49 research outputs found
Hayabusa2's Superior Solar Conjunction Phase Trajectory Design, Guidance and Navigation
Hayabusa2 is the ongoing JAXAâs sample and return mission to the asteroid Ryugu. In late 2018, Ryugu was in superior solar conjunction with the Earth. It is the first time that a spacecraft experiences the blackouts in the communication link with the Earth while hovering around a small celestial body. In this article, the design of the nominal conjunction trajectory flown by the Hayabusa2âs spacecraft is presented. The requirements for the conjunction trajectory were (1) to guarantee a low fuel consumption, (2) to ensure the visibility of the asteroid by the spacecraftâs wide angle camera (60â FoV), and (3) to increase the spacecraft altitude to a safety location (âŒ109 km) from the nominal BOX-A operation of 20 km (Home Position - HP). Finally, (4) to return at BOX-A after the conjunction phase. Given the mission constraints, the designed conjunction trajectory appears to have a fish-shape in the Hill coordinates therefore we renamed it as âayuâ (sweetfish in Japanese) trajectory. The optNEAR tool was developed for the guidance (ÎVs planning) and navigation design of the Hayabusa2âs conjunction mission phase. A preliminary sensitivity analysis in the Hill reference frame proved that the ayu trajectory is a good candidate for the conjunction operation of hovering satellite. The solution in the Hill coordinates is refined in the full-body planetary dynamics (optNEAR Tool) before flight. The ayu conjunction trajectory requires (a) two deterministic ÎVs at the Conjunction Orbit Insertion (COI) point and at the Home-position Recovery Maneuver (HRM) point respectively. (b) Two stochastic ÎVs, known as Trajectory Correction Manoeuvres (TCMs), before and after the deep conjunction phase are also required. The constraint linear covariance analysis in the full-body dynamics is here derived and used for the preliminary guidance and navigation planning. The results of the covariance analysis were validated in a nonlinear sense with a Monte Carlo approach which proved the validity of the semi-analytic method for the stochastic ÎVs planning derived in this paper
A generalised methodology for analytic construction of 1:1 resonances around irregular bodies: Application to the asteroid Ryuguâs ejecta dynamics
An analytic construction of 1:1 resonances around irregular bodies is here investigated. A SPH-Mas based gravity model allows a semi-analytic expression of the linearised equations around the equilibrium points. Depending on the sphere packing distribution, the SPH-Mas model can retrieve the same dynamical objects common to others gravity models (i.e. spherical harmonics and polyhedron) or for non uniform density objects. This model has the advantage to define the same particles mesh distribution for both astrophysical and astrodynamics tools and it is computationally optimised for Matlab. The Hayabusa2âs Small Carry-on Impactor operation is used as a scenario to study the ejecta particle dynamics around an irregular body. The goNEAR tool was used to simulate the impact operation in a non-linear sense when the effect of the solar radiation pressure perturbation is taken into account for particles size of 10âŻcm, 5âŻcm, 1âŻcm and 1âŻmm in diameter
Mechanical Design of Self-Reconfiguring 4D-Printed OrigamiSats: A New Concept for Solar Sailing
In this article, a self-reconfiguring OrigamiSat concept is presented. The reconfiguration of the proposed OrigamiSat is triggered by combining the effect of 4D material (i.e. origamiâs edges) and changes in the local surface optical properties (i.e., origamiâs facets) to harness the solar radiation pressure acceleration. The proposed OrigamiSat uses the principle of solar sailing to enhance the effect of the Sun radiation to generate momentum on the Aluminised Kapton (Al-Kapton) origami surface by transitioning from mirror-like to diffusely reflecting optical properties of each individual facet. Numerical simulations have demonstrated that local changes in the optical properties can trigger reconfiguration. A minimum of 1-m edge size facet is required for a thick-origami to generate enough forces from the Sun radiation. The thick-origami pattern is 3D-printed directly on a thin Al-Kapton film (the solar sail substrate which is highly reflective). An elastic filament (thermoplastic polyurethane TPU) showed best performance when printing directly on the Al-Kapton and the Acrylonitrile Butadiene Styrene with carbon fiber reinforcement (ABS/cc) is added to augment the origami mechanical properties. The 4D material (shape memory polymer) is integrated only at specific edges to achieve self-deployment by applying heat. Two different folding mechanisms were studied: 1) the cartilage-like, where the hinge is made combining the TPU and the 4D material which make the mounts or valleys fully stretchable, and 2) the mechanical hinge, where simple hinges are made solely of ABS/cc. Numerical simulations have demonstrated that the cartilage-like hinge is the most suitable design for light-weight reconfigurable OrigamiSat when using the solar radiation pressure acceleration. We have used build-in electric board to heat up the 4D material and trigger the folding. We envisage embedding the heat wire within the 4D hinge in the future.</jats:p
Pre-encounter predictions of DART impact ejecta behavior and observability
We overview various efforts within the DART Investigation Teamâs Ejecta Working Group to predict the characteristics, quantity, dynamical behavior, and observability of DART impact ejecta. We discuss various methodologies for simulation of the impact/cratering process with their advantages and drawbacks in relation to initializing ejecta for subsequent dynamical propagation through and away from the Didymos system. We discuss the most relevant forces acting on ejecta once decoupled from Dimorphosâs surface and highlight various software packages we have developed and used to dynamically simulate ejecta under the action of those forces. With some additional software packages, we explore the influence of additional perturbing effects, such as interparticle collisions within true N-body codes and nonspherical and rotating particlesâ interplay with solar radiation pressure. We find that early-timescale and close-proximity ejecta evolution is highly sensitive to some of these effects (e.g., collisions) while relatively insensitive to other factors. We present a methodology for turning the time-evolving size- and spatially discretized number density field output from ejecta simulations into synthetic images for multiple platforms/cameras over wide-ranging vantage points and timescales. We present such simulated images and apply preliminary analyses to them for nominal and off-nominal cases bracketing realistic total mass of ejecta and ejecta cumulative sizeâfrequency distribution slope. Our analyses foreshadow the information content we may be able to extract from the actual images taken during and after the DART encounter by both LICIACube and Earth-vicinity telescopes.ANII: FCE_1_2019_1_15645
Double Asteroid Redirection Test (DART): Structural and Dynamic Interactions between Asteroidal Elements of Binary Asteroid (65803) Didymos
Abstract NASA's Double Asteroid Redirection Test (DART) mission is the first full-scale planetary defense mission. The target is the binary asteroid (65803) Didymos, in which the smaller component Dimorphos (âŒ164 m equivalent diameter) orbits the larger component Didymos (âŒ780 m equivalent diameter). The DART spacecraft will impact Dimorphos, changing the systemâs mutual orbit by an amount that correlates with DART's kinetic deflection capability. The spacecraft collision with Dimorphos creates an impact crater, which reshapes the body. Also, some particles ejected from the DART impact site on Dimorphos eventually reach Didymos. Because Didymosâs rapid spin period (2.26 hr) may be close to its stability limit for structural failure, the ejecta reaching Didymos may induce surface disturbance on Didymos. While large uncertainties exist, nonnegligible reshaping scenarios on Didymos and Dimorphos are possible if certain conditions are met. Our analysis shows that given a surface slope uncertainty on Dimorphos of 45°, with no other information about its local topography, and if the DART-like impactor is treated as spherical, the ejecta cone crosses Didymos with speeds âł14 m sâ1 in 13% of simulations. Additional work is necessary to determine the amount of mass delivered to Didymos from the DART impact and whether the amount of kinetic energy delivered is sufficient to overcome cohesive forces in those cases. If nonnegligible (but small) reshaping occurs for either of these asteroids, the resulting orbit perturbation and reshaping are measurable by Earth-based observations.</jats:p
Hayabusa2âs superior solar conjunction mission operations: planning and post-operation results
Abstract In late 2018, the asteroid Ryugu was in the Sunâs shadow during the superior solar conjunction phase. As the Sun-Earth-Ryugu angle decreased to below 3°, the Hayabusa2 spacecraft experienced 21 days of planned blackout in the Earth-probe communication link. This was the first time a spacecraft had experienced solar conjunction while hovering around a minor body. For the safety of the spacecraft, a low energy transfer trajectory named Ayu was designed in the Hill reference frame to increase its altitude from 20 to 110 km. The trajectory was planned with the newly developed optNEAR tool and validated with real time data. This article shows the results of the conjunction operation, from planning to flight data.</jats:p
After DART: Using the First Full-scale Test of a Kinetic Impactor to Inform a Future Planetary Defense Mission
NASAâs Double Asteroid Redirection Test (DART) is the first full-scale test of an asteroid deflection technology. Results from the hypervelocity kinetic impact and Earth-based observations, coupled with LICIACube and the later Hera mission, will result in measurement of the momentum transfer efficiency accurate to âŒ10% and characterization of the Didymos binary system. But DART is a single experiment; how could these results be used in a future planetary defense necessity involving a different asteroid? We examine what aspects of Dimorphosâs response to kinetic impact will be constrained by DART results; how these constraints will help refine knowledge of the physical properties of asteroidal materials and predictive power of impact simulations; what information about a potential Earth impactor could be acquired before a deflection effort; and how design of a deflection mission should be informed by this understanding. We generalize the momentum enhancement factor ÎČ, showing that a particular direction-specific ÎČ will be directly determined by the DART results, and that a related direction-specific ÎČ is a figure of merit for a kinetic impact mission. The DART ÎČ determination constrains the ejecta momentum vector, which, with hydrodynamic simulations, constrains the physical properties of Dimorphosâs near-surface. In a hypothetical planetary defense exigency, extrapolating these constraints to a newly discovered asteroid will require Earth-based observations and benefit from in situ reconnaissance. We show representative predictions for momentum transfer based on different levels of reconnaissance and discuss strategic targeting to optimize the deflection and reduce the risk of a counterproductive deflection in the wrong direction
After DART: Using the first full-scale test of a kinetic impactor to inform a future planetary defense mission
NASA's Double Asteroid Redirection Test (DART) is the first full-scale test
of an asteroid deflection technology. Results from the hypervelocity kinetic
impact and Earth-based observations, coupled with LICIACube and the later Hera
mission, will result in measurement of the momentum transfer efficiency
accurate to ~10% and characterization of the Didymos binary system. But DART is
a single experiment; how could these results be used in a future planetary
defense necessity involving a different asteroid? We examine what aspects of
Dimorphos's response to kinetic impact will be constrained by DART results; how
these constraints will help refine knowledge of the physical properties of
asteroidal materials and predictive power of impact simulations; what
information about a potential Earth impactor could be acquired before a
deflection effort; and how design of a deflection mission should be informed by
this understanding. We generalize the momentum enhancement factor ,
showing that a particular direction-specific will be directly
determined by the DART results, and that a related direction-specific
is a figure of merit for a kinetic impact mission. The DART
determination constrains the ejecta momentum vector, which, with hydrodynamic
simulations, constrains the physical properties of Dimorphos's near-surface. In
a hypothetical planetary defense exigency, extrapolating these constraints to a
newly discovered asteroid will require Earth-based observations and benefit
from in-situ reconnaissance. We show representative predictions for momentum
transfer based on different levels of reconnaissance and discuss strategic
targeting to optimize the deflection and reduce the risk of a counterproductive
deflection in the wrong direction
After DART: Using the First Full-scale Test of a Kinetic Impactor to Inform a Future Planetary Defense Mission
After DART: Using the First Full-scale Test of a Kinetic Impactor to Inform a Future
Planetary Defense Mission
Thomas S. Statler 1 , Sabina D. Raducan 2 , Olivier S. Barnouin 3 , Mallory E. DeCoster 3 , Steven R. Chesley 4 ,
Brent Barbee 5
, Harrison F. Agrusa 6 , Saverio Cambioni 7 , Andrew F. Cheng 3 , Elisabetta Dotto 8
, Siegfried Eggl9 ,
Eugene G. Fahnestock 4
, Fabio Ferrari 2 , Dawn Graninger 3 , Alain Herique 10
, Isabel Herreros 11
, Masatoshi Hirabayashi 12,13 ,
Stavro Ivanovski 14
, Martin Jutzi 2
, ĂzgĂŒr Karatekin 15
, Alice Lucchetti 16
, Robert Luther 17 , Rahil Makadia 9 ,
Francesco Marzari 18 , Patrick Michel 19 , Naomi Murdoch 20
, Ryota Nakano13 , Jens Ormö 11 , Maurizio Pajola 16 ,
Andrew S. Rivkin3 , Alessandro Rossi 21 , Paul SĂĄnchez 22 , Stephen R. Schwartz 23
, Stefania Soldini 24
, Damya Souami 19
,
Angela Stickle 3 , Paolo Tortora 25
, Josep M. Trigo-RodrĂguez 26,27 , Flaviane Venditti 28 , Jean-Baptiste Vincent 29
, and
Kai WĂŒnnemann 17,30
1 Planetary Defense Coordination Office and Planetary Science Division, NASA Headquarters, 300 Hidden Figures Way SW, Washington, DC 20546, USA
[email protected]
2 Space Research and Planetary Sciences, Physics Institute, University of Bern, Bern, 3012, Switzerland
3 Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA
4 Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
5 NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
6 Department of Astronomy, University of Maryland, College Park, MD 20742, USA
7 Department of Earth, Atmospheric & Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
8 INAF-Osservatorio Astronomico di Roma, Rome, I-00078, Italy
9 Department of Aerospace Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
10 Univ. Grenoble Alpes, CNRS, CNES, IPAG, F-38000 Grenoble, France
11 Centro de AstrobiologĂa CSIC-INTA, Instituto Nacional de TĂ©cnica Aeroespacial, E-28850 TorrejĂłn de Ardoz, Spain
12 Department of Geosciences, Auburn University, Auburn, AL 36849, USA
13 Department of Aerospace Engineering, Auburn University, Auburn, AL 36849, USA
14 INAF- Osservatorio Astronomico di Trieste, Trieste I-34143, Italy
15 Royal Observatory of Belgium, Belgium
16 INAF-Astronomical Observatory of Padova, Padova I-35122, Italy
17 Museum fĂŒr NaturkundeâLeibniz Institute for Evolution and Biodiversity Science, Germany
18 University of Padova, Padova, Italy
19 UniversitĂ© CĂŽte dâAzur, Observatoire de la CĂŽte dâAzur, CNRS, Laboratoire Lagrange, Nice F-06304, France
20 Institut SupĂ©rieur de lâAĂ©ronautique et de lâEspace (ISAE-SUPAERO), UniversitĂ© de Toulouse, Toulouse, France
21 IFAC-CNR, Sesto Fiorentino I-50019, Italy
22 Colorado Center for Astrodynamics Research, University of Colorado Boulder, Boulder, CO 80303, USA
23 Planetary Science Institute, Tucson, AZ 85719, USA
24 Department of Mechanical, Materials and Aerospace Engineering, University of Liverpool, Liverpool, UK
25 Alma Mater StudiorumâUniversitĂ di Bologna, Department of Industrial Engineering, Interdepartmental Center for Industrial Research in Aerospace, Via
Fontanelle 40âForlĂŹ (FC)âI-47121, Italy
26 Institute of Space Sciences (ICE, CSIC), Cerdanyola del VallĂšs, E-08193 Barcelona, Catalonia, Spain
27 Institut dâEstudis Espacials de Catalunya (IEEC), Ed. Nexus, E-08034 Barcelona, Catalonia, Spain
28 Arecibo Observatory, University of Central Florida, HC-3 Box 53995, Arecibo, PR 00612, USA
29 German Aerospace Center, DLR Berlin, Germany
30 Freie UniversitÀt Berlin, Germany
Received 2022 August 9; revised 2022 September 18; accepted 2022 September 22; published 2022 October 28
Abstract
NASAâs Double Asteroid Redirection Test (DART) is the first full-scale test of an asteroid deflection technology.
Results from the hypervelocity kinetic impact and Earth-based observations, coupled with LICIACube and the later
Hera mission, will result in measurement of the momentum transfer efficiency accurate to âŒ10% and
characterization of the Didymos binary system. But DART is a single experiment; how could these results be used
in a future planetary defense necessity involving a different asteroid? We examine what aspects of Dimorphosâs
response to kinetic impact will be constrained by DART results; how these constraints will help refine knowledge
of the physical properties of asteroidal materials and predictive power of impact simulations; what information
about a potential Earth impactor could be acquired before a deflection effort; and how design of a deflection
mission should be informed by this understanding. We generalize the momentum enhancement factor ÎČ, showing
that a particular direction-specific ÎČ will be directly determined by the DART results, and that a related direction-
specific ÎČ is a figure of merit for a kinetic impact mission. The DART ÎČ determination constrains the ejecta
momentum vector, which, with hydrodynamic simulations, constrains the physical properties of Dimorphosâs near-
surface. In a hypothetical planetary defense exigency, extrapolating these constraints to a newly discovered
asteroid will require Earth-based observations and benefit from in situ reconnaissance. We show representative predictions for momentum transfer based on different levels of reconnaissance and discuss strategic targeting to
optimize the deflection and reduce the risk of a counterproductive deflection in the wrong direction