Pub Date : 2017-03-04DOI: 10.1109/AERO.2017.7943574
Dayton L. Jones, J. Romney, V. Dhawan, W. Folkner, R. Jacobson, C. Jacobs, E. Fomalont
The Cassini spacecraft has been in orbit about Saturn since 2004. During this time, regular astrometric measurements of Cassini's sky position have been made with the Very Long Baseline Array (VLBA). These are high precision differential measurements that determine the position of Cassini with respect to angularly nearby extragalactic radio sources. Differential, narrow-angle astrometry reduces many error sources, particularly those associated with signal propagation effects in the ionosphere and troposphere. The background radio sources positions are tied to the inertial International Celestial Reference Frame (ICRF) by other international VLBI observations. Thus, we obtain a series of ICRF positions for Cassini, which can be combined with spacecraft orbit solutions from Deep Space Network Doppler tracking to get ICRF positions for the center of mass of the Saturn system. These positions have typical accuracies at the nano-radian level. For some epochs uncertainties in the background source positions are a major component of the total error, but these positions are being constantly improved as additional VLBI observations are incorporated into radio source catalogs. The planetary ephemeris group at the Jet Propulsion Laboratory uses our position measurements to fit improved orbital solutions for Saturn. As a result the orientation of the plane of Saturn's orbit is now known to approximately 0.25 milli-arcseconds (1.25 nrad), nearly an order of magnitude improvement over its pre-VLBA uncertainty. We will continue this observing program until the end of the Cassini mission in late 2017. By that time we will have covered about 1/3 of Saturn's orbital longitude range. Future improvements to this technique will include the use of higher spacecraft downlink frequencies (Ka band instead of X band) and higher ground array sensitivity to permit the use of weaker but angularly closer reference sources. In addition, the continuing international campaigns to enhance the accuracy of radio source catalogs will be extended to weaker sources, improving their ties to the ICRF.
{"title":"A decade of astrometric observations of Cassini: Past results and future prospects","authors":"Dayton L. Jones, J. Romney, V. Dhawan, W. Folkner, R. Jacobson, C. Jacobs, E. Fomalont","doi":"10.1109/AERO.2017.7943574","DOIUrl":"https://doi.org/10.1109/AERO.2017.7943574","url":null,"abstract":"The Cassini spacecraft has been in orbit about Saturn since 2004. During this time, regular astrometric measurements of Cassini's sky position have been made with the Very Long Baseline Array (VLBA). These are high precision differential measurements that determine the position of Cassini with respect to angularly nearby extragalactic radio sources. Differential, narrow-angle astrometry reduces many error sources, particularly those associated with signal propagation effects in the ionosphere and troposphere. The background radio sources positions are tied to the inertial International Celestial Reference Frame (ICRF) by other international VLBI observations. Thus, we obtain a series of ICRF positions for Cassini, which can be combined with spacecraft orbit solutions from Deep Space Network Doppler tracking to get ICRF positions for the center of mass of the Saturn system. These positions have typical accuracies at the nano-radian level. For some epochs uncertainties in the background source positions are a major component of the total error, but these positions are being constantly improved as additional VLBI observations are incorporated into radio source catalogs. The planetary ephemeris group at the Jet Propulsion Laboratory uses our position measurements to fit improved orbital solutions for Saturn. As a result the orientation of the plane of Saturn's orbit is now known to approximately 0.25 milli-arcseconds (1.25 nrad), nearly an order of magnitude improvement over its pre-VLBA uncertainty. We will continue this observing program until the end of the Cassini mission in late 2017. By that time we will have covered about 1/3 of Saturn's orbital longitude range. Future improvements to this technique will include the use of higher spacecraft downlink frequencies (Ka band instead of X band) and higher ground array sensitivity to permit the use of weaker but angularly closer reference sources. In addition, the continuing international campaigns to enhance the accuracy of radio source catalogs will be extended to weaker sources, improving their ties to the ICRF.","PeriodicalId":224475,"journal":{"name":"2017 IEEE Aerospace Conference","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129839125","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-04DOI: 10.1109/AERO.2017.7943819
D. Israel, B. Edwards, J. Staren
This paper provides a concept for an evolution of NASA's optical communications near Earth relay architecture. NASA's Laser Communications Relay Demonstration (LCRD), a joint project between NASA's Goddard Space Flight Center (GSFC), the Jet Propulsion Laboratory — California Institute of Technology (JPL), and the Massachusetts Institute of Technology Lincoln Laboratory (MIT LL). LCRD will provide a minimum of two years of high data rate optical communications service experiments in geosynchronous orbit (GEO), following launch in 2019. This paper will provide an update of the LCRD mission status and planned capabilities and experiments, followed by a discussion of the path from LCRD to operational network capabilities.
{"title":"Laser Communications Relay Demonstration (LCRD) update and the path towards optical relay operations","authors":"D. Israel, B. Edwards, J. Staren","doi":"10.1109/AERO.2017.7943819","DOIUrl":"https://doi.org/10.1109/AERO.2017.7943819","url":null,"abstract":"This paper provides a concept for an evolution of NASA's optical communications near Earth relay architecture. NASA's Laser Communications Relay Demonstration (LCRD), a joint project between NASA's Goddard Space Flight Center (GSFC), the Jet Propulsion Laboratory — California Institute of Technology (JPL), and the Massachusetts Institute of Technology Lincoln Laboratory (MIT LL). LCRD will provide a minimum of two years of high data rate optical communications service experiments in geosynchronous orbit (GEO), following launch in 2019. This paper will provide an update of the LCRD mission status and planned capabilities and experiments, followed by a discussion of the path from LCRD to operational network capabilities.","PeriodicalId":224475,"journal":{"name":"2017 IEEE Aerospace Conference","volume":"132 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126135428","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-04DOI: 10.1109/AERO.2017.7943623
Ilana Gat, T. Talon
Deep-space travel is limited by the costly voyage to leave Earth's atmosphere and gravitational pull. The volume of propellants per unit mass of the payload required for that segment constrains the payload size and payload destination. To circumvent that limitation, this paper presents the feasibility of a refueling station using Lunar resources, called Lunarport. On Earth's moon, an unmanned station will robotically mine, produce, and store fuel and oxidizer from water ice at the poles. A first-stage-like rocket, called the Lunar Resupply Shuttle (LRS), stationed there and propelled with mined resources, will launch and dock with a passing payload-carrying rocket. That rocket will be reloaded with propellants by the LRS, after which the LRS will detach and the payload-carrying rocket will continue its journey to its desired trajectory. The LRS will wait in Lower Lunar Orbit (LLO, to avoid deterioration from Lunar regolith) until another payload-carrying rocket is launched from Earth, after which, the LRS will land back on the Moon, reload propellants, and launch again to dock with the next rocket. This paper elaborates on Lunarport, presenting proof-of-concept calculations of the increase in payload size sent to various payload destinations as well as a cost-benefit analysis. By way of example, NASA's Space Launch System (SLS) en-route to Mars that refuels at Lunarport can have a payload approximately 17 metric tons (mT) heavier than one traveling straight to Mars from Earth. This increase of more than 50% [1] is just to a relatively nearby planet — Mars. Sending a payload farther offers larger benefits with Lunarport. Wear-and-tear issues the port will be subjected to are also discussed. A full analysis of Lunarport will be done during the 2017 Caltech Space Challenge sponsored by Airbus Defence and Space held from March 26–31, 2017.
{"title":"Lunarport: A proposed Lunar-resource station to expand deep-space travel horizons","authors":"Ilana Gat, T. Talon","doi":"10.1109/AERO.2017.7943623","DOIUrl":"https://doi.org/10.1109/AERO.2017.7943623","url":null,"abstract":"Deep-space travel is limited by the costly voyage to leave Earth's atmosphere and gravitational pull. The volume of propellants per unit mass of the payload required for that segment constrains the payload size and payload destination. To circumvent that limitation, this paper presents the feasibility of a refueling station using Lunar resources, called Lunarport. On Earth's moon, an unmanned station will robotically mine, produce, and store fuel and oxidizer from water ice at the poles. A first-stage-like rocket, called the Lunar Resupply Shuttle (LRS), stationed there and propelled with mined resources, will launch and dock with a passing payload-carrying rocket. That rocket will be reloaded with propellants by the LRS, after which the LRS will detach and the payload-carrying rocket will continue its journey to its desired trajectory. The LRS will wait in Lower Lunar Orbit (LLO, to avoid deterioration from Lunar regolith) until another payload-carrying rocket is launched from Earth, after which, the LRS will land back on the Moon, reload propellants, and launch again to dock with the next rocket. This paper elaborates on Lunarport, presenting proof-of-concept calculations of the increase in payload size sent to various payload destinations as well as a cost-benefit analysis. By way of example, NASA's Space Launch System (SLS) en-route to Mars that refuels at Lunarport can have a payload approximately 17 metric tons (mT) heavier than one traveling straight to Mars from Earth. This increase of more than 50% [1] is just to a relatively nearby planet — Mars. Sending a payload farther offers larger benefits with Lunarport. Wear-and-tear issues the port will be subjected to are also discussed. A full analysis of Lunarport will be done during the 2017 Caltech Space Challenge sponsored by Airbus Defence and Space held from March 26–31, 2017.","PeriodicalId":224475,"journal":{"name":"2017 IEEE Aerospace Conference","volume":"116 10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130067534","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-04DOI: 10.1109/AERO.2017.7943794
P. Nolan, D. Paley, Kenneth Kroeger
This paper presents an augmented path-planning technique for unmanned aerial systems to generate focused trajectories about one or more areas of interest for non-uniform sensor data collection. The technique described in this paper uses a coordinate transformation that augments the work space with a temporary, virtual space in which existing path-planning and control algorithms can be used to provide uniform coverage. Transforming back to the original work space forces the planned trajectories to focus on regions of interest. We illustrate the application to precision farming, where regions of interest in a crop field correspond to stressed crop health. When collecting aerial survey data, we seek to have a higher density of sensor data in areas of interest (e.g., RGB images, multispectral images, etc.). The technique presented in this paper offers a method for concentrating sensor measurements around these regions of stressed crop health for one or more vehicles. In agricultural domains with multiple regions of interest, a Voronoi partitioning algorithm partitions the operating area into individual regions in which the augmented path-planning technique is applied. The path-planning in each region takes into account the resources available — i.e., vehicles with larger sensor footprints are assigned to larger regions and execute trajectories that are more broadly spread as compared to vehicles with smaller sensor footprints. Theoretical results are applied to commercial off-the-shelf unmanned systems, both in simulation and in a fully realized precision agriculture demonstration field experiment.
{"title":"Multi-UAS path planning for non-uniform data collection in precision agriculture","authors":"P. Nolan, D. Paley, Kenneth Kroeger","doi":"10.1109/AERO.2017.7943794","DOIUrl":"https://doi.org/10.1109/AERO.2017.7943794","url":null,"abstract":"This paper presents an augmented path-planning technique for unmanned aerial systems to generate focused trajectories about one or more areas of interest for non-uniform sensor data collection. The technique described in this paper uses a coordinate transformation that augments the work space with a temporary, virtual space in which existing path-planning and control algorithms can be used to provide uniform coverage. Transforming back to the original work space forces the planned trajectories to focus on regions of interest. We illustrate the application to precision farming, where regions of interest in a crop field correspond to stressed crop health. When collecting aerial survey data, we seek to have a higher density of sensor data in areas of interest (e.g., RGB images, multispectral images, etc.). The technique presented in this paper offers a method for concentrating sensor measurements around these regions of stressed crop health for one or more vehicles. In agricultural domains with multiple regions of interest, a Voronoi partitioning algorithm partitions the operating area into individual regions in which the augmented path-planning technique is applied. The path-planning in each region takes into account the resources available — i.e., vehicles with larger sensor footprints are assigned to larger regions and execute trajectories that are more broadly spread as compared to vehicles with smaller sensor footprints. Theoretical results are applied to commercial off-the-shelf unmanned systems, both in simulation and in a fully realized precision agriculture demonstration field experiment.","PeriodicalId":224475,"journal":{"name":"2017 IEEE Aerospace Conference","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124077441","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-04DOI: 10.1109/AERO.2017.7943877
N. Vandermey, William M. Heventhal, T. Ray
The Cassini F-Ring & Proximal Orbits (FRPO) is a new and unique mission; to ensure the highest priority science gets implemented, the POST (Proximal Orbit Science Team) was created to pre-allocate the time around periapse for all 22 proximal orbits. The F-ring orbits, and proximal time outside of POST, were handled similar to Cassini's Solstice Mission using the Pre-Integrated Event (PIE) process. The new and unique properties of the spacecraft's trajectory required much forethought to be flown safely while still planning for the most and best science return possible. Some ring-plane crossings (RPX) will be protected against dust impacts by turning the high gain antenna (HGA) to the dust RAM direction (HGA2RAM). If on the first proximal RPX higher than expected dust readings are seen then the Project Office may choose to require more (all) subsequent RPX to be HGA2RAM, implemented via a real-time command overlay for uplinked sequences. The pointing uncertainties will be larger than usual after the final targeted flyby; some of the process changes to address this include adding extra orbit trim maneuvers (OTMs) (fuel permitting) to resync to the reference trajectory and reduce pointing uncertainties; and movable blocks of commands to be used for some periapses where atmospheric drag may cause large timing shifts Changes made for FRPO to address perceptions that these sequences will be hard to implement include requiring early pointing designs (during integration) for certain types of observations, requiring teams to check early on that they can turn to and from their observation attitude, and that their attitude is safe, and adjusting the Implementation process to give more time for science observation designers. This paper will discuss these process changes and lessons learned so far.
{"title":"The Cassini grand finale mission: Planning for a new mission environment","authors":"N. Vandermey, William M. Heventhal, T. Ray","doi":"10.1109/AERO.2017.7943877","DOIUrl":"https://doi.org/10.1109/AERO.2017.7943877","url":null,"abstract":"The Cassini F-Ring & Proximal Orbits (FRPO) is a new and unique mission; to ensure the highest priority science gets implemented, the POST (Proximal Orbit Science Team) was created to pre-allocate the time around periapse for all 22 proximal orbits. The F-ring orbits, and proximal time outside of POST, were handled similar to Cassini's Solstice Mission using the Pre-Integrated Event (PIE) process. The new and unique properties of the spacecraft's trajectory required much forethought to be flown safely while still planning for the most and best science return possible. Some ring-plane crossings (RPX) will be protected against dust impacts by turning the high gain antenna (HGA) to the dust RAM direction (HGA2RAM). If on the first proximal RPX higher than expected dust readings are seen then the Project Office may choose to require more (all) subsequent RPX to be HGA2RAM, implemented via a real-time command overlay for uplinked sequences. The pointing uncertainties will be larger than usual after the final targeted flyby; some of the process changes to address this include adding extra orbit trim maneuvers (OTMs) (fuel permitting) to resync to the reference trajectory and reduce pointing uncertainties; and movable blocks of commands to be used for some periapses where atmospheric drag may cause large timing shifts Changes made for FRPO to address perceptions that these sequences will be hard to implement include requiring early pointing designs (during integration) for certain types of observations, requiring teams to check early on that they can turn to and from their observation attitude, and that their attitude is safe, and adjusting the Implementation process to give more time for science observation designers. This paper will discuss these process changes and lessons learned so far.","PeriodicalId":224475,"journal":{"name":"2017 IEEE Aerospace Conference","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133257246","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-04DOI: 10.1109/AERO.2017.7943774
Shawn C. Johnson, A. Pini, D. Reeves, A. S. Martin, Keith Deweese, J. Brophy
Electric propulsion may play a crucial role in the implementation of the gravity tractor planetary defense technique. Gravity tractors were devised to take advantage of the mutual gravitational force between a spacecraft flying in formation with the target celestial body to slowly alter the celestial body's trajectory. No physical contact is necessary, which bypasses issues associated with surface contact such as landing, anchoring, or spin compensation. The gravity tractor maneuver can take several forms, from the originally proposed constant thrust in-line hover to the offset halo orbit. Both can be enhanced with the collection of mass at the asteroid. The form of the gravity tractor ultimately impacts the required thrust magnitude to maintain the formation, as well as constraints on the vectoring of the thrust direction. Solar electric propulsion systems provide an efficient mechanism for tugging the spacecraft-asteroid system due to their high specific impulse. Electric propulsion systems can generate thrust continuously at high efficiency, which is an ideal property for gravity tractors that may require years of operation to achieve the desired deflection because of the very low coupling force provided by the gravitational attraction. The performance and feasibility of the deflection are predicated on having the propulsion capability to maintain the gravity tractor. This paper describes the impacts of constraining the solar electric propulsion thrust magnitude and thrust vectoring capability. It is shown that uncertainty in asteroid density and size, when combined with the enforcement of the electric propulsion constraints, can preclude the feasibility of certain gravity tractor configurations. Additionally, odd thruster configurations are shown to drive the gimbal performance and to have major impacts on eroding incident spacecraft surfaces due to plume interaction. Center of gravity movement further exacerbates issues with gimbaling and plume interaction. A tighter plume divergence angle is therefore always desired, but this paper shows that there is an optimal momentum balance between plume interaction and asteroid-plume avoidance. Several gravity tractor techniques are compared based on metrics of time efficacy, as measured by the induced asteroid delta-V per unit time, and mass efficiency, as measured by the induced asteroid delta-V per unit mass of fuel. Given the propulsion constraints, halo orbits can be infeasible for smaller asteroids unless the mass of the spacecraft is augmented with collected material through a technique called the Enhanced Gravity Tractor. Another proposed method is to alter the halo period by canting the thrusters. In-line hover gravity tractors can always be moved along the net thrust direction to conform to the given propulsion system at the expense of performance, except in the case of smaller asteroids with propulsion systems that are limited in lower throttle range or maximum gimbal angle. Alternative str
{"title":"The effects of constrained electric propulsion on gravity tractors for planetary defense","authors":"Shawn C. Johnson, A. Pini, D. Reeves, A. S. Martin, Keith Deweese, J. Brophy","doi":"10.1109/AERO.2017.7943774","DOIUrl":"https://doi.org/10.1109/AERO.2017.7943774","url":null,"abstract":"Electric propulsion may play a crucial role in the implementation of the gravity tractor planetary defense technique. Gravity tractors were devised to take advantage of the mutual gravitational force between a spacecraft flying in formation with the target celestial body to slowly alter the celestial body's trajectory. No physical contact is necessary, which bypasses issues associated with surface contact such as landing, anchoring, or spin compensation. The gravity tractor maneuver can take several forms, from the originally proposed constant thrust in-line hover to the offset halo orbit. Both can be enhanced with the collection of mass at the asteroid. The form of the gravity tractor ultimately impacts the required thrust magnitude to maintain the formation, as well as constraints on the vectoring of the thrust direction. Solar electric propulsion systems provide an efficient mechanism for tugging the spacecraft-asteroid system due to their high specific impulse. Electric propulsion systems can generate thrust continuously at high efficiency, which is an ideal property for gravity tractors that may require years of operation to achieve the desired deflection because of the very low coupling force provided by the gravitational attraction. The performance and feasibility of the deflection are predicated on having the propulsion capability to maintain the gravity tractor. This paper describes the impacts of constraining the solar electric propulsion thrust magnitude and thrust vectoring capability. It is shown that uncertainty in asteroid density and size, when combined with the enforcement of the electric propulsion constraints, can preclude the feasibility of certain gravity tractor configurations. Additionally, odd thruster configurations are shown to drive the gimbal performance and to have major impacts on eroding incident spacecraft surfaces due to plume interaction. Center of gravity movement further exacerbates issues with gimbaling and plume interaction. A tighter plume divergence angle is therefore always desired, but this paper shows that there is an optimal momentum balance between plume interaction and asteroid-plume avoidance. Several gravity tractor techniques are compared based on metrics of time efficacy, as measured by the induced asteroid delta-V per unit time, and mass efficiency, as measured by the induced asteroid delta-V per unit mass of fuel. Given the propulsion constraints, halo orbits can be infeasible for smaller asteroids unless the mass of the spacecraft is augmented with collected material through a technique called the Enhanced Gravity Tractor. Another proposed method is to alter the halo period by canting the thrusters. In-line hover gravity tractors can always be moved along the net thrust direction to conform to the given propulsion system at the expense of performance, except in the case of smaller asteroids with propulsion systems that are limited in lower throttle range or maximum gimbal angle. Alternative str","PeriodicalId":224475,"journal":{"name":"2017 IEEE Aerospace Conference","volume":"132 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121568022","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-04DOI: 10.1109/AERO.2017.7943732
A. Erlank, Christopher P. Bridges
While small, low-cost satellites continue to increase in capability and popularity, their reliability remains a problem. Traditional techniques for increasing system reliability are well known to satellite developers, however, their implementation on low-cost satellites is often limited due to intrinsic mass, volume and budgetary restrictions. Aiming for graceful degeneration, therefore, may be a more promising route. To this end, a stem-cell-inspired, multicellular architecture is being developed using commercial-off-the-shelf components. It aims to replace a significant portion of a typical satellite's bus avionics with a set of initially identical cells. Analogous to biological cells, the artificial cells are able to differentiate during runtime to take on a variety of tasks thanks to a set of artificial proteins. Each cell reconfigures its own proteins within the context of a system-wide distributed task management strategy. In this way, essential tasks can be maintained, even as system cells fail. This paper focusses on two hardware implementations of the stem-cell inspired architecture. The first implementation, based on a single cell, serves as the Payload Interface Computer on a CubeSat named SME-SAT. The second hardware implementation is a benchtop system composed of several cells intended to demonstrate a complete multicellular system in operation. In order to demonstrate the feasibility of these multicellular architectures, the physical attributes of the hardware implementations are compared to those of more traditional implementations and are shown to have enhanced reliability at the cost of increased power and internal bus bandwidth.
{"title":"Satellite stem cells: The benefits & overheads of reliable, multicellular architectures","authors":"A. Erlank, Christopher P. Bridges","doi":"10.1109/AERO.2017.7943732","DOIUrl":"https://doi.org/10.1109/AERO.2017.7943732","url":null,"abstract":"While small, low-cost satellites continue to increase in capability and popularity, their reliability remains a problem. Traditional techniques for increasing system reliability are well known to satellite developers, however, their implementation on low-cost satellites is often limited due to intrinsic mass, volume and budgetary restrictions. Aiming for graceful degeneration, therefore, may be a more promising route. To this end, a stem-cell-inspired, multicellular architecture is being developed using commercial-off-the-shelf components. It aims to replace a significant portion of a typical satellite's bus avionics with a set of initially identical cells. Analogous to biological cells, the artificial cells are able to differentiate during runtime to take on a variety of tasks thanks to a set of artificial proteins. Each cell reconfigures its own proteins within the context of a system-wide distributed task management strategy. In this way, essential tasks can be maintained, even as system cells fail. This paper focusses on two hardware implementations of the stem-cell inspired architecture. The first implementation, based on a single cell, serves as the Payload Interface Computer on a CubeSat named SME-SAT. The second hardware implementation is a benchtop system composed of several cells intended to demonstrate a complete multicellular system in operation. In order to demonstrate the feasibility of these multicellular architectures, the physical attributes of the hardware implementations are compared to those of more traditional implementations and are shown to have enhanced reliability at the cost of increased power and internal bus bandwidth.","PeriodicalId":224475,"journal":{"name":"2017 IEEE Aerospace Conference","volume":"57 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114153941","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-04DOI: 10.1109/AERO.2017.7943974
T. Setterfield, David W. Miller, J. Leonard, A. Saenz-Otero
This paper presents a method of obtaining the maximum a posteriori estimate of an inspector satellite's trajectory about an unknown tumbling target while on-orbit. An inspector equipped with radar or a 3D visual sensor (such as LiDAR or stereo cameras), an inertial measurement unit, and a star tracker is used to obtain measurements of range and bearing to the target's centroid, angular velocity, acceleration, and orientation in the inertial frame. A smoothing-based trajectory estimation scheme is presented that makes use of all the input sensor data to estimate the inspector's trajectory. Open-source incremental smoothing and mapping (iSAM2) software is used to implement the smoothing-based trajectory estimation algorithm; this facilitates computationally efficient evaluation of the entire trajectory, which can be performed incrementally, and in real time on a computer capable of processing 3D visual sensor data in real time. The presented algorithm was tested on data obtained in 6 degree-of-freedom microgravity using the SPHERES-VERTIGO robotic test platform on the International Space Station (ISS). In these tests, a SPHERES inspector satellite with attached stereo cameras circumnavigated a passive SPHERES target satellite, making visual observations of it. The results of these tests demonstrate accurate estimation of the inspector satellite's trajectory.
{"title":"Smoothing-based estimation of an inspector satellite trajectory relative to a passive object","authors":"T. Setterfield, David W. Miller, J. Leonard, A. Saenz-Otero","doi":"10.1109/AERO.2017.7943974","DOIUrl":"https://doi.org/10.1109/AERO.2017.7943974","url":null,"abstract":"This paper presents a method of obtaining the maximum a posteriori estimate of an inspector satellite's trajectory about an unknown tumbling target while on-orbit. An inspector equipped with radar or a 3D visual sensor (such as LiDAR or stereo cameras), an inertial measurement unit, and a star tracker is used to obtain measurements of range and bearing to the target's centroid, angular velocity, acceleration, and orientation in the inertial frame. A smoothing-based trajectory estimation scheme is presented that makes use of all the input sensor data to estimate the inspector's trajectory. Open-source incremental smoothing and mapping (iSAM2) software is used to implement the smoothing-based trajectory estimation algorithm; this facilitates computationally efficient evaluation of the entire trajectory, which can be performed incrementally, and in real time on a computer capable of processing 3D visual sensor data in real time. The presented algorithm was tested on data obtained in 6 degree-of-freedom microgravity using the SPHERES-VERTIGO robotic test platform on the International Space Station (ISS). In these tests, a SPHERES inspector satellite with attached stereo cameras circumnavigated a passive SPHERES target satellite, making visual observations of it. The results of these tests demonstrate accurate estimation of the inspector satellite's trajectory.","PeriodicalId":224475,"journal":{"name":"2017 IEEE Aerospace Conference","volume":"254 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117091386","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-04DOI: 10.1109/AERO.2017.7943593
B. Alsalam, K. Morton, D. Campbell, Felipe Gonzalez
In recent years, a phenomenal increase in the development of Unmanned Aerial Vehicles (UAVs) has been observed in a broad range of applications in various fields of study. Precision agriculture has emerged as a major field of interest, integrating unmanned monitoring of crop health into general agricultural practices for researchers are utilizing UAV to collect data for post-analysis. This paper describes a modular and generic system that is able to control the UAV using computer vision. A configuration approach similar to the Observation, Orientation, Decision and Action (OODA) loop has been implemented to allow the system to perform on-board decision making. The detection of an object of interest is performed by computer vision functionality. This allows the UAV to change its planned path accordingly and approach the target in order to perform a close inspection, or conduct a manoeuvres such as the application of herbicide or collection of higher resolution agricultural images. The results show the ability of the developed system to dynamically change its current goal and implement an inspection manoeuvre to perform necessary actions after detecting the target. The vision based navigation system and on-board decision making were demonstrated in three types of tests: ArUco Marker detection, colour detection and weed detection. The results are measured based on the sensitivity and the selectivity of the algorithm. The sensitivity is the ability of the algorithm to identify and detect the true positive target while the selectivity is the capability of the algorithm to filter out the false negatives for detection targets. Results indicate that the system is capable of detecting ArUco Markers with 99% sensitivity and 100% selectivity at 5 m above the ground level. The system is also capable of detecting a red target with 96% sensitivity and 99% selectivity at the same height during a test height at 5 metres. This system has potential applicability in the field of precision agriculture such as, crop health monitoring, pest plant detection which causes detrimental financial damage to crop yields if not noticed at an early stage.
{"title":"Autonomous UAV with vision based on-board decision making for remote sensing and precision agriculture","authors":"B. Alsalam, K. Morton, D. Campbell, Felipe Gonzalez","doi":"10.1109/AERO.2017.7943593","DOIUrl":"https://doi.org/10.1109/AERO.2017.7943593","url":null,"abstract":"In recent years, a phenomenal increase in the development of Unmanned Aerial Vehicles (UAVs) has been observed in a broad range of applications in various fields of study. Precision agriculture has emerged as a major field of interest, integrating unmanned monitoring of crop health into general agricultural practices for researchers are utilizing UAV to collect data for post-analysis. This paper describes a modular and generic system that is able to control the UAV using computer vision. A configuration approach similar to the Observation, Orientation, Decision and Action (OODA) loop has been implemented to allow the system to perform on-board decision making. The detection of an object of interest is performed by computer vision functionality. This allows the UAV to change its planned path accordingly and approach the target in order to perform a close inspection, or conduct a manoeuvres such as the application of herbicide or collection of higher resolution agricultural images. The results show the ability of the developed system to dynamically change its current goal and implement an inspection manoeuvre to perform necessary actions after detecting the target. The vision based navigation system and on-board decision making were demonstrated in three types of tests: ArUco Marker detection, colour detection and weed detection. The results are measured based on the sensitivity and the selectivity of the algorithm. The sensitivity is the ability of the algorithm to identify and detect the true positive target while the selectivity is the capability of the algorithm to filter out the false negatives for detection targets. Results indicate that the system is capable of detecting ArUco Markers with 99% sensitivity and 100% selectivity at 5 m above the ground level. The system is also capable of detecting a red target with 96% sensitivity and 99% selectivity at the same height during a test height at 5 metres. This system has potential applicability in the field of precision agriculture such as, crop health monitoring, pest plant detection which causes detrimental financial damage to crop yields if not noticed at an early stage.","PeriodicalId":224475,"journal":{"name":"2017 IEEE Aerospace Conference","volume":"54 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116921129","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-04DOI: 10.1109/AERO.2017.7943876
A. Schmidt, G. Weisz, M. French, T. Flatley, C. Villalpando
The SpaceCubeX project is motivated by the need for high performance, modular, and scalable on-board processing to help scientists answer critical 21st century questions about global climate change, air quality, ocean health, and ecosystem dynamics, while adding new capabilities such as low-latency data products for extreme event warnings. These goals translate into on-board processing throughput requirements that are on the order of 100–1,000x more than those of previous Earth Science missions for standard processing, compression, storage, and downhnk operations. To study possible future architectures to achieve these performance requirements, the SpaceCubeX project provides an evolvable testbed and framework that enables a focused design space exploration of candidate hybrid CPU/FPGA/DSP processing architectures. The framework includes ArchGen, an architecture generator tool populated with candidate architecture components, performance models, and IP cores, that allows an end user to specify the type, number, and connectivity of a hybrid architecture. The framework requires minimal extensions to integrate new processors, such as the anticipated High Performance Spaceflight Computer (HPSC), reducing time to initiate benchmarking by months. To evaluate the framework, we leverage a wide suite of high performance embedded computing benchmarks and Earth science scenarios to ensure robust architecture characterization. We report on our projects Year 1 efforts and demonstrate the capabihties across four simulation testbed models, a baseline SpaceCube 2.0 system, a dual ARM A9 processor system, a hybrid quad ARM A53 and FPGA system, and a hybrid quad ARM A53 and DSP system.
{"title":"SpaceCubeX: A framework for evaluating hybrid multi-core CPU/FPGA/DSP architectures","authors":"A. Schmidt, G. Weisz, M. French, T. Flatley, C. Villalpando","doi":"10.1109/AERO.2017.7943876","DOIUrl":"https://doi.org/10.1109/AERO.2017.7943876","url":null,"abstract":"The SpaceCubeX project is motivated by the need for high performance, modular, and scalable on-board processing to help scientists answer critical 21st century questions about global climate change, air quality, ocean health, and ecosystem dynamics, while adding new capabilities such as low-latency data products for extreme event warnings. These goals translate into on-board processing throughput requirements that are on the order of 100–1,000x more than those of previous Earth Science missions for standard processing, compression, storage, and downhnk operations. To study possible future architectures to achieve these performance requirements, the SpaceCubeX project provides an evolvable testbed and framework that enables a focused design space exploration of candidate hybrid CPU/FPGA/DSP processing architectures. The framework includes ArchGen, an architecture generator tool populated with candidate architecture components, performance models, and IP cores, that allows an end user to specify the type, number, and connectivity of a hybrid architecture. The framework requires minimal extensions to integrate new processors, such as the anticipated High Performance Spaceflight Computer (HPSC), reducing time to initiate benchmarking by months. To evaluate the framework, we leverage a wide suite of high performance embedded computing benchmarks and Earth science scenarios to ensure robust architecture characterization. We report on our projects Year 1 efforts and demonstrate the capabihties across four simulation testbed models, a baseline SpaceCube 2.0 system, a dual ARM A9 processor system, a hybrid quad ARM A53 and FPGA system, and a hybrid quad ARM A53 and DSP system.","PeriodicalId":224475,"journal":{"name":"2017 IEEE Aerospace Conference","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125687102","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：