Navigating to the Moon Along Low-Energy Transfers

This paper presents a navigation strategy to fly to the Moon along a Weak Stability Boundary transfer trajectory. A particular strategy is devised to ensure capture into an uncontrolled relatively stable orbit at the Moon. Both uncertainty in the orbit determination process and in the control of the thrust vector are included in the navigation analysis. The orbit determination process is based on the definition of an optimal filtering technique that is able to meet accuracy requirements at an acceptable computational cost. Three sequential filtering techniques are analysed: an extended Kalman filter, an Unscented Kalman filter and a Kalman filter based on high order expansions. The analysis shows that only the unscented Kalman filter meets the accuracy requirements at an acceptable computational cost. This paper demonstrates lunar weak capture for all trajectories within a capture corridor defined by all the trajectories in the neighbourhood of the nominal one, in state space. A minimum f'v strategy is presented to extend the lifetime of the spacecraft around the Moon. The orbit determination and navigation strategies are applied to the case of the European Student Moon Orbiter

Asteroid debris: Temporary capture and escape orbits

We investigate the dynamical behaviour of debris ejected from the surface of an asteroid, due to a generic – natural or artificial – surface process. We make an extensive statistical study of the dynamics of particles flowing from the asteroid. We observe different behaviours: particles which fall again on the asteroid surface, or rather escape from its gravitational field or are temporary trapped in orbit around the asteroid. The tests are made by varying different parameters, like the size of the asteroid, its eccentricity, the angular velocity of the asteroid, the area-to-mass ratio of the debris. We also extend the study to the case of a sample of binary asteroids with a mass ratio equal to 10−3; we vary the distance of the moonlet from the asteroid, to see its effect on the debris dynamics. Our simulations aim to identify regions where the debris can temporarily orbit around the asteroid or rather escape from it or fall back on the surface. These results give an important information on where a spacecraft could be safely stay after the end of the process which has produced the debris

A in Situ Resource Utilisation Demonstrator for the Moon: Preliminary Design and Dynamic Model

The paper presents a preliminary study and development for a lunar In Situ Resource Utilisation (ISRU) plant. To make the human space colonisation a fundamental step is represented by enabling technologies to exploit local resource, limiting a periodical refurbishment from Earth. Here a possible technological demonstrator mission is deeply analyzing taking care of any possible technological and design trade-offs. Firstly the selection of the material to be treated is presented, based on the analysis of the available resources on our satellite. As a second step the different methods of extraction are compared and the process of oxygen manufacturing is proposed as the most important element to both support life and supplying fuel for propulsion applications. Oxygen manufacture can be obtained thanks to different processes such as the hydrogen reduction of ilmenite, molten silicates electrolysis, pyrolisis and carbothermal reduction of anorthite. The last has been selected for the presented design as it offers the best compromise in terms of feasibility and innovation. The Malapert Mountain turned out to be the zone with the best-suited superficial soil composition to collect the anorthite, having a smooth morphology, quite good light exposition too. The requirements the ISRU technological demonstrator has been design include the production of 3-5 kg oxygen within 6 months. Moreover, the exploitation of a European launcher such the Ariane 5 is has been posted. As a consequence, strong limitations on launcheable mass and ISRU dimensions must have been taken into account while sizing. Five modules - each of which has been preliminarily designed - compose the overall plant. To better understand and analyze the feasibility and the process effectiveness the dynamic model of the entire plant has been implemented. The dynamic modelling of the ISRU demonstrator helped in refining the preliminary design of the modules and to simulate different operational mode of the plant itself. The ISRU architecture includes the following modules: 1. a Beneficiation modulus, whose aim is the selection of fine particles of anorthite from other species in order to satisfy reactor requirements; 2. a Reactor, the core of the system, i.e. the chamber where the reaction of reduction with methane takes place and monoxide and hydrogen are produced; 3. a Reverse Steam Reforming chamber, where water and methane are obtained from monoxide an hydrogen, coming from reactor and tanks where a surplus of hydrogen is stowed; 4. a Water Electrolysis modulus, where oxygen and water are produced from water; 5. a Power Generation system, which provides required power to every unit thanks to solar panels and fuel cells. A previous research and study in the field of analogous applications on Earth and Moon was followed by a thorough analysis to define the best configuration, in terms of dimensions and dynamic respond, which fitted in with mission requirements. Dynamic simulation needed the identification of mathematical model, capable of describing behaviours of every system. Thanks to this operation a numerical model was built in Matlab/Simulink environment. A parametrical analysis was conducted: this allowed to define running performances of every system and to describe different situations, such as non-optimal or critical working conditions. This part of the study involved an important contribution to dimensional statements and it could be a starting-point to improve reliability. The result of the dynamic analysis was the creation of a dynamic model library which represents and describes every single modulus of the unit, whose elements can be interfaced to simulate the behaviour of the entire unit. This kind of approach to the problem allowed us to create completely parametrical elements of the library, applicable to bigger-size systems, flexible because they can be interfaced in many ways to solve different configurations, and integrable with external components

Nova informação sobre a transição Pleistoceno-Holoceno e o Holoceno inicial no extremo sul do Maciço de Deseado (Patagônia, Argentina)

El objetivo de este trabajo es presentar los nuevos resultados obtenidos en torno a las ocupaciones tempranas en el sitio La Gruta 1, área de La Gruta, extremo sur del Macizo del Deseado, Patagonia argentina. Éstos se refieren tanto a la transición Pleistoceno-Holoceno como al Holoceno temprano y abarcan aspectos paleoambientales, nuevos fechados radiocarbónicos, además de la disponibilidad y utilización de materias primas. Se presentan los resultados de los nuevos análisis polínicos, realizados en un mallín del área ubicado en la meseta central, cerca de la localidad arqueológica Viuda Quenzana, con una edad basal de ca. 12.500 años AP (14.500 cal AP). Por otra parte, a partir de los resultados obtenidos se infiere una vegetación similar a la reconstruida por otros registros polínicos del área que sugieren condiciones húmedas durante el segundo período de ocupación humana del sitio arqueológico La Gruta 1, comprendido entre ca. 11.000 y 8000 cal AP Las evidencias procedentes de la ampliación de las excavaciones en este sitio muestran la falta de continuidad entre los fechados correspondientes a la transición Pleistoceno-Holoceno y los del Holoceno temprano. En ambos períodos existe evidencia de transporte de materias primas desde otros espacios, que incluyen artefactos bifaciales, lo que es consistente con la información obtenida previamente.This work presents new results obtained regarding early occupations at La Gruta 1 site, in the area of La Gruta, at the southern extreme of the Deseado Massif, Argentine Patagonia. These results encompass both the Pleistocene-Holocene transition and the Early Holocene and include paleoenvironmental information and new radiocarbon dates, as well as additional data on the availability and utilization of lithic raw materials. We present the results of the analysis of the lowest part of a wet meadow located in the Deseado Massif, close to the Viuda Quenzana archaeological locality. Its base is dated at ca. 12,500 years BP (14,500 cal BP). The results obtained allow us to infer the existence of vegetation similar to the one reconstructed for other sites of the area, suggesting the occurrence of more humid conditions during the second period of human occupation in La Gruta 1, dated between ca. 11,000 and 8000 cal BP Evidences obtained through broadening of the excavation show a lack of continuity between the samples dating from the Pleistocene-Holocene transition and those that correspond to the Early Holocene. Both periods present evidences of the transport of raw material from other zones into the area, including bifacial artifacts, which is consistent with human behavior during this time period.O objetivo deste trabalho é apresentar os novos resultados obtidos em torno das ocupações iniciais no sítio de La Gruta 1, região de La Gruta, extremo sul do Maciço de Deseado, Patagônia argentina. Referem-se tanto à transição Pleistoceno-Holoceno quanto ao Holoceno inicial e abrangem aspectos paleoambientais, novas datação radiocarbônicas, além da disponibilidade e uso de matérias-primas. Apresentam-se os resultados das novas análises de pólen, realizadas em um banhado da área localizado no planalto central, próximo à localidade arqueológica Viuda Quenzana, com idade basal de ca. 12.500 anos AP (14.500 cal AP). Por outro lado, a partir dos resultados obtidos infere-se uma vegetação similar à reconstruída por outros registros polínicos da área que sugerem condições úmidas durante o segundo período de ocupação humana do sítio arqueológico La Gruta 1, compreendido entre ca. 11.000 e 8000 cal AP As evidências procedentes da expansão das escavações neste sítio mostram a falta de continuidade entre as datações correspondentes à transição Pleistoceno-Holoceno e as do Holoceno inicial. Nos dois períodos há evidência de transporte de matérias-primas de outros espaços, que incluem artefatos bifaciais, o que é consistente com a informação obtida previamente.Facultad de Ciencias Naturales y Muse

Nova informação sobre a transição Pleistoceno-Holoceno e o Holoceno inicial no extremo sul do Maciço de Deseado (Patagônia, Argentina)

El objetivo de este trabajo es presentar los nuevos resultados obtenidos en torno a las ocupaciones tempranas en el sitio La Gruta 1, área de La Gruta, extremo sur del Macizo del Deseado, Patagonia argentina. Éstos se refieren tanto a la transición Pleistoceno-Holoceno como al Holoceno temprano y abarcan aspectos paleoambientales, nuevos fechados radiocarbónicos, además de la disponibilidad y utilización de materias primas. Se presentan los resultados de los nuevos análisis polínicos, realizados en un mallín del área ubicado en la meseta central, cerca de la localidad arqueológica Viuda Quenzana, con una edad basal de ca. 12.500 años AP (14.500 cal AP). Por otra parte, a partir de los resultados obtenidos se infiere una vegetación similar a la reconstruida por otros registros polínicos del área que sugieren condiciones húmedas durante el segundo período de ocupación humana del sitio arqueológico La Gruta 1, comprendido entre ca. 11.000 y 8000 cal AP Las evidencias procedentes de la ampliación de las excavaciones en este sitio muestran la falta de continuidad entre los fechados correspondientes a la transición Pleistoceno-Holoceno y los del Holoceno temprano. En ambos períodos existe evidencia de transporte de materias primas desde otros espacios, que incluyen artefactos bifaciales, lo que es consistente con la información obtenida previamente.This work presents new results obtained regarding early occupations at La Gruta 1 site, in the area of La Gruta, at the southern extreme of the Deseado Massif, Argentine Patagonia. These results encompass both the Pleistocene-Holocene transition and the Early Holocene and include paleoenvironmental information and new radiocarbon dates, as well as additional data on the availability and utilization of lithic raw materials. We present the results of the analysis of the lowest part of a wet meadow located in the Deseado Massif, close to the Viuda Quenzana archaeological locality. Its base is dated at ca. 12,500 years BP (14,500 cal BP). The results obtained allow us to infer the existence of vegetation similar to the one reconstructed for other sites of the area, suggesting the occurrence of more humid conditions during the second period of human occupation in La Gruta 1, dated between ca. 11,000 and 8000 cal BP Evidences obtained through broadening of the excavation show a lack of continuity between the samples dating from the Pleistocene-Holocene transition and those that correspond to the Early Holocene. Both periods present evidences of the transport of raw material from other zones into the area, including bifacial artifacts, which is consistent with human behavior during this time period.O objetivo deste trabalho é apresentar os novos resultados obtidos em torno das ocupações iniciais no sítio de La Gruta 1, região de La Gruta, extremo sul do Maciço de Deseado, Patagônia argentina. Referem-se tanto à transição Pleistoceno-Holoceno quanto ao Holoceno inicial e abrangem aspectos paleoambientais, novas datação radiocarbônicas, além da disponibilidade e uso de matérias-primas. Apresentam-se os resultados das novas análises de pólen, realizadas em um banhado da área localizado no planalto central, próximo à localidade arqueológica Viuda Quenzana, com idade basal de ca. 12.500 anos AP (14.500 cal AP). Por outro lado, a partir dos resultados obtidos infere-se uma vegetação similar à reconstruída por outros registros polínicos da área que sugerem condições úmidas durante o segundo período de ocupação humana do sítio arqueológico La Gruta 1, compreendido entre ca. 11.000 e 8000 cal AP As evidências procedentes da expansão das escavações neste sítio mostram a falta de continuidade entre as datações correspondentes à transição Pleistoceno-Holoceno e as do Holoceno inicial. Nos dois períodos há evidência de transporte de matérias-primas de outros espaços, que incluem artefatos bifaciais, o que é consistente com a informação obtida previamente.Dossier: Ocupaciones tempranas en América: voces desde el Cono SurFacultad de Ciencias Naturales y Muse

Nova informação sobre a transição Pleistoceno-Holoceno e o Holoceno inicial no extremo sul do Maciço de Deseado (Patagônia, Argentina)

El objetivo de este trabajo es presentar los nuevos resultados obtenidos en torno a las ocupaciones tempranas en el sitio La Gruta 1, área de La Gruta, extremo sur del Macizo del Deseado, Patagonia argentina. Éstos se refieren tanto a la transición Pleistoceno-Holoceno como al Holoceno temprano y abarcan aspectos paleoambientales, nuevos fechados radiocarbónicos, además de la disponibilidad y utilización de materias primas. Se presentan los resultados de los nuevos análisis polínicos, realizados en un mallín del área ubicado en la meseta central, cerca de la localidad arqueológica Viuda Quenzana, con una edad basal de ca. 12.500 años AP (14.500 cal AP). Por otra parte, a partir de los resultados obtenidos se infiere una vegetación similar a la reconstruida por otros registros polínicos del área que sugieren condiciones húmedas durante el segundo período de ocupación humana del sitio arqueológico La Gruta 1, comprendido entre ca. 11.000 y 8000 cal AP Las evidencias procedentes de la ampliación de las excavaciones en este sitio muestran la falta de continuidad entre los fechados correspondientes a la transición Pleistoceno-Holoceno y los del Holoceno temprano. En ambos períodos existe evidencia de transporte de materias primas desde otros espacios, que incluyen artefactos bifaciales, lo que es consistente con la información obtenida previamente.This work presents new results obtained regarding early occupations at La Gruta 1 site, in the area of La Gruta, at the southern extreme of the Deseado Massif, Argentine Patagonia. These results encompass both the Pleistocene-Holocene transition and the Early Holocene and include paleoenvironmental information and new radiocarbon dates, as well as additional data on the availability and utilization of lithic raw materials. We present the results of the analysis of the lowest part of a wet meadow located in the Deseado Massif, close to the Viuda Quenzana archaeological locality. Its base is dated at ca. 12,500 years BP (14,500 cal BP). The results obtained allow us to infer the existence of vegetation similar to the one reconstructed for other sites of the area, suggesting the occurrence of more humid conditions during the second period of human occupation in La Gruta 1, dated between ca. 11,000 and 8000 cal BP Evidences obtained through broadening of the excavation show a lack of continuity between the samples dating from the Pleistocene-Holocene transition and those that correspond to the Early Holocene. Both periods present evidences of the transport of raw material from other zones into the area, including bifacial artifacts, which is consistent with human behavior during this time period.O objetivo deste trabalho é apresentar os novos resultados obtidos em torno das ocupações iniciais no sítio de La Gruta 1, região de La Gruta, extremo sul do Maciço de Deseado, Patagônia argentina. Referem-se tanto à transição Pleistoceno-Holoceno quanto ao Holoceno inicial e abrangem aspectos paleoambientais, novas datação radiocarbônicas, além da disponibilidade e uso de matérias-primas. Apresentam-se os resultados das novas análises de pólen, realizadas em um banhado da área localizado no planalto central, próximo à localidade arqueológica Viuda Quenzana, com idade basal de ca. 12.500 anos AP (14.500 cal AP). Por outro lado, a partir dos resultados obtidos infere-se uma vegetação similar à reconstruída por outros registros polínicos da área que sugerem condições úmidas durante o segundo período de ocupação humana do sítio arqueológico La Gruta 1, compreendido entre ca. 11.000 e 8000 cal AP As evidências procedentes da expansão das escavações neste sítio mostram a falta de continuidade entre as datações correspondentes à transição Pleistoceno-Holoceno e as do Holoceno inicial. Nos dois períodos há evidência de transporte de matérias-primas de outros espaços, que incluem artefatos bifaciais, o que é consistente com a informação obtida previamente.Facultad de Ciencias Naturales y Muse

End-of-life disposal concepts for Libration Point Orbit and Highly Elliptical Orbit missions

Libration Point Orbits (LPOs) and Highly Elliptical Orbits (HEOs) are often selected for astrophysics and solar terrestrial missions. No guidelines currently exist for their end-of-life disposal. However, as current and future missions are planned to be placed on these orbits, it is a critical aspect to clear these regions at the end of operations to avoid damage to other spacecraft and ensure on-ground safety. This paper presents an analysis of possible disposal strategies for LPO and HEO missions as a result of a European Space Agency study. The dynamical models and the design approach are presented for each disposal option. Five current missions are selected as test cases Herschel, Gaia, SOHO as LPOs, and INTEGRAL and XMM-Newton as HEOs. A trade-off on the disposal options is made considering technical feasibility, as well as the sustainability context

End-of-life disposal trajectories for libration point and highly elliptical orbit missions

Libration Point Orbits (LPOs) and Highly EllipticalOrbits (HEOs) are often selected for astrophysics and solar terrestrial missions as they offer vantage points for the observation of the Earth, the Sun and the Universe. Orbits around L1and L2 are relatively inexpensive to be reached from the Earth and ensure a nearly constant geometry for observation and telecoms, in addition to advantages for thermal system design. On the other hand, HEOs about the Earth guarantee long dwelling times at an altitude outside the Earth’s radiation belt; therefore, long periods of uninterrupted scientific observation are possible with nearly no background noise from radiations. No guidelines currently exist for LPO and HEO missions’ end-of-life; however, as current and future missions are planned to be placed on these orbits, it is a critical aspect to clear these regions at the end of operations. Orbits about the Libration point or Earth-centred orbits with very high apogee lie in a highly perturbed environment due to the chaotic behaviour of the multi-body dynamics1; moreover, due to their challenging mission requirements, they are characterised by large-size spacecraft. Therefore, the uncontrolled s/c on manifold trajectories could re-enter to Earth or cross the protected regions. Finally, the end-of-life phase can enhance the science return of the mission and the operational knowledge base. In this paper, a detailed analysis of possible disposal strategies for LPO and HEO missions is presented as a result of an ESA/GSP study. End-of-life disposal options are proposed, which exploit the multi-body dynamics in the Earth environment and in the Sun–Earth system perturbed by the effects of solar radiation, the Earth potential and atmospheric drag. The options analysed are Earth re-entry, or injection into a graveyard orbit for HEOs, while spacecraft on LPOs can be disposed through an Earth re-entry, or can be injected onto trajectories towards a Moon impact, or towards the inner or the outer solar system, by means of delta-v manoeuvres or the enhancement of solar radiation pressure with some deployable light reflective surfaces. On the base of the operational cost, complexity and demanding delta-v manoeuvres, some disposal options were preliminary analysed and later discarded such as the HEO disposal through transfer to a LPO or disposal through Moon capture 2. The paper presents the dynamical models considered for each disposal design: in the case of HEOs the long term variation of the orbit is propagated through semi-analytical techniques 2, considering the interaction of the luni/solar perturbations with the zonal harmonics of the Earth’s gravity field. In the case of LPOs the Circular Restricted Three Body Problem 4 (CR3BP) or the full-body dynamics is employed for the Earth re-entry option and the transfer towards the inner or the outer solar system, while the coupled restricted three-body problem 5 is used for the Moon disposal option. The approach to design the transfer trajectories is presented. In order to perform a parametric study, different starting dates and conditions for the disposal are considered, while the manoeuvre is optimised considering the constraints on the available fuel at the end-of-life. Five ESA missions are selected as scenarios: Herschel, GAIA, SOHO as LPOs, and INTEGRAL and XMM-Newton as HEOs. For each mission the disposal strategies are analysed, in terms of optimal window for the disposal manoeuvre, manoeuvre sequences, time of flight and disposal characteristics, such as re-entry conditions or the hyperbolic excess velocity at arrival in case of a Moon impact. In a second step, a high accuracy approach is used for validating the optimised trajectories. Finally, a trade-off is made considering technical feasibility (in terms of the available on-board resources and ∆vrequirements), as well as the sustainability context and the collision probability in the protected regions. General recommendations will be drawn in terms of system requirements and mission planning

Practical uncertainty quantification in orbital mechanics

The chapter provides an overview of methods to quantify uncertainty in orbital mechanics. It also provides an initial classification of these methods with particular attention to whether the quantification method requires a knowledge of the system model or not. For some methods the chapter provides applications examples and numerical comparisons on selected test cases

End-of-life disposal trajectories for libration point and highly elliptical orbit missions

In this paper a preliminary analysis of the possible disposal strategies for Lagrange Point Orbits (LPO) and Highly Elliptical Obits (HEO) is presented. Five ESA missions currently (or in the future) operating on LPO and HEO are selected, namely, Hershel, GAIA, SOHO as LPO, and Integral and XMM-Newton as HEO. LPO disposal options comprehend disposal through Earth re-entry, disposal towards the Moon, disposal towards the Sun or a planet; while for HEO disposal the proposed options are end-of-life disposal through Moon capture, disposal through Earth re-entry or graveyard orbit, or LPO targeting from HEO. For each strategy the design methodology is presented and results are shown in terms of Av requirements and disposal parameters. ©2013 by the International Astronautical Federation. All rights reserved