BETsMA v2.0: a friendly software for the analysis of electrodynamic tether missions in Jupiter

Proceeding of: Eruoplanet Science Congress 2020, EPSC2020 (vitual meeting), 21 September - 9 October 2020.Space Electrodynamic Tethers (EDTs) are km-long conductors that exchange momentum and energy with a planet magnetosphere through the Lorentz force exerted by the planet's magnetic field on the tether current. Since the conducting medium (plasma) and the magnetic field of the planetary environment are essential for their operation, tether are appropriate for applications in Low Earth Orbits (LEO) and the neighborhood of giant planets like Jupiter [1, 2, 3, 4], Saturn [5], and Neptune [6]. However, the design and analysis of missions in outer planets typically requires deep knowledge on tethers modeling. The main goal of this work is spreading the use of tethers and presenting a friendly software for the mission analysis and simulation of tethers in Jupiter.This work has received funding from the European Unions Horizon 2020 research and innovation programme under grant agreement No 828902 (E.T.PACK project). GSA work is supported by the Ministerio de Ciencia e Innovación of Spain under the Grant RYC-2014-15357.Publicad

Simulations without data updates using analytical attitude propagator GSAM for spin stabilized satellites

The objective of this work is to validate the GSAM propagator using new data provided by the National Institute for Space Research (INPE) from SCD1 and SCD2 data collection satellites, with emphasis on long interval simulations without daily data updates. Originally, only 40 days of data were available to test the program, constraining any attempts to measure its precision more accurately. Recently, over two decades of data regarding both satellites' orbital and attitude parameters were provided, allowing further studies and validation of the program. The rotational motion equations are composed by the gravity gradient torque, aerodynamic torque, solar radiation pressure torque, residual and eddy current magnetic torques, the latter using a dipole geomagnetic model. The results are considered fitting when the mean deviation between the calculated variables and the real satellite data stay within 0.5× for the right ascension and declination angles and 0.5 rpm for the spin velocity. Intervals that meet the required precision were found for all years, from three to up to 15 days of simulation without data update. The consistent detection of such intervals further corroborate the use of the propagator to estimate the orientation of the satellites studied in their missions.The authors thank CNPq (Universal Project 421672/2016-1) for supporting the project

A code for the analysis of missions with electrodynamic tethers

The main novelties and capabilities of the second version of the Bare Electrodynamic Tether Mission Analysis Software (BETsMA v2.0) are presented. Recent advances on Orbital-Motion-Theory have been incorporated to the electric model of Low-Work-function Tethers (LWTs). An electric model that considers a switch to embed a power supply or a resistor between a Bare Electrodynamic Tether (BET) and an electron emitter is also introduced. For both types of tethers (LWT and BET) and modes of operations (active and passive), robust and efficient numerical algorithms to compute the current and voltage profiles were constructed based on a change of variable proposed in a previous work. The capabilities of the code are illustrated by considering two relevant scenarios. For a BET in the passive mode, it was shown that onboard power can enhance tether performance and reduce significantly the deorbit time. For a BET in the active mode, a performance map varying the orbit inclination, the length of the insulated tether segment, and the power was constructed. For both cases, the code was used to investigate through simulations the conditions to keep constant the electric current at the electron emitter.This work was supported by the European Union’s Horizon 2020 Research and Innovation Programme under grant agreement No 828902 (E.T.PACK project)

(130) Elektra Delta -- on the stability of the new third moonlet

The aim of this work is to verify the stability of the proposed orbital solutions for the third moonlet (Delta) taking into account a realistic gravitational potential for the central body of the quadruple system (Alpha). We also aim to estimate the location and size of a stability region inside the orbit of Gamma. First, we created a set of test particles with intervals of semi-major axis, eccentricities, and inclinations that covers the region interior to the orbit of Gamma, including the proposed orbit of Delta and a wide region around it. We considered three different models for the gravitational potential of Alpha: irregular polyhedron, ellipsoidal body and oblate body. For a second scenario, Delta was considered a massive spherical body and Alpha an irregular polyhedron. Beta and Gamma were assumed as spherical massive bodies in both scenarios. The simulations showed that a large region of space is almost fully stable only when Alpha was modeled as simply as an oblate body. For the scenario with Delta as a massive body, the results did not change from those as massless particles. Beta and Gamma do not play any relevant role in the dynamics of particles interior to the orbit of Gamma. Delta's predicted orbital elements are fully unstable and far from the nearest stable region. The primary instability source is Alpha's elongated shape. Therefore, in the determination of the orbital elements of Delta, it must be taken into account the gravitational potential of Alpha assuming, at least, an ellipsoidal shape

2001 SN263-the contribution of their irregular shapes on the neighbourhood dynamics

The first proposed Brazilian mission to deep space, the ASTER mission, has the triple asteroid system (153591) 2001 SN263 as a target. One of the mission's main goals is to analyse the physical and dynamical structures of the system to understand its origin and evolution. This work aims to analyse how the asteroid's irregular shape interferes with the stability around the system. The results show that the irregular shape of the bodies plays an important role in the dynamics nearby the system. For instance, the perturbation due to the (153591) 2001 SN263 Alpha's shape affects the stability in the (153591) 2001 SN263 Gamma's vicinity. Similarly, the (153591) 2001 SN263 Beta's irregularity causes a significant instability in its nearby environment. As expected, the prograde case is the most unstable, while the retrograde scenario presents more stability. Additionally, we investigate how the solar radiation pressure perturbs particles of different sizes orbiting the triple system. We found that particles with a 10-50 cm radius could survive the radiation pressure for the retrograde case. Meanwhile, to resist solar radiation, the particles in prograde orbit must be larger than the particles in retrograde orbits, at least one order of magnitude.This study was financed in part by the Brazilian Federal Agency for Support and Evaluation of Graduate Education (CAPES), in the scope of the Program CAPES-PrInt, process number 88887.310463/2018-00, International Cooperation Project number 3266, Fundaçao de Amparo à Pesquisa do Estado de Sao Paulo (FAPESP) - Proc. 2016/24561-0 and Proc. 2019/23963-5, Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) - Proc. 305210/2018-1. RS acknowledges support by the DFG German Research Foundation (project 446102036). We also would like to thanks the referee, Alex B Davis, for a suggestion that impro v ed the paper

Deployment requirements for deorbiting electrodynamic tether technology

In the last decades, green deorbiting technologies have begun to be investigated and have raised a great interest in the space community. Among the others, electrodynamic tethers appear to be a promising option. By interacting with the surrounding ionosphere, electrodynamic tethers generate a drag Lorentz force to decrease the orbit altitude of the satellite, causing its re-entry in the atmosphere without using propellant. In this work, the requirements that drive the design of the deployment mechanism proposed for the H2020 Project E.T.PACK—Electrodynamic Tether Technology for Passive Consumable-less Deorbit Kit—are presented and discussed. Additionally, this work presents the synthesis of the reference profiles used by the motor of the deployer to make the tethered system reach the desired final conditions. The result is a strategy for deploying electrodynamic tape-shaped tethers used for deorbiting satellites at the end of their operational life.Open Access funding provided by Università degli Studi di Padova. This work was supported by European Union’s H2020 Research and Innovation Programme under Grant Agreement No. 828902 (E.T.PACK Project). Gonzalo Sánchez-Arriaga's work is supported by the Ministerio de Ciencia, Innovación y Universidades of Spain under the Grant RYC-2014-15357

Predição analítica do movimento rotacional de satélites estabilizados por rotação

Uma abordagem analítica para o movimento rotacional de satélites arti ciais estabilizados por rotação é apresentada, considerando os satélites em órbita elíptica de baixa excentricidade e a in uência conjunta do torque aerodinâmico, o torque de gradiente de gravidade, o torque magnético residual, o torque magnético devido às correntes de Foucault e o torque de pressão de radiação solar. Modelos matemáticos são apresentados para todos os torques e os componentes médios de cada torque são determinados para um período orbital. O torque médio já inclui os principais efeitos de cada torque sobre o movimento rotacional e são necessários nas equações do movimento. As equações do movimento são descritas em termos do módulo da velocidade ângular de rotação do satélite, da declinação e da ascensão reta do eixo de rotação do satélite. Uma solução analítica para as equações do movimento rotacional é determinada, considerando os valores dos torques externos médios em um período orbital, sendo válida para um período orbital. Por esta solução observa-se que o torque gradiente de gravidade e torque magnético devido às correntes de Foucault afetam o módulo da velocidade angular de rotação, contribuindo também para as variações temporais da ascensão reta e declinação do eixo de rotação, associadas com a precessão e deriva do eixo de rotação do satélite. O torque magnético residual, o torque aerodinâmico e o torque de pressão de radiação solar afetam apenas a ascensão reta e declinação do eixo de rotação, pois o componente que afeta a velocidade de rotação é nulo nestes torques. Aplicações são realizadas para os Satélites de Coleta de Dados Brasileiros SCD1 e SCD2, através de uma primeira abordagem com atualização diária dos dados de atitude e órbita e uma segunda abordagem...gradient torque, residual magnetic torque, magnetic torque due to the Foucault currents and solar radiation pressure torque on the rotational motion of spin-stabilized arti cial satellites. The mathematical model for these torques are determined for a cylindrical satellite, and their components are determined in a satellite xed system. Analytical solutions are gotten for the equation of motion and these solutions are numerically implemented and the results are compared with the actual data Satellites Brazilian Data Collection - SCD1 and SCD2, provided by INPE. This solution is valid for an orbital period. Through this solution, it is noticed that the gravity gradient torque and the magnetic torque due to the Foucault currents a ects the spin velocity and the spin axis. The temporal variations of right ascension and declination of the spin axis causes the precession and drift of the spin axis. The residual magnetic torque, the aerodynamic torque and the solar radiation pressure torque, does not a ect the spin velocity because the component that a ect the spin velocity is null in these torques. Applications are made for the Brazilian Data Collection Satellites SCD1 and SCD2, through a rst approach with daily updates of the attitude and orbit data, and a second approach without the daily update of these data. The results show a good agreement between the results obtained by theory and data supplied by the Satellite Control Center of INPE in the rst approach during 40 days. For the approach without updates, the results prove to be suitable only for 3 days of simulation. To validate the analytical solution, the pointing error (deviation from the rotational axis calculated by theory with the actual rotational axis) and the solar aspect angle are checked, being that the deviations obtained were within the required precisions for the missions of these satellites. The ... (Complete abstract click electronic access below

Satélites estabilizados por rotação e torque de radiação solar direta

The aims of this work are to analyze the direct solar radiation pressure torque (TPRS) in the rotational motion of spin-stabilized artificial satellites, to numerically implement these solutions and to compare the results with real data of the Brazilian Satellite Data Collection – SCD1 and SCD2, supplied by INPE. The mathematical model for this torque is determined for a cylindrical satellite, and the components of this torque are determined in a fixed system in the satellite. An analytical solution for the spin motion equations is proposed, in which TPRSD does not affect the spin velocity of the satellite. Two approaches are adopted in the numerical implementation of the developed theory: the first one considers the proposed theory and the second introduces a variation in the spin velocity based on its real variation. The results obtained indicate that the solar radiation pressure torque has little influence in the right ascension and declination axis of rotation due to the small dimension of the satellite and altitude in which it is found. To better validate the application of the presented theory, the angular deviation of the spin axis and solar aspect angle were also analyzed. The comparison of the results of the approaches conducted with real data show good precision in the theory, which can be applied in the prediction of the rotational motion of the spin-stabilized artificial satellites, when others external torques are considered besides the direct solar radiation pressure torqueEste trabalho tem por objetivo analisar a influência do torque de pressão de radiação solar direta (TPRS) no movimento rotacional de satélites artificiais estabilizados por rotação, implementar numericamente estas soluções e comparar os resultados com os dados reais dos Satélites Brasileiros de Coleta de Dados – SCD1 e SCD2, fornecidos pelo INPE. Um modelo matemático para o torque de pressão de radiação solar direta é apresentado, seus componentes determinados em um sistema fixo no satélite e uma solução analítica para as equações do movimento rotacional é proposta. É usada a solução do torque de radiação solar direta para um satélite cilíndrico. São utilizadas duas formas de abordagens, a primeira simplesmente leva em conta a teoria proposta e a segunda introduz uma função baseada na variação da velocidade de rotação real para acompanhar a implementação, visto que o torque de pressão de radiação solar direta não tem componente que atua na velocidade de rotação. Os resultados de ambas as abordagens apontam que este torque tem pouca influência na ascensão reta e declinação do eixo de rotação, devido a pequena magnitude deste torque para o satélite com as características do SCD1 e SCD2. Para melhor validar a aplicação do modelo aqui desenvolvido, são também analisados o desvio angular do eixo de rotação e o ângulo de aspecto solar. As comparações dos resultados das abordagens realizadas com os dados reais acenam para uma coerência na teoria, podendo ser aplicada na predição do movimento rotacional de satélites artificiais estabilizados por rotação munido de outros torques externos além do torque de pressão de radiação solar diret

2001 SN263 -- the contribution of their irregular shapes on the neighborhood dynamics

The first proposed Brazilian mission to deep space, the ASTER mission, has the triple asteroid system (153591) 2001 SN263 as a target. One of the mission's main goals is to analyze the physical and dynamical structures of the system to understand its origin and evolution. The present work aims to analyze how the asteroid's irregular shape interferes with the stability around the system. The results show that the irregular shape of the bodies plays an important role in the dynamics nearby the system. For instance, the perturbation due to the (153591) 2001 SN263 Alpha's shape affects the stability in the (153591) 2001 SN263 Gamma's vicinity. Similarly, the (153591) 2001 SN263 Beta's irregularity causes a significant instability in its nearby environment. As expected, the prograde case is the most unstable, while the retrograde scenario presents more stability. Additionally, we investigate how the solar radiation pressure perturbs particles of different sizes orbiting the triple system. We found that particles with a 10-50 cm radius could survive the radiation pressure for the retrograde case. Meanwhile, to resist solar radiation, the particles in prograde orbit must be larger than the particles in retrograde orbits, at least one order of magnitude.Comment: 12 pages, 13 figure