E. Turan
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14 records found
1
Autonomous Navigation for Satellite Formations
Advancing Missions Beyond Earth with Inter-satellite Radio Tracking
In this context, various autonomous navigation strategies exist, and one of them stands out as a promising approach: Crosslink navigation, using existing systems to provide navigation solutions based on inter-satellite measurements, which primarily offers relative navigation solutions but can also facilitate absolute navigation solutions when integrated with ground-based tracking. However, absolute state knowledge, crucial for tasks such as station-keeping, often relies on ground-based commands, limiting autonomy. Alternatively, Satellite-to-Satellite Tracking (SST) data can be used for absolute state estimation, where an on-board navigation filter estimates spacecraft position and velocity, i.e. with respect to a fixed reference frame. Previous studies have shown that depending on the orbital dynamics, SST-data can provide absolute state estimation. However, this is not always straightforward, especially when inter-satellite measurements are not accurate or the observation geometry is not optimal. Since inter-satellite measurements cannot always be collected due to operational constraints, careful planning of optimal tracking windows is required. This planning can be challenging when considering possibly conflicting operational needs, such as commanding. Moreover, since radio frequency measurement techniques are used to derive navigation data, system performances must be investigated, considering varying systematic and random errors. It remained a significant challenge to determine which types of navigation data—range, range-rate, or angle—yield the most effective navigation solutions across different deep space scenarios. Since real-time navigation solutions may be needed, designing a robust on-board estimation filter can be challenging, including decisions on which parameters to be estimated or neglected.
Given these complexities, this research investigated SST-based autonomous orbit determination for satellite formations, consisting of small spacecraft, aiming to enhance current methodologies and explore new capabilities in both cislunar and deep space environments. ...
In this context, various autonomous navigation strategies exist, and one of them stands out as a promising approach: Crosslink navigation, using existing systems to provide navigation solutions based on inter-satellite measurements, which primarily offers relative navigation solutions but can also facilitate absolute navigation solutions when integrated with ground-based tracking. However, absolute state knowledge, crucial for tasks such as station-keeping, often relies on ground-based commands, limiting autonomy. Alternatively, Satellite-to-Satellite Tracking (SST) data can be used for absolute state estimation, where an on-board navigation filter estimates spacecraft position and velocity, i.e. with respect to a fixed reference frame. Previous studies have shown that depending on the orbital dynamics, SST-data can provide absolute state estimation. However, this is not always straightforward, especially when inter-satellite measurements are not accurate or the observation geometry is not optimal. Since inter-satellite measurements cannot always be collected due to operational constraints, careful planning of optimal tracking windows is required. This planning can be challenging when considering possibly conflicting operational needs, such as commanding. Moreover, since radio frequency measurement techniques are used to derive navigation data, system performances must be investigated, considering varying systematic and random errors. It remained a significant challenge to determine which types of navigation data—range, range-rate, or angle—yield the most effective navigation solutions across different deep space scenarios. Since real-time navigation solutions may be needed, designing a robust on-board estimation filter can be challenging, including decisions on which parameters to be estimated or neglected.
Given these complexities, this research investigated SST-based autonomous orbit determination for satellite formations, consisting of small spacecraft, aiming to enhance current methodologies and explore new capabilities in both cislunar and deep space environments.
This manuscript aims to present and evaluate the applicability of combining optical line-of-sight (LoS) navigation with crosslink radiometric navigation for deep-space cruising distributed space systems. To do so, a set of four distributed space systems architectures is presented, and for each of those, the applicability of the combination is evaluated, comparing it to the baseline solutions, which are based on only optical navigation. The comparison is done by studying the performance in a circular heliocentric orbit in seven different time intervals (ranging from 2024 to 2032) and exploiting the observation of all the pairs of planets from Mercury to Saturn. The distance between spacecraft is kept around 200 km. Later, a NEA mission test case is generated in order to explore the applicability to a more realistic case. This analysis shows that the technique can also cope with a variable inter-satellite distance, and the best performance is obtained when the spacecraft get closer to each other.
LUMIO
A CubeSat for observing and characterizing micro-meteoroid impacts on the Lunar far side
The Earth-Moon system is constantly bombarded by meteoroids of different size and impact speed. Observation of the impacts on the Moon can enable thorough characterization of the Lunar meteoroid flux, which is similar to that of the Earth. While Earth-based Lunar observations are restricted by weather, geometric and illumination conditions, a Lunar-based observation campaign can improve the detection rate and, when observing the Lunar far side, complement in both space and time the observations taken from Earth. The Lunar Meteoroid Impact Observer (LUMIO), one of the two winning concepts of the ESA SysNova Lunar CubeSats for Exploration challenge, is a mission designed to observe, quantify, and characterize the micro-meteoroid impacts on the Lunar far side. It is based on a 12U CubeSat that carries the LUMIO-Cam, a custom-designed optical instrument capable of detecting light flashes in the visible spectrum. The spacecraft is placed on a halo orbit about the Earth–Moon L2 point, where permanent full-disk observation of the Lunar far side can be performed with excellent quality, given the absence of Earth background noise. After passing Phase 0 and an independent feasibility study in the ESA Concurrent Design Facility, the mission has successfully completed its Phase A in March 2021. Although the Phase 0 design of the LUMIO spacecraft was assessed as feasible by the ESA CDF study, a number of critical issues were identified, which have been tackled by the Phase A design. The paper presents the outcome of this Phase A design effort for the LUMIO spacecraft. Particularly relevant changes or updates in the spacecraft design include: a consolidated design of the LUMIO-Cam, with longer baffle for straylight protection; a set of ADCS sensors and actuators with increased redundancy; a combination of Direct-to-Earth communication and inter-satellite link with a mothership in Lunar orbit; use of Earth ranging to complement and validate the current innovative autonomous navigation strategy based on optical observations of the Moon by means of the LUMIO-Cam; re-assessment of the COTS components selection for the power and propulsion systems.
The Lunar Meteoroid Impacts Observer (LUMIO) is a CubeSat mission to observe, quantify, and characterize the meteoroid impacts on the lunar farside by detecting their flashes. This complements the knowledge gathered by Earth-based observations of the lunar nearside, thus synthesizing global information on the lunar meteoroid environment and contributing to the lunar situational awareness. The goal of LUMIO is to advance our current knowledge of meteoroid models in the solar system. In this work, we present the methodology devised to predict the scientific contribution of LUMIO. Our approach relies on combined modeling and simulation of payload, orbit, and environment. The analyses carried out have been used to drive the design of the LUMIO mission and its payload, the LUMIO-Cam. A payload radiometric model is derived and exploited to assess the quality of the scientific measurements. A dedicated study about straylight rejection is carried out to assess how straylight noise affects LUMIO-Cam measurements. Our results indicate that a 150 mm baffle grants good performance when the Sun angle is between 20° and 90°. Furthermore, the present-day LUMIO mission has the potential to detect more than 6000 impact flashes during the activity peak of the Geminids in 2024 in the range of the equivalent impact kinetic energy at Earth of [10 −6,10 −1]kton TNT Equivalent. Compared to previous programmes, LUMIO could refine information and fill the knowledge gap about the meteoroid population in the ranges of the equivalent impact kinetic energy at Earth of [10 −6,10 −4]kton TNT Equivalent and [10 −4,10 −1]kton TNT Equivalent, respectively.
Autonomous navigation for deep space small satellites
Scientific and technological advances
In recent years, there is a growing interest in small satellites for deep space exploration. The current approach for planetary navigation is based on ground-based radiometric tracking. A new era of low-cost small satellites for space exploration will require autonomous deep space navigation. This will decrease the reliance on ground-based tracking and provide a substantial reduction in operational costs because of crowded communication networks. In addition, it will be an enabler for future missions currently impossible. This review investigates available deep space navigation methods from an autonomy perspective, considering trends in proposed deep space small satellite missions. Autonomous crosslink radiometric navigation, which is one of the best methods for small satellites due to its simplicity and the use of existing technologies, is studied, including available measurement methods, enabling technologies, and applicability to the currently proposed missions. The main objective of this study is to fill the gap in the scientific literature on the autonomous deep space navigation methods, deeply for crosslink radiometric navigation and to aim at showing the potential advantages that this technique could offer to the missions being analyzed. In this study, a total of 64 proposed deep space small satellite missions have been analyzed found from a variety of sources including journal papers, conference proceedings, and mission websites. In those missions, the most popular destinations are found to be cislunar space and small bodies with the purpose of surface mapping and characterization. Even though various autonomous navigation methods have been proposed for those missions, most of them have planned to use the traditional ground-based radiometric tracking for navigation purposes. This study also shows that more than half of the missions can benefit from the crosslink radiometric navigation through the inter-satellite link.
Recent advances in space technology provide an opportunity for small satellites to be launched in cislunar space. However, tracking these small satellites still depends on ground-based operations. Autonomous navigation could be a possible solution considering the challenges presented by costly ground operations and limited onboard power available for small satellites. There have been various studies on autonomous navigation methods for cislunar missions. One of them, LiAISON, provides an autonomous orbit determination solution solely using inter-satellite measurements. This study aims at providing a detailed performance analysis of crosslink radiometric measurements based on autonomous orbit determination for cislunar small satellite formations considering the effects of measurement type, measurement accuracy, bias, formation geometry, and network topology. This study shows that range observations provide better state estimation performance than range-rate observations for the autonomous navigation system in cislunar space. Line-of-sight angle measurements derived from radiometric measurements do not improve the overall system performance. In addition, less precise crosslink measurement methods could be an option for formations in highly observable orbital configurations. It was found that measurement biases and measurements with high intervals reduce the overall system performance. In case there are more than two spacecraft in the formation, the navigation system in the mesh topology provides a better overall state estimation than the centralized topology.
Designing the Radio Link for a Lunar CubeSat
The LUMIO Case