The Experts below are selected from a list of 90 Experts worldwide ranked by ideXlab platform
Martin Lara - One of the best experts on this subject based on the ideXlab platform.
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Repeat Ground Track Lunar Orbits in the Full-Potential Plus Third-Body Problem
2016Co-Authors: Ryan P Russell, Martin LaraAbstract:A high degree and order Lunar Gravitational Field is superimposed on the Earth-Moon Restricted Three Body model to capture the dominating forces on a spacecraft in the vicinity of the Moon. For the synchronously rotating Moon, periodic orbits in this un-averaged model map repeat ground tracks and represent higher order solutions to the frozen orbit problem. The stable or near-stable solutions are found over a wide range of defining characteristics making them suitable for long-lifetime parking applications such as science orbits, crew exploration vehicle parking orbits, and global coverage constellation orbits. A full ephemeris is considered for selected orbits to evaluate the validity of the time-invariant, simplified model. Of the most promising results are the low-altitude families of near-circular, inclined orbits that maintain long-term stability despite the highly non-spherical Lunar gravity. The method is systematic and enables rapid design and analysis of long-life orbits around any tidally-locked celestial body with an arbitrarily high degree and order spherical harmonic gravity Field
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long lifetime Lunar repeat ground track orbits
Journal of Guidance Control and Dynamics, 2007Co-Authors: Ryan P Russell, Martin LaraAbstract:A high degree and order Lunar Gravitational Field is superimposed on the Earth-moon restricted three-body model to capture the dominating forces on a spacecraft in the vicinity of the moon. For the synchronously rotating moon, periodic orbits in this unaveraged model map repeat ground tracks and represent higher-order solutions to the frozen orbit problem. The stable or near-stable solutions are found over a wide range of defining characteristics, making them suitable for long-lifetime parking applications such as science orbits, crew exploration vehicle parking orbits, and global coverage constellation orbits. A full ephemeris is considered for selected orbits to evaluate the validity of the time-invariant, simplified model. Of the most promising results are the low-altitude families of near-circular, inclined orbits that maintain long-term stability despite the highly nonspherical Lunar gravity. The method is systematic and enables rapid design and analysis of long-life orbits around any tidally locked celestial body with an arbitrarily high degree and order spherical harmonic gravity Field.
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repeat ground track Lunar orbits in the full potential plus third body problem
AIAA AAS Astrodynamics Specialist Conference and Exhibit, 2006Co-Authors: Ryan P Russell, Martin LaraAbstract:A high degree and order Lunar Gravitational Field is superimposed on the Earth-Moon Restricted Three Body model to capture the dominating forces on a spacecraft in the vicinity of the Moon. For the synchronously rotating Moon, periodic orbits in this model map repeat ground tracks and represent higher order solutions to the frozen orbit problem. The near-circular, stable or near-stable solutions are found over a wide range of defining characteristics making them suitable for long-lifetime parking applications such as science orbits, crew exploration vehicle parking orbits, and global coverage constellation orbits. A full ephemeris is considered for selected orbits to evaluate the validity of the time-invariant, simplified model. Of the most promising results are the low-altitude families of near-circular, inclined orbits that maintain long-term stability despite the highly non-spherical Lunar gravity. The method is systematic and enables rapid design and analysis of long-life orbits around any tidally-locked celestial body with an arbitrarily high degree and order spherical harmonic gravity Field. .
Ryan P Russell - One of the best experts on this subject based on the ideXlab platform.
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Repeat Ground Track Lunar Orbits in the Full-Potential Plus Third-Body Problem
2016Co-Authors: Ryan P Russell, Martin LaraAbstract:A high degree and order Lunar Gravitational Field is superimposed on the Earth-Moon Restricted Three Body model to capture the dominating forces on a spacecraft in the vicinity of the Moon. For the synchronously rotating Moon, periodic orbits in this un-averaged model map repeat ground tracks and represent higher order solutions to the frozen orbit problem. The stable or near-stable solutions are found over a wide range of defining characteristics making them suitable for long-lifetime parking applications such as science orbits, crew exploration vehicle parking orbits, and global coverage constellation orbits. A full ephemeris is considered for selected orbits to evaluate the validity of the time-invariant, simplified model. Of the most promising results are the low-altitude families of near-circular, inclined orbits that maintain long-term stability despite the highly non-spherical Lunar gravity. The method is systematic and enables rapid design and analysis of long-life orbits around any tidally-locked celestial body with an arbitrarily high degree and order spherical harmonic gravity Field
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long lifetime Lunar repeat ground track orbits
Journal of Guidance Control and Dynamics, 2007Co-Authors: Ryan P Russell, Martin LaraAbstract:A high degree and order Lunar Gravitational Field is superimposed on the Earth-moon restricted three-body model to capture the dominating forces on a spacecraft in the vicinity of the moon. For the synchronously rotating moon, periodic orbits in this unaveraged model map repeat ground tracks and represent higher-order solutions to the frozen orbit problem. The stable or near-stable solutions are found over a wide range of defining characteristics, making them suitable for long-lifetime parking applications such as science orbits, crew exploration vehicle parking orbits, and global coverage constellation orbits. A full ephemeris is considered for selected orbits to evaluate the validity of the time-invariant, simplified model. Of the most promising results are the low-altitude families of near-circular, inclined orbits that maintain long-term stability despite the highly nonspherical Lunar gravity. The method is systematic and enables rapid design and analysis of long-life orbits around any tidally locked celestial body with an arbitrarily high degree and order spherical harmonic gravity Field.
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repeat ground track Lunar orbits in the full potential plus third body problem
AIAA AAS Astrodynamics Specialist Conference and Exhibit, 2006Co-Authors: Ryan P Russell, Martin LaraAbstract:A high degree and order Lunar Gravitational Field is superimposed on the Earth-Moon Restricted Three Body model to capture the dominating forces on a spacecraft in the vicinity of the Moon. For the synchronously rotating Moon, periodic orbits in this model map repeat ground tracks and represent higher order solutions to the frozen orbit problem. The near-circular, stable or near-stable solutions are found over a wide range of defining characteristics making them suitable for long-lifetime parking applications such as science orbits, crew exploration vehicle parking orbits, and global coverage constellation orbits. A full ephemeris is considered for selected orbits to evaluate the validity of the time-invariant, simplified model. Of the most promising results are the low-altitude families of near-circular, inclined orbits that maintain long-term stability despite the highly non-spherical Lunar gravity. The method is systematic and enables rapid design and analysis of long-life orbits around any tidally-locked celestial body with an arbitrarily high degree and order spherical harmonic gravity Field. .
Meijuan Yun - One of the best experts on this subject based on the ideXlab platform.
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Sensitivity Analysis for Key Payloads and Orbital Parameters from the Next-Generation Moon-Gradiometer Satellite Gravity Program
Surveys in Geophysics, 2014Co-Authors: Wei Zheng, Houtse Hsu, Min Zhong, Meijuan YunAbstract:This research principally focuses on the requirements analysis in terms of the next-generation Moon-Gradiometer satellite gravity program. Firstly, the new single and combined analytical error models applied to estimate the accuracy of the Lunar Gravitational Field (e.g., geopotential coefficients, cumulative geoid height and cumulative gravity anomaly) influenced by the main error sources consisting of the satellite gravity gradient and satellite orbital position are created for the next-generation Moon-Gradiometer program. Secondly, the dependability of the new single and combined analytical error models is validated by the conformity of the cumulative Lunar geoid height errors between the gravity gradient and orbital position. Finally, taking the current GRAIL (Gravity Recovery and Interior Laboratory) satellite gravity mission for reference, the sensitivity analysis for the next-generation Moon-Gradiometer gravity satellite system is comprehensively carried out. We propose to equip this with the new-type pivotal payloads of the Lunar spacecraft comprising the electrostatic suspension gravity gradiometer and the drag-free control system and bring forward the matching measurement precision of the space-borne instruments (involving 3 × 10−12/s2 in the gravity gradient and 60 m in the orbital position) and the preferred orbital parameters (including an orbital altitude of 25 km, an observation period of 28 days and a sampling interval of 1 s) in the next-generation Moon-Gradiometer program.
Christian May - One of the best experts on this subject based on the ideXlab platform.
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Thermal Design and Test of the Gravity Recovery and Interior Laboratory (GRAIL) Ka-Band Ranging (KBR) Payload
41st International Conference on Environmental Systems, 2011Co-Authors: Charles Phillips, Michael Etters, Amy Smith, Christian MayAbstract:The Gravity Recovery and Interior Laboratory (GRAIL) mission is a part of the NASA Discovery Program and is managed by California Institute of Technology’s Jet Propulsion Laboratory. Scheduled to launch aboard a Delta-2 l aunch vehicle on September 8th, 2011, GRAIL will map the Lunar Gravitational Field in unprecedented detail for 90 days. Gathered measurements will allow scientists to better unders tand the evolution of our Moon as well as the composition of the Lunar core. GRAIL will accomplish these science objectives by accurately measuring the distance between two co-orbiting spacecraft spaced by approximately 100km. The GRAIL mission primary payload accomplishes this by means of a Ka-Band Ranging (KBR) RF Horn. Measurement time between the two orbiters is synchronized using an S-Band link. Doppler ranging of the two orbiters from Earth also places both orbiters within the same reference frame. Changes in the local Gravitational Field will yield a change in the distance between t he two orbiters. By accurately recording this change in distance, a detailed Gravitational m ap can be resolved. Given the sensitivity of these measurements, GRAIL’s science quality depends on minimizing thermal, structural, and mass perturbations as well as being able to qua ntify other “small forces” such as the reradiation of thermal energy and the out-gassing of materials. Reducing these perturbations is particularly challenging for Lunar spacecraft due to intense changes in IR-heating into and out of eclipse. This manuscript describes the luna r environmental assumption, KBR thermal design, analysis, and test program used to successfully meet these science requirements using only passive thermal control. A “small forces” analysis was also performed to better understand how the re-radiation of thermal energy from spacecraft external surfaces would affect the quality science measurement.
Wei Zheng - One of the best experts on this subject based on the ideXlab platform.
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Sensitivity Analysis for Key Payloads and Orbital Parameters from the Next-Generation Moon-Gradiometer Satellite Gravity Program
Surveys in Geophysics, 2014Co-Authors: Wei Zheng, Houtse Hsu, Min Zhong, Meijuan YunAbstract:This research principally focuses on the requirements analysis in terms of the next-generation Moon-Gradiometer satellite gravity program. Firstly, the new single and combined analytical error models applied to estimate the accuracy of the Lunar Gravitational Field (e.g., geopotential coefficients, cumulative geoid height and cumulative gravity anomaly) influenced by the main error sources consisting of the satellite gravity gradient and satellite orbital position are created for the next-generation Moon-Gradiometer program. Secondly, the dependability of the new single and combined analytical error models is validated by the conformity of the cumulative Lunar geoid height errors between the gravity gradient and orbital position. Finally, taking the current GRAIL (Gravity Recovery and Interior Laboratory) satellite gravity mission for reference, the sensitivity analysis for the next-generation Moon-Gradiometer gravity satellite system is comprehensively carried out. We propose to equip this with the new-type pivotal payloads of the Lunar spacecraft comprising the electrostatic suspension gravity gradiometer and the drag-free control system and bring forward the matching measurement precision of the space-borne instruments (involving 3 × 10−12/s2 in the gravity gradient and 60 m in the orbital position) and the preferred orbital parameters (including an orbital altitude of 25 km, an observation period of 28 days and a sampling interval of 1 s) in the next-generation Moon-Gradiometer program.
