† We would like to recognize the extraordinary effort which this decadal has taken and the member... more † We would like to recognize the extraordinary effort which this decadal has taken and the members of our community who were unable to participate in this work. We would also like to acknowledge conversations with additional white paper teams on data management, automation, and other machine learning relevant contributions and we encourage you to review these data science relevant papers submitted to the survey.
American Astronomical Society Meeting Abstracts, Dec 1, 2007
The Very Energetic Radiation Imaging Telescope Array System (VERITAS) is an array of four 12m dia... more The Very Energetic Radiation Imaging Telescope Array System (VERITAS) is an array of four 12m diameter Imaging Atmospheric Cherenkov Technique (IACT) telescopes operated at the base of Mt. Hopkins in southern Arizona. The full four-telescope experiment is operational since February 2007, and is one of the most sensitive gamma ray instruments in the >100; GeV energy range worldwide. We report on using data taken with the VERITAS experiment to study the performance of IACT experiments as function of various design parameters. Using different subsets of the four-telescope data, we study the dependence of the angular resolution, gamma-hadron separation, and gamma ray source sensitivity of two-telescope IACT experiments as function of the separation between the two telescopes. Furthermore, we report on how the performance of an IACT system scales with the number of IACTs in the system. Last but not least, we corroborate our results by comparing the experimental data with simulated Monte Carlo data.
<p><strong>Science rationale:</strong> Our knowledge of... more <p><strong>Science rationale:</strong> Our knowledge of the internal structure of asteroids entirely relies on inferences from remote sensing observations of the surface combined with theoretical modeling [1]. Is Apophis a rubble-pile, as expected, or a monolithic rock, and how high is the porosity? What is the typical size of the constituent blocks? Are these blocks homogeneous or heterogeneous? If Apophis is bilobed, how does the material differ between each lobe?</p> <p>After many asteroid rendezvous and fly-by missions from different nations, these crucial and yet basic questions remain open. Direct measurements of the deep interior structure and composition are needed to better understand the accretion and dynamical evolution of asteroids in general. These measurements at Apophis in particular will directly improve our ability to understand and predict stability conditions as well as to interpret the response of Apophis to the tidal forces induced by its close approach to the Earth. This information is also crucial to plan any interaction of a spacecraft with Apophis and other similar asteroids, especially for Planetary Defense purposes.</p> <p>Direct observations of asteroid subsurfaces in general are also required to better model the dynamics of granular materials in low gravity, and to determine material composition and mineralogy, while space weathering and thermal cycling alter surface properties as observed by optical remote sensing.</p> <p><strong>DROID mission concept: </strong>Radar observation of Apophis from a spacecraft is the most mature technique capable of achieving these objectives, by providing a direct measurement of its interior. This is the goal of DROID – (Distributed Radar Observations of Interior Distributions), a mission concept developed in collaboration between NASA JPL and CNES [2] and discussed in more detail in the accompanying presentation [3].</p> <p>The DROID mothership will release two CubeSats each carrying a low-frequency radar. The radar will be a version of JuRa (60 MHz) [4], modified to operate in a bistatic mode and using an inter-satellite link as a synchronization channel. The mothership and the two CubeSats (daughtercraft) will also have cameras for both science and navigation.</p> <p><strong>Radar observation: </strong>Each daughtercraft radar can operate in a monostatic mode, or in a bistatic mode using the two platforms to measure the signal transmitted throughout Apophis, as CONSERT did onboard Rosetta orbiter and Philae lander [1,5,6,7].</p> <p><em>Monostatic radar. </em>A radar at 60 MHz offers a larger penetration (up to 100 meters or more) with a limited resolution (≈5 m). It corresponds to the instrument under implementation for the Juventas Cubesat on the Hera/ESA mission [4].</p> <p>Furthermore, multi-pass processing allows us to build a 3D tomographic image of the interior to identify internal structure like layers, voids and sub-aggregates, to bring out the aggregate structure and to characterize its constituent blocks in terms of size distribution and heterogeneity at different scales (from sub-metric to global). Initial dynamics modeling of the two Cubesats orbiting Apophis at 3 body radii indicates that 20% full Doppler coverage is possible in 40 days [2,8].</p> <p>Shallow subsurface characterization and radar images to support the shape modeling are also possible in this configuration, but with degraded performance due to a limited resolution.</p> <p><em>Bistatic radar. </em>The bistatic radar will firstly measure the signal in transmission, allowing us to achieve a direct measurement of the dielectric permittivity, which is related to composition and microporosity [6]. This objective is less demanding in terms of data volume and operation compared to full bistatic coverage. Partial transmission coverage will provide slices of the body with average characterization and its special variability. With dense coverage, benefiting from a larger diversity of observation angles, the bistatic mode will allow a complete 3D tomography [8,9]. In general, multi-angular acquisition allows for a better decorrelation of the size effect and permittivity contrast in the return power.</p> <p><em>Ground-to-space:</em> In addition to radar observation at close proximity, there is the possibility for joint ground-to-space radar observations at the epoch of the Apophis close approach. [10]. Such measurements would make use of high-power transmitters or sensitive radio astronomy observatories on Earth [11]. Ground-to-space configurations would be used to collect echoes in unique bistatic configurations or to collect echoes during spacecraft maneuvers at close approach (e.g., required spacecraft stand-off).</p>…
Mentor: Henric Krawczynski From the Washington University Undergraduate Research Digest: WUURD, V... more Mentor: Henric Krawczynski From the Washington University Undergraduate Research Digest: WUURD, Volume 2, Issue 2, Spring 2007. Published by the Office of Undergraduate Research. Henry Biggs, Director of Undergraduate Research and Associate Dean in the College of Arts & Sciences; Joy Zalis Kiefer, Undergraduate Research Coordinator, Editor, and Assistant Dean in the College of Arts & Sciences; Kristin Sobotka, Co-editor
Mentor: Michael A. Swartwout From the Washington University Undergraduate Research Digest: WUURD,... more Mentor: Michael A. Swartwout From the Washington University Undergraduate Research Digest: WUURD, Volume 3, Issue 1, Fall 2007. Published by the Office of Undergraduate Research. Henry Biggs, Director of Undergraduate Research and Associate Dean in the College of Arts & Sciences; Joy Zalis Kiefer, Undergraduate Research Coordinator, Co-editor, and Assistant Dean in the College of Arts & Sciences; Kristin Sobotka, Editor
The prospect of finding love may be scary but the prospect of committing to a relationship for th... more The prospect of finding love may be scary but the prospect of committing to a relationship for the rest of your life is almost certainly scary. The secretary problem is a parallel to romantic decision making where an individual decides when to be satisfied with a selection choice in the face of uncertain future options. However, the secretary problem and its variations still do not provide a practical solution in a world where individual preference, goals, and societal context create a highly complex space of values that factor into decision making. In light of these complexities, we offer a general process that can determine the value of romantic options in a highly personal context. This algorithm is currently being developed into a service that will be available in 2015 for the general public. Expressions and equations used and referenced in this release are for illustrative purposes and may not reflect the actual methodologies employed. Moreover, only some features and routines incorporated in the algorithm are described.
In this report, we present a robotic platform, the Shapeshifter, that allows multi-domain and red... more In this report, we present a robotic platform, the Shapeshifter, that allows multi-domain and redundant mobility on Saturn's moon Titan-and potentially other bodies with atmospheres. The Shapeshifter is a collection of simple and affordable robotic units, called Cobots, comparable to personal palm-size quadcopters. By attaching and detaching with each other, multiple Cobots can shape-shift into novel structures, capable of (a) rolling on a flat surface, to increase the traverse range, (b) flying in a flight array formation, and (c) swimming on or under liquid. A ground station, called the Home-base, complements the robotic platform, hosting science instrumentation and providing power to recharge the batteries of the Cobots. An artist's concept of the platform, depicted in an exploration mission on Titan, is represented in Figure 1.
While numerous scientifically compelling missions have visited the outer solar system during the ... more While numerous scientifically compelling missions have visited the outer solar system during the past four decades, the science return has been limited partly by contemporary power and propulsion technologies that limit a spacecraft's ability to carry heavy or high power demand payloads to its destination in a timely manner. Recent studies have endorsed radioisotope electric propulsion (REP) as a strong candidate for enhancing those capabilities. REP mission possibilities include Cassini level science at Neptune or Dawn-like coverage of a Kuiper Belt Object (KBO). This report will discuss the science benefits associated with the use of REP, a trade space analysis of mission architectures, and case studies of REP missions to regions beyond Saturn, with specific distinction to giant planet and small body targets. In addition to these, necessary REP flight qualification developments will be outlined.
Autonomous planning and scheduling is a key enabling technology for future robotic Solar System e... more Autonomous planning and scheduling is a key enabling technology for future robotic Solar System explorers: as missions venture farther in the Solar System, light-speed delays and low available bandwidth make on-board autonomy increasingly attractive to maximize science returns and enable otherwise-infeasible observations of transient phenomena, e.g. storms on gas giants and plumes on icy worlds. However, ground operations of future autonomous explorers will require a paradigm shift, moving from the current practice of specifying timed sequences of commands, to specifying high-level goals that on-board autonomy should elaborate based on the spacecraft's state and the sensed environment. In this paper, we explore the problem of adapting ground operations processes, roles, and tools to accommodate on-board planning and scheduling. We design and prototype a framework of user interfaces and algorithmic tools to support uplink and downlink processes of future autonomous spacecraft. The framework's goals are to allow scientists and engineers to both convey their desired intent to the spacecraft in a format compatible with the on-board planner, and reconstruct and explain the decisions made onboard and their impact on the state of the spacecraft. We assess the performance of the framework through a design simulation where JPL scientists and operators simulate realistic operations of an Ice Giant multi-flyby mission concept, aided by the proposed framework. The design simulation confirms that the proposed approach holds promise to enable operators to interact with on-board autonomy, and suggest a number of recommendations for the next generation of operations tools supporting autonomous spacecraft.
<p><strong>Science rationale:</strong> Our knowledge of... more <p><strong>Science rationale:</strong> Our knowledge of the internal structure of asteroids entirely relies on inferences from remote sensing observations of the surface combined with theoretical modeling [1]. Is Apophis a rubble-pile, as expected, or a monolithic rock, and how high is the porosity? What is the typical size of the constituent blocks? Are these blocks homogeneous or heterogeneous? If Apophis is bilobed, how does the material differ between each lobe?</p> <p>After many asteroid rendezvous and fly-by missions from different nations, these crucial and yet basic questions remain open. Direct measurements of the deep interior structure and composition are needed to better understand the accretion and dynamical evolution of asteroids in general. These measurements at Apophis in particular will directly improve our ability to understand and predict stability conditions as well as to interpret the response of Apophis to the tidal forces induced by its close approach to the Earth. This information is also crucial to plan any interaction of a spacecraft with Apophis and other similar asteroids, especially for Planetary Defense purposes.</p> <p>Direct observations of asteroid subsurfaces in general are also required to better model the dynamics of granular materials in low gravity, and to determine material composition and mineralogy, while space weathering and thermal cycling alter surface properties as observed by optical remote sensing.</p> <p><strong>DROID mission concept: </strong>Radar observation of Apophis from a spacecraft is the most mature technique capable of achieving these objectives, by providing a direct measurement of its interior. This is the goal of DROID – (Distributed Radar Observations of Interior Distributions), a mission concept developed in collaboration between NASA JPL and CNES [2] and discussed in more detail in the accompanying presentation [3].</p> <p>The DROID mothership will release two CubeSats each carrying a low-frequency radar. The radar will be a version of JuRa (60 MHz) [4], modified to operate in a bistatic mode and using an inter-satellite link as a synchronization channel. The mothership and the two CubeSats (daughtercraft) will also have cameras for both science and navigation.</p> <p><strong>Radar observation: </strong>Each daughtercraft radar can operate in a monostatic mode, or in a bistatic mode using the two platforms to measure the signal transmitted throughout Apophis, as CONSERT did onboard Rosetta orbiter and Philae lander [1,5,6,7].</p> <p><em>Monostatic radar. </em>A radar at 60 MHz offers a larger penetration (up to 100 meters or more) with a limited resolution (≈5 m). It corresponds to the instrument under implementation for the Juventas Cubesat on the Hera/ESA mission [4].</p> <p>Furthermore, multi-pass processing allows us to build a 3D tomographic image of the interior to identify internal structure like layers, voids and sub-aggregates, to bring out the aggregate structure and to characterize its constituent blocks in terms of size distribution and heterogeneity at different scales (from sub-metric to global). Initial dynamics modeling of the two Cubesats orbiting Apophis at 3 body radii indicates that 20% full Doppler coverage is possible in 40 days [2,8].</p> <p>Shallow subsurface characterization and radar images to support the shape modeling are also possible in this configuration, but with degraded performance due to a limited resolution.</p> <p><em>Bistatic radar. </em>The bistatic radar will firstly measure the signal in transmission, allowing us to achieve a direct measurement of the dielectric permittivity, which is related to composition and microporosity [6]. This objective is less demanding in terms of data volume and operation compared to full bistatic coverage. Partial transmission coverage will provide slices of the body with average characterization and its special variability. With dense coverage, benefiting from a larger diversity of observation angles, the bistatic mode will allow a complete 3D tomography [8,9]. In general, multi-angular acquisition allows for a better decorrelation of the size effect and permittivity contrast in the return power.</p> <p><em>Ground-to-space:</em> In addition to radar observation at close proximity, there is the possibility for joint ground-to-space radar observations at the epoch of the Apophis close approach. [10]. Such measurements would make use of high-power transmitters or sensitive radio astronomy observatories on Earth [11]. Ground-to-space configurations would be used to collect echoes in unique bistatic configurations or to collect echoes during spacecraft maneuvers at close approach (e.g., required spacecraft stand-off).</p>…
† We would like to recognize the extraordinary effort which this decadal has taken and the member... more † We would like to recognize the extraordinary effort which this decadal has taken and the members of our community who were unable to participate in this work. We would also like to acknowledge conversations with additional white paper teams on data management, automation, and other machine learning relevant contributions and we encourage you to review these data science relevant papers submitted to the survey.
American Astronomical Society Meeting Abstracts, Dec 1, 2007
The Very Energetic Radiation Imaging Telescope Array System (VERITAS) is an array of four 12m dia... more The Very Energetic Radiation Imaging Telescope Array System (VERITAS) is an array of four 12m diameter Imaging Atmospheric Cherenkov Technique (IACT) telescopes operated at the base of Mt. Hopkins in southern Arizona. The full four-telescope experiment is operational since February 2007, and is one of the most sensitive gamma ray instruments in the >100; GeV energy range worldwide. We report on using data taken with the VERITAS experiment to study the performance of IACT experiments as function of various design parameters. Using different subsets of the four-telescope data, we study the dependence of the angular resolution, gamma-hadron separation, and gamma ray source sensitivity of two-telescope IACT experiments as function of the separation between the two telescopes. Furthermore, we report on how the performance of an IACT system scales with the number of IACTs in the system. Last but not least, we corroborate our results by comparing the experimental data with simulated Monte Carlo data.
<p><strong>Science rationale:</strong> Our knowledge of... more <p><strong>Science rationale:</strong> Our knowledge of the internal structure of asteroids entirely relies on inferences from remote sensing observations of the surface combined with theoretical modeling [1]. Is Apophis a rubble-pile, as expected, or a monolithic rock, and how high is the porosity? What is the typical size of the constituent blocks? Are these blocks homogeneous or heterogeneous? If Apophis is bilobed, how does the material differ between each lobe?</p> <p>After many asteroid rendezvous and fly-by missions from different nations, these crucial and yet basic questions remain open. Direct measurements of the deep interior structure and composition are needed to better understand the accretion and dynamical evolution of asteroids in general. These measurements at Apophis in particular will directly improve our ability to understand and predict stability conditions as well as to interpret the response of Apophis to the tidal forces induced by its close approach to the Earth. This information is also crucial to plan any interaction of a spacecraft with Apophis and other similar asteroids, especially for Planetary Defense purposes.</p> <p>Direct observations of asteroid subsurfaces in general are also required to better model the dynamics of granular materials in low gravity, and to determine material composition and mineralogy, while space weathering and thermal cycling alter surface properties as observed by optical remote sensing.</p> <p><strong>DROID mission concept: </strong>Radar observation of Apophis from a spacecraft is the most mature technique capable of achieving these objectives, by providing a direct measurement of its interior. This is the goal of DROID – (Distributed Radar Observations of Interior Distributions), a mission concept developed in collaboration between NASA JPL and CNES [2] and discussed in more detail in the accompanying presentation [3].</p> <p>The DROID mothership will release two CubeSats each carrying a low-frequency radar. The radar will be a version of JuRa (60 MHz) [4], modified to operate in a bistatic mode and using an inter-satellite link as a synchronization channel. The mothership and the two CubeSats (daughtercraft) will also have cameras for both science and navigation.</p> <p><strong>Radar observation: </strong>Each daughtercraft radar can operate in a monostatic mode, or in a bistatic mode using the two platforms to measure the signal transmitted throughout Apophis, as CONSERT did onboard Rosetta orbiter and Philae lander [1,5,6,7].</p> <p><em>Monostatic radar. </em>A radar at 60 MHz offers a larger penetration (up to 100 meters or more) with a limited resolution (≈5 m). It corresponds to the instrument under implementation for the Juventas Cubesat on the Hera/ESA mission [4].</p> <p>Furthermore, multi-pass processing allows us to build a 3D tomographic image of the interior to identify internal structure like layers, voids and sub-aggregates, to bring out the aggregate structure and to characterize its constituent blocks in terms of size distribution and heterogeneity at different scales (from sub-metric to global). Initial dynamics modeling of the two Cubesats orbiting Apophis at 3 body radii indicates that 20% full Doppler coverage is possible in 40 days [2,8].</p> <p>Shallow subsurface characterization and radar images to support the shape modeling are also possible in this configuration, but with degraded performance due to a limited resolution.</p> <p><em>Bistatic radar. </em>The bistatic radar will firstly measure the signal in transmission, allowing us to achieve a direct measurement of the dielectric permittivity, which is related to composition and microporosity [6]. This objective is less demanding in terms of data volume and operation compared to full bistatic coverage. Partial transmission coverage will provide slices of the body with average characterization and its special variability. With dense coverage, benefiting from a larger diversity of observation angles, the bistatic mode will allow a complete 3D tomography [8,9]. In general, multi-angular acquisition allows for a better decorrelation of the size effect and permittivity contrast in the return power.</p> <p><em>Ground-to-space:</em> In addition to radar observation at close proximity, there is the possibility for joint ground-to-space radar observations at the epoch of the Apophis close approach. [10]. Such measurements would make use of high-power transmitters or sensitive radio astronomy observatories on Earth [11]. Ground-to-space configurations would be used to collect echoes in unique bistatic configurations or to collect echoes during spacecraft maneuvers at close approach (e.g., required spacecraft stand-off).</p>…
Mentor: Henric Krawczynski From the Washington University Undergraduate Research Digest: WUURD, V... more Mentor: Henric Krawczynski From the Washington University Undergraduate Research Digest: WUURD, Volume 2, Issue 2, Spring 2007. Published by the Office of Undergraduate Research. Henry Biggs, Director of Undergraduate Research and Associate Dean in the College of Arts & Sciences; Joy Zalis Kiefer, Undergraduate Research Coordinator, Editor, and Assistant Dean in the College of Arts & Sciences; Kristin Sobotka, Co-editor
Mentor: Michael A. Swartwout From the Washington University Undergraduate Research Digest: WUURD,... more Mentor: Michael A. Swartwout From the Washington University Undergraduate Research Digest: WUURD, Volume 3, Issue 1, Fall 2007. Published by the Office of Undergraduate Research. Henry Biggs, Director of Undergraduate Research and Associate Dean in the College of Arts & Sciences; Joy Zalis Kiefer, Undergraduate Research Coordinator, Co-editor, and Assistant Dean in the College of Arts & Sciences; Kristin Sobotka, Editor
The prospect of finding love may be scary but the prospect of committing to a relationship for th... more The prospect of finding love may be scary but the prospect of committing to a relationship for the rest of your life is almost certainly scary. The secretary problem is a parallel to romantic decision making where an individual decides when to be satisfied with a selection choice in the face of uncertain future options. However, the secretary problem and its variations still do not provide a practical solution in a world where individual preference, goals, and societal context create a highly complex space of values that factor into decision making. In light of these complexities, we offer a general process that can determine the value of romantic options in a highly personal context. This algorithm is currently being developed into a service that will be available in 2015 for the general public. Expressions and equations used and referenced in this release are for illustrative purposes and may not reflect the actual methodologies employed. Moreover, only some features and routines incorporated in the algorithm are described.
In this report, we present a robotic platform, the Shapeshifter, that allows multi-domain and red... more In this report, we present a robotic platform, the Shapeshifter, that allows multi-domain and redundant mobility on Saturn's moon Titan-and potentially other bodies with atmospheres. The Shapeshifter is a collection of simple and affordable robotic units, called Cobots, comparable to personal palm-size quadcopters. By attaching and detaching with each other, multiple Cobots can shape-shift into novel structures, capable of (a) rolling on a flat surface, to increase the traverse range, (b) flying in a flight array formation, and (c) swimming on or under liquid. A ground station, called the Home-base, complements the robotic platform, hosting science instrumentation and providing power to recharge the batteries of the Cobots. An artist's concept of the platform, depicted in an exploration mission on Titan, is represented in Figure 1.
While numerous scientifically compelling missions have visited the outer solar system during the ... more While numerous scientifically compelling missions have visited the outer solar system during the past four decades, the science return has been limited partly by contemporary power and propulsion technologies that limit a spacecraft's ability to carry heavy or high power demand payloads to its destination in a timely manner. Recent studies have endorsed radioisotope electric propulsion (REP) as a strong candidate for enhancing those capabilities. REP mission possibilities include Cassini level science at Neptune or Dawn-like coverage of a Kuiper Belt Object (KBO). This report will discuss the science benefits associated with the use of REP, a trade space analysis of mission architectures, and case studies of REP missions to regions beyond Saturn, with specific distinction to giant planet and small body targets. In addition to these, necessary REP flight qualification developments will be outlined.
Autonomous planning and scheduling is a key enabling technology for future robotic Solar System e... more Autonomous planning and scheduling is a key enabling technology for future robotic Solar System explorers: as missions venture farther in the Solar System, light-speed delays and low available bandwidth make on-board autonomy increasingly attractive to maximize science returns and enable otherwise-infeasible observations of transient phenomena, e.g. storms on gas giants and plumes on icy worlds. However, ground operations of future autonomous explorers will require a paradigm shift, moving from the current practice of specifying timed sequences of commands, to specifying high-level goals that on-board autonomy should elaborate based on the spacecraft's state and the sensed environment. In this paper, we explore the problem of adapting ground operations processes, roles, and tools to accommodate on-board planning and scheduling. We design and prototype a framework of user interfaces and algorithmic tools to support uplink and downlink processes of future autonomous spacecraft. The framework's goals are to allow scientists and engineers to both convey their desired intent to the spacecraft in a format compatible with the on-board planner, and reconstruct and explain the decisions made onboard and their impact on the state of the spacecraft. We assess the performance of the framework through a design simulation where JPL scientists and operators simulate realistic operations of an Ice Giant multi-flyby mission concept, aided by the proposed framework. The design simulation confirms that the proposed approach holds promise to enable operators to interact with on-board autonomy, and suggest a number of recommendations for the next generation of operations tools supporting autonomous spacecraft.
<p><strong>Science rationale:</strong> Our knowledge of... more <p><strong>Science rationale:</strong> Our knowledge of the internal structure of asteroids entirely relies on inferences from remote sensing observations of the surface combined with theoretical modeling [1]. Is Apophis a rubble-pile, as expected, or a monolithic rock, and how high is the porosity? What is the typical size of the constituent blocks? Are these blocks homogeneous or heterogeneous? If Apophis is bilobed, how does the material differ between each lobe?</p> <p>After many asteroid rendezvous and fly-by missions from different nations, these crucial and yet basic questions remain open. Direct measurements of the deep interior structure and composition are needed to better understand the accretion and dynamical evolution of asteroids in general. These measurements at Apophis in particular will directly improve our ability to understand and predict stability conditions as well as to interpret the response of Apophis to the tidal forces induced by its close approach to the Earth. This information is also crucial to plan any interaction of a spacecraft with Apophis and other similar asteroids, especially for Planetary Defense purposes.</p> <p>Direct observations of asteroid subsurfaces in general are also required to better model the dynamics of granular materials in low gravity, and to determine material composition and mineralogy, while space weathering and thermal cycling alter surface properties as observed by optical remote sensing.</p> <p><strong>DROID mission concept: </strong>Radar observation of Apophis from a spacecraft is the most mature technique capable of achieving these objectives, by providing a direct measurement of its interior. This is the goal of DROID – (Distributed Radar Observations of Interior Distributions), a mission concept developed in collaboration between NASA JPL and CNES [2] and discussed in more detail in the accompanying presentation [3].</p> <p>The DROID mothership will release two CubeSats each carrying a low-frequency radar. The radar will be a version of JuRa (60 MHz) [4], modified to operate in a bistatic mode and using an inter-satellite link as a synchronization channel. The mothership and the two CubeSats (daughtercraft) will also have cameras for both science and navigation.</p> <p><strong>Radar observation: </strong>Each daughtercraft radar can operate in a monostatic mode, or in a bistatic mode using the two platforms to measure the signal transmitted throughout Apophis, as CONSERT did onboard Rosetta orbiter and Philae lander [1,5,6,7].</p> <p><em>Monostatic radar. </em>A radar at 60 MHz offers a larger penetration (up to 100 meters or more) with a limited resolution (≈5 m). It corresponds to the instrument under implementation for the Juventas Cubesat on the Hera/ESA mission [4].</p> <p>Furthermore, multi-pass processing allows us to build a 3D tomographic image of the interior to identify internal structure like layers, voids and sub-aggregates, to bring out the aggregate structure and to characterize its constituent blocks in terms of size distribution and heterogeneity at different scales (from sub-metric to global). Initial dynamics modeling of the two Cubesats orbiting Apophis at 3 body radii indicates that 20% full Doppler coverage is possible in 40 days [2,8].</p> <p>Shallow subsurface characterization and radar images to support the shape modeling are also possible in this configuration, but with degraded performance due to a limited resolution.</p> <p><em>Bistatic radar. </em>The bistatic radar will firstly measure the signal in transmission, allowing us to achieve a direct measurement of the dielectric permittivity, which is related to composition and microporosity [6]. This objective is less demanding in terms of data volume and operation compared to full bistatic coverage. Partial transmission coverage will provide slices of the body with average characterization and its special variability. With dense coverage, benefiting from a larger diversity of observation angles, the bistatic mode will allow a complete 3D tomography [8,9]. In general, multi-angular acquisition allows for a better decorrelation of the size effect and permittivity contrast in the return power.</p> <p><em>Ground-to-space:</em> In addition to radar observation at close proximity, there is the possibility for joint ground-to-space radar observations at the epoch of the Apophis close approach. [10]. Such measurements would make use of high-power transmitters or sensitive radio astronomy observatories on Earth [11]. Ground-to-space configurations would be used to collect echoes in unique bistatic configurations or to collect echoes during spacecraft maneuvers at close approach (e.g., required spacecraft stand-off).</p>…
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