Impact Mission Research Articles

Social entrepreneurship in Trujillo, Peru: The case of Nisolo

This exploratory research examines Nisolo, a social entrepreneurship enterprise based in Trujillo, Peru, where currently its production facility seeks to hire local workers and build the surrounding community. Nisolo produces high-end shoes and tries to distribute its profits to the community of Trujillo. Using a case-study approach, our research intent is to develop a better understanding of this social entrepreneurship enterprise regarding social impact. The research uses a variety of data collection tools, including participatory observation, interviews, and a systematic review of sources consisting of private emails, photographs, videos, and newspaper articles. The findings indicate that Nisolo’s social impact mission positively impacts nearly 400 individuals in the local community. By providing consistent employment, fair wages, health care, livelihood training, and a savings and salary advance program, Nisolo is not only focusing on driving social change, but on creating a sustainable model that highlights potential fashion industry changes.

Ejecta cloud from the AIDA space project kinetic impact on the secondary of a binary asteroid: II. Fates and evolutionary dependencies

This paper presents a quantitative study of the evolution of the ejecta cloud released from a hypervelocity impact on a binary asteroid. We performed numerical simulations of the post-impact dynamics of the ejecta cloud in the framework of the current mission scenario of AIDA mission project. A grid search of launching sites of ejecta was defined over the globe of Didymoon, and considering a wide range of possible ejection speeds, we determined the dependency of ejecta fate on launching sites (projectile impact sites) and speeds. This range allows us to track all the complex cases that include different types of dynamical fates. Two major mechanisms are found to be working broadly during the post-ejection evolution of the ejecta cloud: 1) ejecta on mean motion resonance orbits with Didymoon produce long-term quasi-periodic showers onto Didymoon over at least a couple of weeks after the projectile impact, 2) ejecta on non-resonant orbits produce a rapid and high re-accretion flux. This rapid and high flux occurs just once because ejecta on such orbits leave the system unless they experience a collision during their first encounter. For the second part of this study, we performed full-scale simulations of the ejecta cloud released from 6 hypothetical impact sites. We considered two kinds of material composing Didymoon's subsurface and then combined a power-law size distribution of the ejecta with an ejection speed distribution. We find that the ejecta cloud evolution can be divided in two periods. It starts with a first violent period (<10 hr) with fast re-accretion or ejection from the system. A second period is found to be more sensitive to the launching site than the first one. During this second period, ejecta will either re-accrete or being ejected from the system, depending both on their sizes and on their average survival time in close proximity of the binary components.

A radar package for asteroid subsurface investigations: Implications of implementing and integration into the MASCOT nanoscale landing platform from science requirements to baseline design

The internal structure of asteroids is still poorly known and has never been analyzed directly by measurements. Our knowledge relies entirely on inferences from remote sensing observations of the surface and theoretical modeling. Direct measurements are crucial to characterize an asteroid's internal structure and heterogeneity from sub-metric to global scale. The radar package developed in the frame of the phase A/B1 of the Asteroid Impact Mission (AIM) as part of the larger Asteroid Impact & Deflection Assessment (AIDA) mission is a mature instrument suite to answer this question and to improve our ability to understand and model the mechanisms driving Near Earth Asteroids (NEA). It is of main interest for science, exploration and planetary defense. This instrument suite consists of a monostatic high frequency radar (HFR) to investigate the stratigraphy of surface regolith and a bistatic low frequency radar (LFR) to characterize the deep interior. The chosen platform to deliver the surface unit of the LFR and other instruments for a close-up study of the target asteroid is the MASCOT nanolander, which already flies on Hayabusa2 (HY2) in a mineralogy scout configuration. In this paper, we present the chosen instrumentation for radar science, baseline mission requirements and the initial design for integration into the lander platform, including all peculiarities and constraints.

Modeling the Deep Impact Near-nucleus Observations of H2O and CO2 in Comet 9P/Tempel 1 Using Asymmetric Spherical Coupled Escape Probability

Abstract We have applied our asymmetric spherical adaptation of Coupled Escape Probability to the modeling of optically thick cometary comae. Expanding on our previously published work, here we present models including asymmetric comae. Near-nucleus observations from the Deep Impact mission have been modeled, including observed coma morphology features. We present results for two primary volatile species of interest, H2O and CO2, for comet 9P/Tempel 1. Production rates calculated using our best-fit models are notably greater than those derived from the Deep Impact data based on the assumption of optically thin conditions, both for H2O and CO2 but more so for CO2, and fall between the Deep Impact values and the global pre-impact production rates measured at other observatories and published by Schleicher et al. (2006), Mumma et al. (2005), and Mäkinen et al. (2007).

AIDA DART asteroid deflection test: Planetary defense and science objectives

Abstract The Asteroid Impact & Deflection Assessment (AIDA) mission is an international cooperation between NASA and ESA. NASA plans to provide the Double Asteroid Redirection Test (DART) mission which will perform a kinetic impactor experiment to demonstrate asteroid impact hazard mitigation. ESA proposes to provide the Hera mission which will rendezvous with the target to monitor the deflection, perform detailed characterizations, and measure the DART impact outcomes and momentum transfer efficiency. The primary goals of AIDA are (i) to demonstrate the kinetic impact technique on a potentially hazardous near-Earth asteroid and (ii) to measure and characterize the deflection caused by the impact. The AIDA target will be the binary asteroid (65803) Didymos, which is of spectral type Sq, with the deflection experiment to occur in October, 2022. The DART impact on the secondary member of the binary at ∼6 km/s changes the orbital speed and the binary orbit period, which can be measured by Earth-based observatories with telescope apertures as small as 1 m. The DART impact will in addition alter the orbital and rotational states of the Didymos binary, leading to excitation of eccentricity and libration that, if measured by Hera, can constrain internal structure of the target asteroid. Measurements of the DART crater diameter and morphology can constrain target properties like cohesion and porosity based on numerical simulations of the DART impact.

Autonomous vision-based navigation for proximity operations around binary asteroids

Future missions to small bodies demand higher level of autonomy in the Guidance, Navigation and Control system for higher scientific return and lower operational costs. Different navigation strategies have been assessed for ESA’s asteroid impact mission (AIM). The main objective of AIM is the detailed characterization of binary asteroid Didymos. The trajectories for the proximity operations shall be intrinsically safe, i.e., no collision in presence of failures (e.g., spacecraft entering safe mode), perturbations (e.g., non-spherical gravity field), and errors (e.g., maneuver execution error). Hyperbolic arcs with sufficient hyperbolic excess velocity are designed to fulfil the safety, scientific, and operational requirements. The trajectory relative to the asteroid is determined using visual camera images. The ground-based trajectory prediction error at some points is comparable to the camera Field Of View (FOV). Therefore, some images do not contain the entire asteroid. Autonomous navigation can update the state of the spacecraft relative to the asteroid at higher frequency. The objective of the autonomous navigation is to improve the on-board knowledge compared to the ground prediction. The algorithms shall fit in off-the-shelf, space-qualified avionics. This note presents suitable image processing and relative-state filter algorithms for autonomous navigation in proximity operations around binary asteroids.

Hayabusa2–Sample return and kinetic impact mission to near-earth asteroid Ryugu

Abstract The Japan Aerospace Exploration Agency launched the asteroid sample return spacecraft “Hayabusa2” on December 3, 2014. Hayabusa2 will reach the C-type asteroid 162173 Ryugu in 2018, and return back to the Earth in 2020. Sample collections from three sites, four surface rovers deployment and a 4 MJ-class kinetic impact crater forming are planned in the 1.5 years of the asteroid-proximity operation. The mission objective of Hayabusa2 has three aspects, science, engineering and exploration, all of which would be expanded by the successful round-trip journey. The objectives and technologies used in this mission is not a direct solution for the future planetary defense, but should contribute to this field by increasing general asteroid knowledge and enhancing human capabilities of small body-surface access/roving/sampling/impacting. This paper describes the outline of the Hayabusa2 mission, overviews the kinetic impact technology as an example of planetary defense-related technologies and the current flight status after the two and a half years of the interplanetary cruise.

Reaction: Chemistry Driven by the Harsh Space Environment

Dr. Bill Farrell is a plasma physicist at NASA's Goddard Space Flight Center. He is a co-investigator on the Cassini mission to Saturn and the Parker Solar Probe mission. He is also principal investigator of the DREAM2 Center for Space Environments (http://ssed.gsfc.nasa.gov/dream/), which examines the exosphere formation, radiation effects, and plasma interactions of the Moon and other airless bodies. Dr. Farrell has authored or co-authored over 200 journal articles on various aspects of space science, including the hydroxylation at the Moon, the curious plasma effects within the Enceladus plume, and the possibility of electricity generated in Martian dust devils.

Reading Science, Technology and Education

In this paper, we present an interdisciplinary discussion on the relations between Science–Technology Education and Culture both historical standpoint and nowadays. The idea that a human mind can produce an intellectual revolution within science and its approaches (methods and methodologies also integrated with contradictions and criticisms) strongly crossed like a paradigm both in the history of sciences and disciplines–literatures (reasoning, early enlightenment, positivism, etc.): but what about its social impact and science mission, as well? To describe the impact of the disseminated knowledge is a consequent aim. A case study on energy conceptualization and its exhibitions in Society in Context is discussed; their correlations with education (pedagogical aspects included), science–techniques, industry and social impacts are discussed, as well.

European component of the AIDA mission to a binary asteroid: Characterization and interpretation of the impact of the DART mission

The European component of the joint ESA-NASA Asteroid Impact & Deflection Assessment (AIDA) mission has been redesigned from the original version called Asteroid Impact Mission (AIM), and is now called Hera. The main objectives of AIDA are twofold: (1) to perform an asteroid deflection test by means of a kinetic impactor under detailed study at NASA (called DART, for Double Asteroid Redirection Test); and (2) to investigate with Hera the changes in geophysical and dynamical properties of the target binary asteroid after the DART impact. This joint mission will allow extrapolating the results of the kinetic impact to other asteroids and therefore fully validate such asteroid deflection techniques. Hera leverages technology and payload pre-developments of the previous AIM, and focuses on key measurements to validate impact models such as the detailed characterisation of the impact crater. As such, AIDA will be the first documented deflection experiment and binary asteroid investigation. In particular, it will be the first mission to investigate a binary asteroid, and return new scientific knowledge with important implications for our understanding of asteroid formation and solar system history. Hera will investigate the smallest asteroid visited so far therefore providing a unique opportunity to shed light on the role cohesion and Van der Waals forces may play in the formation and resulting internal structure of such small bodies.

Design and validation of a GNC system for missions to asteroids: the AIM scenario

Deep space missions, and in particular missions to asteroids, impose a certain level of autonomy that depends on the mission objectives. If the mission requires the spacecraft to perform close approaches to the target body (the extreme case being a landing scenario), the autonomy level must be increased to guarantee the fast and reactive response which is required in both nominal and contingency operations. The GNC system must be designed in accordance with the required level of autonomy. The GNC system designed and tested in the frame of ESA’s Asteroid Impact Mission (AIM) system studies (Phase A/B1 and Consolidation Phase) is an example of an autonomous GNC system that meets the challenging objectives of AIM. The paper reports the design of such GNC system and its validation through a DDVV plan that includes Model-in-the-Loop and Hardware-in-the-Loop testing. Main focus is the translational navigation, which is able to provide online the relative state estimation with respect to the target body using exclusively cameras as relative navigation sensors. The relative navigation outputs are meant to be used for nominal spacecraft trajectory corrections as well as to estimate the collision risk with the asteroid and, if needed, to command the execution of a collision avoidance manoeuvre to guarantee spacecraft safety

Radio science investigations with the Asteroid impact mission

Abstract The Asteroid Impact & Deflection Assessment (AIDA) mission is a joint ESA/NASA collaboration to study the binary Near-Earth Asteroid (65,803) Didymos and assess the feasibility of the kinetic impactor technique to deflect an asteroid. The European contribution to AIDA is the Asteroid Impact Mission (AIM), which will characterize in detail the Didymos system, investigating the surface, subsurface, and internal properties of the asteroid. This paper presents a possible Radio Science Experiment (RSE) to be performed with AIM focused at its precise orbit determination within the Didymos system, providing an assessment of the accuracies achievable in the estimation of the scientific parameters of interest, like the masses and the extended gravity fields of Didymos primary and secondary, their relative orbit, and their rotational states. The experiment expected performances were assessed through numerical simulations, based upon a complete and realistic dynamical model of the Didymos system and the AIM spacecraft. Given the small mass of the Didymos system, optical navigation images proved to be crucial to obtain good accuracies for the scientific parameters of interest, even keeping AIM at relatively large distances from Didymos. At 10 km, after 8 flybys dedicated to gravity science, the masses of the primary and secondary can be estimated to about 0.2% and 1.6% (1-sigma), respectively, with the mass of the secondary being mainly given by observing the wobble of the primary around the common center of mass due to the mutual orbital motion; the orbital motion of the secondary around the primary can be estimated to about 1 m, and the pole orientation of the primary and the secondary can be estimated to about 0.1 deg and 0.4 deg, respectively (1-sigma).

Ballistic landing design on binary asteroids: The AIM case study

Abstract The close-proximity exploration of small celestial bodies of our Solar System is the current frontier of space exploration. Trajectory design and exploitation of the natural dynamics around such bodies represents a very challenging astrodynamics problem, due to their weak and highly chaotic gravitational environment. The paper discusses design solutions for the ballistic landing of a small and passive probe, released to land on the smaller of a binary asteroid couple. The work is focused on the Asteroid Impact Mission (AIM) case study, although the methods and analyses presented are general and applicable to any binary asteroid scenario. The binary system is modeled using a shape-based three-body problem and three-body solutions are investigated within the Didymos binary system. Manifold dynamics near libration points associated to the asteroid three-body system are exploited to find low-energy and high-success landing trajectories. The validity of implemented approach and solutions found are discussed and results in terms of success rate and landing dispersion are shown.

Constraints on the perturbed mutual motion in Didymos due to impact-induced deformation of its primary after the DART impact

Binary near-Earth asteroid (65803) Didymos is the target of the proposed NASA Double Asteroid Redirection Test (DART), part of the Asteroid Impact & Deflection Assessment (AIDA) mission concept. In this mission, the DART spacecraft is planned to impact the secondary body of Didymos, perturbing mutual dynamics of the system. The primary body is currently rotating at a spin period close to the spin barrier of asteroids, and materials ejected from the secondary due to the DART impact are likely to reach the primary. These conditions may cause the primary to reshape, due to landslides, or internal deformation, changing the permanent gravity field. Here, we propose that if shape deformation of the primary occurs, the mutual orbit of the system would be perturbed due to a change in the gravity field. We use a numerical simulation technique based on the full two-body problem to investigate the shape effect on the mutual dynamics in Didymos after the DART impact. The results show that under constant volume, shape deformation induces strong perturbation in the mutual motion. We find that the deformation process always causes the orbital period of the system to become shorter. If surface layers with a thickness greater than ~0.4 m on the poles of the primary move down to the equatorial region due to the DART impact, a change in the orbital period of the system and in the spin period of the primary will be detected by ground-based measurement.

Creep stability of the proposed AIDA mission target 65803 Didymos: I. Discrete cohesionless granular physics model

As the target of the proposed Asteroid Impact & Deflection Assessment (AIDA) mission, the near-Earth binary asteroid 65803 Didymos represents a special class of binary asteroids, those whose primaries are at risk of rotational disruption. To gain a better understanding of these binary systems and to support the AIDA mission, this paper investigates the creep stability of the Didymos primary by representing it as a cohesionless self-gravitating granular aggregate subject to rotational acceleration. To achieve this goal, a soft-sphere discrete element model (SSDEM) capable of simulating granular systems in quasi-static states is implemented and a quasi-static spin-up procedure is carried out. We devise three critical spin limits for the simulated aggregates to indicate their critical states triggered by reshaping and surface shedding, internal structural deformation, and shear failure, respectively. The failure condition and mode, and shear strength of an aggregate can all be inferred from the three critical spin limits. The effects of arrangement and size distribution of constituent particles, bulk density, spin-up path, and interparticle friction are numerically explored. The results show that the shear strength of a spinning self-gravitating aggregate depends strongly on both its internal configuration and material parameters, while its failure mode and mechanism are mainly affected by its internal configuration. Additionally, this study provides some constraints on the possible physical properties of the Didymos primary based on observational data and proposes a plausible formation mechanism for this binary system. With a bulk density consistent with observational uncertainty and close to the maximum density allowed for the asteroid, the Didymos primary in certain configurations can remain geo-statically stable without including cohesion.

Nanoindenting the Chelyabinsk Meteorite to Learn about Impact Deflection Effects in asteroids

Abstract The Chelyabinsk meteorite is a highly shocked, low porosity, ordinary chondrite, probably similar to S- or Q-type asteroids. Therefore, nanoindentation experiments on this meteorite allow us to obtain key data to understand the physical properties of near-Earth asteroids. Tests at different length scales provide information about the local mechanical properties of the minerals forming this meteorite: reduced Young’s modulus, hardness, elastic recovery, and fracture toughness. Those tests are also useful to understand the potential to deflect threatening asteroids using a kinetic projectile. We found that the differences in mechanical properties between regions of the meteorite, which increase or reduce the efficiency of impacts, are not a result of compositional differences. A low mean particle size, attributed to repetitive shock, can increase hardness, while low porosity promotes a higher momentum multiplication. Momentum multiplication is the ratio between the change in momentum of a target due to an impact, and the momentum of the projectile, and therefore, higher values imply more efficient impacts. In the Chelyabinsk meteorite, the properties of the light-colored lithology materials facilitate obtaining higher momentum multiplication values, compared to the other regions described for this meteorite. Also, we found a low value of fracture toughness in the shock-melt veins of Chelyabinsk, which would promote the ejection of material after an impact and therefore increase the momentum multiplication. These results are relevant to the growing interest in missions to test asteroid deflection, such as the recent collaboration between the European Space Agency and NASA, known as the Asteroid Impact and Deflection Assessment mission.

Thermophysical modeling of Didymos’ moon for the Asteroid Impact Mission

Abstract Although typically less resolved through observations, the secondary in a binary system of asteroids is an interesting target for space missions such as the Asteroid Impact Mission. Estimates of the surface temperature distribution are important for mission design. Based on known, assumed and derived physical properties, a thermophysical model of the smaller body in the 65803 Didymos system is established. Because of the unknown thermal inertia, a parameter study has been carried out for a thermal inertia range of Γ = 50 –1000 J m−2 K−1 s−1/2. Results are presented for the minimum and maximum values of this range and a likely value of Γ = 500 J m−2 K−1 s−1/2. The parameter study extends from the unshadowed to the eclipsed case where shadowing through the primary is simulated in a simplified manner assuming that the orbit of the moon lies in the equatorial plane of the primary with its z-axis normal to this plane. Results from this study are used to investigate performance for instruments foreseen for the Asteroid Impact Mission. Preliminary results are obtained for the signal-to-noise ratio of a proposed thermal infrared imager. Furthermore, MASCOT-2 Lander thermal survivability has been investigated for several possible landing sites and specific settings.

Numerical investigation of the dynamical environment of 65803 Didymos

Abstract The Asteroid Impact & Deflection Assessment (AIDA) mission is planning to visit the Didymos binary system in 2022 in order to perform the first demonstration ever of the kinetic impact technique. Binary asteroids are an ideal target for this since the deflection of the secondary body can be accurately measured by a satellite orbiting in the system. However, these binaries offer an extremely rich dynamical environment whose accurate investigation through analytical approaches is challenging at best and requires a significant number of restrictive assumptions. For this reason, a numerical investigation of the dynamical environment in the vicinity of the Didymos system is offered in this paper. After computing various families of periodic orbits, their robustness is assessed in a high-fidelity environment consisting of the perturbed restricted full three-body problem. The results of this study suggest that several nominally stable trajectories, including the triangular libration points, should not be considered as safe as a state vector perturbation may cause the spacecraft to drift from the nominal orbit and possibly impact one of the primary bodies within a few days. Nonetheless, there exist two safe solutions, namely terminator and interior retrograde orbits. The first one is adequate for observation purposes of the entire system and for communications. The second one is more suitable to perform close investigations of the primary body.

Ejecta cloud from the AIDA space project kinetic impact on the secondary of a binary asteroid: I. mechanical environment and dynamical model

An understanding of the post-impact dynamics of ejecta clouds are crucial to the planning of a kinetic impact mission to an asteroid, and also has great implications for the history of planetary formation. The purpose of this article to track the evolution of ejecta produced by AIDA mission, which targets for kinetic impact the secondary of near-Earth binary asteroid 65803 Didymos on 2022, and to feedback essential informations to AIDA's ongoing phase-A study. We present a detailed dynamic model for the simulation of an ejecta cloud from a binary asteroid that synthesizes all relevant forces based on a previous analysis of the mechanical environment. We apply our method to gain insight into the expected response of Didymos to the AIDA impact, including the subsequent evolution of debris and dust. The crater scaling relations from laboratory experiments are employed to approximate the distributions of ejecta mass and launching speed. The size composition of fragments is modeled with a power law fitted from observations of real asteroid surface. A full-scale demonstration is simulated using parameters specified by the mission. We report the results of the simulation, which include the computed spread of the ejecta cloud and the recorded history of ejecta accretion and escape. The violent period of the ejecta evolution is found to be short, and is followed by a stage where the remaining ejecta is gradually cleared. Solar radiation pressure proves to be efficient in cleaning dust-size ejecta, and the simulation results after two weeks shows that large debris on polar orbits (perpendicular to the binary orbital plane) has a survival advantage over smaller ejecta and ejecta that keep to low latitudes.

Incidence, Etiology and Risk Factors for Travelers' Diarrhea during a Hospital Ship-Based Military Humanitarian Mission: Continuing Promise 2011.

Travelers’ diarrhea (TD) is the most common ailment affecting travelers, including deployed U.S. military. Continuing Promise 2011 was a 5-month humanitarian assistance/disaster response (HA/DR) military and non-governmental organization training mission aboard the hospital ship USNS Comfort, which deployed to Central and South America and the Caribbean between April and September 2011. Enhanced TD surveillance was undertaken during this mission for public health purposes. Passive surveillance (clinic visits), active surveillance (self-reported questionnaires), and stool samples were collected weekly from shipboard personnel. Descriptive statistics and multivariate-logistic regression methods were used to estimate disease burden and risk factor identification. Two polymerase chain reaction methods on frozen stool were used for microbiological identification. TD was the primary complaint for all clinic visits (20%) and the leading cause of lost duties days due to bed rest confinement (62%), though underreported, as the active self-reported incidence was 3.5 times higher than the passive clinic-reported incidence. Vomiting (p = 0.002), feeling lightheaded or weak (p = 0.005), and being a food handler (p = 0.017) were associated with increased odds of lost duty days. Thirty-eight percent of self-reported cases reported some amount of performance impact. Based on the epidemiological curve, country of exercise and liberty appeared to be temporally associated with increased risk. From the weekly self-reported questionnaire risk factor analysis, eating off ship in the prior week was strongly associated (adjusted odds ratio [OR] 2.4, p<0.001). Consumption of seafood increased risk (aOR 1.7, p = 0.03), though consumption of ice appeared protective (aOR 0.3, p = 0.01). Etiology was bacterial (48%), with enterotoxigenic Escherichia coli as the predominant pathogen (35%). Norovirus was identified as a sole pathogen in 12%, though found as a copathogen in an additional 6%. Despite employment of current and targeted preventive interventions, ship-board HA/DR missions may experience a significant risk for TD among deployed US military personnel and potentially impact mission success.