be shorter despite the similar initial velocity and launch angle. The results demonstrated that the spin characteristics, especially the side spin component, were different for different batting directions, and indicated that these characteristics affected the ball trajectory and flight distance.

Agraïments: Anna Miriam Benini was partially supported by the ERC grant HEVO - Holomorphic Evolution Equations n. 277691. Both authors were supported by the European network MRTN-CT-2006-035651-2-CODY MRTN-CT-2006-035651-2-CODY We study the distribution of periodic points for a wide class of maps, namely entire transcendental functions of finite order and with bounded set of singular values, or compositions thereof. Fix p ∈ N and assume that all dynamic rays which are invariant under f p land. An interior p-periodic point is a fixed point of f p which is not the landing point of any periodic ray invariant under f p . Points belonging to attracting, Siegel or Cremer cycles are examples of interior periodic points. For functions as above, we show that rays which are invariant under f p , together with their landing points, separate the plane into finitely many regions, each containing exactly one interior p−periodic point or one parabolic immediate basin invariant under f p . This result generalizes the Goldberg-Milnor Separation Theorem for polynomials [GM], and has several corollaries. It follows, for example, that two periodic Fatou components can always be separated by a pair of periodic rays landing together; that there cannot be Cremer points on the boundary of Siegel disks; that "hidden components" of a bounded Siegel disk have to be either wandering domains or preperiodic to the Siegel disk itself; or that there are only finitely many non-repelling cycles of any given period, regardless of the number of singular values.

Extended reach drilling (ERD) wells involves numerous drilling challenges that in many cases causes cost overrun and delays for such wells. This paper presents a new approach used to drill a 10,000 ft long departure using a slim design to replace the conventionally well design that uses heavy casings. This approach eliminated the 22" hole section and the associated 18 5/8" casing reducing 20 days form the well duration and saving $1 million. Achieving such a long departure requires a shallower kick off and requires building inclination as early as possible crossing reactive shales and need high mud weight to guarantee hole stability. Historically an additional casing string used in order to isolate a loss zone prior to the shale formation to drill it with high mud weight. This approach limited the inclination across shales and penetrated it along with the loss zone in same section by controlling the WBM weight to be just high enough for bore stability and minimizing the loss rate but increasing the challenges in the next sections. Drilling the single horizontal oil producer well started with a 16" hole size, kicked off at 300 ft and built to 22-degree inclination in that section and isolated with 13-3/8" surface casing. A 12-1/4" hole was drilled across the loss zone and reactive shales formation keep the WBM weight as 9.4 ppg (70 PCF) while drilling the loss zone and increased later to 9.9 ppg (74 pcf) prior to drilling the reactive shale where the inclination was limited to 27 degree across it and built later to 32 deg at the end of 12 ¼" hole section and isolated with 9-5/8" production casing.8 ½" hole section was drilled with 12.3 ppg (92 pcf) OBM in order to built 82 deg before penetrating the reactive shale and hold it tangent to cover the maximum departure and built to 90 deg to land in target reservoir with total departure of 10,755 ft and isolated with 8,150 ft long 7" production liner, followed by 4,000 ft 6‘‘ horizontal open hole. This novel light casing design avoided drilling a hole section of 22‘’ and the associated 18-5/8" casing, saving at least 20 days in well duration and nearly $1 million in well cost. The new slim well design explained in this paper, which is used to drill long departure well with 10,000 ft, is the first of its kind in ADNOC Onshore field. It has proved that such long departure wells can be completed with light casing design and achieve 100% integrity.

This paper demonstrates a technique for improving the performance of neural network-based models for saccade landing point estimation. Performance improvement is achieved by augmenting available training data with time-shifted replicates in order to improve prediction robustness to variations in saccade onset timing. The technique is validated for both long short-term memory (LSTM) and feed-forward neural network models for 5,893 saccades extracted from the recordings of 322 individuals during free-viewing of a movie trailer. The proposed augmentation strategy is demonstrated to improve the median accuracy of landing point estimates for LSTM models formulated using both the raw position and relative displacement of the gaze location.

Fish residue management plan for the Craft Fishing Port of Coquimbo Resumen En Chile, el Puerto Pesquero Artesanal de la ciudad de Coquimbo es usado como el principal centro de desembarque de la región. Una de las principales actividades que se realiza es el eviscerado y limpieza de pescados, cuyo resultado es la generación de un gran volumen de residuos. Estos son almacenados durante el día en contenedores plásticos con escurridores, ubicados en el patio del Puerto. Debido a que no están bajo una cubierta, estos están expuestos a la radiación solar, por tanto su descomposición se acelera, favoreciendo la generación de malos olores y atrayendo moscas por el escurrimiento de sangre. Dichos residuos son utilizados para la fabricación de harina de pescado, pero cuando estos no son retirados sistemáticamente, se dispone que sean arrojados al mar. En el presente trabajo se plantean dos propuestas de manejo para los residuos: la elaboración de compost y el diseño de un proceso para la adecuada recolección, segregación, transporte, tratamiento y disposición final de los mismos. Palabras clave: pescado eviscerado; resíduos de pescado; compost; recursos hidrobiológicos; viruta. Abstract In Chile, the Artisanal Fishing Port of the city of Coquimbo is used as the main landing point for the region. One of the main activities is the evisceration and cleaning of fish, which results in the generation of a large volume of waste. This waste is stored during the day in plastic containers with colanders, located in the backyard of the Port. Because it is not covered, the waste is exposed to solar radiation, accelerating its decomposition and therefore generating bad odors and attracting flies. Although the waste is used for the production of fish flour, it is also thrown into the sea, because it is not constantly removed from the port. In the present work, two waste management proposals are presented: the elaboration of compost and the design of a process for the adequate collection, segregation, transport, treatment and final disposal of the waste. Keywords: gutted fish; fish waste; compost; hydrobiological resources; chips.

The paper deal with the question of developing the unmanned aerial vehicle (UAV) landing system, which would allow to determine flight and navigation UAV parameters during landing. The paper analyzes in detail the existing UAV's landing systems. It is shown that the main direction of improvement in the UAV landing is to increase the UAV injection accuracy to the optimal landing point with defined motion parameters to provide the optimal approach and landing trajectory. Also, the paper proposes the polarimetric principle for determining the UAV position during landing and the polarimetric principle for forming a landing glide for UAVs of aircraft and helicopter types. The paper proposes a polarimetric UAV landing system, which provides determining the basic UAV flight and navigation parameters during landing. The paper provides mathematical modeling results of the proposed landing system's operation. The proposed landing system provides determining UAV deviation from the optimal landing trajectory and its attitude with high accuracy and sensitivity.

In this study, a bioinspired multi-finger robot system (MFRS) is designed based on the characteristics of eagle claws. The MFRS is attached to a rotary-wing unmanned aerial vehicle (RUAV), which can be enabled to land on uneven terrain. In addition, the robot can also grab target objects or perch on a cylinder. The finger of the robot can simultaneously rotate three revolute joints only relying on one motor, to achieve an action similar to the grip of the eagle claw. The hardware structure and control system architecture of the MFRS are established. Based on depth vision, an adaptive landing algorithm that can achieve real-time optimal landing point selection is proposed. The outdoor experiments show that the robot can effectively land the RUAV on the slopes, steps, and unstructured terrains.

In this paper, we describe the process to construct a pico-satellite mounted in a bottle of polyethylene terephthalate (PET) of 345 ml. The assembly and tests were made during the 6th CanSat Leader Training Program (CLTP-6) at University Hokkaido-Japan in the summer 2015. The pico-satellite was launched in the facilities of Uematsu Electric Co. Ltd. in Akabira-Japan by a paper model rocket, which achieved a height of approximately 100 m. The mission was designed to measure physical variables, such as temperature and humidity using electronic sensors. During the flight, we observed that the temperature inside the rocket was ∼0.5◦C higher than the temperature of the environment. We registered a humidity difference of ∼5%, measured between the maximum height and the landing point. The flight pattern was projected to a plane that covers an area of 50 m × 50 m by means the coordinates of a GPS.

The mechanism of sputtering due to cluster impacting which has been widely studied is an important but unsolved problem. In present research, we discuss the effect of the landing point on the sputtering with the method of molecular dynamics. The results show that the landing points play significant roles on sputter yield when the temperature of target is low. Specific landing points can cause particular sputtering patterns which lead to different sputtering yield and moving directions of sputtered atoms. The mechanism of this phenomenon is that specific landing keeps symmetries and anisotropies of target lattice, which influence the sputtering yield.

A hybrid surface composed of superhydrophobic patterns on hydrophilic substrate was fabricated by selective painting. The impingement of a water drop on this surface was investigated using lattice Boltzmann simulation. When a drop impinged on the boundary line between the superhydrophobic and hydrophilic area, the drop would spread preferentially to the hydrophilic area while the spreading at the superhydrophobic area was highly impeded. The maximum spreading diameters as well as the spreading time, which are extremely important for the heat transfer on solid surfaces, were analyzed in detail. By adjusting the distance between the landing point and the boundary line of the superhydrophobic/hydrophilic area, the maximum spreading diameter and spreading time could be altered precisely. The impinging velocity has been found to be important on the manipulation of the dynamic droplet as well.

The judgment of table tennis falling point has a great influence on the hitting effect. Many athletes judge the falling point of table tennis by the position of the racket (the position and posture of the racket and the posture below) when the opponent hits the ball. This paper proposes to verify the influence of the pose of the racket on the ping-pong track and the drop point based on the visual. First, the ball is subjected to force analysis, a sports model of table tennis is established, and the predicted trajectory and landing point of the ball are obtained. Then, we use the threshold cut method to set multiple thresholds to identify the pose of the racket when hitting the ball. Finally, the binocular vision system is used to obtain the true trajectory and landing point of the ball after hitting the ball. Successfully verified the correctness of our motion model. And through the falling point of the ball, we confirmed that the pose of the racket has an influence on the ball trajectory and the falling point when hitting the ball.

Aiming at the characteristics of robot application, a technology research on 100W level frameless motor for robot field is carried out. Taking the load characteristics as the starting point and taking the performance as the landing point, the design of the motor is optimized from the point of design, material selection, electromagnetic characteristics and thermal characteristics.

Three or more forces which act through a common point, but are not all in the same plane are called non-coplanar concurrent forces. Such a loading situation necessitates a three dimensional (3D) analysis. Algebraically, the solution is well known with the resultant magnitude described as:where Fx, Fy and Fz are mutually orthogonal components, sometimes called the i, j, k vectors. These three components need not align with any pre-determined x, y, z axes, but they must be mutually perpendicular, i.e. they must have 90° angles between them.

Traditional parafoil homing usually uses a point as object. As the mobility of parafoil is limited by its glide ratio and wind, in some cases when the parafoil scatter area is large, or the glide ratio of parafoil is small, the deviation of its landing point to object point will be arduous to control. Accordingly, during these situations, when parafoil is used in recovery of spacecraft or satellite, the landing area of parafoil can be set as a rectangle, and the object of parafoil can be set as a line segment. The thesis of this work is designing an algorithm for parafoil homing using line segment as object. The algorithm of wind velocity and direction calculation in different flying segments was also investigated. The algorithm designed navigates the parafoil to land into the predestined area and largely reduce the probability of recovery loads falling to unwanted area to damage houses and people.

Lidar-based hazard avoidance landing system for lunar lander calculates hazard cost with respect to the desired local landing area in order to identify hazard and designate safe landing point where the cost is minimum basically using slope and roughness of the landing area. In this case, if the parameters are only considered, chosen landing target can be designated near hazard threatening the lander. In order to solve this problem and select optimal safe landing point, hazard cost based on relative distance to hazard should not be considered as well as cost based on terrain parameters. In this paper, the effect of hazard cost based on relative distance to hazard on safe landing performance was analyzed and it was confirmed that landing site designation with two relative distances to hazard results in the best safe landing performance by an experiment using three-dimensional depth camera.

Whenever we move our eyes, some visual information obtained before a saccade is combined with the visual information obtained after a saccade. Interestingly, saccades rarely land exactly on the saccade target, which may pose a problem for transsaccadic perception as it could affect the quality of postsaccadic input. Recently, however, we showed that transsaccadic feature integration is actually unaffected by deviations of saccade landing points. Possibly, transsaccadic integration remains unaffected because the presaccadic shift of attention follows the intended saccade target and not the actual saccade landing point during regular saccades. Here, we investigated whether saccade landing point errors can in fact alter transsaccadic perception when the presaccadic shift of attention follows the saccade landing point deviation. Given that saccadic adaptation not only changes the saccade vector, but also the presaccadic shift of attention, we combined a feature report paradigm with saccadic adaptation. Observers reported the color of the saccade target, which occasionally changed slightly during a saccade to the target. This task was performed before and after saccadic adaptation. The results showed that, after adaptation, presaccadic color information became less precise and transsaccadic perception had a stronger reliance on the postsaccadic color estimate. Therefore, although previous studies have shown that transsaccadic perception is generally unaffected by saccade landing point deviations, our results reveal that this cannot be considered a general property of the visual system. When presaccadic shifts of attention follow altered saccade landing points, transsaccadic perception is affected, suggesting that transsaccadic feature perception might be dependent on visual spatial attention.

A atividade pesqueira no litoral amazônico, apresenta uma heterogeneidade, tanto na ictiofáuna de importância comercial, quanto nos métodos de captura. Diante da diversidade íctica, tem-se o bijupirá Ranchycentron canadum, espécie pelágica, migradora, de médio a grande porte, desembarcada ao longo dos municípios costeiros do Pará. Diante disso, o estudo objetivou descrever a pescaria incidente sob essa espécie e variação ao longo do tempo, além de determinação da CPUE e de ciclos periódicos, por meio dos dados de esforço e captura fornecidos pelo programa estatpesca. A metodologia aplicada consistiu na análise exploratória dos dados, aplicação da análise de cluster, para verificação das possíveis relações de desembarque entre os municípios, as relações da captura com o esforço foram realizadas por meio da correlação de Pearson, e a correlação da CPUE utilizada por meio da correlação linear e através dessa estimativa, verificamos por meio da análise de wavelet (ondeleta), os possíveis ciclos periódicos existentes. A série temporal da CPUE do bijupirá foi realizada pelo método da PCNM, no entanto, por meio do teste de Mann Kendall não apresentou tendência significativa. O município de São João de Pirabas foi o principal ponto de desembarque da espécie, em outros municípios são ocasionais. A CPUE identificada neste estudo foi a média da captura de barcos de pequeno porte que utilizaram a rede serreira em relação à média do número de pescadores (r=0,48) e por meio dessa estimativa de abundância do bijupirá, identificou-se ciclos periódicos de 11,3 meses.

The company vision development plan to capitalize on oil production, sustainability, maximise recovery and as cost effective to reduce number of wells to be drilled requests to drill extended horizontal drains (Oil producer and water Injector). Subsurface well location optimisation, focus in detail on targets location and the related risks. The present offshore case study, demonstrate furthermore how important to study in detail all hazards along the well path, such as lithology of side-track formation. The risk of well bore stability, collapse is very high in such formation. Subsequently, in case of collapse or drop of scratched portion of rocks, the horizontal drain will be plugged and cease to produce. This case study, demonstrate how this event happens and adequate solution was successfully applied. To efficiently perform the proposed plan, and develop multilayer geological units with poor to moderate limestone, a detailed reservoir study was performed including all subsurface team and drilling division. It was proposed to drill and complete wells as extended horizontal drain (+3000 ft.), with several designs: multilateral drains or step down 6″open hole. The first planned well was dual oil producer, two targets, one deviated and the second 6 inch horizontal 3000 ft. length. Feasibility with drilling engineer was performed to study all drilling parameters, drilling hazards, logging requirement, geosteering, equipment preparation and simulation for acid stimulation was showing easy to be executed with barge.

Within the next few years, unmanned quadrotors are likely to become an important vehicle in humans' daily life. However, their automatic navigation and landing in indoor environments are among the commonly discussed topics in this regard. In fact, the quadrotor should be able to automatically find the landing point from the nearby position, navigate toward it, and finally, land on it accurately and smoothly. In this paper, we proposed a low-cost and thorough solution to this problem by using both bottom-facing and front-facing cameras of the drone. In addition, in the case that vision data were unavailable, inertial measurements alongside a Kalman filter were used to navigate the drone to achieve the promising continuity and reliability. An AR.Drone 2.0 quadrotor, as well as an ArUco marker, were employed in order to test the proposed method experimentally. The results indicated that the drone successfully landed on the predefined position with an acceptable time and accuracy.

Titan’s lakes and seas are targets of particular interest for future exploration. We review candidate splashdown areas in Ligeia and Kraken Mare, and Ontario Lacus. Titan’s thick and dense atmosphere means that landing dispersions of spacecraft are dominated by uncertainties in wind drift, and thus the feasibility of landing safely in the sea with a simple Huygens-like descent system (i.e. without guidance or propulsion) is dependent upon these uncertainties being small enough that the landing point dispersion lies within the sea. Because Titan’s winds vary with season, notably through the formation of a high-speed stratospheric jet in the winter hemisphere, landing point dispersions are seasonally-dependent as well as latitude-dependent. Ligeia Mare, at 78 o N, sees relatively small dispersions but offers viable Direct-to-Earth (DTE) communication only until 2024. A wide part of Kraken Mare (450 × 90 km) at 70 o N can be comfortably reached at all times, and is viable for assured Direct-to-Earth communication until 2026, or with a relay spacecraft thereafter. The seasonal geometry permits DTE from the northern seas again after 2040. Wind dispersions are always too large for Ontario, unless a steerable parachute or similar system is used to tighten the landing ellipse.