The Community at the Bargaining Table. A Report on the Community's Role in Collective Bargaining in the Schools.

ERIC Educational Resources Information Center

Institute for Responsive Education, Boston, MA.

The Institute for Responsive Education and its study team are looking at ways to widen the scope of collective bargaining to provide room for communities to participate in policy formulation in their schools. The traditional management-labor approach was designed to resolve differences about wages, fringe benefits, and the rules, rights, and…

Fighting The Network: Manet Management In Support Of Littoral Operations

DTIC Science & Technology

2016-03-01

Solomon , 2015). DL widens the scope of naval Surface Action Groups (SAG) operations, introducing the concept of Adaptive Force Package (AFP...be implemented in littoral tactical networks. CENETIX research utilizes three Wave Relay radio models for experimentation : the Man-Portable Unit...enable seamless continuity in the transfer of research knowledge to subsequent testing and CONOPS development. CENETIX field experimentation

The Design and Development of an Intelligent Planning Aid

DTIC Science & Technology

1986-07-01

reasons why widening the scope of TACPLAK’s applicability make sense. First# plan execution and monitoring (and the re-planning that then occurs) are...Orsssnu, contracting officer’s representative I», KKY voees o Decision Making Tactical Planning Taxonomy Problem Solving ii M ifrntitr *r MM* I...planning aid. It documents the development of a decision- making , planning, and decision-aiding analytical framework comprising a set of models, s generic

Enactments in Psychoanalysis: Therapeutic Benefits.

PubMed

Stern, Stanley

The therapeutic benefits of enactments are addressed. Relevant literature reveals disparate conceptions about the nature and use of enactments. Clarification of the term is discussed. This analyst's theoretical and technical evolution is addressed; it is inextricably related to using enactments. How can it not be? A taxonomy of enactments is presented. The article considers that enactments may be fundamental in the evolution from orthodox to contemporary analytic technique. Assumptions underlying enactments are explored, as are guidelines for using enactments. Finally, the article posits that enactments have widened the scope of analysis and contributed to its vitality.

International Lunar Decade Status

NASA Astrophysics Data System (ADS)

Beldavs, VZ; Crisafulli, J.; Dunlop, D.; Foing, B.

2017-09-01

The International Lunar Decade is a global decadal event designed to provide a framework for strategically directed international cooperation for permanent return to the Moon. To be launched July 20, 2019, the 50th anniversary of the giant leap for mankind marked by Neil Armstrong's first step on the Moon, the ILD launch will include events around the world to celebrate space exploration, science, and the expansion of humanity into the Solar System. The ILD framework links lunar exploration and space sciences with the development of enabling technologies, infrastructure, means of financing, laws and policies aimed at lowering the costs and risks of venturing into space. Dramatically reduced costs will broaden the range of opportunities available in space and widen access to space for more states, companies and people worldwide. The ILD is intended to bring about the efflorescence of commercial business based on space resources from the Moon, asteroids, comets and other bodies in the Solar System.

Sedna Orbit Animation

NASA Technical Reports Server (NTRS)

2004-01-01

This animation shows the location of the newly discovered planet-like object, dubbed 'Sedna,' in relation to the rest of the solar system. Starting at the inner solar system, which includes the orbits of Mercury, Venus, Earth, and Mars (all in yellow), the view pulls away through the asteroid belt and the orbits of the outer planets beyond (green). Pluto and the distant Kuiper Belt objects are seen next until finally Sedna comes into view. As the field widens the full orbit of Sedna can be seen along with its current location. Sedna is nearing its closest approach to the Sun; its 10,000 year orbit typically takes it to far greater distances. Moving past Sedna, what was previously thought to be the inner edge of the Oort cloud appears. The Oort cloud is a spherical distribution of cold, icy bodies lying at the limits of the Sun's gravitational pull. Sedna's presence suggests that this Oort cloud is much closer than scientists believed.

Welfare benefits' screening and referral: a new direction for community nurses?

PubMed

Hoskins, Robert; Carter, Diana E.

2000-11-01

The White Paper, Towards a Healthier Scotland considerably widens the community nursing scope for health promotion, as it recognises that disadvantaged life circumstances as well as unhealthy lifestyles contribute to poor health. It has been shown that income and health are interrelated. This evidence has demonstrated that it is not how rich a nation is that determines the overall health of its inhabitants; it is how equitably its wealth is distributed that counts: countries that have narrow income differentials tend to have better health. Both the income and health divide in Britain widened considerably between 1980 and 1992. It is argued that increasing income inequality leads to social isolation and chronic stress, which can impact on psycho-social pathways and damages life expectancy. This paper suggests that community nurses can address adverse life circumstances by finding ways of improving the economic status of their most vulnerable clients, and that one way of doing this would be to ensure that clients claim their full quota of welfare entitlement, given that there is several billion pounds of social security benefits that remain unclaimed in Britain every year.

Overview of robotic colorectal surgery: Current and future practical developments

PubMed Central

Roy, Sudipta; Evans, Charles

2016-01-01

Minimal access surgery has revolutionised colorectal surgery by offering reduced morbidity and mortality over open surgery, while maintaining oncological and functional outcomes with the disadvantage of additional practical challenges. Robotic surgery aids the surgeon in overcoming these challenges. Uptake of robotic assistance has been relatively slow, mainly because of the high initial and ongoing costs of equipment but also because of limited evidence of improved patient outcomes. Advances in robotic colorectal surgery will aim to widen the scope of minimal access surgery to allow larger and more complex surgery through smaller access and natural orifices and also to make the technology more economical, allowing wider dispersal and uptake of robotic technology. Advances in robotic endoscopy will yield self-advancing endoscopes and a widening role for capsule endoscopy including the development of motile and steerable capsules able to deliver localised drug therapy and insufflation as well as being recharged from an extracorporeal power source to allow great longevity. Ultimately robotic technology may advance to the point where many conventional surgical interventions are no longer required. With respect to nanotechnology, surgery may eventually become obsolete. PMID:26981188

Improving collaboration between large and small-medium enterprises in automobile production

NASA Astrophysics Data System (ADS)

Sung, Soyoung; Kim, Yanghoon; Chang, Hangbae

2018-01-01

Inter-organisational collaboration is important for achieving qualitative and quantitative performance improvement in the global competitive environment. In particular, the extent of collaboration between the mother company and its suppliers is important for the profitability and sustainability of a company in the automobile industry, which is carried out using a customisation and order production system. As a result of the empirical analysis in this study, the collaborative information sharing cycle is shortened and the collaborative information sharing scope is widened. Therefore, the level of collaboration is improved by constructing an IT collaboration system.

Virtual Screening Approaches towards the Discovery of Toll-Like Receptor Modulators

PubMed Central

Pérez-Regidor, Lucía; Zarioh, Malik; Ortega, Laura; Martín-Santamaría, Sonsoles

2016-01-01

This review aims to summarize the latest efforts performed in the search for novel chemical entities such as Toll-like receptor (TLR) modulators by means of virtual screening techniques. This is an emergent research field with only very recent (and successful) contributions. Identification of drug-like molecules with potential therapeutic applications for the treatment of a variety of TLR-regulated diseases has attracted considerable interest due to the clinical potential. Additionally, the virtual screening databases and computational tools employed have been overviewed in a descriptive way, widening the scope for researchers interested in the field. PMID:27618029

[Anorectal manifestations of sexually transmissible diseases. Kaposi's sarcoma].

PubMed

Libeskind, M; Malbran, J; Agard, D; Pannetier, C; Lecouillard, C; Ivanovic, A

1984-01-01

The proctologist is above all concerned with the known recrudescence of venereal diseases. Examples reviewed are diseases of bacterial origin (syphilis, gonorrhea, soft chancre, donovanosis and chlamydiosis), appropriate antibiotic therapy and diseases of viral origin (herpes, condyloma acuminatum). Also noted are other bacterial, viral and parasitic diseases and, indeed, cancers of which Kaposi's sarcoma is the example, even though these are not manifested anorectally. New data on Kaposi's sarcoma, its' relationships with venereal disease and AIDS are presented. With these complex problems, the central role of male homosexuality and lowered cellular immunity widens considerably the professional scope of the proctologist.

Assessment of the scope of practice of physicians participating in the Mais Médicos (More Doctors) Program, and associated factors.

PubMed

Girardi, Sábado Nicolau; Carvalho, Cristiana Leite; Pierantoni, Célia Regina; Costa, Juliana de Oliveira; Stralen, Ana Cristina de Sousa van; Lauar, Thaís Viana; David, Renata Bernardes

2016-09-01

The purpose of this study was to characterize the scope of practice of physicians working in primary healthcare participating in the Mais Médicos (More Doctors) Program ('PMM') and investigate the factors associated with execution of a larger number of clinical activities. It is an exploratory study carried over January to March 2016, through a self-applied questionnaire containing a list of 49 procedures, activities and actions carried out in primary healthcare. A total of 1,241 physicians took part in the study, most of them female, between age 40 and 49, and of Cuban nationality. The physicians carried out an average of 22.8 ± 8.2 procedures; they reported knowing how to carry out a larger number of procedures. Factors associated with executing a larger number of procedures were: being male, having graduated more recently, two years or less practicing in their primary healthcare unit, practicing in the North or South geographical regions, in small towns and more distant from the regional health headquarters. The main reason for not carrying out the procedures and activities that they reported knowing how to do was the lack of materials and inadequate infrastructure. The results show that the scope of practice of the physicians of the PMM is lower than their capacities, and that interventions with the intention of widening their scope are necessary.

Common marsh plants of the United States and Canada

USGS Publications Warehouse

Hotchkiss, Neil

1970-01-01

This is the fourth of a series of publications on field identification of North American marsh and water plants. It describes the emergent and semiemergent plants most likely to be found in inland and coastal marshes. It omits hundreds of uncommon marsh plants and plants less characteristic of marshes than of marsh edges, lake and stream shores, or wet meadows. The first of the series, "Pondweeds and Pondweedlike Plants of Eastern North America," Circular 187, was broadened in scope as Resource Publication 44, "Underwater and Floating-leaved Plants of the United States and Canada," and is superseded by it. The present publication, widens the scope of "Bulrushes and Bulrushlike Plants of Eastern North America," Circular 221, and contains most of the species listed therein. This guide is designed for identification of marsh plants without recourse to technical botanical keys. To use it, read pages 1 to 4 and then look at the drawings. To identify a plant, find the group in which it fits, then find a drawing and description that match it.

Primary health care, community participation and community-financing: experiences of two middle hill villages in Nepal.

PubMed

Sepehri, A; Pettigrew, J

1996-03-01

Although community involvement in health related activities is generally acknowledged by international and national health planners to be the key to the successful organization of primary health care, comparatively little is known about its potential and limitations. Drawing on the experiences of two middle hill villages in Nepal, this paper reports on research undertaken to compare and contrast the scope and extent of community participation in the delivery of primary health care in a community run and financed health post and a state run and financed health post. Unlike many other health posts in Nepal these facilities do provide effective curative services, and neither of them suffer from chronic shortage of drugs. However, community-financing did not appear to widen the scope and the extent of participation. Villagers in both communities relied on the health post for the treatment of less than one-third of symptoms, and despite the planners' intentions, community involvement outside participation in benefits was found to be very limited.

The Contribution of Drug Overdose to Educational Gradients in Life Expectancy in the United States, 1992-2011.

PubMed

Ho, Jessica Y

2017-06-01

Since the mid-1990s, the United States has witnessed a dramatic rise in drug overdose mortality. Educational gradients in life expectancy widened over the same period, and drug overdose likely plays a role in this widening, particularly for non-Hispanic whites. The contemporary drug epidemic is distinctive in terms of its scope, the nature of the substances involved, and its geographic patterning, which influence how it impacts different education groups. I use vital statistics and National Health Interview Survey data to examine the contribution of drug overdose to educational gradients in life expectancy from 1992-2011. I find that over this period, years of life lost due to drug overdose increased for all education groups and for both males and females. The contribution of drug overdose to educational gradients in life expectancy has increased over time and is greater for non-Hispanic whites than for the population as a whole. Drug overdose accounts for a sizable proportion of the increases in educational gradients in life expectancy, particularly at the prime adult ages (ages 30-60), where it accounts for 25 % to 100 % of the widening in educational gradients between 1992 and 2011. Drug overdose mortality has increased more rapidly for females than for males, leading to a gender convergence. These findings shed light on the processes driving recent changes in educational gradients in life expectancy and suggest that effective measures to address the drug overdose epidemic should take into account its differential burden across education groups.

The Contribution of Drug Overdose to Educational Gradients in Life Expectancy in the United States, 1992–2011

PubMed Central

Ho, Jessica Y.

2017-01-01

Over the past two decades, the United States has witnessed a dramatic rise in drug overdose mortality. Educational gradients in life expectancy widened over the same period, and it is likely that drug overdose plays a role in this widening, particularly for non-Hispanic whites. The contemporary drug epidemic is distinctive in terms of its scope, the nature of the substances involved, and its geographic patterning, which influence how it impacts different education groups. I use data from vital statistics and from the National Health Interview Survey to examine the contribution of drug overdose to educational gradients in life expectancy from 1992–2011. I find that over this period, years of life lost due to drug overdose increased for all education groups and for both males and females. The contribution of drug overdose to educational gradients in life expectancy has increased over time and is greater for non-Hispanic whites than for the population as a whole. Drug overdose accounts for a sizeable proportion of the increases in educational gradients in life expectancy, particularly at the prime adult ages (ages 30–60) where it accounts for 25–100% of the widening in educational gradients between 1992–2011. Over time, drug overdose mortality has increased more rapidly for females than for males, leading to a gender convergence. These findings shed light on the processes driving recent changes in educational gradients in life expectancy and suggest that effective measures to address the drug overdose epidemic should take into account its differential burden across education groups. PMID:28324483

The recovery model and complex health needs: what health psychology can learn from mental health and substance misuse service provision.

PubMed

Webb, Lucy

2012-07-01

This article reviews key arguments around evidence-based practice and outlines the methodological demands for effective adoption of recovery model principles. The recovery model is outlined and demonstrated as compatible with current needs in substance misuse service provision. However, the concepts of evidence-based practice and the recovery model are currently incompatible unless the current value system of evidence-based practice changes to accommodate the methodologies demanded by the recovery model. It is suggested that critical health psychology has an important role to play in widening the scope of evidence-based practice to better accommodate complex social health needs.

Committee Opinion No. 709: Commercial Enterprises in Medical Practice.

PubMed

2017-08-01

Monetary reimbursement of physicians in exchange for medical advice and treatment is well established and accepted in medical practice. However, financial pressures and the pervasiveness of entrepreneurial values have led some physicians to widen the scope of activities for which they seek reimbursement. Some of these commercial activities are ethically problematic in the clinical setting. Obstetrician-gynecologists should strive to ensure that commercial enterprises in medical practice do not compromise the patient-focused mission of clinical care. In this Committee Opinion, the American College of Obstetricians and Gynecologists' Committee on Ethics differentiates between commercial activities judged to be generally ethically appropriate for obstetrician-gynecologists and those that are not.

Committee Opinion No. 709 Summary: Commercial Enterprises in Medical Practice.

PubMed

2017-08-01

Monetary reimbursement of physicians in exchange for medical advice and treatment is well established and accepted in medical practice. However, financial pressures and the pervasiveness of entrepreneurial values have led some physicians to widen the scope of activities for which they seek reimbursement. Some of these commercial activities are ethically problematic in the clinical setting. Obstetrician-gynecologists should strive to ensure that commercial enterprises in medical practice do not compromise the patient-focused mission of clinical care. In this Committee Opinion, the American College of Obstetricians and Gynecologists' Committee on Ethics differentiates between commercial activities judged to be generally ethically appropriate for obstetrician-gynecologists and those that are not.

Breaking the Dogma of Aldolase Specificity: Simple Aliphatic Ketones and Aldehydes are Nucleophiles for Fructose-6-phosphate Aldolase.

PubMed

Roldán, Raquel; Sanchez-Moreno, Israel; Scheidt, Thomas; Hélaine, Virgil; Lemaire, Marielle; Parella, Teodor; Clapés, Pere; Fessner, Wolf-Dieter; Guérard-Hélaine, Christine

2017-04-11

d-Fructose-6-phosphate aldolase (FSA) was probed for extended nucleophile promiscuity by using a series of fluorogenic substrates to reveal retro-aldol activity. Four nucleophiles ethanal, propanone, butanone, and cyclopentanone were subsequently confirmed to be non-natural substrates in the synthesis direction using the wild-type enzyme and its D6H variant. This exceptional widening of the nucleophile substrate scope offers a rapid entry, in good yields and high stereoselectivity, to less oxygenated alkyl ketones and aldehydes, which was hitherto impossible. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Recently Patented Viral Nucleotide Sequences and Generation of Virus-Derived Vaccines.

PubMed

Venkataraman, Srividhya; Ahmad, Tauqeer; Haidar, Mounir A; Hefferon, Kathleen L

2017-01-01

With an increase in comprehension of the molecular biology of viruses, there has been a recent surge in the application of virus sequences and viral gene expression strategies towards the diagnosis and treatment of diseases. The scope of the patenting landscape has widened as a result and the current review discusses patents pertaining to live / attenuated viral vaccines. The vaccines addressed here have been developed by both conventional means as well as by the state-of-the-art genetic engineering techniques. This review also addresses the applications of these patents for clinical and biotechnological purposes. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

What is "neuromarketing"? A discussion and agenda for future research.

PubMed

Lee, Nick; Broderick, Amanda J; Chamberlain, Laura

2007-02-01

Recent years have seen advances in neuroimaging to such an extent that neuroscientists are able to directly study the frequency, location, and timing of neuronal activity to an unprecedented degree. However, marketing science has remained largely unaware of such advances and their huge potential. In fact, the application of neuroimaging to market research--what has come to be called "neuromarketing"--has caused considerable controversy within neuroscience circles in recent times. This paper is an attempt to widen the scope of neuromarketing beyond commercial brand and consumer behaviour applications, to include a wider conceptualisation of marketing science. Drawing from general neuroscience and neuroeconomics, neuromarketing as a field of study is defined, and some future research directions are suggested.

Happy but still focused: failures to find evidence for a mood-induced widening of visual attention.

PubMed

Bruyneel, Lynn; van Steenbergen, Henk; Hommel, Bernhard; Band, Guido P H; De Raedt, Rudi; Koster, Ernst H W

2013-05-01

In models of affect and cognition, it is held that positive affect broadens the scope of attention. Consistent with this claim, previous research has indeed suggested that positive affect is associated with impaired selective attention as evidenced by increased interference of spatially distant distractors. However, several recent findings cast doubt on the reliability of this observation. In the present study, we examined whether selective attention in a visual flanker task is influenced by positive mood induction. Across three experiments, positive affect consistently failed to exert any impact on selective attention. The implications of this null-finding for theoretical models of affect and cognition are discussed.

The 14th international workshop on wave hindcasting and forecasting and the 5th coastal hazards symposium

NASA Astrophysics Data System (ADS)

Breivik, Øyvind; Alves, Jose Henrique; Greenslade, Diana; Horsburgh, Kevin; Swail, Val

2017-04-01

Following the 14th International Workshop on Wave Hindcasting and Forecasting and 5th Coastal Hazards Symposium in November 2014 in Key West, Florida, a topical collection has appeared in recent issues of Ocean Dynamics. Here, we give a brief overview of the 16 papers published in this topical collection as well as an overview of the widening scope of the conference in recent years. A general trend in the field has been towards closer integration between the wave and ocean modelling communities. This is also seen in this topical collection, with several papers exploring the interaction between surface waves and mixed layer dynamics and sea ice.

The engagement of optical angular momentum in nanoscale chirality

NASA Astrophysics Data System (ADS)

Andrews, David L.

2017-09-01

Wide-ranging developments in optical angular momentum have recently led to refocused attention on issues of material chirality. The connection between optical spin and circular polarization, linking to well-known and utilized probes of chirality such as circular dichroism, has prompted studies aiming to achieve enhanced means of differentiating enantiomers - molecules or particles of opposite handedness. A number of newly devised schemes for physically separating mirror-image components by optical methods have also been gaining traction, together with a developing appreciation of how the scale of physical dimensions ultimately determines any capacity to differentially select for material chirality. The scope of such enquiries has substantially widened on recognition that suitably structured, topologically charged beams of light - often known as `twisted light' or `optical vortices' can additionally convey orbital angular momentum. A case can be made that understanding the full scope and constraints upon chiroptical interactions in the nanoscale regime involves the resolution of CPT symmetry conditions governing the fundamental interactions between matter and photons. The principles provide a sound theoretical test-bed for new methodologies.

Pressure-accelerated azide-alkyne cycloaddition: micro capillary versus autoclave reactor performance.

PubMed

Borukhova, Svetlana; Seeger, Andreas D; Noël, Timothy; Wang, Qi; Busch, Markus; Hessel, Volker

2015-02-01

Pressure effects on regioselectivity and yield of cycloaddition reactions have been shown to exist. Nevertheless, high pressure synthetic applications with subsequent benefits in the production of natural products are limited by the general availability of the equipment. In addition, the virtues and limitations of microflow equipment under standard conditions are well established. Herein, we apply novel-process-window (NPWs) principles, such as intensification of intrinsic kinetics of a reaction using high temperature, pressure, and concentration, on azide-alkyne cycloaddition towards synthesis of Rufinamide precursor. We applied three main activation methods (i.e., uncatalyzed batch, uncatalyzed flow, and catalyzed flow) on uncatalyzed and catalyzed azide-alkyne cycloaddition. We compare the performance of two reactors, a specialized autoclave batch reactor for high-pressure operation up to 1800 bar and a capillary flow reactor (up to 400 bar). A differentiated and comprehensive picture is given for the two reactors and the three methods of activation. Reaction speedup and consequent increases in space-time yields is achieved, while the process window for favorable operation to selectively produce Rufinamide precursor in good yields is widened. The best conditions thus determined are applied to several azide-alkyne cycloadditions to widen the scope of the presented methodology. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Exploring the scope of practice and training of obstetricians and gynaecologists in England, Italy and Belgium: a qualitative study.

PubMed

Risso-Gill, Isabelle; Kiasuwa, Regine; Baeten, Rita; Caldarelli, Ilenia; Mitro, Silva; Merriel, Abi; Amadio, Giulia; McKee, Martin; Legido-Quigley, Helena

2014-09-01

This study explores the scope of practice of Obstetrics and Gynaecology specialists in Italy, Belgium and England, in light of the growth of professional and patient mobility within the EU which has raised concerns about a lack of standardisation of medical speciality practice and training. Semi-structured qualitative interviews were conducted with 29 obstetricians and gynaecologists from England, Belgium and Italy, exploring training and scope of practice, following a common topic guide. Interviews were recorded, transcribed and coded following a common coding framework in the language of the country concerned. Completed coding frames, written summaries and key quotes were then translated into English and were cross-analysed among the researchers to identify emerging themes and comparative findings. Although medical and specialty qualifications in each country are mutually recognised, there were great differences in training regimes, with different emphases on theory versus practice and recognition of different subspecialties. However all countries shared concerns about the impact of the European Working Time Directive on trainees' skills development. Reflecting differences in models of care, the scope of practice of OBGYN varied among countries, with pronounced differences between the public and private sector within countries. Technological advances and the growth of co-morbidities resulting from ageing populations have created new opportunities and greater links with other specialties. In turn new ethical concerns around abortion and fertility have also arisen, with stark cultural differences between the countries. Variations exist in the training and scope of practice of OBGYN specialists among these three countries, which could have significant implications for the expectations of patients seeking care and specialists practising in other EU countries. Changes within the specialty and advances in technology are creating new opportunities and challenges, although these may widen existing differences. Harmonisation of the training and scope of practice of OBGYN within Europe remains a distant goal. Further research on the scope of practice of medical professionals would better inform future policies on professional mobility. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rotman, D.

Exxon chemical says it has made linear low-density polyethylene (LLDPE) using metallocene catalysts at its world-scale gas-phase plant in Mont Belvieu, TX. Exxon also says it has received a broad US patent that covers the use of metallocenes in gas-phase reactors that use condensing mode technology and that it plans to license the know-how. The moves, say industry experts, greatly strengthen Exxon`s position in metallocenes, particularly in pushing metallocene-based PE into commodity markets. The use of gas-phase technology {open_quotes}had to happen{close_quotes} to allow metallocene polymers to compete as commodities, says David Highfield, v.p. at Catalyst Consultants (Spring House, PA). {open_quotes}It`smore » very important and very significant in widening the scope of [metallocene] technology.{close_quotes}« less

Encounter of a different kind: Rosetta observes asteroid at close quarters

NASA Astrophysics Data System (ADS)

2008-09-01

ESA's comet chaser, Rosetta, last night flew by a small body in the main asteroid belt, asteroid Steins, collecting a wealth of information about this rare type of minor Solar System body. At 20:58 CEST (18:58 UT) last night, ESA's Rosetta probe approached asteroid 2867 Steins, coming to within a distance of only 800 km from it. Steins is Rosetta's first nominal scientific target in its 11½ year mission to ultimately explore the nucleus of Comet 67P/Churyumov-Gerasimenko. The success of this 'close' encounter was confirmed at 22:14 CEST, when ESA's ground control team at the European Space Operations Centre (ESOC) in Darmstadt, Germany, received initial telemetry from the spacecraft. During the flyby operations, Rosetta was out of reach as regards communication links because its antenna had to be turned away from Earth. At a distance of about 2.41 AU (360 million kilometres) from our planet, the radio signal from the probe took 20 minutes to reach the ground. Steins is a small asteroid of irregular shape with a diameter of only 4.6 km. It belongs to the rare class of E-type asteroids, which had not been directly observed by an interplanetary spacecraft before. Such asteroids are quite small in size and orbit and are mostly found in the inner part of the main asteroid belt located between Mars and Jupiter. They probably originate from the mantle of larger asteroids destroyed in the early history of the Solar System, and are thought to be composed mainly of silicate minerals with little or no iron content. The data collected by Rosetta last night and which will be analysed over the coming days and weeks will finally unveil the true nature of Steins. Through the study of minor bodies such as asteroids, Rosetta is opening up a new window onto the early history of our Solar System. It will give us a better understanding of the origins and evolution of the planets, and also a key to better interpreting asteroid data collected from the ground. Under Rosetta's scope This is not Rosetta's first look at Steins. Over two years ago, in March 2006, the Osiris camera onboard Rosetta observed the brightness variations of this rotating asteroid from a distance of 159 million kilometres (a little over the distance between Earth and the Sun), and was able to determine that the tiny asteroid spins around its axis in about six hours. Together with the two navigation cameras onboard, Osiris was again pointed towards Steins on 4 August and continued to observe the asteroid until 4 September, in order to assist Rosetta's navigation by optical means - a first in the history of ESA spacecraft operations. A few days before the flyby, most of the Rosetta orbiter instruments, as well as the Philae lander magnetometer, were switched on to collect science data on the asteroid, with ever-increasing accuracy as the spacecraft closed in on it. Rosetta's powerful instruments have initially been focusing on the asteroid's orbital motion, rotation, shape and density. As the distance has diminished, the investigation has broadened to take in the observation of surface properties and features, and the analysis of the chemical and mineralogical composition of the terrains, as well as their relative ages and the effects of the solar wind on the surface. At its closest approach, Rosetta flew by Steins at a relative speed of 8.6 km/s. To keep the small asteroid in the field of view of its instruments, the spacecraft had to perform a rapid and highly demanding rotation manoeuvre, which had been successfully rehearsed in March this year. A preliminary analysis of the first data from the flyby was presented to the press at ESOC at 12:00 CEST today. To Steins and beyond "Steins might be small, but we're making big science here", said Dr David Southwood, ESA's Director of Science and Robotic Exploration. "The better we learn to know the different kinds of asteroids, the better we will understand our origins in the past. Moreover, when such Solar System wanderers escape from the belt they could become a threat to Earth. The better we know them, the better we will be able to mitigate the risks some of them might present in the future." "Rosetta performed very well all along," Southwood continued. " This was a complex manoeuvre to keep such a small target in sight, but the spacecraft came through with flying colours. Now we are even more confident in its capacity to conduct the complex tasks that await it at comet Churyumov-Gerasimenko." Science observations of Steins will continue until 10 September. Since its launch by an Ariane 5 rocket on 2 March 2004, Rosetta has already travelled about 3.7 thousand million kilometres and swung by the Earth twice and Mars once for gravity-assist manoeuvres. On 17 December this year Rosetta will reach the maximum distance from the Sun in its current orbit, and will then head back towards Earth for the next and last gravitational kick from our planet on 13 November 2009. This will give the probe its final push toward its cometary target. On its way, Rosetta is scheduled to conduct another flyby, this time with the much larger (21) Lutetia asteroid, on 10 July 2010. Arrival at 67P/Churyumov-Gerasimenko is due by mid-2014. By that time the probe will have covered a distance of about 6.5 thousand million kilometres.

Study on the Old Girders in the Widening Hollow Slab Girder Bridge

NASA Astrophysics Data System (ADS)

Wang, Ying; Zhang, Li Fang; Ma, Hai Yan

2018-06-01

Taking the bridge widening project of Shanghai-Hangzhou-Ningbo expressway widening construction project (China) as the background in this paper, the variation law of the internal force of the old bridge in the widening hollow slab girder bridge under vehicle load is studied, which is under the condition of different span lengths and different widening widths. Three different span lengths of the pre-tensioned prestressed hollow slab girder bridges are selected, the spatial finite element models of both the old bridge and the whole structure of widening bridge are established and calculated respectively by Midas/Civil software. The influences of widening and load increasing on the old bridges under the vehicle load are compared and analyzed. In addition, the authors also analyze the influences of different widening widths on the force state of old bridges under the condition of widening the same number of lane. Moreover , the effects on the old bridges that are caused by the uneven foundation settlement of widening bridge structure are also studied in this paper. This paper can provide some references for widening design of hollow slab bridges.

The Mixing of Regolith on the Moon and Beyond; A Model Refreshed

NASA Astrophysics Data System (ADS)

Costello, E.; Ghent, R. R.; Lucey, P. G.

2017-12-01

Meteoritic impactors constantly mix the lunar regolith, affecting stratigraphy, the lifetime of rays and other anomalous surface features, and the burial, exposure, and break down of volatiles and rocks. In this work we revisit the pioneering regolith mixing model presented by Gault et al. (1974), with updated assumptions and input parameters. Our updates significantly widen the parameter space and allow us to explore mixing as it is driven by different impactors in different materials (e.g. radar-dark halos and melt ponds). The updated treatment of micrometeorites suggests a very high rate of processing at the immediate lunar surface, with implications for rock breakdown and regolith production on melt ponds. We find that the inclusion of secondary impacts has a very strong effect on the rate and magnitude of mixing at all depths and timescales. Our calculations are in good agreement with the timescale of reworking in the top 2-3 cm of regolith that was predicted by observations of LROC temporal pairs and by the depth profile of 26Al abundance in Apollo drill cores. Further, our calculations with secondaries included are consistent with the depth profile of in situ exposure age calculated from Is/FeO and cosmic track abundance in Apollo deep drill cores down to 50cm. The mixing we predict is also consistent with the erasure of density anomalies, or `cold spots', observed in the top decimeters of regolith by LRO Diviner, and the 1Gyr lifetime of 1-10m thick Copernican rays. This exploration of Moon's surface evolution has profound implications for our understanding of other planetary bodies. We take advantage of this computationally inexpensive analytic model and apply it to describe mixing on a variety of bodies across the solar system; including asteroids, Mercury, and Europa. We use the results of ongoing studies that describe porosity calculations and cratering laws in porous asteroid-like material to explore the reworking rate experienced by an asteroid. On Mercury, we apply this model to describe the rate at which reworking depletes water ice and calculate the maximum age of Mercury's polar ice deposits. We apply the model to Europa to understand the impact portion of its regolith evolution and provide insight into the sampling zone intended for a future Europa lander.

Genomic futures of prenatal screening: ethical reflection.

PubMed

Dondorp, W J; Page-Christiaens, G C M L; de Wert, G M W R

2016-05-01

The practice of prenatal screening is undergoing important changes as a result of the introduction of genomic testing technologies at different stages of the screening trajectory. It is expected that eventually it will become possible to routinely obtain a comprehensive 'genome scan' of all fetuses. Although this will still take several years, there are clear continuities between present developments and this future scenario. As this review shows, behind the still limited scope of screening for common aneuploidies, a rapid widening of the range of conditions tested for is already taking shape at the invasive testing stage. But the continuities are not just technical; they are also ethical. If screening for Down's syndrome is a matter of providing autonomous reproductive choice, then why would providing the choice to have a full fetal genome scan be something entirely different? There is a clear need for a sustainable normative framework that will have to answer three challenges: the indeterminateness of the autonomy paradigm, the need to acknowledge the future child as an interested stakeholder, and the prospect of broad-scope genomic prenatal screening with a double purpose: autonomy and prevention. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Asteroid mining

NASA Astrophysics Data System (ADS)

Gertsch, Richard E.

The earliest studies of asteroid mining proposed retrieving a main belt asteroid. Because of the very long travel times to the main asteroid belt, attention has shifted to the asteroids whose orbits bring them fairly close to the Earth. In these schemes, the asteroids would be bagged and then processed during the return trip, with the asteroid itself providing the reaction mass to propel the mission homeward. A mission to one of these near-Earth asteroids would be shorter, involve less weight, and require a somewhat lower change in velocity. Since these asteroids apparently contain a wide range of potentially useful materials, our study group considered only them. The topics covered include asteroid materials and properties, asteroid mission selection, manned versus automated missions, mining in zero gravity, and a conceptual mining method.

Asteroid mining

NASA Technical Reports Server (NTRS)

Gertsch, Richard E.

1992-01-01

The earliest studies of asteroid mining proposed retrieving a main belt asteroid. Because of the very long travel times to the main asteroid belt, attention has shifted to the asteroids whose orbits bring them fairly close to the Earth. In these schemes, the asteroids would be bagged and then processed during the return trip, with the asteroid itself providing the reaction mass to propel the mission homeward. A mission to one of these near-Earth asteroids would be shorter, involve less weight, and require a somewhat lower change in velocity. Since these asteroids apparently contain a wide range of potentially useful materials, our study group considered only them. The topics covered include asteroid materials and properties, asteroid mission selection, manned versus automated missions, mining in zero gravity, and a conceptual mining method.

Semiquantum key distribution with secure delegated quantum computation

PubMed Central

Li, Qin; Chan, Wai Hong; Zhang, Shengyu

2016-01-01

Semiquantum key distribution allows a quantum party to share a random key with a “classical” party who only can prepare and measure qubits in the computational basis or reorder some qubits when he has access to a quantum channel. In this work, we present a protocol where a secret key can be established between a quantum user and an almost classical user who only needs the quantum ability to access quantum channels, by securely delegating quantum computation to a quantum server. We show the proposed protocol is robust even when the delegated quantum server is a powerful adversary, and is experimentally feasible with current technology. As one party of our protocol is the most quantum-resource efficient, it can be more practical and significantly widen the applicability scope of quantum key distribution. PMID:26813384

From the History of Science to the History of Knowledge - and Back.

PubMed

Renn, Jürgen

2015-02-01

The history of science can be better understood against the background of a history of knowledge comprising not only theoretical but also intuitive and practical knowledge. This widening of scope necessitates a more concise definition of the concept of knowledge, relating its cognitive to its material and social dimensions. The history of knowledge comprises the history of institutions in which knowledge is produced and transmitted. This is an essential but hitherto neglected aspect of cultural evolution. Taking this aspect into account one is led to the concept of extended evolution, which integrates the perspectives of niche construction and complex regulative networks. The paper illustrates this concept using four examples: the emergence of language, the Neolithic revolution, the invention of writing and the origin of mechanics.

From the History of Science to the History of Knowledge – and Back

PubMed Central

Renn, Jürgen

2015-01-01

The history of science can be better understood against the background of a history of knowledge comprising not only theoretical but also intuitive and practical knowledge. This widening of scope necessitates a more concise definition of the concept of knowledge, relating its cognitive to its material and social dimensions. The history of knowledge comprises the history of institutions in which knowledge is produced and transmitted. This is an essential but hitherto neglected aspect of cultural evolution. Taking this aspect into account one is led to the concept of extended evolution, which integrates the perspectives of niche construction and complex regulative networks. The paper illustrates this concept using four examples: the emergence of language, the Neolithic revolution, the invention of writing and the origin of mechanics. PMID:25684777

Evaluation of NDI compressed air foam system (cafs) applied as a retrofit. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duncan, S.

1994-08-01

Army Engineer Firefighting Detachments require increased firefighting capability to compensate for deficiencies in structural, brush, or wildland and large petroleum storage site fires. Additionally, Army fire departments responsible for protection and prevention on posts, camps and stations have difficulty accessing new or emerging technology do not possess state-of-the-art equipment. The results of this evaluation and subsequent projects, will be reported throughout the Army in an attempt to mitigate operational deficiencies and widen the scope of knowledge in the Army fire service. The evaluation of non-developmental retrofitted compressed air foam systems show an efficiency of suppressive capabilities of water superseded bymore » water alone. Retrofitting the equipment was not easy or inexpensive but it was very successful.« less

Asteroid mass estimation using Markov-chain Monte Carlo

NASA Astrophysics Data System (ADS)

Siltala, Lauri; Granvik, Mikael

2017-11-01

Estimates for asteroid masses are based on their gravitational perturbations on the orbits of other objects such as Mars, spacecraft, or other asteroids and/or their satellites. In the case of asteroid-asteroid perturbations, this leads to an inverse problem in at least 13 dimensions where the aim is to derive the mass of the perturbing asteroid(s) and six orbital elements for both the perturbing asteroid(s) and the test asteroid(s) based on astrometric observations. We have developed and implemented three different mass estimation algorithms utilizing asteroid-asteroid perturbations: the very rough 'marching' approximation, in which the asteroids' orbital elements are not fitted, thereby reducing the problem to a one-dimensional estimation of the mass, an implementation of the Nelder-Mead simplex method, and most significantly, a Markov-chain Monte Carlo (MCMC) approach. We describe each of these algorithms with particular focus on the MCMC algorithm, and present example results using both synthetic and real data. Our results agree with the published mass estimates, but suggest that the published uncertainties may be misleading as a consequence of using linearized mass-estimation methods. Finally, we discuss remaining challenges with the algorithms as well as future plans.

Self-organizing control strategy for asteroid intelligent detection swarm based on attraction and repulsion

NASA Astrophysics Data System (ADS)

An, Meiyan; Wang, Zhaokui; Zhang, Yulin

2017-01-01

The self-organizing control strategy for asteroid intelligent detection swarm, which is considered as a space application instance of intelligent swarm, is developed. The leader-follower model for the asteroid intelligent detection swarm is established, and the further analysis is conducted for massive asteroid and small asteroid. For a massive asteroid, the leader spacecraft flies under the gravity field of the asteroid. For a small asteroid, the asteroid gravity is negligible, and a trajectory planning method is proposed based on elliptic cavity virtual potential field. The self-organizing control strategy for the follower spacecraft is developed based on a mechanism of velocity planning and velocity tracking. The simulation results show that the self-organizing control strategy is valid for both massive asteroid and small asteroid, and the exploration swarm forms a stable configuration.

BILLIARDS: Baseline Instrumented Lithology Lander, Inspector and Asteroid Redirection Demonstration System

NASA Technical Reports Server (NTRS)

Marcus, Matthew; Sloane, Joshua; Ortiz, Oliver; Barbee, Brent

2015-01-01

BILLIARDS Baseline Instrumented Lithology Lander, Inspector, and Asteroid Redirection Demonstration System Proposed demonstration mission for Billiard-Ball concept Select asteroid pair with natural close approach to minimize cost and complexity Primary Objectives Rendezvous with a small (10m), near Earth (alpha) asteroid Maneuver the alpha asteroid to a collision with a 100m (beta) asteroid Produce a detectable deflection or disruption of the beta asteroid Secondary objectives Contribute knowledge of asteroid composition and characteristics Contribute knowledge of small-body formation Opportunity for international collaboration

Explosive volcanism and the graphite-oxygen fugacity buffer on the parent asteroid(s) of the ureilite meteorites

NASA Technical Reports Server (NTRS)

Warren, Paul H.; Kallemeyn, Gregory W.

1992-01-01

A new model of the production of the uniformly low plagioclase and Al contents of ureilites is proposed. It is argued that those contents are consequences of widespread explosive volcanism during the evolution of the parent asteroid(s). It is noted that the great abundance of graphite on the ureilite asteroid(s) made them ideal sites for explosive volcanism driven by oxidation of graphite in partial melts ascending within the asteroid(s).

Asteroid team

NASA Technical Reports Server (NTRS)

Matson, D. L.

1988-01-01

The purpose of this task is to support asteroid research and the operation of an Asteroid Team within the Earth and Space Sciences Division at the Jet Propulsion Laboratory (JPL). The Asteroid Team carries out original research on asteroids in order to discover, better characterize and define asteroid properties. This information is needed for the planning and design of NASA asteroid flyby and rendezvous missions. The asteroid Team also provides scientific and technical advice to NASA and JPL on asteroid related programs. Work on asteroid classification continued and the discovery of two Earth-approaching M asteroids was published. In the asteroid photometry program researchers obtained N or Q photometry for more than 50 asteroids, including the two M-earth-crossers. Compositional analysis of infrared spectra (0.8 to 2.6 micrometer) of asteroids is continuing. Over the next year the work on asteroid classification and composition will continue with the analysis of the 60 reduced infrared spectra which we now have at hand. The radiometry program will continue with the reduction of the N and Q bandpass data for the 57 asteroids in order to obtain albedos and diameters. This year the emphasis will shift to IRAS follow-up observations; which includes objects not observed by IRAS and objects with poor or peculiar IRAS data. As in previous year, we plan to give top priority to any opportunities for observing near-Earth asteroids and the support (through radiometric lightcurve observations from the IRTF) of any stellar occultations by asteroids for which occultation observation expeditions are fielded. Support of preparing of IRAS data for publication and of D. Matson for his participation in the NASA Planetary Astronomy Management and Operations Working Group will continue.

International Asteroid Mission (IAM)

NASA Astrophysics Data System (ADS)

Yamaguchi, Ryuuji

1991-07-01

International Asteroid Mission (IAM) is a program aimed at developing resources of asteroids abundantly existing near the earth. This report describes the research results of design project of the International Space University (ISU) held in 1990 at Tront-York University. ISU research and asteroid survey results, and the manned asteroid mining mission are outlined. Classification of asteroids existing near the earth and asteroid resource processing and use analyses are conducted. Asteroid selection flow charts are introduced, and the 1982HR-Orpheus is selected as a candidate asteroid because it takes an approaching orbit toward the earth, requires small delta V, and possesses abundant carbonaceous chondrites. Characteristics of 1982HR-Orpheus are presented. Mission requirements, mission outlines, transportation systems, and mining and processing systems for manned asteroid mining missions are presented.

Widening Participation; Widening Capability

ERIC Educational Resources Information Center

Walker, Melanie

2008-01-01

This paper proposes that widening participation in higher education might distinctively be conceptualised beyond economically driven human capital outcomes, as a matter of widening capability. Specifically, the paper proposes forming the capability of students to become and to be "strong evaluators", able to make reflexive and informed…

Natural History of Plexiform Neurofibromas in NF1. Addendum

DTIC Science & Technology

2008-10-01

neural foraminal widening, greater sciatic notch widening, and spinal cord com- pression were evaluated. Lesion signal intensity charac- teristics were...neural foraminal widening (n=20), greater sciatic foramina widening (n=2), and neural canal involvement (n=18). Target-like appearance was noted in 53

Widen the belt of habitability!

PubMed

Möhlmann, D

2012-06-01

Among the key-parameters to characterize habitability are presence or availability of liquid water, an appropriate temperature range, and the time scale of reference. These criteria for habitability are discussed and described from the point of view of water- and ice-physics, and it is shown that liquid water may exist in the sub-surfaces of planetary bodies like Mars, and possibly of inner asteroids and internally heated ice-moons. Water can remain fluid there also at temperatures far below the "canonical" 0 °C. This behaviour is made possible as a consequence of the freezing point depression due to salty solutes in water or "brines", as they can be expected to exist in nature more frequently than pure liquid water. On the other hand, low temperatures cause a slowing down of chemical processes, as can be described by Arrhenius's relation. The resulting smaller reaction rates probably will have the consequence to complicate the detection of low-temperature life processes, if they exist. Furthermore, the adaptation potential of life is to be mentioned in this context as a yet partially unknown process. Resulting recommendations are given to improve the use of criteria to characterize habitable conditions.

The Asteroid Impact Mission - Deflection Demonstration (AIM - D2)

NASA Astrophysics Data System (ADS)

Küppers, M.; Michel, P.; Carnelli, I.

2017-09-01

The Asteroid Impact Mission (AIM) is ESA's contribution to the international Asteroid Impact Deflection Assessment (AIDA) cooperation, targeting the demonstration of deflection of a hazardous near-earth asteroid. AIM will also be the first in-depth investigation of a binary asteroid and make measurements that are relevant for the preparation of asteroid resource utilisation. AIM is foreseen to rendezvous with the binary near-Earth asteroid (65803) Didymos and to observe the system before, during, and after the impact of NASA's Double Asteroid Redirection Test (DART) spacecraft. Here we describe the observations to be done by the simplified version Asteroid Impact Mission - Deflection Demonstration (AIM-D2) and show that most of the original AIM objectives can still be achieved.

Project RAMA: Reconstructing Asteroids Into Mechanical Automata

NASA Technical Reports Server (NTRS)

Dunn, Jason; Fagin, Max; Snyder, Michael; Joyce, Eric

2017-01-01

Many interesting ideas have been conceived for building space-based infrastructure in cislunar space. From O'Neill's space colonies, to solar power satellite farms, and even prospecting retrieved near earth asteroids. In all the scenarios, one thing remained fixed - the need for space resources at the outpost. To satisfy this need, O'Neill suggested an electromagnetic railgun to deliver resources from the lunar surface, while NASA's Asteroid Redirect Mission called for a solar electric tug to deliver asteroid materials from interplanetary space. At Made In Space, we propose an entirely new concept. One which is scalable, cost effective, and ensures that the abundant material wealth of the inner solar system becomes readily available to humankind in a nearly automated fashion. We propose the RAMA architecture, which turns asteroids into self-contained spacecraft capable of moving themselves back to cislunar space. The RAMA architecture is just as capable of transporting conventional-sized asteroids on the 10-meter length scale as transporting asteroids 100 meters or larger, making it the most versatile asteroid retrieval architecture in terms of retrieved-mass capability. This report describes the results of the Phase I study funded by the NASA NIAC program for Made In Space to establish the concept feasibility of using space manufacturing to convert asteroids into autonomous, mechanical spacecraft. Project RAMA, Reconstituting Asteroids into Mechanical Automata, is designed to leverage the future advances of additive manufacturing (AM), in-situ resource utilization (ISRU) and in-situ manufacturing (ISM) to realize enormous efficiencies in repeated asteroid redirect missions. A team of engineers at Made In Space performed the study work with consultation from the asteroid mining industry, academia, and NASA. Previous studies for asteroid retrieval have been constrained to studying only asteroids that are both large enough to be discovered, and small enough to be captured and transported using Earth-launched propulsion technology. Project RAMA is not forced into this constraint. The mission concept studied involved transporting a much larger approximately 50-meter asteroid to cislunar space. Demonstration of transport of a 50-meter-class asteroid has several ground-breaking advantages. First, the returned material is of an industrial, rather than just scientific, quantity (greater than 10,000 tonnes versus approximately10s of tonnes). Second, the "useless" material in the asteroid is gathered and expended as part of the asteroid's propulsion system, allowing the returned asteroid to be considerably "purer" than a conventional asteroid retrieval mission. Third, the infrastructure used to convert and return the asteroid is reusable, and capable of continually returning asteroids to cislunar space.

Effects of YORP-induced rotational fission on the small size end of the Main Belt asteroid size distribution

NASA Astrophysics Data System (ADS)

Rossi, Alessandro; Jacobson, S.; Marzari, F.; Scheeres, D.; Davis, D. R.

2013-10-01

From the results of a comprehensive asteroid population evolution model, we conclude that the YORP-induced rotational fission hypothesis has strong repercussions for the small size end of the Main Belt asteroid size frequency distribution. These results are consistent with observed asteroid population statistics. The foundation of this model is the asteroid rotation model of Marzari et al. (2011), which incorporates both the YORP effect and collisional evolution. This work adds to that model the rotational fission hypothesis (i.e. when the rotation rate exceeds a critical value, erosion and binary formation occur). The YORP effect timescale for large asteroids with diameters D > ~6 km is longer than the collision timescale in the Main Belt, thus the frequency of large asteroids is determined by a collisional equilibrium (e.g. Bottke 2005), but for small asteroids with diameters D < ~6 km, the asteroid population evolution model confirms that YORP-induced rotational fission destroys small asteroids more frequently than collisions. Therefore, the frequency of these small asteroids is determined by an equilibrium between the creation of new asteroids out of the impact debris of larger asteroids and the destruction of these asteroids by YORP-induced rotational fission. By introducing a new source of destruction that varies strongly with size, YORP-induced rotational fission alters the slope of the size frequency distribution. Using the outputs of the asteroid population evolution model and a 1-D collision evolution model, we can generate this new size frequency distribution and it matches the change in slope observed by the SKADS survey (Gladman 2009). This agreement is achieved with both an accretional power-law or a truncated “Asteroids were Born Big” size frequency distribution (Weidenschilling 2010, Morbidelli 2009).

Near-Earth Asteroid Returned Sample (NEARS)

NASA Technical Reports Server (NTRS)

Shoemaker, Eugene M.; Cheng, Andrew F.

1994-01-01

The concept of the Near-Earth Asteroid Returned Sample (NEARS) mission is to return to Earth 10-100 g from each of four to six sites on a near-Earth asteroid and to perform global characterization of the asteroid and measure mass, volume, and density to ten percent. The target asteroid for the mission is 4660 Nereus, probably a primitive C-type asteroid, with the alternate target being 1989ML, an extremely accessible asteroid of unknown type. Launch dates will be 1998, 2000, 2002, and 2004 on the Delta II-7925 launch vehicle. The mission objectives are three-fold. (1) Provide first direct and detailed petrological, chemical, age, and isotopic characterization of a near-Earth asteroid and relate it to terrestrial, lunar, and meteoritic materials. (2) Sample the asteroid regolith and characterize any exotic fragments. (3) Identify heterogeneity in the asteroid's isotopic properties, age, and elemental chemistry.

Asteroid size distributions for the main belt and for asteroid families

NASA Astrophysics Data System (ADS)

Kazantzev, A.; Kazantzeva, L.

2017-12-01

The asteroid-size distribution for he Eos family was constructed. The WISE database containing the albedo p and the size D of over 80,000 asteroids was used. The b parameter of the power-law dependence has a minimum at some average values of the asteroid size of the family. A similar dependence b(D) exists for the whole asteroid belt. An assumption on the possible similarity of the formation mechanisms of the asteroid belt as a whole and separate families is made.

Flyght Dynamics of Artificial Satellite of the Minor Asteroid

NASA Astrophysics Data System (ADS)

Zakharov, Alexander; Eismont, Natan; Ledkov, Anton; Simonov, Alexander; Pol, Vadim

During last years the scientific interest to the asteroid is constantly growing. It may be explained by different reasons. One of the most important from them is confirmation of the fact that the asteroids present the real hazard to the Earth. The Chelyabinsk event demonstrates strong in support of this statement. Besides, the asteroids exploration promises to supply new data for understanding of the solar system origin and evolution. And the projects aimed to reach this goal have begun from the NASA NEAR mission to Eros. It was the first one when the spacecraft was landed on the surface of the asteroid. The other successive mission was fulfilled by JAXA with Hayabusa spacecraft which has returned to the Earth soil samples of Itokawa asteroid. In the nearest future the mission to RQ 36 asteroid is planned supposing landing and soil samples return. Unavoidable phase of such missions is the spacecraft flight in vicinity of the target asteroid, for example on the asteroid satellite orbit. It should be mentioned that quite visible number of asteroids has geometric form which is far from being sphere. Accordingly the gravity field of such asteroid cannot be presented as the one close to sphere. The problem is that prior to the mission to the asteroid one cannot receive good enough knowledge of its gravity field and even its gravity field constant. In the paper the flight dynamics problem of spacecraft moving along asteroid satellite orbit is explored. It is supposed that the asteroid is comparatively small with diameter (maximum size) about 300 m, like Apophis asteroid has, or less. To approximate the gravity field of asteroid the last is considered as totality of mass points. We assume such approach as more simple and effective as compared with the commonly accepted use of Legendre polynomial expansion. Different orbits near asteroid are analyzed with the sets of orbital parameters determining the size of orbit, its shape and position with respect to the Sun. The goal of this analysis is to understand what initial orbital parameters deliver stability of the orbit in terms of avoiding the collision with the asteroid surface. The orbital heights are calculated which allow to consider the asteroid gravity field as close to the spherical one de-pending on the shape of asteroid. Also maneuvers are estimated necessary for keeping the spacecraft on asteroid satellite orbit and for changing orbital parameters. Taking into account that gravity field parameters of the target asteroids may have pure accuracy it is supposed that spacecraft starts its motion in vicinity of the asteroid from the high enough orbit and then after processing of the tracking data maneuvers are executed to decrease spacecraft altitude. Methods of this procedure optimization are explored.

Edge-on View of Near-Earth Asteroids

NASA Image and Video Library

2012-05-16

NEOWISE, the asteroid-hunting portion of NASA WISE mission, illustrates the differences between orbits of a typical near-Earth asteroid blue and a potentially hazardous asteroid, or PHA orange. PHAs are a subset of the near-Earth asteroids NEAs.

Small bodies and the outer planets and Appendices 1 and 2

NASA Technical Reports Server (NTRS)

Davis, D. R.

1974-01-01

Correlations of asteroid spectral reflectivity characteristics with orbital parameters have been sought. Asteroid proper elements and extreme heliocentric distance were examined. Only general trends were noted, primarily red asteroids and asteroids with IR (.95 micron) absorption bands are concentrated toward the inner part of the belt. Also, asteroids with the pyroxene band tend to have larger proper eccentricities relative to non-banded asteroids.

Cerebro-rhino orbital mucormycosis: an update.

PubMed

Wali, Upender; Balkhair, Abdullah; Al-Mujaini, Abdullah

2012-04-01

Mucormycosis is an uncommon fungal infection which can lead to fulminant necrotizing infection under optimal host condition. Fungi have the ability to invade blood vessels and can affect different parts of the body. The most common, though the most aggressive, form is cerebro-rhino-orbital mucormycosis that occurs in debilitated patients, in conjunction with sinus or para-sinus involvement. Due to increased number of newly diagnosed cases of mucormycosis world-wide resulting from uncontrolled metabolic conditions, this paper intends to widen the reader's scope and knowledge about the nature of the disease and its multicomplexity that require a collaborative effort for careful management. Patients who are at risks both at the onset of the disease and during its management have been identified in the paper. Copyright © 2012 King Saud Bin Abdulaziz University for Health Sciences. Published by Elsevier Ltd. All rights reserved.

Both size-frequency distribution and sub-populations of the main-belt asteroid population are consistent with YORP-induced rotational fission

NASA Astrophysics Data System (ADS)

Jacobson, S.; Scheeres, D.; Rossi, A.; Marzari, F.; Davis, D.

2014-07-01

From the results of a comprehensive asteroid-population-evolution model, we conclude that the YORP-induced rotational-fission hypothesis has strong repercussions for the small size end of the main-belt asteroid size-frequency distribution and is consistent with observed asteroid-population statistics and with the observed sub-populations of binary asteroids, asteroid pairs and contact binaries. The foundation of this model is the asteroid-rotation model of Marzari et al. (2011) and Rossi et al. (2009), which incorporates both the YORP effect and collisional evolution. This work adds to that model the rotational fission hypothesis (i.e. when the rotation rate exceeds a critical value, erosion and binary formation occur; Scheeres 2007) and binary-asteroid evolution (Jacobson & Scheeres, 2011). The YORP-effect timescale for large asteroids with diameters D > ˜ 6 km is longer than the collision timescale in the main belt, thus the frequency of large asteroids is determined by a collisional equilibrium (e.g. Bottke 2005), but for small asteroids with diameters D < ˜ 6 km, the asteroid-population evolution model confirms that YORP-induced rotational fission destroys small asteroids more frequently than collisions. Therefore, the frequency of these small asteroids is determined by an equilibrium between the creation of new asteroids out of the impact debris of larger asteroids and the destruction of these asteroids by YORP-induced rotational fission. By introducing a new source of destruction that varies strongly with size, YORP-induced rotational fission alters the slope of the size-frequency distribution. Using the outputs of the asteroid-population evolution model and a 1-D collision evolution model, we can generate this new size-frequency distribution and it matches the change in slope observed by the SKADS survey (Gladman 2009). This agreement is achieved with both an accretional power-law or a truncated ''Asteroids were Born Big'' size-frequency distribution (Weidenschilling 2010, Morbidelli 2009). The binary-asteroid evolution model is highly constrained by the modeling done in Jacobson & Scheeres, and therefore the asteroid-population evolution model has only two significant free parameters: the ratio of low-to-high-mass-ratio binaries formed after rotational fission events and the mean strength of the binary YORP (BYORP) effect. Using this model, we successfully reproduce the observed small-asteroid sub-populations, which orthogonally constrain the two free parameters. We find the outcome of rotational fission most likely produces an initial mass-ratio fraction that is four to eight times as likely to produce high-mass-ratio systems as low-mass-ratio systems, which is consistent with rotational fission creating binary systems in a flat distribution with respect to mass ratio. We also find that the mean of the log-normal BYORP coefficient distribution B ≈ 10^{-2}.

Mission options for rendezvous with the most accessible Near-Earth Asteroid - 1989 ML

NASA Technical Reports Server (NTRS)

Mcadams, Jim V.

1992-01-01

The recent discovery of the Amor-class 1989 ML, the most accessible known asteroid for minimum-energy rendezvous missions, has expedited the search for frequent, low-cost Near-Earth Asteroid rendezvous and round-trip missions. This paper identifies trajectory characteristics and assesses mass performance for low Delta V ballistic rendezvous opportunities to 1989 ML during the period 1996-2010. This asteroid also offers occasional unique extended mission opportunities, such as the lowest known Delta V requirement for any asteroid sample return mission as well as pre-rendezvous asteroid flyby and post-rendezvous comet flyby opportunities requiring less than 5.25 km/sec total Delta V. This paper also briefly comments concerning mission opportunities for asteroid 1991 JW, which recently replaced other known asteroids as the most accessible Near-Earth Asteroid for fast rendezvous and round-trip missions.

Speckle interferometry of asteroids

NASA Technical Reports Server (NTRS)

Drummond, Jack

1988-01-01

This final report for NASA Contract NAGw-867 consists of abstracts of the first three papers in a series of four appearing in Icarus that were funded by the preceding contract NAGw-224: (1) Speckle Interferometry of Asteroids I. 433 Eros; (2) Speckle Interferometry of Asteroids II. 532 Herculina; (3) Speckle Interferometry of Asteroids III. 511 Davida and its Photometry; and the fourth abstract attributed to NAGw-867, (4) Speckle Interferometry of Asteroids IV. Reconstructed images of 4 Vesta; and a review of the results from the asteroid interferometry program at Steward Observatory prepared for the Asteroids II book, (5) Speckle Interferometry of Asteroids. Two papers on asteroids, indirectly related to speckle interferometry, were written in part under NAGw-867. One is in press and its abstract is included here: Photometric Geodesy of Main-Belt Asteroids. II. Analysis of Lightcurves for Poles, Periods and Shapes; and the other paper, Triaxial Ellipsoid Dimensions and Rotational Pole of 2 Pallas from Two Stellar Occultations, is included in full.

32 CFR 644.422 - Authorized widening of a public highway, street, or alley.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 32 National Defense 4 2010-07-01 2010-07-01 true Authorized widening of a public highway, street... and Easement Interests § 644.422 Authorized widening of a public highway, street, or alley. 40 U.S.C... authorized widening of a public highway, street, or alley. The conveyance may be made with or without...

32 CFR 644.422 - Authorized widening of a public highway, street, or alley.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 32 National Defense 4 2013-07-01 2013-07-01 false Authorized widening of a public highway, street... and Easement Interests § 644.422 Authorized widening of a public highway, street, or alley. 40 U.S.C... authorized widening of a public highway, street, or alley. The conveyance may be made with or without...

32 CFR 644.422 - Authorized widening of a public highway, street, or alley.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 32 National Defense 4 2012-07-01 2011-07-01 true Authorized widening of a public highway, street... and Easement Interests § 644.422 Authorized widening of a public highway, street, or alley. 40 U.S.C... authorized widening of a public highway, street, or alley. The conveyance may be made with or without...

32 CFR 644.422 - Authorized widening of a public highway, street, or alley.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 32 National Defense 4 2014-07-01 2013-07-01 true Authorized widening of a public highway, street... and Easement Interests § 644.422 Authorized widening of a public highway, street, or alley. 40 U.S.C... authorized widening of a public highway, street, or alley. The conveyance may be made with or without...

32 CFR 644.422 - Authorized widening of a public highway, street, or alley.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 32 National Defense 4 2011-07-01 2011-07-01 false Authorized widening of a public highway, street... and Easement Interests § 644.422 Authorized widening of a public highway, street, or alley. 40 U.S.C... authorized widening of a public highway, street, or alley. The conveyance may be made with or without...

Collaborating for Change? Managing Widening Participation in Further and Higher Education.

ERIC Educational Resources Information Center

Stuart, Mary

This book, which is addressed to managers in further education and higher education across Great Britain, explains what managers must do to enable the changes required to widen participation in their sectors. The following are among the topics discussed: (1) the why and how of widening participation (the importance of widening participation in a…

Asteroid mass estimation using Markov-Chain Monte Carlo techniques

NASA Astrophysics Data System (ADS)

Siltala, Lauri; Granvik, Mikael

2016-10-01

Estimates for asteroid masses are based on their gravitational perturbations on the orbits of other objects such as Mars, spacecraft, or other asteroids and/or their satellites. In the case of asteroid-asteroid perturbations, this leads to a 13-dimensional inverse problem where the aim is to derive the mass of the perturbing asteroid and six orbital elements for both the perturbing asteroid and the test asteroid using astrometric observations. We have developed and implemented three different mass estimation algorithms utilizing asteroid-asteroid perturbations into the OpenOrb asteroid-orbit-computation software: the very rough 'marching' approximation, in which the asteroid orbits are fixed at a given epoch, reducing the problem to a one-dimensional estimation of the mass, an implementation of the Nelder-Mead simplex method, and most significantly, a Markov-Chain Monte Carlo (MCMC) approach. We will introduce each of these algorithms with particular focus on the MCMC algorithm, and present example results for both synthetic and real data. Our results agree with the published mass estimates, but suggest that the published uncertainties may be misleading as a consequence of using linearized mass-estimation methods. Finally, we discuss remaining challenges with the algorithms as well as future plans, particularly in connection with ESA's Gaia mission.

Asteroid/meteorite streams

NASA Astrophysics Data System (ADS)

Drummond, J.

The independent discovery of the same three streams (named alpha, beta, and gamma) among 139 Earth approaching asteroids and among 89 meteorite producing fireballs presents the possibility of matching specific meteorites to specific asteroids, or at least to asteroids in the same stream and, therefore, presumably of the same composition. Although perhaps of limited practical value, the three meteorites with known orbits are all ordinary chondrites. To identify, in general, the taxonomic type of the parent asteroid, however, would be of great scientific interest since these most abundant meteorite types cannot be unambiguously spectrally matched to an asteroid type. The H5 Pribram meteorite and asteroid 4486 (unclassified) are not part of a stream, but travel in fairly similar orbits. The LL5 Innisfree meteorite is orbitally similar to asteroid 1989DA (unclassified), and both are members of a fourth stream (delta) defined by five meteorite-dropping fireballs and this one asteroid. The H5 Lost City meteorite is orbitally similar to 1980AA (S type), which is a member of stream gamma defined by four asteroids and four fireballs. Another asteroid in this stream is classified as an S type, another is QU, and the fourth is unclassified. This stream suggests that ordinary chondrites should be associated with S (and/or Q) asteroids. Two of the known four V type asteroids belong to another stream, beta, defined by five asteroids and four meteorite-dropping (but unrecovered) fireballs, making it the most probable source of the eucrites. The final stream, alpha, defined by five asteroids and three fireballs is of unknown composition since no meteorites have been recovered and only one asteroid has an ambiguous classification of QRS. If this stream, or any other as yet undiscovered ones, were found to be composed of a more practical material (e.g., water or metalrich), then recovery of the associated meteorites would provide an opportunity for in-hand analysis of a potential near-Earth resource.

Asteroid/meteorite streams

NASA Technical Reports Server (NTRS)

Drummond, J.

1991-01-01

The independent discovery of the same three streams (named alpha, beta, and gamma) among 139 Earth approaching asteroids and among 89 meteorite producing fireballs presents the possibility of matching specific meteorites to specific asteroids, or at least to asteroids in the same stream and, therefore, presumably of the same composition. Although perhaps of limited practical value, the three meteorites with known orbits are all ordinary chondrites. To identify, in general, the taxonomic type of the parent asteroid, however, would be of great scientific interest since these most abundant meteorite types cannot be unambiguously spectrally matched to an asteroid type. The H5 Pribram meteorite and asteroid 4486 (unclassified) are not part of a stream, but travel in fairly similar orbits. The LL5 Innisfree meteorite is orbitally similar to asteroid 1989DA (unclassified), and both are members of a fourth stream (delta) defined by five meteorite-dropping fireballs and this one asteroid. The H5 Lost City meteorite is orbitally similar to 1980AA (S type), which is a member of stream gamma defined by four asteroids and four fireballs. Another asteroid in this stream is classified as an S type, another is QU, and the fourth is unclassified. This stream suggests that ordinary chondrites should be associated with S (and/or Q) asteroids. Two of the known four V type asteroids belong to another stream, beta, defined by five asteroids and four meteorite-dropping (but unrecovered) fireballs, making it the most probable source of the eucrites. The final stream, alpha, defined by five asteroids and three fireballs is of unknown composition since no meteorites have been recovered and only one asteroid has an ambiguous classification of QRS. If this stream, or any other as yet undiscovered ones, were found to be composed of a more practical material (e.g., water or metalrich), then recovery of the associated meteorites would provide an opportunity for in-hand analysis of a potential near-Earth resource.

Asteroid selection for mission opportunities. Appendix: Asteroid data sheets

NASA Technical Reports Server (NTRS)

1972-01-01

The characteristics of asteroids selected as possible space mission objectives are presented. The asteroids are described according to: (1) magnitude, (2) spectral reflectivity; (3) phase factors, (4) polarization, (5) light curve, and (6) physical parameters. The data are tabulated on specific formats for each asteroid considered.

Asteroid surface mineralogy: Evidence from earth-based telescope observations

NASA Technical Reports Server (NTRS)

Mccord, T. B.

1978-01-01

The interpretation of asteroid reflectance spectrophotometry in terms of mineralogical types gives inferred mineral assemblages for about 60 asteroids. Asteroid surface materials are compared with similar materials that make up many meteorites. The absence of asteroids with spectra that match identically the ordinary chondrites is noted.

Telepathology Impacts and Implementation Challenges: A Scoping Review.

PubMed

Meyer, Julien; Paré, Guy

2015-12-01

Telepathology is a particular form of telemedicine that fundamentally alters the way pathology services are delivered. Prior reviews in this area have mostly focused on 2 themes, namely technical feasibility issues and diagnosis accuracy. To synthesize the literature on telepathology implementation challenges and broader organizational and societal impacts and to propose a research agenda to guide future efforts in this domain. Two complementary databases were systematically searched: MEDLINE (PubMed) and ABI/INFORM (ProQuest). Peer-reviewed articles and conference proceedings were considered. The final sample consisted of 159 papers published between 1992 and 2013. This review highlights the diversity of telepathology networks and the importance of considering these distinctions when interpreting research findings. Various network structures are associated with different benefits. Although the dominant rationale in single-site projects is financial, larger centralized and decentralized telepathology networks are targeting a more diverse set of benefits, including extending access to pathology to a whole region, achieving substantial economies of scale in workforce and equipment, and improving quality by standardizing care. Importantly, our synthesis reveals that the nature and scale of encountered implementation challenges also varies depending on the network structure. In smaller telepathology networks, organizational concerns are less prominent, and implementers are more focused on usability issues. As the network scope widens, organizational and legal issues gain prominence.

Meteoritic and Asteroidal Constraints on the Identification and Collisional Evolution of Asteroid Families

NASA Technical Reports Server (NTRS)

Gaffey, Michael J.; Kelley, Michael S.; Hardersen, Paul S.

2002-01-01

Studies of meteorites and observations of asteroids can provide important constraints on the formation and evolution of asteroid families. The iron meteorites alone require the disruption of 85 differentiated asteroids, and the potential formation of 85 families. Additional information is contained in the original extended abstract.

REVIEWS OF TOPICAL PROBLEMS: Satellites of asteroids

NASA Astrophysics Data System (ADS)

Prokof'eva, Valentina V.; Tarashchuk, V. P.; Gor'kavyi, N. N.

1995-06-01

More than 6000 asteroids in the Solar System have now been discovered and enumerated, and about 500 of them have been investigated in detail by different methods. This rewiew gives observational evidence which indicates that no fewer than 10% of asteroids may be composed of two or more bodies. This was supported by the detection of a satellite of the asteroid Ida by the Galileo spacecraft. This discovery symbolises the change of both observational and theoretical paradigms. Space and ground observations of asteroids by modern teghniques may give extensive new data for modelling double asteroids. The analysis of problems of stability, formation and dynamics of asteroid satellites shows that their sphere of stable motion extends up to several hundred asteroid radii. The idea that the origin of the asteroid satellites may be explained in the frame of a unified accretion model of planetary satellite formation is proposed and justified.

Asteroid rotation. I - Tabulation and analysis of rates, pole positions and shapes. II - A theory for the collisional evolution of rotation rates

NASA Technical Reports Server (NTRS)

Harris, A. W.; Burns, J. A.

1979-01-01

Rotation properties and shape data for 182 asteroids are compiled and analyzed, and a collisional model for the evolution of the mean rotation rate of asteroids is proposed. Tabulations of asteroid rotation rates, taxonomic types, pole positions, sizes and shapes and plots of rotation frequency and light curve amplitude against size indicate that asteroid rotational frequency increases with decreasing size for all asteroids except those of the C or S classes. Light curve data also indicate that small asteroids are more irregular in shape than large asteroids. The dispersion in rotation rates observed is well represented by a three dimensional Maxwellian distribution, suggestive of collisional encounters between asteroids. In the proposed model, the rotation rate is found to tend toward an equilibrium value, at which spin-up due to infrequent, large collisions is balanced by a drag due to the larger number of small collisions. The lower mean rotation rate of C-type asteroids is attributed to a lower means density of that class, and the increase in rotation rate with decreasing size is interpreted as indicative of a substantial population of strong asteroids.

Physical studies of asteroids. XXXII. Rotation periods and UBVRI-colours for selected asteroids

NASA Astrophysics Data System (ADS)

Piironen, J.; Lagerkvist, C.-I.; Erikson, A.; Oja, T.; Magnusson, P.; Festin, L.; Nathues, A.; Gaul, M.; Velichko, F.

1998-03-01

We present lightcurves of selected asteroids. Most of the asteroids were included to obtain refined spin periods. Enhanced periods were determined for 11 Parthenope, 306 Unitas and 372 Palma. We confirmed the spin periods of 8 Flora, 13 Egeria, 71 Niobe, 233 Asterope, 291 Alice, 409 Aspasia, 435 Ella and 512 Taurinensis. We determined also BV-colours for most of the included asteroids and UBVRI-colours for a total of 22 asteroids.

Simultaneous Mass Determination for Gravitationally Coupled Asteroids

NASA Astrophysics Data System (ADS)

Baer, James; Chesley, Steven R.

2017-08-01

The conventional least-squares asteroid mass determination algorithm allows us to solve for the mass of a large subject asteroid that is perturbing the trajectory of a smaller test asteroid. However, this algorithm is necessarily a first approximation, ignoring the possibility that the subject asteroid may itself be perturbed by the test asteroid, or that the encounter’s precise geometry may be entangled with encounters involving other asteroids. After reviewing the conventional algorithm, we use it to calculate the masses of 30 main-belt asteroids. Compared to our previous results, we find new mass estimates for eight asteroids (11 Parthenope, 27 Euterpe, 51 Neimausa, 76 Freia, 121 Hermione, 324 Bamberga, 476 Hedwig, and 532 Herculina) and significantly more precise estimates for six others (2 Pallas, 3 Juno, 4 Vesta, 9 Metis, 16 Psyche, and 88 Thisbe). However, we also find that the conventional algorithm yields questionable results in several gravitationally coupled cases. To address such cases, we describe a new algorithm that allows the epoch state vectors of the subject asteroids to be included as solve-for parameters, allowing for the simultaneous solution of the masses and epoch state vectors of multiple subject and test asteroids. We then apply this algorithm to the same 30 main-belt asteroids and conclude that mass determinations resulting from current and future high-precision astrometric sources (such as Gaia) should conduct a thorough search for possible gravitational couplings and account for their effects.

Asteroid Lightcurve Analysis at Isaac Aznar Observatory Aras De Los Olmos, Valencia, Spain

NASA Astrophysics Data System (ADS)

Macias, Amadeo Aznar

2015-01-01

The Isaac Aznar Observatory conducts astrometric and photometric studies of asteroids. This paper contains the photometric results of four asteroids obtained from 2014 April to August. These asteroids were selected from the Collaborative Asteroid Lightcurve Link (CALL) web site: 1088 Mitaka, 2956 Yeomans, 3894 Williamcooke, and (4555) 1974QL.

Rotational and translational considerations in kinetic impact deflection of potentially hazardous asteroids

NASA Astrophysics Data System (ADS)

Zhang, Fei; Xu, Bo; Circi, Christian; Zhang, Lei

2017-04-01

Kinetic impact may be the most reliable and easily implemented method to deflect hazardous asteroids using current technology. Depending on warning time, it can be effective on asteroids with diameters of a few hundred meters. Current impact deflection research often focuses on the orbital dynamics of asteroids. In this paper, we use the ejection outcome of a general oblique impact to calculate how an asteroid's rotational and translational state changes after impact. The results demonstrate how small impactors affect the dynamical state of small asteroids having a diameter of about 100 m. According to these consequences, we propose using several small impactors to hit an asteroid continuously and gently, making the deflection mission relatively flexible. After calculating the rotational variation, we find that the rotational state, especially of slender non-porous asteroids, can be changed significantly. This gives the possibility of using multiple small impactors to mitigate a potentially hazardous asteroid by spinning it up into pieces, or to despin one for future in-situ investigation (e.g., asteroid retrieval or mining).

Small main-belt asteroid spectroscopic survey: Initial results

NASA Technical Reports Server (NTRS)

Xu, Shui; Binzel, Richard P.; Burbine, Thomas H.; Bus, Schelte J.

1995-01-01

The spectral characterization of small asteroids is important for understanding the evolution of their compositional and mineralogical properties. We report the results of a CCD spectroscopic survey of small main-belt asteroids which we call the Small Main-belt Asteroid Spectroscopic Survey (SMASS). Spectra of 316 asteroids were obtained, with wavelength coverage ranging from 4000 to 10000 A (0.4 to 1 micrometers). More than half of the objects in our survey have diameters less than 20 km. Survey results include the identification of the first object resembling ordinary chondrite meteorites among the main-belt asteroids (Binzel, R. P., et al, 1993) and observations of more than 20 asteroids showing basaltic achondrite spectral absorption features that strongly link Vesta as the parent body for the basaltic achondrite meteorites (Binzel, R. P., and S. Xu 1993). A potential Mars-crossing asteroid analog to ordinary chondrite meteorites (H chondrites), 2078 Nanking, is reported here. Through a principal component analysis, we have assigned classifications to the members of our sample. The majority of the small main-belt asteroids belong to S and C classes, similar to large asteroids. Our analysis shows that two new classes are justified which we label as J and O. Small asteroids display more diversity in spectral absorption features than the larger ones, which may indicate a greater variation of compositions in the small asteroid population. We found a few candidates for olivine-rich asteroids within the S class. Although the total number of olivine-rich candidates is relatively small, we present evidence suggesting that such objects are more prevalent at smaller sizes.

The Asteroid Impact and Deflection Assessment Mission and its Potential Contributions to Human Exploration of Asteroids

NASA Technical Reports Server (NTRS)

Abell, Paul A.; Rivkin, Andy S.

2014-01-01

The joint ESA and NASA Asteroid Impact and Deflection Assessment (AIDA) mission will directly address aspects of NASA's Asteroid Initiative and will contribute to future human exploration. The NASA Asteroid Initiative is comprised of two major components: the Grand Challenge and the Asteroid Mission. The first component, the Grand Challenge, focuses on protecting Earth's population from asteroid impacts by detecting potentially hazardous objects with enough warning time to either prevent them from impacting the planet, or to implement civil defense procedures. The Asteroid Mission, involves sending astronauts to study and sample a near-Earth asteroid (NEA) prior to conducting exploration missions of the Martian system, which includes Phobos and Deimos. AIDA's primary objective is to demonstrate a kinetic impact deflection and characterize the binary NEA Didymos. The science and technical data obtained from AIDA will aid in the planning of future human exploration missions to NEAs and other small bodies. The dual robotic missions of AIDA, ESA's Asteroid Impact Monitor (AIM) and NASA's Double Asteroid Redirection Test (DART), will provide a great deal of technical and engineering data on spacecraft operations for future human space exploration while conducting in-depth scientific examinations of the binary target Didymos both prior to and after the kinetic impact demonstration. The knowledge gained from this mission will help identify asteroidal physical properties in order to maximize operational efficiency and reduce mission risk for future small body missions. The AIDA data will help fill crucial strategic knowledge gaps concerning asteroid physical characteristics that are relevant for human exploration considerations at similar small body destinations.

Compositional studies of primitive asteroids

NASA Technical Reports Server (NTRS)

Vilas, Faith

1991-01-01

Primitive asteroids in the solar system (C, P, D class and associated subclasses) are believed to have undergone less thermal processing compared with the differential (S class) asteroids. Telescopic spectra of C class asteroids show effects of aqueous alteration products produced when heating of the asteroids was sufficient to melt surface water, but not strong enough to produce differentiation. Spectrum analysis of P and D class asteroids suggests that aqueous alteration terminated in the outer belt and did not operate at the distance of Jupiter's orbit.

Studies of asteroids, comets, and Jupiter's outer satellites

NASA Technical Reports Server (NTRS)

Bowell, Edward

1991-01-01

Observational, theoretical, and computational research was performed, mainly on asteroids. Two principal areas of research, centering on astrometry and photometry, are interrelated in their aim to study the overall structure of the asteroid belt and the physical and orbital properties of individual asteroids. Two highlights are: detection of CN emission from Chiron; and realization that 1990 MB is the first known Trojan type asteroid of a planet other than Jupiter. A new method of asteroid orbital error analysis, based on Bayesian theory, was developed.

Asteroid exploration and utilization: The Hawking explorer

NASA Technical Reports Server (NTRS)

Carlson, Alan; Date, Medha; Duarte, Manny; Erian, Neil; Gafka, George; Kappler, Peter; Patano, Scott; Perez, Martin; Ponce, Edgar; Radovich, Brian

1991-01-01

The Earth is nearing depletion of its natural resources at a time when human beings are rapidly expanding the frontiers of space. The resources which may exist on asteroids could have enormous potential for aiding and enhancing human space exploration as well as life on Earth. With the possibly limitless opportunities that exist, it is clear that asteroids are the next step for human existence in space. This report comprises the efforts of NEW WORLDS, Inc. to develop a comprehensive design for an asteroid exploration/sample return mission. This mission is a precursor to proof-of-concept missions that will investigate the validity of mining and materials processing on an asteroid. Project STONER (Systematic Transfer of Near Earth Resources) is based on two utilization scenarios: (1) moving an asteroid to an advantageous location for use by Earth; and (2) mining an asteroids and transporting raw materials back to Earth. The asteroid explorer/sample return mission is designed in the context of both scenarios and is the first phase of a long range plane for humans to utilize asteroid resources. The report concentrates specifically on the selection of the most promising asteroids for exploration and the development of an exploration scenario. Future utilization as well as subsystem requirements of an asteroid sample return probe are also addressed.

Asteroid exploration and utilization: The Hawking explorer

NASA Astrophysics Data System (ADS)

Carlson, Alan; Date, Medha; Duarte, Manny; Erian, Neil; Gafka, George; Kappler, Peter; Patano, Scott; Perez, Martin; Ponce, Edgar; Radovich, Brian

1991-12-01

The Earth is nearing depletion of its natural resources at a time when human beings are rapidly expanding the frontiers of space. The resources which may exist on asteroids could have enormous potential for aiding and enhancing human space exploration as well as life on Earth. With the possibly limitless opportunities that exist, it is clear that asteroids are the next step for human existence in space. This report comprises the efforts of NEW WORLDS, Inc. to develop a comprehensive design for an asteroid exploration/sample return mission. This mission is a precursor to proof-of-concept missions that will investigate the validity of mining and materials processing on an asteroid. Project STONER (Systematic Transfer of Near Earth Resources) is based on two utilization scenarios: (1) moving an asteroid to an advantageous location for use by Earth; and (2) mining an asteroids and transporting raw materials back to Earth. The asteroid explorer/sample return mission is designed in the context of both scenarios and is the first phase of a long range plane for humans to utilize asteroid resources. The report concentrates specifically on the selection of the most promising asteroids for exploration and the development of an exploration scenario. Future utilization as well as subsystem requirements of an asteroid sample return probe are also addressed.

Autonomous NanoTechnology Swarm (ANTS) Prospecting Asteroid Mission (PAM), Asteroid Proximity Operations

NASA Technical Reports Server (NTRS)

Marr, Greg; Cooley, Steve; Roithmayr, Carlos; Kay-Bunnell, Linda; Williams, Trevor

2004-01-01

The Autonomous NanoTechnology Swarm (ANTS) is a generic mission architecture based on spatially distributed spacecraft, autonomous and redundant components, and hierarchical organization. The ANTS Prospecting Asteroid Mission (PAM) is an ANTS application which will nominally use a swarm of 1000 spacecraft. There would be 10 types of "specialists" with common spacecraft buses. There would be 10 subswarms of approximately 100 spacecraft each or approximately 10 of each specialist in each swarm. The ANTS PAM primary objective is the exploration of the asteroid belt in search of resources and material with astrobiologically relevant origins and signatures. The ANTS PAM spacecraft will nominally be released from a station in an Earth-Moon L1 libration point orbit, and they will use Solar sails for propulsion. The sail structure would be highly flexible, capable of changing morphology to change cross-section for capture of sunlight or to form effective "tip vanes" for attitude control. ANTS PAM sails would be capable of full to partial deployment, to change effective sail area and center of pressure, and thus allow attitude control. Results of analysis of a transfer trajectory from Earth to a sample target asteroid will be presented. ANTS PAM will require continuous coverage of different asteroid locations as close as one to two asteroid "diameters" from the surface of the asteroid for periods of science data collection during asteroid proximity operations. Hovering spacecraft could meet the science data collection objectives. The results of hovering analysis will be presented. There are locations for which hovering is not possible, for example on the illuminated side of the asteroid. For cases where hovering is not possible, the results of utilizing asteroid formations to orbit the asteroid and achieve the desired asteroid viewing will be presented for sample asteroids. The ability of ANTS PAM to reduce the area of the solar sail during asteroid proximity operations is critical to the maintenance of orbiting formations for a period of time. Results of analysis of potential "traffic" problems during asteroid proximity operations will be presented.

Lunar and Planetary Science XXXV: Asteroids, Meteors, Comets

NASA Technical Reports Server (NTRS)

2004-01-01

Reports included:Long Term Stability of Mars Trojans; Horseshoe Asteroids and Quasi-satellites in Earth-like Orbits; Effect of Roughness on Visible Reflectance Spectra of Planetary Surface; SUBARU Spectroscopy of Asteroid (832) Karin; Determining Time Scale of Space Weathering; Change of Asteroid Reflectance Spectra by Space Weathering: Pulse Laser Irradiation on Meteorite Samples; Reflectance Spectra of CM2 Chondrite Mighei Irradiated with Pulsed Laser and Implications for Low-Albedo Asteroids and Martian Moons; Meteorite Porosities and Densities: A Review of Trends in the Data; Small Craters in the Inner Solar System: Primaries or Secondaries or Both?; Generation of an Ordinary-Chondrite Regolith by Repetitive Impact; Asteroid Modal Mineralogy Using Hapke Mixing Models: Validation with HED Meteorites; Particle Size Effect in X-Ray Fluorescence at a Large Phase Angle: Importance on Elemental Analysis of Asteroid Eros (433); An Investigation into Solar Wind Depletion of Sulfur in Troilite; Photometric Behaviour Dependent on Solar Phase Angle and Physical Characteristics of Binary Near-Earth-Asteroid (65803) 1996 GT; Spectroscopic Observations of Asteroid 4 Vesta from 1.9 to 3.5 micron: Evidence of Hydrated and/or Hydroxylated Minerals; Multi-Wavelength Observations of Asteroid 2100 Ra-Shalom: Visible, Infrared, and Thermal Spectroscopy Results; New Peculiarities of Cometary Outburst Activity; Preliminary Shape Modeling for the Asteroid (25143) Itokawa, AMICA of Hayabusa Mission; Scientific Capability of MINERVA Rover in Hayabusa Asteroid Mission; Characteristics and Current Status of Near Infrared Spectrometer for Hayabusa Mission; Sampling Strategy and Curation Plan of Hayabusa Asteroid Sample Return Mission; Visible/Near-Infrared Spectral Properties of MUSES C Target Asteroid 25143 Itokawa; Calibration of the NEAR XRS Solar Monitor; Modeling Mosaic Degradation of X-Ray Measurements of 433 Eros by NEAR-Shoemaker; Scattered Light Remediation and Recalibration of near Sheomaker s NIS Global Dataaset at 433 Eros; Evaluation of Preparation and Measuring Techniques for Interplanetary Dust Particles for the MIDAS Experiment on Rosetta; Chiron: a Proposed Remote Sensing Prompt Gamma Ray Activation Analysis Instrument for a Nuclear Powered Prometheus Mission;From Present Surveying to Future Prospecting of the Asteroid Belt; Asteroid Physical Properties Probe Microgravity Testing of a Surface Sampling System for Sample Return from Small Solar System Bodies;and Penetrator Coring Apparatus for Cometary Surfaces.

Asteroid surface materials - Mineralogical characterizations and cosmological implications

NASA Technical Reports Server (NTRS)

Gaffey, M. J.; Mccord, T. B.

1977-01-01

The theoretical basis for the interpretation of diagnostic spectral features is examined and previous characterizations of asteroid surface materials are considered. A summary is provided of results reported by Gaffey and McCord (1977) who have utilized the most sophisticated interpretive techniques available to interpret the spectral reflectance data of about 65 asteroids for mineralogic and petrologic information. Cosmological implications related to the study of asteroid surface materials are also considered, taking into account source bodies for the meteorites, postaccretionary thermal history, significant factors of asteroid thermal history, and the Apollo and Amor asteroids. It is found that the asteroids exhibit surface materials made up of assemblages of meteoritic minerals. The relative abundance of meteorite types reaching the earth's surface is very different from the population of mineralogic types on asteroid surfaces. The earth-crossing or -approaching asteroids apparently derive from a restricted source region or population which is very strongly depleted in the C2-like assemblages that dominate the belt as a whole.

Compositional differences between meteorites and near-Earth asteroids.

PubMed

Vernazza, P; Binzel, R P; Thomas, C A; DeMeo, F E; Bus, S J; Rivkin, A S; Tokunaga, A T

2008-08-14

Understanding the nature and origin of the asteroid population in Earth's vicinity (near-Earth asteroids, and its subset of potentially hazardous asteroids) is a matter of both scientific interest and practical importance. It is generally expected that the compositions of the asteroids that are most likely to hit Earth should reflect those of the most common meteorites. Here we report that most near-Earth asteroids (including the potentially hazardous subset) have spectral properties quantitatively similar to the class of meteorites known as LL chondrites. The prominent Flora family in the inner part of the asteroid belt shares the same spectral properties, suggesting that it is a dominant source of near-Earth asteroids. The observed similarity of near-Earth asteroids to LL chondrites is, however, surprising, as this meteorite class is relatively rare ( approximately 8 per cent of all meteorite falls). One possible explanation is the role of a size-dependent process, such as the Yarkovsky effect, in transporting material from the main belt.

How diverse is the asteroid belt?

NASA Technical Reports Server (NTRS)

Burbine, Thomas H.; Bell, Jeffrey F.

1993-01-01

For approximately twenty years, many different asteroid taxonomies, which used many different observational data sets, have been developed to try to group asteroids into classes that contain members with similar spectral characteristics. However, to understand the structure of the asteroid belt, the resulting classes are only useful if they are grouping together asteroids with somewhat similar mineralogies and thermal histories. Until recently, these taxonomies have focused on spectral reflectance data from 0.3 to 1.1 microns and visual albedo. But in the last five years, observational data sets (e.g., 0.8 to 2.5 microns spectra, CCD spectra, 3 microns spectra, and radar albedos) for a small number of asteroids were compiled that can give a better mineralogical interpretation, but whose use in asteroid taxonomy was relatively limited. Analyses of these 'supplementary' data sets show that most asteroid classes contain members with different compositions and/or thermal histories. To understand the diversity of the asteroid belt, the number of objects with these observations must be expanded and used in the next generation of taxonomies.

The Steward Observatory asteroid relational database

NASA Technical Reports Server (NTRS)

Sykes, Mark V.; Alvarezdelcastillo, Elizabeth M.

1992-01-01

The Steward Observatory Asteroid Relational Database (SOARD) was created as a flexible tool for undertaking studies of asteroid populations and sub-populations, to probe the biases intrinsic to asteroid databases, to ascertain the completeness of data pertaining to specific problems, to aid in the development of observational programs, and to develop pedagogical materials. To date SOARD has compiled an extensive list of data available on asteroids and made it accessible through a single menu-driven database program. Users may obtain tailored lists of asteroid properties for any subset of asteroids or output files which are suitable for plotting spectral data on individual asteroids. A browse capability allows the user to explore the contents of any data file. SOARD offers, also, an asteroid bibliography containing about 13,000 references. The program has online help as well as user and programmer documentation manuals. SOARD continues to provide data to fulfill requests by members of the astronomical community and will continue to grow as data is added to the database and new features are added to the program.

Origin of Martian Moons from Binary Asteroid Dissociation

NASA Technical Reports Server (NTRS)

Landis, Geoffrey A.; Lyons, Valerie J. (Technical Monitor)

2001-01-01

The origin of the Martian moons Deimos and Phobos is controversial. A common hypothesis for their origin is that they are captured asteroids, but the moons show no signs of having been heated by passage through a (hypothetical) thick martian atmosphere, and the mechanism by which an asteroid in solar orbit could shed sufficient orbital energy to be captured into Mars orbit has not been previously elucidated. Since the discovery by the space probe Galileo that the asteroid Ida has a moon 'Dactyl', a significant number of asteroids have been discovered to have smaller asteroids in orbit about them. The existence of asteroid moons provides a mechanism for the capture of the Martian moons (and the small moons of the outer planets). When a binary asteroid makes a close approach to a planet, tidal forces can strip the moon from the asteroid. Depending on the phasing, either or both can then be captured. Clearly, the same process can be used to explain the origin of any of the small moons in the solar system.

Detection of ice and organics on an asteroidal surface.

PubMed

Rivkin, Andrew S; Emery, Joshua P

2010-04-29

Recent observations, including the discovery in typical asteroidal orbits of objects with cometary characteristics (main-belt comets, or MBCs), have blurred the line between comets and asteroids, although so far neither ice nor organic material has been detected on the surface of an asteroid or directly proven to be an asteroidal constituent. Here we report the spectroscopic detection of water ice and organic material on the asteroid 24 Themis, a detection that has been independently confirmed. 24 Themis belongs to the same dynamical family as three of the five known MBCs, and the presence of ice on 24 Themis is strong evidence that it also is present in the MBCs. We conclude that water ice is more common on asteroids than was previously thought and may be widespread in asteroidal interiors at much smaller heliocentric distances than was previously expected.

Meteorite spectroscopy and characterization of asteroid surface materials

NASA Technical Reports Server (NTRS)

Gaffey, Michael J.

1991-01-01

The analysis of visible and near-infrared reflectance spectra is the primary means to determine surface mineralogy and petrology of individual asteroids. These individual studies provide the data to investigate the broader relationships between the asteroids and meteorites and between asteroids at different heliocentric distances. The main purpose is to improve the understanding of the origin, evolution, and inter-relationships of the asteroids; of their relationships to the meteorites; and of the processes active and the conditions present in the early inner solar system. Empirical information from the study of asteroids and the meteorites is essential to the adequate development and testing of the theoretical models for the accretion of the terrestrial planets, and for their early post-accretionary evolution. The recent results are outined in the following sections: (1) asteroid igneous processes, and (2) spinel-bearing asteroids and the nebular compositional gradient.

Asteroid Properties from Photometric Observations: Constraining Non-Gravitational Processes in Asteroids

NASA Astrophysics Data System (ADS)

Pravec, P.

2013-05-01

From October 2012 we run our NEOSource project on the Danish 1.54-m telescope on La Silla. The primary aim of the project is to study non-gravitational processes in asteroids near the Earth and in their source regions in the main asteroidal belt. In my talk, I will give a brief overview of our current knowledge of the asteroidal non- gravitational processes and how we study them with photometric observations. I will talk especially about binary and paired asteroids that appear to be formed by rotational fission, about detecting the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) and BYORP (binary YORP) effects of anisotropic thermal emission from asteroids that change their spins and satellite orbits, and about non-principal axis rotators (the so called "tumblers") among the smallest, super-critically rotating asteroids with sizes < 100 meters.

Simultaneous Mass Determination for Gravitationally Coupled Asteroids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baer, James; Chesley, Steven R., E-mail: jimbaer1@earthlink.net

The conventional least-squares asteroid mass determination algorithm allows us to solve for the mass of a large subject asteroid that is perturbing the trajectory of a smaller test asteroid. However, this algorithm is necessarily a first approximation, ignoring the possibility that the subject asteroid may itself be perturbed by the test asteroid, or that the encounter’s precise geometry may be entangled with encounters involving other asteroids. After reviewing the conventional algorithm, we use it to calculate the masses of 30 main-belt asteroids. Compared to our previous results, we find new mass estimates for eight asteroids (11 Parthenope, 27 Euterpe, 51more » Neimausa, 76 Freia, 121 Hermione, 324 Bamberga, 476 Hedwig, and 532 Herculina) and significantly more precise estimates for six others (2 Pallas, 3 Juno, 4 Vesta, 9 Metis, 16 Psyche, and 88 Thisbe). However, we also find that the conventional algorithm yields questionable results in several gravitationally coupled cases. To address such cases, we describe a new algorithm that allows the epoch state vectors of the subject asteroids to be included as solve-for parameters, allowing for the simultaneous solution of the masses and epoch state vectors of multiple subject and test asteroids. We then apply this algorithm to the same 30 main-belt asteroids and conclude that mass determinations resulting from current and future high-precision astrometric sources (such as Gaia ) should conduct a thorough search for possible gravitational couplings and account for their effects.« less

AIDA: Asteroid Impact & Deflection Assessment

NASA Astrophysics Data System (ADS)

Cheng, Andrew; Michel, Patrick; Ulamec, Stephan; Reed, Cheryl; Galvez, Andres; Carnelli, Ian

On Feb. 15, 2013, an exceptionally close approach to Earth by the small asteroid 2012 DA14 was eagerly awaited by observers, but another small asteroid impacted Earth over Chelyabinsk, Russia the same day without warning, releasing several hundred kilotons TNT of energy and injuring over 1500 people. These dramatic events remind us of the needs to discover hazardous asteroids and to learn how to mitigate them. The AIDA mission is the first demonstration of a mitigation technique to protect the Earth from a potential asteroid impact, by performing a spacecraft kinetic impact on an asteroid to deflect it from its trajectory. We will provide an update on the status of parallel AIDA mission studies supported by ESA and NASA. AIDA is an international collaboration consisting of two independent but mutually supporting missions, one of which is the asteroid kinetic impactor, and the other is the characterization spacecraft which will orbit the asteroid system to monitor the deflection experiment and measure the results. These two missions are the NASA Double Asteroid Redirection Test (DART), which is the kinetic impactor, and the European Space Agency's Asteroid Impact Monitoring (AIM) mission, which is the characterization spacecraft. The target of the AIDA mission will be a binary asteroid, in which DART will target the secondary, smaller member in order to deflect the binary orbit. The resulting period change can be measured to within 10% by ground-based observations. The asteroid deflection will be measured to higher accuracy, and additional results of the DART impact, like the impact crater, will be studied in great detail by the AIM mission. AIDA will return vital data to determine the momentum transfer efficiency of the kinetic impact and key physical properties of the target asteroid. The two mission components of AIDA, DART and AIM, are each independently valuable, but when combined they provide a greatly increased knowledge return. The AIDA mission will combine US and European space experience and expertise to address an international problem, the asteroid impact hazard. AIDA will also be a valuable precursor to human spaceflight to an asteroid, as it would return unique information on an asteroid's strength and internal structure and would be particularly relevant to a human mission for asteroid mitigation. AIDA will furthermore return fundamental new science data on impact cratering, surface properties and interior structure. AIDA will target the binary Near-Earth asteroid Didymos with two independently launched spacecraft, with the deflection experiment to occur in October, 2022.

Near-earth asteroids - Possible sources from reflectance spectroscopy

NASA Technical Reports Server (NTRS)

Mcfadden, L. A.; Gaffey, M. J.; Mccord, T. B.

1985-01-01

The diversity of reflectance spectra noted among near-earth asteroids that were compared with selected asteroids, planets and satellites to determine possible source regions is indicative of different mineralogical composition and, accordingly, of more than one source region. Spectral signatures that are similar to those of main belt asteroids support models deriving some of these asteroids from the 5:2 Kirkwood gap and the Flora family, by way of gravitational perturbations. The differences in composition found between near-earth asteroids and planetary and satellite surfaces are in keeping with theoretical arguments that such bodies should not be sources. While some near-earth asteroids furnish portions of the earth's meteorite flux, other sources must also contribute.

The breakup of a main-belt asteroid 450 thousand years ago.

PubMed

Nesvorný, David; Vokrouhlický, David; Bottke, William F

2006-06-09

Collisions in the asteroid belt frequently lead to catastrophic breakups, where more than half of the target's mass is ejected into space. Several dozen large asteroids have been disrupted by impacts over the past several billion years. These impact events have produced groups of fragments with similar orbits called asteroid families. Here we report the discovery of a very young asteroid family around the object 1270 Datura. Our work takes advantage of a method for identification of recent breakups in the asteroid belt using catalogs of osculating (i.e., instantaneous) asteroid orbits. The very young families show up in these catalogs as clusters in a five-dimensional space of osculating orbital elements.

Accessibility of near-Earth asteroids, 1990

NASA Technical Reports Server (NTRS)

Hulkower, Neal D.; Child, Jack B.

1991-01-01

Previous research which analyzed the accessibility of all known near-Earth asteroids is updated. Since then, many new near-Earth asteroids have been discovered, and 1928 DB, the most accessible asteroid at that time, has been recovered. Many of these recently discovered near-Earth asteroids have promising orbital characteristics. In addition to accessibility (as defined by minimum global delta v), ideal rendezvous opportunities are identified.

CCD scanning for asteroids and comets

NASA Technical Reports Server (NTRS)

Gehrels, T.; Mcmillan, R. S.

1986-01-01

A change coupled device (CCD) is used in a scanning mode to find new asteroids and recover known asteroids and comet nuclei. Current scientific programs include recovery of asteroids and comet nuclei requested by the Minor Planet Center (MPC), discovery of new asteroids in the main belt and of unusual orbital types, and follow-up astrometry of selected new asteroids discovered. The routine six sigma limiting visual magnitude is 19.6 and slightly more than a square degree is scanned three times every 90 minutes of observing time during the fortnight centered on New Moon. Semiautomatic software for detection of moving objects is in routine use; angular speeds as low as 11.0 arcseconds per hour were distinguished from the effects of the Earth's atmosphere on the field of view. A typical set of three 29-minute scans near the opposition point along the ecliptic typically nets at least 5 new main-belt asteroids down to magnitude 19.6. In 18 observing runs (months) 43 asteroids were recovered, astrometric and photometric data on 59 new asteroids were reported, 10 new asteroids with orbital elements were consolidated, and photometry and positions of 22 comets were reported.

Asteroid search program

NASA Astrophysics Data System (ADS)

This document is dedicated first to the criteria used to select a candidate asteroid. It contains the known characteristics of this asteroid as well as the assumptions made about it. It ends with a preliminary study of other possible more favorable candidates which might be found in the near future. Special attention is paid to the possible existence of Earth-Sun Trojan asteroids. Second, there is a description of the current state of our limited knowledge about the asteroids, and of the instruments and techniques being used to improve this knowledge. The contribution to asteroid research which can be expected from the new instruments already in space or due to be launched in this decade is then discussed. The last part of this document gives a description of different ways of improving our knowledge about the asteroids, both quantitatively and qualitatively. A proposal requiring reasonable financing and manpower to improve asteroid research is presented. It is believed that the implementation of such a program would have a dramatic effect on asteroid research. For example, a significant increase in both the rate of discovery of asteroids and their corresponding orbital parameters would be obtained. This program could be fully operational 3 years after its implementation.

Studies of asteroids, comets, and Jupiter's outer satellites

NASA Technical Reports Server (NTRS)

Bowell, Edward

1988-01-01

The work comprises observational, theoretical, and computational research on asteroids, together with a smaller effort concerning the astrometry of comets and Jupiter's satellites JVI through JXIII. Two principal areas of research, centering on astrometry and photometry, are interrelated in their aim to study the overall structure of the asteroid belt and the physical and orbital properties of individual asteroids. About 2000 accurate photographic positions of asteroids and comets, including a number from the Lowell, Palomar, and Goethe-Link archival plate collections, the last of which was donated to us last winter by Indiana University were measured and published. Charge coupled device (CCD) astrometry of 36 faint targets was undertaken, including 4 comets; JVI, JVII, JVIII, JLX, JXI, and JXII; and 26 asteroids, most of which are Earth-approachers. A deep, bias-correctable asteroid survey (LUKAS), the aim of which is to determine the true spatial distribution of asteroids down to subkilometer diameters was started. A series of eight plates at the UK Schmidt telescope that contain images of asteroids as faint as V approximately 22 mag was obtained. Analysis of microdensitometric scans of two plates has shown that about 98 percent of the asteroid images could be identified completely automatically.

Storyboard GALILEO CRUISE SCIENCE OPPORTUNITIES describes asteroid encounters

NASA Technical Reports Server (NTRS)

1989-01-01

Storyboard with mosaicked image of an asteroid and entitled GALILEO CRUISE SCIENCE OPPORTUNITIES describes asteroid objectives. These objectives include: first asteroid encounter; surface geology, composition size, shape, mass; and relation of primitive bodies to meteorites.

Improvement of widening joint design and construction practices for flexible pavements.

DOT National Transportation Integrated Search

2015-09-01

Few guidelines exist statewide, or even nationwide, for assisting designers in selecting : appropriate roadway widening techniques. Current Florida Department of Transportation : (FDOT) specifications provide a basic framework for widening hot-mix as...

Earth-approaching asteroid streams

NASA Astrophysics Data System (ADS)

Drummond, J. D.

1991-01-01

Three association patterns have been noted among 139 earth-approaching asteroids on the basis of current orbital similarity; these asteroid streams, consisting of two groups of five members and one of four, can be matched to three of the four meteorite-producing fireball streams determined by Halliday et al. (1990). If the asteroid streams are true nonrandom associations, the opportunity arises for studies of an 'exploded' asteroid in the near-earth environment. Near-earth asteroid-search projects are encouraged to search the mean orbit of the present streams in order to discover additional association members.

Depletion of the Outer Asteroid Belt

PubMed

Liou; Malhotra

1997-01-17

During the early history of the solar system, it is likely that the outer planets changed their distance from the sun, and hence, their influence on the asteroid belt evolved with time. The gravitational influence of Jupiter and Saturn on the orbital evolution of asteroids in the outer asteroid belt was calculated. The results show that the sweeping of mean motion resonances associated with planetary migration efficiently destabilizes orbits in the outer asteroid belt on a time scale of 10 million years. This mechanism provides an explanation for the observed depletion of asteroids in that region.

Asteroid volatiles inventory

NASA Technical Reports Server (NTRS)

Lebofsky, L. A.; Jones, T. D.; Herbert, F.

1989-01-01

Asteroids appear in light of telescopic and meteority studies to be the most accessible repositories of early solar system history available. In the cooler regions of the outer asteroid belt, apparently unaffected by severe heating, the C, P, and D populations appear to harbor significant inventories of volatiles; the larger primordial belt population may have had an even greater percentage of volatile-rich, low-albedo asteroids, constituting a potent asteroid for veneering early terrestrial planet atmospheres. The volatile-rich asteroids contain carbon, structurally bound and adsorbed water, as well as remnants of interstellar material predating the solar system.

Depletion of the Outer Asteroid Belt

NASA Technical Reports Server (NTRS)

Liou, Jer-Chyi; Malhotra, Renu

1997-01-01

During the early history of the solar system, it is likely that the outer planets changed their distance from the sun, and hence, their influence on the asteroid belt evolved with time. The gravitational influence of Jupiter and Saturn on the orbital evolution of asteroids in the outer asteroid belt was calculated. The results show that the sweeping of mean motion resonances associated with planetary migration efficiently destabilizes orbits in the outer asteroid belt on a time scale of 10 million years. This mechanism provides an explanation for the observed depletion of asteroids in that region.

Recovering and Mining Asteroids with a Gas-Sealed Enclosure

NASA Astrophysics Data System (ADS)

Jenniskens, P.; Damer, B.; Norkus, R.; Pilotz, S.; Grigsby, B.; Adams, C.; Blair, B. R.

2015-01-01

The internal structure of weakly consolidated rubble piles and primitive asteroids can be studied closer to home, and such asteroids can be mined, if it is possible to create a gas-sealed enclosure around the asteroid.

The Steward Observatory asteroid relational database

NASA Technical Reports Server (NTRS)

Sykes, Mark V.; Alvarezdelcastillo, Elizabeth M.

1991-01-01

The Steward Observatory Asteroid Relational Database (SOARD) was created as a flexible tool for undertaking studies of asteroid populations and sub-populations, to probe the biases intrinsic to asteroid databases, to ascertain the completeness of data pertaining to specific problems, to aid in the development of observational programs, and to develop pedagogical materials. To date, SOARD has compiled an extensive list of data available on asteroids and made it accessible through a single menu-driven database program. Users may obtain tailored lists of asteroid properties for any subset of asteroids or output files which are suitable for plotting spectral data on individual asteroids. The program has online help as well as user and programmer documentation manuals. The SOARD already has provided data to fulfill requests by members of the astronomical community. The SOARD continues to grow as data is added to the database and new features are added to the program.

Identification of a primordial asteroid family constrains the original planetesimal population.

PubMed

Delbo', Marco; Walsh, Kevin; Bolin, Bryce; Avdellidou, Chrysa; Morbidelli, Alessandro

2017-09-08

A quarter of known asteroids is associated with more than 100 distinct asteroid families, meaning that these asteroids originate as impact fragments from the family parent bodies. The determination of which asteroids of the remaining population are members of undiscovered families, or accreted as planetesimals from the protoplanetary disk, would constrain a critical phase of planetary formation by unveiling the unknown planetesimal size distribution. We discovered a 4-billion-year-old asteroid family extending across the entire inner part of the main belt whose members include most of the dark asteroids previously unlinked to families. This allows us to identify some original planetesimals, which are all larger than 35 kilometers, supporting the view of asteroids being born big. Their number matches the known distinct meteorite parent bodies. Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

Shape and spin of asteroid 967 Helionape

NASA Astrophysics Data System (ADS)

Apostolovska, G.; Kostov, A.; Donchev, Z.; Bebekovska, E. Vchkova; Kuzmanovska, O.

2018-04-01

Knowledge of the spin and shape parameters of the asteroids is very important for understanding of the conditions during the creation of our planetary system and formation of asteroid populations. The main belt asteroid and Flora family member 967 Helionape was observed during five apparitions. The observations were made at the Bulgarian National Astronomical Observatory (BNAO) Rozhen, since March 2006 to March 2016. Lihtcurve inversion method (Kaasalainen et al. (2001)), applied on 12 relative lightcurves obtained at various geometric conditions of the asteroid, reveals the spin vector, the sense of rotation and the preliminary shape model of the asteroid. Our aim is to contribute in increasing the set of asteroids with known spin and shape parameters. This could be done with dense lightcurves, obtained during small number of apparitions, in combination with sparse data produced by photometric asteroid surveys such as the Gaia satellite (Hanush (2011)).

Large-Scale Experimental Planetary Science Meets Planetary Defense: Deorbiting an Asteroidal Satellite

NASA Technical Reports Server (NTRS)

Cintala, M. J.; Durda, D. D.; Housen, K. R.

2005-01-01

Other than remote-sensing and spacecraft-derived data, the only information that exists regarding the physical and chemical properties of asteroids is that inferred through calculations, numerical simulations, extrapolation of experiments, and meteorite studies. Our understanding of the dynamics of accretion of planetesimals, collisional disruption of asteroids, and the macroscopic, shock-induced modification of the surfaces of such small objects is also, for the most part, founded on similar inferences. While considerable strides have been made in improving the state of asteroid science, too many unknowns remain to assert that we understand the parameters necessary for the more practical problem of deflecting an asteroid or asteroid pair on an Earth-intersecting trajectory. Many of these deficiencies could be reduced or eliminated by intentionally deorbiting an asteroidal satellite and monitoring the resulting collision between it and the primary asteroid, a capability that is well within the limitations of current technology.

Workshop on Oxygen in Asteroids and Meteorites

NASA Technical Reports Server (NTRS)

2005-01-01

Contents include the following: Constraints on the detection of solar nebula's oxidation state through asteroid observation. Oxidation/Reduction Processes in Primitive Achondrites. Low-Temperature Chemical Processing on Asteroids. On the Formation Location of Asteroids and Meteorites. The Spectral Properties of Angritic Basalts. Correlation Between Chemical and Oxygen Isotopic Compositions in Chondrites. Effect of In-Situ Aqueous Alteration on Thermal Model Heat Budgets. Oxidation-Reduction in Meteorites: The Case of High-Ni Irons. Ureilite Atmospherics: Coming up for Air on a Parent Body. High Temperature Effects Including Oxygen Fugacity, in Pre-Planetary and Planetary Meteorites and Asteroids. Oxygen Isotopic Variation of Asteroidal Materials. High-Temperature Chemical Processing on Asteroids: An Oxygen Isotope Perspective. Oxygen Isotopes and Origin of Opaque Assemblages from the Ningqiang Carbonaceous Chondrite. Water Distribution in the Asteroid Belt. Comparative Planetary Mineralogy: V Systematics in Planetary Pyroxenes and fo 2 Estimates for Basalts from Vesta.

ASIME 2016 White Paper: Answers to Questions from the Asteroid Miners

NASA Astrophysics Data System (ADS)

Galache, Jl; Graps, A. L.; Asime 2016 Contributors, 30

2017-09-01

The aim of the Asteroid Science Intersections with In-Space Mine Engineering (ASIME) 2016 conference on September 21-22, 2016 in Luxembourg City was to provide an environment for the detailed discussion of the specific properties of asteroids, with the engineering needs of space missions that utilise asteroids. The ASIME 2016 Conference produced a layered record of discussions from the asteroid scientists and the asteroid miners to understand each other's key concerns and to address key scientific questions from the asteroid mining companies: Planetary Resources, Deep Space Industries and TransAstra. These Questions were the focus of the two-day conference, were addressed by scientists inside and outside of the ASIME 2016 Conference and were the focus of this White Paper. The answers in this White Paper point to the Science Knowledge Gaps (SKGs) for advancing the asteroid in-space resource utilisation domain.

Assessment of the Gaussian Covariance Approximation over an Earth-Asteroid Encounter Period

NASA Technical Reports Server (NTRS)

Mattern, Daniel

2017-01-01

In assessing the risk an asteroid may pose to the Earth, the asteroids state is often predicted for many years, often decades. Only by accounting for the asteroids initial state uncertainty can a measure of the risk be calculated. With the asteroids state uncertainty growing as a function of the initial velocity uncertainty, orbit velocity at the last state update, and the time from the last update to the epoch of interest, the asteroids position uncertainties can grow to many times the size of the Earth when propagated to the encounter risk corridor. This paper examines the merits of propagating the asteroids state covariance as an analytical matrix. The results of this study help to bound the efficacy of applying different metrics for assessing the risk an asteroid poses to the Earth. Additionally, this work identifies a criterion for when different covariance propagation methods are needed to continue predictions after an Earth-encounter period.

Asteroid Initiative Industry and Partner Day

NASA Image and Video Library

2013-06-18

NASA Deputy Administrator Lori Garver discusses the progress being made on NASA's mission to capture, redirect, and explore an asteroid during the Asteroid Initiative Industry and Partner Day at NASA Headquarters on Tuesday, June 18, 2013 in Washington. NASA also announced an Asteroid Grand Challenge focused on finding all asteroid threats to human populations and knowing what to do about them. Photo Credit: (NASA/Bill Ingalls)

A Study of Cybele Asteroids. I. Spin Properties of Ten Asteroids

NASA Astrophysics Data System (ADS)

Lagerkvist, Claes-Ingvar; Erikson, Anders; Lahulla, Felix; De Martino, Mario; Nathues, Andreas; Dahlgren, Mats

2001-01-01

As a part of an observational program on Cybele asteroids we have obtained lightcurves of 10 of the larger asteroids. In this paper the results are presented for 229 Adelinda, 260 Huberta, 401 Ottilia, 420 Bertholda, 466 Tisiphone, 522 Helga, 570 Kythera, 713 Luscinia, 909 Ulla, and 1467 Mashona. Spin properties have been determined for the first time for 8 of these asteroids.

Surprise! The oft-ignored Moon might actually be important for changing the spins of asteroids during Earth flybys

NASA Astrophysics Data System (ADS)

Tuttle Keane, James; Siu, Hosea C.; Moskovitz, Nicholas A.; Binzel, Richard P.

2015-11-01

Analysis near-Earth asteroid archival data has revealed that asteroids with Earth MOIDs (minimum orbit intersection distance; a proxy for flyby distance) smaller than 1.0-1.5 lunar distances have a systematically larger dispersion in spin rate than more distant flybys (Siu, et al. 2015, DPS). While tidal torques during close encounters are expected to alter the spin states of asteroids (e.g. Scheeres et al. 2000, Icarus), there is no intrinsic reason to expect the observed sharp transition in spin rate distribution at 1.0-1.5 lunar distances, as tidal forces drop off smoothly with distance.While the Moon itself is too diminutive to directly alter the spin-states of asteroids, we show that its presence is enough to significantly affect asteroid encounter trajectories. Asteroids entering the Earth-Moon system are subject to three-body dynamics (due to the combined gravitational effects of the Earth and Moon). Depending on the flyby geometry, the Moon can act as a temporary sink for the asteroid's geocentric orbital energy. This allows some fraction of asteroids to have closer approaches with the Earth than expected when considering the Earth-Moon barycenter alone. In rare cases (~0.1%) this process enables the capture of temporary moons around the Earth (Granvik et al. 2012, Icarus). Asteroids that undergo these "enhanced" flybys can have both closer-than-expected encounter distances (resulting in more significant tidal perturbations), and repeated encounters with the Earth and Moon before leaving the system (resulting in the accumulation of multiple tidal interactions). By numerically solving the circular restricted three-body problem, we show that this process naturally produces a sharp transition in the asteroid population: asteroids with MOIDs less than 1.5 lunar distances can undergo these enhanced close approaches, possibly explaining the sharp transition in the dispersion of asteroid spin rates at this distance. Future work will investigate the efficiency of this process, and the relationship between the physical response of the asteroid to tidal perturbations and the statistical distribution of asteroid spin rates.

A Facile Methodology for Engineering the Morphology of CsPbX3 Perovskite Nanocrystals under Ambient Condition

NASA Astrophysics Data System (ADS)

Seth, Sudipta; Samanta, Anunay

2016-11-01

A facile and highly reproducible room temperature, open atmosphere synthesis of cesium lead halide perovskite nanocrystals of six different morphologies is reported just by varying the solvent, ligand and reaction time. Sequential evolution of the quantum dots, nanoplates and nanobars in one medium and nanocubes, nanorods and nanowires in another medium is demonstrated. These perovskite nanoparticles are shown to be of excellent crystalline quality with high fluorescence quantum yield. A mechanism of the formation of nanoparticles of different shapes and sizes is proposed. Considering the key role of morphology in nanotechnology, this simple method of fabrication of a wide range of high quality nanocrystals of different shapes and sizes of all-inorganic lead halide perovskites, whose potential is already demonstrated in light emitting and photovoltaic applications, is likely to help widening the scope and utility of these materials in optoelectronic devices.

A novel multiple-stage antimalarial agent that inhibits protein synthesis.

PubMed

Baragaña, Beatriz; Hallyburton, Irene; Lee, Marcus C S; Norcross, Neil R; Grimaldi, Raffaella; Otto, Thomas D; Proto, William R; Blagborough, Andrew M; Meister, Stephan; Wirjanata, Grennady; Ruecker, Andrea; Upton, Leanna M; Abraham, Tara S; Almeida, Mariana J; Pradhan, Anupam; Porzelle, Achim; Luksch, Torsten; Martínez, María Santos; Luksch, Torsten; Bolscher, Judith M; Woodland, Andrew; Norval, Suzanne; Zuccotto, Fabio; Thomas, John; Simeons, Frederick; Stojanovski, Laste; Osuna-Cabello, Maria; Brock, Paddy M; Churcher, Tom S; Sala, Katarzyna A; Zakutansky, Sara E; Jiménez-Díaz, María Belén; Sanz, Laura Maria; Riley, Jennifer; Basak, Rajshekhar; Campbell, Michael; Avery, Vicky M; Sauerwein, Robert W; Dechering, Koen J; Noviyanti, Rintis; Campo, Brice; Frearson, Julie A; Angulo-Barturen, Iñigo; Ferrer-Bazaga, Santiago; Gamo, Francisco Javier; Wyatt, Paul G; Leroy, Didier; Siegl, Peter; Delves, Michael J; Kyle, Dennis E; Wittlin, Sergio; Marfurt, Jutta; Price, Ric N; Sinden, Robert E; Winzeler, Elizabeth A; Charman, Susan A; Bebrevska, Lidiya; Gray, David W; Campbell, Simon; Fairlamb, Alan H; Willis, Paul A; Rayner, Julian C; Fidock, David A; Read, Kevin D; Gilbert, Ian H

2015-06-18

There is an urgent need for new drugs to treat malaria, with broad therapeutic potential and novel modes of action, to widen the scope of treatment and to overcome emerging drug resistance. Here we describe the discovery of DDD107498, a compound with a potent and novel spectrum of antimalarial activity against multiple life-cycle stages of the Plasmodium parasite, with good pharmacokinetic properties and an acceptable safety profile. DDD107498 demonstrates potential to address a variety of clinical needs, including single-dose treatment, transmission blocking and chemoprotection. DDD107498 was developed from a screening programme against blood-stage malaria parasites; its molecular target has been identified as translation elongation factor 2 (eEF2), which is responsible for the GTP-dependent translocation of the ribosome along messenger RNA, and is essential for protein synthesis. This discovery of eEF2 as a viable antimalarial drug target opens up new possibilities for drug discovery.

The critical attributes of leadership.

PubMed

Campbell, C A

1992-11-01

The final decade of this century is a period of unprecedented change that by all indicators will continue unabated well into the next millennium. This article explored some elemental and immutable truths about leadership, management, communication, and negotiation essential to organizational success, particularly during periods of accelerated change. The case is made for a level of integrity, ethical conduct, and self-control to match the technical competence essential for managerial success in a technologically intensive work environment. These attributes and skills coupled with a widening scope of institutional vision are critical to sustained leadership and growth in an unstable world. Those without these abilities will be diminished in their capacity to communicate or negotiate. Hence, they will be thwarted or powerless to create task attraction, to effect change, or to promote excellence. These lessons are applicable to the dynamic changes occurring within the health care industrial complex, including health information management.

Electrically tunable infrared filter based on a cascaded liquid-crystal Fabry-Perot for spectral imaging detection.

PubMed

Lin, Jiuning; Tong, Qing; Lei, Yu; Xin, Zhaowei; Wei, Dong; Zhang, Xinyu; Liao, Jing; Wang, Haiwei; Xie, Changsheng

2017-03-01

An electrically tunable infrared (IR) filter based on a key cascaded liquid-crystal Fabry-Perot (C-LC-FP) working in the wavelength range of 3-5 μm is presented. The C-LC-FP is constructed by closely stacking two FP microcavities with different depths of 12 and 15 μm and fully filled by nematic LC materials. Through continuous wavelength selection of both microcavities, radiation with a high transmittance and narrow bandwidth can pass through the filter. According to the electrically controlled birefringence characteristics of nematic LC molecules, the transmission spectrum can be shifted through applying a dual voltage signal over the C-LC-FP. Compared with common LC-FPs with a single microcavity, the C-LC-FP demonstrates better transmittance peak morphology and spectral selection performance. To be more specific, the number and the shifted scope of the IR transmission peak can be decreased and widened, respectively.

History of Science and History of Philologies.

PubMed

Daston, Lorraine; Most, Glenn W

2015-06-01

While both the sciences and the humanities, as currently defined, may be too heterogeneous to be encompassed within a unified historical framework, there is good reason to believe that the history of science and the history of philologies both have much to gain by joining forces. This collaboration has already yielded striking results in the case of the history of science and humanist learning in early modern Europe. This essay argues that first, philology and at least some of the sciences (e.g., astronomy) remained intertwined in consequential ways well into the modern period in Western cultures; and second, widening the scope of inquiry to include other philological traditions in non-Western cultures offers rich possibilities for a comparative history of learned practices. The focus on practices is key; by shifting the emphasis from what is studied to how it is studied, deep commonalities emerge among disciplines--and intellectual traditions--now classified as disparate.

Ethical, Legal, Social, and Policy Implications of Behavioral Genetics

PubMed Central

Berryessa, Colleen M.; Cho, Mildred K.

2015-01-01

The field of behavioral genetics has engendered a host of moral and social concerns virtually since its inception. The policy implications of a genetic basis for behaviors are widespread and extend beyond the clinic to the socially important realms of education, criminal justice, childbearing, and child rearing. The development of new techniques and analytic approaches, including whole-genome sequencing, noninvasive prenatal genetic testing, and optogenetics, has clearly changed the study of behavioral genetics. However, the social context of biomedical research has also changed profoundly over the past few decades, and in ways that are especially relevant to behavioral genetics. The ever-widening scope of behavioral genetics raises ethical, legal, social, and policy issues in the potential new applications to criminal justice, education, the military, and reproduction. These issues are especially critical to address because of their potentially disproportionate effects on vulnerable populations such as children, the unborn, and the incarcerated. PMID:23452225

Enhanced stability of Cu-BTC MOF via perfluorohexane plasma-enhanced chemical vapor deposition.

PubMed

Decoste, Jared B; Peterson, Gregory W; Smith, Martin W; Stone, Corinne A; Willis, Colin R

2012-01-25

Metal organic frameworks (MOFs) are a leading class of porous materials for a wide variety of applications, but many of them have been shown to be unstable toward water. Cu-BTC (1,3,5 benzenetricarboxylic acid, BTC) was treated with a plasma-enhanced chemical vapor deposition (PECVD) of perfluorohexane creating a hydrophobic form of Cu-BTC. It was found that the treated Cu-BTC could withstand high humidity and even submersion in water much better than unperturbed Cu-BTC. Through Monte Carlo simulations it was found that perfluorohexane sites itself in such a way within Cu-BTC as to prevent the formation of water clusters, hence preventing the decomposition of Cu-BTC by water. This PECVD of perfluorohexane could be exploited to widen the scope of practical applications of Cu-BTC and other MOFs. © 2012 American Chemical Society

A novel multiple-stage antimalarial agent that inhibits protein synthesis

NASA Astrophysics Data System (ADS)

Baragaña, Beatriz; Hallyburton, Irene; Lee, Marcus C. S.; Norcross, Neil R.; Grimaldi, Raffaella; Otto, Thomas D.; Proto, William R.; Blagborough, Andrew M.; Meister, Stephan; Wirjanata, Grennady; Ruecker, Andrea; Upton, Leanna M.; Abraham, Tara S.; Almeida, Mariana J.; Pradhan, Anupam; Porzelle, Achim; Martínez, María Santos; Bolscher, Judith M.; Woodland, Andrew; Norval, Suzanne; Zuccotto, Fabio; Thomas, John; Simeons, Frederick; Stojanovski, Laste; Osuna-Cabello, Maria; Brock, Paddy M.; Churcher, Tom S.; Sala, Katarzyna A.; Zakutansky, Sara E.; Jiménez-Díaz, María Belén; Sanz, Laura Maria; Riley, Jennifer; Basak, Rajshekhar; Campbell, Michael; Avery, Vicky M.; Sauerwein, Robert W.; Dechering, Koen J.; Noviyanti, Rintis; Campo, Brice; Frearson, Julie A.; Angulo-Barturen, Iñigo; Ferrer-Bazaga, Santiago; Gamo, Francisco Javier; Wyatt, Paul G.; Leroy, Didier; Siegl, Peter; Delves, Michael J.; Kyle, Dennis E.; Wittlin, Sergio; Marfurt, Jutta; Price, Ric N.; Sinden, Robert E.; Winzeler, Elizabeth A.; Charman, Susan A.; Bebrevska, Lidiya; Gray, David W.; Campbell, Simon; Fairlamb, Alan H.; Willis, Paul A.; Rayner, Julian C.; Fidock, David A.; Read, Kevin D.; Gilbert, Ian H.

2015-06-01

There is an urgent need for new drugs to treat malaria, with broad therapeutic potential and novel modes of action, to widen the scope of treatment and to overcome emerging drug resistance. Here we describe the discovery of DDD107498, a compound with a potent and novel spectrum of antimalarial activity against multiple life-cycle stages of the Plasmodium parasite, with good pharmacokinetic properties and an acceptable safety profile. DDD107498 demonstrates potential to address a variety of clinical needs, including single-dose treatment, transmission blocking and chemoprotection. DDD107498 was developed from a screening programme against blood-stage malaria parasites; its molecular target has been identified as translation elongation factor 2 (eEF2), which is responsible for the GTP-dependent translocation of the ribosome along messenger RNA, and is essential for protein synthesis. This discovery of eEF2 as a viable antimalarial drug target opens up new possibilities for drug discovery.

The equity imperative in tertiary education: Promoting fairness and efficiency

NASA Astrophysics Data System (ADS)

Salmi, Jamil; Bassett, Roberta Malee

2014-06-01

While the share of the tertiary education age cohort (19-25) which is being given the opportunity to study has increased worldwide over the past two decades, this does not in fact translate into reduced inequality. For many young people, especially in the developing world, major obstacles such as disparities in terms of gender, minority population membership or disabilities as well as academic and financial barriers are still standing in their way. The authors of this article propose a conceptual framework to analyse equity issues in tertiary education and document the scope, significance and consequences of disparities in tertiary education opportunities. They throw some light on the main determinants of these inequalities and offer suggestions about effective equity promotion policies directed towards widening participation and improving the chances of success of underprivileged youths in order to create societies which uphold humanistic values.

Leanergy(TM): how lean manufacturing can improve energy efficiency.

PubMed

Riche, Jean-Pierre

2013-01-01

Energy efficiency has become a competitive issue for industrial companies. The evolution of energy prices and regulation will make this issue even more important in the future. For several years, the energy-intensive chemical industry has been implementing corrective actions. Helped by the absorption of base load energy consumption by larger production volumes, specific energy consumption (KWh per production unit) has been significantly reduced in recent years. However, most plants have reached the end of their first action plan based on improving the utilities performance. The Leanergy(TM) method developed by the consultancy company Okavango-energy, is a structured approach based on lean manufacturing which widens the scope of saving sources to process and operations. Starting from the analysis of actual production requirements, Okavango is able to adjust consumption to minimum requirements and so remove any energy consumption that does not contribute to the added value creation.

From symbolizing to non-symbolizing within the scope of a link: from dreams to shouts of terror caused by an absent presence.

PubMed

Levy, Ruggero

2012-08-01

This article examines pathologies in the creation of symbols and those pathologies' ensuing consequences. It relies mainly on the vertices provided by Bion and Meltzer. It studies the different forms in which these lapses occur in symbolic processes, where they may create vacuums in symbolic networks or give rise to 'lies', and even destroy or de-symbolize established symbols. Based on Bion's concept of the minus-contained (-contained), I propose that when a symbol is attacked, a particular mental structure with its own peculiar characteristics comes about. This structure not only creates a vacuum in that mental zone, it ends up damaging the entire symbolization process. This contribution aims to describe that structure from the metapsychological point of view - contained. I end by synthesizing the possible widening of what could be a Bionian negative grid. Copyright © 2012 Institute of Psychoanalysis.

Asteroid Redirect Crewed Mission Nominal Design and Performance

NASA Technical Reports Server (NTRS)

Condon, Gerald; williams, Jacob

2014-01-01

In 2010, the President announced that, in 2025, the U.S. intended to launch a human mission to an asteroid [1]. This announcement was followed by the idea of a Capability Driven Framework (CDF) [2], which is based on the idea of evolving capabilities from less demanding to more demanding missions to multiple possible destinations and with increased flexibility, cost effectiveness and sustainability. Focused missions, such as a NASA inter-Center study that examined the viability and implications of sending a crew to a Near Earth Asteroid (NEA) [3], provided a way to better understand and evaluate the utility of these CDF capabilities when applied to an actual mission. The long duration of the NEA missions were contrasted with a concept described in a study prepared for the Keck Institute of Space Studies (KISS) [4] where a robotic spacecraft would redirect an asteroid to the Earth-Moon vicinity, where a relatively short duration crewed mission could be conducted to the captured asteroid. This mission concept was included in the National Aeronautics and Space Administration (NASA) fiscal year 2014 budget request, as submitted by the NASA Administrator [5]. NASA studies continued to examine the idea of a crewed mission to a captured asteroid in the Earth-Moon vicinity. During this time was an announcement of NASA's Asteroid Grand Challenge [6]. Key goals for the Asteroid Grand Challenge are to locate, redirect, and explore an asteroid, as well as find and plan for asteroid threats. An Asteroid Redirect Mission (ARM) study was being conducted, which supports this Grand Challenge by providing understanding in how to execute an asteroid rendezvous, capture it, and redirect it to Earth-Moon space, and, in particular, to a distant retrograde orbit (DRO). Subsequent to the returning of the asteroid to a DRO, would be the launch of a crewed mission to rendezvous with the redirected asteroid. This report examines that crewed mission by assessing the Asteroid Redirect Crewed Mission (ARCM) nominal design and performance costs associated with an Orion based crewed rendezvous mission to a captured asteroid in an Earth-Moon DRO. The ARM study includes two fundamental mission phases: 1) The Asteroid Redirect Robotic Mission (ARRM) and 2) the ARCM. The ARRM includes a solar electric propulsion based robotic asteroid return vehicle (ARV) sent to rendezvous with a selected near Earth asteroid, capture it, and return it to a DRO in the Earth-Moon vicinity. The DRO is selected over other possible asteroid parking orbits due to its achievability (by both the robotic and crewed vehicles) and by its stability (e.g., no orbit maintenance is required). After the return of the asteroid to the Earth-Moon vicinity, the ARCM is executed and carries a crew of two astronauts to a DRO to rendezvous with the awaiting ARV with the asteroid. The outbound and inbound transfers employ lunar gravity assist (LGA) flybys to reduce the Orion propellant requirement for the overall nominal mission, which provides a nominal mission with some reserve propellant for possible abort situations. The nominal mission described in this report provides a better understanding of the mission considerations as well as the feasibility of such a crewed mission, particularly with regard to spacecraft currently undergoing development, such as the Orion vehicle and the Space Launch System (SLS).

Asteroid Family Associations of Active Asteroids

NASA Astrophysics Data System (ADS)

Hsieh, Henry H.; Novaković, Bojan; Kim, Yoonyoung; Brasser, Ramon

2018-02-01

We report on the results of a systematic search for associated asteroid families for all active asteroids known to date. We find that 10 out of 12 main-belt comets (MBCs) and five out of seven disrupted asteroids are linked with known or candidate families, rates that have ∼0.1% and ∼6% probabilities, respectively, of occurring by chance, given the overall family association rate of 37% for asteroids in the main asteroid belt. We find previously unidentified family associations between 238P/Read and the candidate Gorchakov family, 311P/PANSTARRS and the candidate Behrens family, 324P/La Sagra and the Alauda family, 354P/LINEAR and the Baptistina family, P/2013 R3-B (Catalina-PANSTARRS) and the Mandragora family, P/2015 X6 (PANSTARRS) and the Aeolia family, P/2016 G1 (PANSTARRS) and the Adeona family, and P/2016 J1-A/B (PANSTARRS) and the Theobalda family. All MBCs with family associations belong to families that contain asteroids with primitive taxonomic classifications and low average reported albedos (\\overline{{p}V}≲ 0.10), while disrupted asteroids with family associations belong to families that contain asteroids that span wider ranges of taxonomic types and average reported albedos (0.06< \\overline{{p}V}< 0.25). These findings are consistent with MBC activity being closely correlated to composition (i.e., whether an object is likely to contain ice), while disrupted asteroid activity is not as sensitive to composition. Given our results, we describe a sequence of processes by which the formation of young asteroid families could lead to the production of present-day MBCs.

Resurfacing asteroids from YORP spin-up and failure

NASA Astrophysics Data System (ADS)

Graves, Kevin J.; Minton, David A.; Hirabayashi, Masatoshi; DeMeo, Francesca E.; Carry, Benoit

2018-04-01

The spectral properties of S and Q-type asteroids can change over time due to interaction with the solar wind and micrometeorite impacts in a process known as 'space weathering.' Space weathering raises the spectral slope and decreases the 1 μm absorption band depth in the spectra of S and Q-type asteroids. Over time, Q-type asteroids, which have very similar spectra to ordinary chondrite meteorites, will change into S-type asteroids. Because there are a significant number of Q-type asteroids, there must be some process which is resurfacing S-type asteroids into Q-types. In this study, we use asteroid data from the Sloan Digital Sky Survey to show a trend between the slope through the g‧, r‧, and i‧ filters, called the gri-slope, and size that holds for all populations of S and Q-type asteroids in the inner solar system, regardless of orbit. We model the evolution of a suite of asteroids in a Monte Carlo YORP rotational evolution and space weathering model. We show that spin-up and failure from YORP is one of the key resurfacing mechanisms that creates the observed weathering trends with size. By varying the non-dimensional YORP coefficient and running time of the present model over the range 475-1425 Myr, we find a range of values for the space weathering timescale, τSW ≈ 19-80 Myr at 2.2 AU. We also estimate the time to weather a newly resurfaced Q-type asteroid into an S-complex asteroid at 1 AU, τQ → S(1AU) ≈ 2-7 Myr.

THE ASTEROID DISTRIBUTION IN THE ECLIPTIC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ryan, Erin Lee; Woodward, Charles E.; Dipaolo, Andrea

2009-06-15

We present analysis of the asteroid surface density distribution of main-belt asteroids (mean perihelion {delta} {approx_equal} 2.404 AU) in five ecliptic latitude fields, -17 {approx}> {beta}({sup 0}) {approx}< +15, derived from deep Large Binocular Telescope V-band (85% completeness limit V = 21.3 mag) and Spitzer Space Telescope IRAC 8.0 {mu}m (80% completeness limit {approx}103 {mu}Jy) fields enabling us to probe the 0.5-1.0 km diameter asteroid population. We discovered 58 new asteroids in the optical survey as well as 41 new bodies in the Spitzer fields. The derived power-law slopes of the number of asteroids per square degree are similar withinmore » each {approx}5{sup 0} ecliptic latitude bin with a mean value of -0.111 {+-} 0.077. For the 23 known asteroids detected in all four IRAC channels mean albedos range from 0.24 {+-} 0.07 to 0.10 {+-} 0.05. No low-albedo asteroids (p{sub V} {approx}< 0.1) were detected in the Spitzer FLS fields, whereas in the SWIRE fields they are frequent. The SWIRE data clearly samples asteroids in the middle and outer belts providing the first estimates of these km-sized asteroids' albedos. Our observed asteroid number densities at optical wavelengths are generally consistent with those derived from the Standard Asteroid Model within the ecliptic plane. However, we find an overdensity at {beta} {approx}> 5{sup 0} in our optical fields, while the infrared number densities are underdense by factors of 2 to 3 at all ecliptic latitudes.« less

Basalt or Not? Near-infrared Spectra, Surface Mineralogical Estimates, and Meteorite Analogs for 33 Vp-type Asteroids

NASA Astrophysics Data System (ADS)

Hardersen, Paul S.; Reddy, Vishnu; Cloutis, Edward; Nowinski, Matt; Dievendorf, Margaret; Genet, Russell M.; Becker, Savan; Roberts, Rachel

2018-07-01

Investigations of the main asteroid belt and efforts to constrain that population’s physical characteristics involve the daunting task of studying hundreds of thousands of small bodies. Taxonomic systems are routinely employed to study the large-scale nature of the asteroid belt because they utilize common observational parameters, but asteroid taxonomies only define broadly observable properties and are not compositionally diagnostic. This work builds upon the results of work by Hardersen et al., which has the goal of constraining the abundance and distribution of basaltic asteroids throughout the main asteroid belt. We report on the near-infrared (NIR: 0.7 to 2.5 μm) reflectance spectra, surface mineralogical characterizations, analysis of spectral band parameters, and meteorite analogs for 33 Vp asteroids. NIR reflectance spectroscopy is an effective remote sensing technique to detect most pyroxene group minerals, which are spectrally distinct with two very broad spectral absorptions at ∼0.9 and ∼1.9 μm. Combined with the results from Hardersen et al., we identify basaltic asteroids for ∼95% (39/41) of our inner-belt Vp sample, but only ∼25% (2/8) of the outer-belt Vp sample. Inner-belt basaltic asteroids are most likely associated with (4) Vesta and represent impact fragments ejected from previous collisions. Outer-belt Vp asteroids exhibit disparate spectral, mineralogical, and meteorite analog characteristics and likely originate from diverse parent bodies. The discovery of two additional likely basaltic asteroids provides additional evidence for an outer-belt basaltic asteroid population.

Mining the apollo and amor asteroids.

PubMed

O'leary, B

1977-07-22

Earth-approaching asteroids could provide raw materials for space manufacturing. For certain asteroids the total energy per unit mass for the transfer of asteroidal resources to a manufacturing site in high Earth orbit is comparable to that for lunar materials. For logistical reasons the cost may be many times less. Optical studies suggest that these asteroids have compositions corresponding to those of carbonaceous and ordinary chondrites, with some containing large quantities of iron and nickel; others are thought to contain carbon, nitrogen, and hydrogen, elements that appear to be lacking on the moon. The prospect that several new candidate asteroids will be discovered over the next few years increases the likelihood that a variety of asteroidal resource materials can be retrieved on low-energy missions.

Asteroid surface materials: Mineralogical characterizations from reflectance spectra

NASA Technical Reports Server (NTRS)

Gaffey, M. J.; Mccord, T. B.

1977-01-01

Mineral assemblages analogous to most meteorite types, with the exception of ordinary chondritic assemblages, have been found as surface materials of Main Belt asteroids. C1- and C2-like assemblages (unleached, oxidized meteoritic clay minerals plus opaques such as carbon) dominate the population throughout the Belt, especially in the outer Belt. A smaller population of asteroids exhibit surface materials similar to C3 (CO, CV) meteoritic assemblages (olivine plus opaque, probably carbon) and are also distributed throughout the Belt. The majority of remaining studied asteroids (20) of 65 asteroids exhibit spectral reflectance curves dominated by the presence of metallic nickel-iron in their surface materials. The C2-like materials which dominate the main asteroid belt population appear to be relatively rare on earth-approaching asteroids.

Meteoritic parent bodies - Nature, number, size and relation to present-day asteroids

NASA Technical Reports Server (NTRS)

Lipschutz, Michael E.; Gaffey, Michael J.; Pellas, Paul

1989-01-01

The relationship between meteoritic parent bodies and the present-day asteroids is discussed. Results on oxygen isotopic signatures and chemical distinctions among meteorite classes indicate that meteorites derive from a small number of parent bodies relative to the number of asteroids. The spectral properties of the ordinary chondrites and similar inclusions in meteoritic breccias differ from those of the abundant S asteroids (with no process known that can account for these differences); the closest spectral analogs of these chondrites are the rare near-earth Q-type asteroids. These facts lead to the question of why abundant meteorites have rare asteroidal analogs, while the abundant asteroids have rare meteoritic analogs. This question constitutes a prime topic for future studies.

Mining the Apollo and Amor asteroids

NASA Technical Reports Server (NTRS)

Oleary, B.

1977-01-01

Earth-approaching asteroids could provide raw materials for space manufacturing. For certain asteroids the total energy per unit mass for the transfer of asteroidal resources to a manufacturing site in high earth orbit is comparable to that for lunar materials. For logistical reasons the cost may be many times less. Optical studies suggest that these asteroids have compositions corresponding to those of carbonaceous and ordinary chondrites, with some containing large quantities of iron and nickel; other are thought to contain carbon, nitrogen, and hydrogen, elements that appear to be lacking on the moon. The prospect that several new candidate asteroids will be discovered over the next few years increases the likelihood that a variety of asteroidal resource materials can be retrieved on low-energy missions.

Electromagnetic Spacecraft Used for Magnetic Navigation Within Asteroid Belt, Mining Concepts and Asteroid Magnetic Classification

NASA Astrophysics Data System (ADS)

Kletetschka, G.; Adachi, T.; Mikula, V.

2007-03-01

Application of expandable/collapsible magnetic coil increases/decreases spacecraft velocity without using chemical propellants, allows effective mining of metals from asteroids and is used for the first order classification of asteroids.

V-type candidates and Vesta family asteroids in the Moving Objects VISTA (MOVIS) catalogue

NASA Astrophysics Data System (ADS)

Licandro, J.; Popescu, M.; Morate, D.; de León, J.

2017-04-01

Context. Basaltic asteroids (spectrally classified as V-types) are believed to be fragments of large differentiated bodies. The majority of them are found in the inner part of the asteroid belt, and are current or past members of the Vesta family. Recently, some V-type asteroids have been discovered far from the Vesta family supporting the hypothesis of the presence of multiple basaltic asteroids in the early solar system. The discovery of basaltic asteroids in the outer belt challenged the models of the radial extent and the variability of the temperature distribution in the early solar system. Aims: We aim to identify new basaltic V-type asteroids using near-infrared colors of 40 000 asteroids observed by the VHS-VISTA survey and compiled in the MOVIS-C catalogue. We also want to study their near-infrared colors and to study the near-infrared color distribution of the Vesta dynamical family. Methods: We performed a search in the MOVIS-C catalogue of all the asteroids with (Y-J) and (J-Ks) in the range (Y-J) ≥ 0.5 and (J-Ks) ≤ 0.3, associated with V-type asteroids, and studied their color distribution. We have also analyzed the near-infrared color distribution of 273 asteroid members of the Vesta family and compared them with the albedo and visible colors from WISE and SDSS data. We determined the fraction of V-type asteroids in the family. Results: We found 477 V-type candidates in MOVIS-C, 244 of them outside the Vesta dynamical family. We identified 19 V-type asteroids beyond the 3:1 mean motion resonance, 6 of them in the outer main belt, and 16 V-types in the inner main belt with proper inclination Ip ≤ 3.0°, well below the inclination of the Vesta family. We computed that 85% of the members of the Vesta dynamical family are V-type asteroids, and only 1-2% are primitive class asteroids and unlikely members of the family. Conclusions: This work almost doubles the sample of basaltic asteroid candidates in regions outside the Vesta family. Spectroscopic studies in the near-infrared and dynamical studies are needed to confirm their basaltic composition and to determine their origin.

Overview of the Mission Design Reference Trajectory for NASA's Asteroid Redirect Robotic Mission

NASA Technical Reports Server (NTRS)

Mcguire, Melissa L.; Strange, Nathan J.; Burke, Laura M.; McCarty, Steven L.; Lantoine, Gregory B.; Qu, Min; Shen, Haijun; Smith, David A.; Vavrina, Matthew A.

2017-01-01

The National Aeronautics and Space Administration's (NASA's) recently cancelled Asteroid Redirect Mission was proposed to rendezvous with and characterize a 100 m plus class near-Earth asteroid and provide the capability to capture and retrieve a boulder off of the surface of the asteroid and bring the asteroidal material back to cislunar space. Leveraging the best of NASA's science, technology, and human exploration efforts, this mission was originally conceived to support observation campaigns, advanced solar electric propulsion, and NASA's Space Launch System heavy-lift rocket and Orion crew vehicle. The asteroid characterization and capture portion of ARM was referred to as the Asteroid Redirect Robotic Mission (ARRM) and was focused on the robotic capture and then redirection of an asteroidal boulder mass from the reference target, asteroid 2008 EV5, into an orbit near the Moon, referred to as a Near Rectilinear Halo Orbit where astronauts would visit and study it. The purpose of this paper is to document the final reference trajectory of ARRM and the challenges and unique methods employed in the trajectory design of the mission.

Evolution of the inner asteroid belt: Paradigms and paradoxes from spectral studies

NASA Technical Reports Server (NTRS)

Gaffey, Michael J.

1987-01-01

Recent years have witnessed a significant increase in the sophistication of asteroidal surface material characterizations derived from spectral data. An extensive data base of moderate to high spectral resolution, visible and near-infrared asteroid spectra is now available. Interpretive methodologies and calibrations were developed to determine phase abundance and composition in olivine-pyroxene assemblages and to estimate NiFe metal abundance from such spectra. A modified version of the asteroid classifications system more closely parallels the mineralogic variations of the major inner belt asteroid types. These improvements permit several general conclusions to be drawn concerning the nature of inner belt objects; their history, and that of the inner solar system; and the relationship between the asteroids and meteorites. Essentially all large belt asteroids have or are fragments of parent bodies which have undergone strong post-accretionary heating, varying degrees of melting and magmatic differentiation, and subsequent collisional disruption. These asteroids show a systematic, but not yet well characterized, mineralogic variation with semi-major axis. This suggests that the S-type asteroid families represent relatively recent collisions onto the cores of previously disrupted parent bodies.

Asteroid Size-Frequency Distribution (The ISO Deep Asteroid Survey)

NASA Technical Reports Server (NTRS)

Tedesco, Edward F.

2001-01-01

A total of six deep exposures (using AOT CAM01 with a 6" PFOV) through the ISOCAM LW10 filter (IRAS Band 1, i.e., 12 micro-m) were obtained on an approximately 15 arcminute square field centered on the ecliptic plane. Point sources were extracted using the technique described by Desert, et al. Two known asteroids appear in these frames and 20 sources moving with velocities appropriate for main belt asteroids are present. Most of the asteroids detected have flux densities less than 1 mJy, i.e., between 150 and 350 times fainter than any of the asteroids observed by Infrared Astronomy Satellite (IRAS). These data provide the first direct measurement of the 12 micro-m sky-plane density for asteroids on the ecliptic equator. The median zodiacal foreground, as measured by ISOCAM during this survey, is found to be 22.1 +/- 1.5 mJy per pixel, i.e., 26.2 +/- 1.7 MJy/sr. The results presented here imply that the actual number of kilometer-sized asteroids is significantly greater than previously believed and in reasonable agreement with the Statistical Asteroid Model.

Asteroid and Lava Tube In Situ Resource Utilization (ISRU) Prospecting Free Flyer Project

NASA Technical Reports Server (NTRS)

Falker, John; Zeitlin, Nancy; Mueller, Robert; Dupuis, Michael

2015-01-01

This project seeks to develop a small free flyer that can be used to safely and effectively prospect on an Asteroid while being controlled by the crew. This will enable the characterization of the Asteroid for the In Situ Resource Utilization (ISRU). Lava tubes can be explored remotely from the outside Asteroids can contain vast amounts of resources such as water for propellants and metals for feed stocks. Lava Tubes on Mars and the Moon may contain frozen volatile resources. Before the resources can be used, they must be found with a prospecting method. The NASA Agency Asteroid Grand Challenge seeks new ideas for Asteroid retrieval mission technologies for exploration and utilization of asteroids in a Distant Retrograde Orbit (DRO). This project will develop a small free flying platform that can be used to safely and effectively prospect on an Asteroid with limited autonomy while being controlled by the crew. This will enable the characterization of the Asteroid for ISRU. Lava tubes can be explored remotely from the outside as well using this same technology.

Asteroid Redirect Mission Proximity Operations for Reference Target Asteroid 2008 EV5

NASA Technical Reports Server (NTRS)

Reeves, David M.; Mazanek, Daniel D.; Cichy, Benjamin D.; Broschart, Steve B.; Deweese, Keith D.

2016-01-01

NASA's Asteroid Redirect Mission (ARM) is composed of two segments, the Asteroid Redirect Robotic Mission (ARRM), and the Asteroid Redirect Crewed Mission (ARCM). In March of 2015, NASA selected the Robotic Boulder Capture Option1 as the baseline for the ARRM. This option will capture a multi-ton boulder, (typically 2-4 meters in size) from the surface of a large (greater than approx.100 m diameter) Near-Earth Asteroid (NEA) and return it to cis-lunar space for subsequent human exploration during the ARCM. Further human and robotic missions to the asteroidal material would also be facilitated by its return to cis-lunar space. In addition, prior to departing the asteroid, the Asteroid Redirect Vehicle (ARV) will perform a demonstration of the Enhanced Gravity Tractor (EGT) planetary defense technique2. This paper will discuss the proximity operations which have been broken into three phases: Approach and Characterization, Boulder Capture, and Planetary Defense Demonstration. Each of these phases has been analyzed for the ARRM reference target, 2008 EV5, and a detailed baseline operations concept has been developed.

Trojan Asteroid Shares Orbit with Earth Artist Animation

NASA Image and Video Library

2011-07-27

This artist concept illustrates the first known Earth Trojan asteroid, discovered by NEOWISE, the asteroid-hunting portion of NASA WISE mission. The asteroid is shown in gray and its extreme orbit is shown in green. Objects are not drawn to scale.

Asteroid surface processes: Experimental studies of the solar wind on reflectance and optical properties of asteroids

NASA Technical Reports Server (NTRS)

Mcfadden, Lucy-Ann

1991-01-01

The effect of the solar wind on the optical properties of meteorites was studied to determine whether the solar wind can alter the properties of ordinary chondrite parent bodies resulting in the spectral properties of S-type asteroids. The existing database of optical properties of asteroids was analyzed to determine the effect of solar wind in altering asteroid surface properties.

Asteroid Impact Mission: relevance to asteroid mining

NASA Astrophysics Data System (ADS)

Michel, P.; Kueppers, M.; Carnelli, I.

2017-09-01

The Asteroid Impact Mission (AIM) is the European (ESA) component of the AIDA mission in collaboration with NASA. The objectives of AIDA are: (1) to perform a test of asteroid deflection using a kinetic impactor with the USA (NASA) component DART, and (2) with AIM, to investigate the binary near-Earth asteroid Didymos, in particular its secondary and target of DART, with data of high value for mining purposes.

A Study of the Effects of Faint Dust Comae on the Spectra of Asteroids

NASA Astrophysics Data System (ADS)

Rondón, E.; Carvano, J.; Lorenz-Martins, S.

2017-09-01

The presence of dust comae on asteroids and centaurs is a phenomenon that became accepted in the last decades and which challenges the traditional definitions of asteroids and comets. A possible way of improving the chances of discovery of Active Asteroids is to use large multi-colour surveys or catalogs, like SDSS Moving Object Catalog. In this work we analyze the effects of faint dust comae on asteroid spectra and then use it to investigate the effects that a faint dust comae would have over the spectrum, magnitude, and radial profile of asteroids.

NASA's Human Mission to a Near-Earth Asteroid: Landing on a Moving Target

NASA Technical Reports Server (NTRS)

Smith, Jeffrey H.; Lincoln, William P.; Weisbin, Charles R.

2011-01-01

This paper describes a Bayesian approach for comparing the productivity and cost-risk tradeoffs of sending versus not sending one or more robotic surveyor missions prior to a human mission to land on an asteroid. The expected value of sample information based on productivity combined with parametric variations in the prior probability an asteroid might be found suitable for landing were used to assess the optimal number of spacecraft and asteroids to survey. The analysis supports the value of surveyor missions to asteroids and indicates one launch with two spacecraft going simultaneously to two independent asteroids appears optimal.

Mainbelt asteroids - Dual-polarization radar observations

NASA Technical Reports Server (NTRS)

Ostro, S. J.; Campbell, D. B.; Shapiro, I. I.

1985-01-01

Observations of 20 asteroids in the main belt between Mars and Jupiter provide information about the nature of these objects' surfaces at centimeter-to-kilometer scales. At least one asteroid (Pallas) is extremely smooth at centimeter-to-meter scales. Each asteroid appears much rougher than the moon at some scale between several meters and many kilometers. The range of asteroid radar albedos is very broad and implies substantial variations in porosity or metal concentration (or both). The highest albedo estimate, for the asteroid Psyche, is consistent with a surface having porosities typical of lunar soil and a composition nearly entirely metallic.

Calculation methods for estimating the prospects of a space experiment by means of impact by asteroid Apophis on the Moon surface

NASA Astrophysics Data System (ADS)

Ostrik, A. V.; Kazantsev, A. M.

2018-01-01

The problem of principal change of asteroid 99952 (Apophis) orbit is formulated. Aim of this change is the termination of asteroid motion in Solar system. Instead of the passive rescue tactics from asteroid threat, an option is proposed for using the asteroid for setting up a large-scale space experiment on the impact interaction of the asteroid with the Moon. The scientific and methodical apparatus for calculating the possibility of realization, searching and justification the scientific uses of this space experiment is considered.

NASA's Asteroid Redirect Mission (ARM)

NASA Technical Reports Server (NTRS)

Abell, P. A.; Mazanek, D. D.; Reeves, D. M.; Chodas, P. W.; Gates, M. M.; Johnson, L. N.; Ticker, R. L.

2017-01-01

Mission Description and Objectives: NASA's Asteroid Redirect Mission (ARM) consists of two mission segments: 1) the Asteroid Redirect Robotic Mission (ARRM), a robotic mission to visit a large (greater than approximately 100 meters diameter) near-Earth asteroid (NEA), collect a multi-ton boulder from its surface along with regolith samples, and return the asteroidal material to a stable orbit around the Moon; and 2) the Asteroid Redirect Crewed Mission (ARCM), in which astronauts will explore and investigate the boulder and return to Earth with samples. The ARRM is currently planned to launch at the end of 2021 and the ARCM is scheduled for late 2026.

Stochastic YORP On Real Asteroid Shapes

NASA Astrophysics Data System (ADS)

McMahon, Jay W.

2015-05-01

Since its theoretical foundation and subsequent observational verification, the YORP effect has been understood to be a fundamental process that controls the evolution of small asteroids in the inner solar system. In particular, the coupling of the YORP and Yarkovsky effects are hypothesized to be largely responsible for the transport of asteroids from the main belt to the inner solar system populations. Furthermore, the YORP effect is thought to lead to rotational fission of small asteroids, which leads to the creation of multiple asteroid systems, contact binary asteroids, and asteroid pairs. However recent studies have called into question the ability of YORP to produce these results. In particular, the high sensitivity of the YORP coefficients to variations in the shape of an asteroid, combined with the possibility of a changing shape due to YORP accelerated spin rates can combine to create a stochastic YORP coefficient which can arrest or change the evolution of a small asteroid's spin state. In this talk, initial results are presented from new simulations which comprehensively model the stochastic YORP process. Shape change is governed by the surface slopes on radar based asteroid shape models, where the highest slope regions change first. The investigation of the modification of YORP coefficients and subsequent spin state evolution as a result of this dynamically influenced shape change is presented and discussed.

Spectroscopy of five V-type asteroids in the middle and outer main belt

NASA Astrophysics Data System (ADS)

Migliorini, Alessandra; De Sanctis, M. C.; Lazzaro, D.; Ammannito, E.

2018-03-01

The origin of basaltic asteroids found in the middle and outer main belt is an open question. These asteroids are not dynamically linked to the Vesta collisional family and can be the remnants of other large differentiated asteroids present in the early phases of the main belt but destroyed long ago. Spectroscopic investigation of some V-type asteroids in the middle-outer belt, classified as such by their SLOAN photometric colours (Ivezić et al.) and WISE albedos (Masiero et al.), has revealed that their spectra are more similar to other taxonomic classes, like -Q, R, S, or A (Jasmim et al. and Oszkiewicz et al.). Here, we report about the observation, in the near-infrared spectral range, of five V-type asteroids located beyond 2.5 au. These observations allowed us to infer their taxonomic classification. Two asteroids, (21238) Panarea (observed in a previous campaign but here included for comparison) and (105041) 2000 KO41, confirm their basaltic nature. For asteroids (10800) 1992 OM8 and (15898) Kharasterteam a taxonomic classification is more uncertain, being either Q- or S-type. Asteroid (14390) 1990 QP10 classification is difficult to ascribe to the known taxonomic classes, maybe due to the low-quality spectrum. Further observations are desirable for this asteroid.

V-type asteroids investigation in support to the NASA DAWN mission

NASA Astrophysics Data System (ADS)

de Sanctis, Maria Cristina; Migliorini, Alessandra; Lazzaro, Daniela; Luzia, Flavia; Ammannito, Eleonora; Capria, Maria Teresa; Filacchione, Gianrico; Mottola, Stefano; Boschin, Walter; Fiorenzano, Aldo; Ghinassi, Francesca

4Vesta crust composition suggests that it has undergone extensive differentiation and resur-facing. It is the only large basaltic asteroid known at present (McCord, (1970); McFadden et al., (1977); Binzel, et al., (1997)), and it could be the smallest differentiated body of the Solar System. The NASA mission DAWN, launched on September 2007, is intended to deeper investigate the mineralogical properties of 4Vesta, in order to shed light on this puzzle (Russell et al., 2007). Although 4Vesta is the only large object in the Solar System which shows an almost intact basaltic crust, however an increasing number of small asteroids with a similar surface composition as 4Vesta were discovered thanks to ground-based telescopes (Xu et al., (1995); Burbine et al., (2001); Alvarez-Candal, et al. (2006)), posing the fundamental problem of the presence and distribution of basaltic material in the Solar System. Many of these asteroids were found to be spectrally and dynamically linked to 4Vesta, and they are known as the Vesta family. However, the scenario is much more complicated, because many Main Belt Asteroids, classified as V-type asteroids, were discovered near but not dynamically linked to 4Vesta. However, numerical simulations indicate that a relatively large fraction of the original Vesta family members may have evolved out of the family borders (Nesvorny et al., 2008); on the other hand, this seems not to be true for the low inclined asteroids, for which instead a different origin must be assumed. At present, more than 500 asteroids are classified as potentially V-type asteroids, thanks to new photometric investigation (Roig and Gil-Hutton, (2006); Roig et al., (2008); Moskoviz et al., (2008)). Some of these objects possibly belong to the Vesta-family, according to dynamical considerations, while other asteroids seem to be not clearly related to Vesta. Ground-based observations allow to investigate the spectral properties and hence the miner-alogical composition of such asteroids, which are thought to be linked to 4Vesta, because of their colors, but they are still unclassified. Asteroids were selected among the Vesta and non-Vesta family. The selected asteroids are potentially fragments coming from 4Vesta, after a cratering event on the asteroid. The possible co-existence of distinct mineralogical groups among the V-type asteroids is suggested by previous asteroid observations (Duffard et al., 2004). In this work, we present spectra of V type asteroids. Asteroids belonging to the Vesta family and those classified as non-Vesta family are compared, in order to point out similarities and differences. Results are based on observations obtained with the Telescopio Nazionale Galileo, a 3.5m-telescope in LaPalma. The proposed work is intended to support the future observations of 4Vesta, by DAWN.

Solar wind tans young asteroids

NASA Astrophysics Data System (ADS)

2009-04-01

A new study published in Nature this week reveals that asteroid surfaces age and redden much faster than previously thought -- in less than a million years, the blink of an eye for an asteroid. This study has finally confirmed that the solar wind is the most likely cause of very rapid space weathering in asteroids. This fundamental result will help astronomers relate the appearance of an asteroid to its actual history and identify any after effects of a catastrophic impact with another asteroid. ESO PR Photo 16a/09 Young Asteroids Look Old "Asteroids seem to get a ‘sun tan' very quickly," says lead author Pierre Vernazza. "But not, as for people, from an overdose of the Sun's ultraviolet radiation, but from the effects of its powerful wind." It has long been known that asteroid surfaces alter in appearance with time -- the observed asteroids are much redder than the interior of meteorites found on Earth [1] -- but the actual processes of this "space weathering" and the timescales involved were controversial. Thanks to observations of different families of asteroids [2] using ESO's New Technology Telescope at La Silla and the Very Large Telescope at Paranal, as well as telescopes in Spain and Hawaii, Vernazza's team have now solved the puzzle. When two asteroids collide, they create a family of fragments with "fresh" surfaces. The astronomers found that these newly exposed surfaces are quickly altered and change colour in less than a million years -- a very short time compared to the age of the Solar System. "The charged, fast moving particles in the solar wind damage the asteroid's surface at an amazing rate [3]", says Vernazza. Unlike human skin, which is damaged and aged by repeated overexposure to sunlight, it is, perhaps rather surprisingly, the first moments of exposure (on the timescale considered) -- the first million years -- that causes most of the aging in asteroids. By studying different families of asteroids, the team has also shown that an asteroid's surface composition is an important factor in how red its surface can become. After the first million years, the surface "tans" much more slowly. At that stage, the colour depends more on composition than on age. Moreover, the observations reveal that collisions cannot be the main mechanism behind the high proportion of "fresh" surfaces seen among near-Earth asteroids. Instead, these "fresh-looking" surfaces may be the results of planetary encounters, where the tug of a planet has "shaken" the asteroid, exposing unaltered material. Thanks to these results, astronomers will now be able to understand better how the surface of an asteroid -- which often is the only thing we can observe -- reflects its history. More information This result was presented in a paper published this week in the journal Nature, "Solar wind as the origin of rapid reddening of asteroid surfaces", by P. Vernazza et al. The team is composed of Pierre Vernazza (ESA), Richard Binzel (MIT, Cambridge, USA), Alessandro Rossi (ISTI-CNR, Pisa, Italy), Marcello Fulchignoni (Paris Observatory, France), and Mirel Birlan (IMCCE, CNRS-8028, Paris Observatory, France). A PDF file can be downloaded here. Notes [1] Meteorites are small fragments of asteroids that fall on Earth. While a meteorite enters the Earth's atmosphere its surface can melt and be partially charred by the intense heat. Nevertheless, the meteorite interior remains unaffected, and can be studied in a laboratory, providing a wealth of information on the nature and composition of asteroids. [2] An asteroid family is a group of asteroids that are on similar orbits around the Sun. The members of a given family are believed to be the fragments of a larger asteroid that was destroyed during a collision. [3] The surface of an asteroid is affected by the highly energetic particles forming the solar wind. These particles partially destroy the molecules and crystals on the surface, re-arranging them in other combinations. Over time, these changes give formation of a thin crust or irradiated material with distinct colours and properties.

Developing a web-based information resource for palliative care: an action-research inspired approach

PubMed Central

Street, Annette F; Swift, Kathleen; Annells, Merilyn; Woodruff, Roger; Gliddon, Terry; Oakley, Anne; Ottman, Goetz

2007-01-01

Background General Practitioners and community nurses rely on easily accessible, evidence-based online information to guide practice. To date, the methods that underpin the scoping of user-identified online information needs in palliative care have remained under-explored. This paper describes the benefits and challenges of a collaborative approach involving users and experts that informed the first stage of the development of a palliative care website [1]. Method The action research-inspired methodology included a panel assessment of an existing palliative care website based in Victoria, Australia; a pre-development survey (n = 197) scoping potential audiences and palliative care information needs; working parties conducting a needs analysis about necessary information content for a redeveloped website targeting health professionals and caregivers/patients; an iterative evaluation process involving users and experts; as well as a final evaluation survey (n = 166). Results Involving users in the identification of content and links for a palliative care website is time-consuming and requires initial resources, strong networking skills and commitment. However, user participation provided crucial information that led to the widened the scope of the website audience and guided the development and testing of the website. The needs analysis underpinning the project suggests that palliative care peak bodies need to address three distinct audiences (clinicians, allied health professionals as well as patients and their caregivers). Conclusion Web developers should pay close attention to the content, language, and accessibility needs of these groups. Given the substantial cost associated with the maintenance of authoritative health information sites, the paper proposes a more collaborative development in which users can be engaged in the definition of content to ensure relevance and responsiveness, and to eliminate unnecessary detail. Access to volunteer networks forms an integral part of such an approach. PMID:17854509

Intraoperative Ultrasound Technology in Neuro-Oncology Practice-Current Role and Future Applications.

PubMed

Moiyadi, Aliasgar V

2016-09-01

Surgery for cranial and spinal tumors has evolved tremendously over the years. Not only have neuro-oncologists been able to better understand tumor biology and thereby improve multimodality therapy, but advances in surgical techniques have also directly equipped neurosurgeons with the armamentarium necessary to achieve more radical resections safely. Intraoperative imaging tools are one such adjunct. Though intraoperative magnetic resonance (MR) has emerged as the "gold standard" among these, logistical challenges make it difficult to implement across all centers. On the other hand, the use of ultrasound (US) intraoperatively predates the use of MR. Over the past 4 decades, technologic improvements have refined and expanded the scope and application of intraoperative US technology. Strategies to maximize its efficacy and overcome the various limitations have evolved. A large volume of clinical experience has accumulated with respect to its role as an adjunct specifically in tumor surgery. We performed a literature review to evaluate the role of IOUS in tumor surgery. This review traces the evolution of intraoperative US over the years and reviews the current scope and applications with respect to neuro-oncologic surgery, as well as potential future applications. IOUS has evolved over the years since its introduction. Advances in technology have provided real-time navigated and 3-D techniques, which overcome many of the limitations of older IOUS techniques. This has shown to be very useful in not only localization of lesions, but also in improving resection rates as well as survival. IOUS is a powerful and versatile multipurpose intraoperative adjunct in tumor surgery, especially for resection control. The learning curve is relatively easy to climb and future improvements in technology are likely to widen the scope of its use. Copyright © 2016 Elsevier Inc. All rights reserved.

Direct and indirect capture of near-Earth asteroids in the Earth-Moon system

NASA Astrophysics Data System (ADS)

Tan, Minghu; McInnes, Colin; Ceriotti, Matteo

2017-09-01

Near-Earth asteroids have attracted attention for both scientific and commercial mission applications. Due to the fact that the Earth-Moon L1 and L2 points are candidates for gateway stations for lunar exploration, and an ideal location for space science, capturing asteroids and inserting them into periodic orbits around these points is of significant interest for the future. In this paper, we define a new type of lunar asteroid capture, termed direct capture. In this capture strategy, the candidate asteroid leaves its heliocentric orbit after an initial impulse, with its dynamics modeled using the Sun-Earth-Moon restricted four-body problem until its insertion, with a second impulse, onto the L2 stable manifold in the Earth-Moon circular restricted three-body problem. A Lambert arc in the Sun-asteroid two-body problem is used as an initial guess and a differential corrector used to generate the transfer trajectory from the asteroid's initial obit to the stable manifold associated with Earth-Moon L2 point. Results show that the direct asteroid capture strategy needs a shorter flight time compared to an indirect asteroid capture, which couples capture in the Sun-Earth circular restricted three-body problem and subsequent transfer to the Earth-Moon circular restricted three-body problem. Finally, the direct and indirect asteroid capture strategies are also applied to consider capture of asteroids at the triangular libration points in the Earth-Moon system.

Super-catastrophic disruption of asteroids at small perihelion distances.

PubMed

Granvik, Mikael; Morbidelli, Alessandro; Jedicke, Robert; Bolin, Bryce; Bottke, William F; Beshore, Edward; Vokrouhlický, David; Delbò, Marco; Michel, Patrick

2016-02-18

Most near-Earth objects came from the asteroid belt and drifted via non-gravitational thermal forces into resonant escape routes that, in turn, pushed them onto planet-crossing orbits. Models predict that numerous asteroids should be found on orbits that closely approach the Sun, but few have been seen. In addition, even though the near-Earth-object population in general is an even mix of low-albedo (less than ten per cent of incident radiation is reflected) and high-albedo (more than ten per cent of incident radiation is reflected) asteroids, the characterized asteroids near the Sun typically have high albedos. Here we report a quantitative comparison of actual asteroid detections and a near-Earth-object model (which accounts for observational selection effects). We conclude that the deficit of low-albedo objects near the Sun arises from the super-catastrophic breakup (that is, almost complete disintegration) of a substantial fraction of asteroids when they achieve perihelion distances of a few tens of solar radii. The distance at which destruction occurs is greater for smaller asteroids, and their temperatures during perihelion passages are too low for evaporation to explain their disappearance. Although both bright and dark (high- and low-albedo) asteroids eventually break up, we find that low-albedo asteroids are more likely to be destroyed farther from the Sun, which explains the apparent excess of high-albedo near-Earth objects and suggests that low-albedo asteroids break up more easily as a result of thermal effects.

A path to asteroid bulk densities: Simultaneous size and shape optimization from optical lightcurves and Keck disk-resolved data

NASA Astrophysics Data System (ADS)

Hanus, Josef; Viikinkoski, Matti; Marchis, Franck; Durech, Josef

2015-11-01

A reliable bulk density of an asteroid can be determined from the knowledge of its volume and mass. This quantity provides hints on the internal structure of asteroids and their origin. We compute volume of several asteroids by scaling sizes of their 3D shape models to fit the disk-resolved images, which are available in the Keck Observatory Archive (KOA) and the Virtual Observatory Binary Asteroids Database (VOBAD). The size of an asteroid is optimized together with its shape by the All-Data Asteroid Modelling inversion algorithm (ADAM, Viikinkoski et al., 2015, A&A, 576, A8), while the spin state of the original convex shape model from the DAMIT database is only used as an initial guess for the modeling. Updated sets of optical lightcurves are usually employed. Thereafter, we combine obtained volume with mass estimates available in the literature and derive bulk densities for tens of asteroids with a typical accuracy of 20-50%.On top of that, we also provide a list of asteroids, for which (i) there are already mass estimates with reported uncertainties better than 20% or their masses will be most likely determined in the future from Gaia astrometric observations, and (ii) their 3D shape models are currently unknown. Additional optical lightcurves are necessary in order to determine convex shape models of these asteroids. Our web page (https://asteroid-obs.oca.eu/foswiki/bin/view/Main/Photometry) contains additional information about this observation campaign.

Dynamics of rotationally fissioned asteroids: Source of observed small asteroid systems

NASA Astrophysics Data System (ADS)

Jacobson, Seth A.; Scheeres, Daniel J.

2011-07-01

We present a model of near-Earth asteroid (NEA) rotational fission and ensuing dynamics that describes the creation of synchronous binaries and all other observed NEA systems including: doubly synchronous binaries, high- e binaries, ternary systems, and contact binaries. Our model only presupposes the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect, "rubble pile" asteroid geophysics, and gravitational interactions. The YORP effect torques a "rubble pile" asteroid until the asteroid reaches its fission spin limit and the components enter orbit about each other (Scheeres, D.J. [2007]. Icarus 189, 370-385). Non-spherical gravitational potentials couple the spin states to the orbit state and chaotically drive the system towards the observed asteroid classes along two evolutionary tracks primarily distinguished by mass ratio. Related to this is a new binary process termed secondary fission - the secondary asteroid of the binary system is rotationally accelerated via gravitational torques until it fissions, thus creating a chaotic ternary system. The initially chaotic binary can be stabilized to create a synchronous binary by components of the fissioned secondary asteroid impacting the primary asteroid, solar gravitational perturbations, and mutual body tides. These results emphasize the importance of the initial component size distribution and configuration within the parent asteroid. NEAs may go through multiple binary cycles and many YORP-induced rotational fissions during their approximately 10 Myr lifetime in the inner Solar System. Rotational fission and the ensuing dynamics are responsible for all NEA systems including the most commonly observed synchronous binaries.

78 FR 31977 - NASA Asteroid Initiative Call for Ideas

Federal Register 2010, 2011, 2012, 2013, 2014

2013-05-28

... NATIONAL AERONAUTICS AND SPACE ADMINISTRATION [Notice: 13-060] NASA Asteroid Initiative Call for... agency's asteroid initiative planning and to encourage feedback and ideas from the global community and... Perspective--Tom Kalil 9:55-10:15 Asteroid Initiative--Associate Administrator Lightfoot [[Page 31978

Asteroid/comet encounter opportunities for the Galileo VEEGA mission

NASA Technical Reports Server (NTRS)

Johannesen, Jennie R.; Nolan, Brian G.; Byrnes, Dennis V.; D'Amario, Louis A.

1988-01-01

The opportunity for the Galileo spacecraft to perform a close flyby of an asteroid or distant observation of a comet while on the Venus-Earth-Earth-Gravity-Assist (VEEGA) mission to Jupiter is discussed. More than 120 nominal trajectories were used in a scan program to identify asteroids passing within 30 million km of the spacecraft. A total of 47 asteroids were examined to determine the propellant cost of a close flyby. The possible flybys include a double asteroid flyby with No. 951 in October, 1991, with a flyby of No. 243 in August 1993. The factors considered in the selection of an asteroid include the propellant margin cost of modifying a nominal trajectory to include a close flyby, the size and type of asteroid, and the Jupiter arrival date.

Geophysical Evolution of Ch Asteroids and Testable Hypotheses for Future Missions

NASA Astrophysics Data System (ADS)

Castillo, J. C.

2017-12-01

The main population of asteroids related to meteorites in the collections remains to be explored in situ. Ch asteroids are the only midsized asteroids that display a signature of hydration (besides Pallas) and the spectral connection between Ch asteroids and CM chondrites suggests that the former represent potential parent bodies for the latter. This class of asteroids is particularly interesting because it hosts many objects 100-200 km in size, which are believed to belong to a primordial population of planetesimals. This presentation will explore multiple evolution pathways for Ch-asteroids leading to possible hypotheses on the geological, petrological, and geophysical properties that a disrupted parent body would present to a future mission. This work is being carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract to NASA.

Ultraviolet reflectance properties of asteroids

NASA Astrophysics Data System (ADS)

Butterworth, P. S.; Meadows, A. J.

1985-05-01

An analysis of the UV spectra of 28 asteroids obtained with the Internal Ultraviolet Explorer (IUE) satellite is presented. The spectra lie within the range 2100-3200 A. The results are examined in terms of both asteroid classification and of current ideas concerning the surface mineralogy of asteroids. For all the asteroids examined, UV reflectivity declines approximately linearly toward shorter wavelengths. In general, the same taxonomic groups are seen in the UV as in the visible and IR, although there is some evidence for asteroids with anomalous UV properties and for UV subclasses within the S class. No mineral absorption features are reported of strength similar to the strongest features in the visible and IR regions, but a number of shallow absorptions do occur and may provide valuable information on the surface composition of many asteroids.

Origin of igneous meteorites and differentiated asteroids

NASA Astrophysics Data System (ADS)

Scott, E.; Goldstein, J.; Asphaug, E.; Bottke, W.; Moskovitz, N.; Keil, K.

2014-07-01

Introduction: Igneously formed meteorites and asteroids provide major challenges to our understanding of the formation and evolution of the asteroid belt. The numbers and types of differentiated meteorites and non-chondritic asteroids appear to be incompatible with an origin by fragmentation of numerous Vesta-like bodies by hypervelocity impacts in the asteroid belt over 4 Gyr. We lack asteroids and achondrites from the olivine-rich mantles of the parent bodies of the 12 groups of iron meteorites and the ˜70 ungrouped irons, the 2 groups of pallasites and the 4--6 ungrouped pallasites. We lack mantle and core samples from the parent asteroids of the basaltic achondrites that do not come from Vesta, viz., angrites and the ungrouped eucrites like NWA 011 and Ibitira. How could core samples have been extracted from numerous differentiated bodies when Vesta's basaltic crust was preserved? Where is the missing Psyche family of differentiated asteroids including the complementary mantle and crustal asteroids [1]? Why are meteorites derived from far more differentiated parent bodies than chondritic parent bodies even though C and S class chondritic asteroids dominate the asteroid belt? New paradigm. Our studies of meteorites, impact modeling, and dynamical studies suggest a new paradigm in which differentiated asteroids accreted at 1--2 au less than 2 Myr after CAI formation [2]. They were rapidly melted by 26Al and disrupted by hit-and-run impacts [3] while still molten or semi-molten when planetary embryos were accreting. Metallic Fe-Ni bodies derived from core material cooled rapidly with little or no silicate insulation less than 4 Myr after CAI formation [4]. Fragments of differentiated planetesimals were subsequently tossed into the asteroid belt. Meteorite evidence for early disruption of differentiated asteroids. If iron meteorites were samples of Fe-Ni cores of bodies that cooled slowly inside silicate mantles over ˜50--100 Myr, irons from each core would have almost indistinguishable cooling rates as thermal gradients across cores would have been minimal. Irons in groups IIIAB, IVA, and IVB have chemical crystallization trends showing that they cooled in three separate bodies. However, each shows a wide range of cooling rates [4]. Group IVA irons cooled through 500°C at 6600--100 °C/Myr in a metallic body of radius 150 ± 50 km with scarcely any silicate insulation [5]. The Pb-Pb age of 4565.3 ± 0.1 Myr for a IVA iron [6] confirms that these irons cooled to ˜300°C only 2--3 Myr after CAI formation. Multiple hit-and-run impacts may have separated core and mantle material during accretion [7] as hypervelocity impacts do not efficiently separate cores from mantles. Thermal histories and magnetic properties of main group pallasites also require early catastrophic disruption of their primary parent body [8,9]. Conclusions. The anomalous properties of differentiated asteroids and meteorites cannot be explained by concealing differentiated planetesimals under chondritic crusts [10] as meteorite breccias and the apparent compositional homogeneity of asteroid families are inconsistent with this model. Like Burbine et al. [11], we attribute the lack of olivine mantle meteorites and asteroids to collisional grinding of weaker silicate and the preferential survival of stronger metallic Fe,Ni fragments. But we infer that asteroid break up occurred very early inside 2 au, not in the asteroid belt over 4 Gyr. Vesta may have preserved its crust due to early ejection into the asteroid belt. It is the smallest terrestrial planet --- not an archetypal differentiated asteroid.

Impact risk assessment and planetary defense mission planning for asteroid 2015 PDC

NASA Astrophysics Data System (ADS)

Vardaxis, George; Sherman, Peter; Wie, Bong

2016-05-01

In this paper, an integrated utilization of analytic keyhole theory, B-plane mapping, and planetary encounter geometry, augmented by direct numerical simulation, is shown to be useful in determining the impact risk of an asteroid with the Earth on a given encounter, as well on potential future encounters via keyhole passages. The accurate estimation of the impact probability of hazardous asteroids is extremely important for planetary defense mission planning. Asteroids in Earth resonant orbits are particularly troublesome because of the continuous threat they pose in the future. Based on the trajectories of the asteroid and the Earth, feasible mission trajectories can be found to mitigate the impact threat of hazardous asteroids. In order to try to ensure mission success, trajectories are judged based on initial and final mission design parameters that would make the mission easier to complete. Given the potential of a short-warning time scenario, a disruption mission considered in this paper occurs approximately one year prior to the anticipated impact date. Expanding upon the established theory, a computational method is developed to estimate the impact probability of the hazardous asteroid, in order to assess the likelihood of an event, and then investigate the fragmentation of the asteroid due to a disruption mission and analyze its effects on the current and future encounters of the fragments with Earth. A fictional asteroid, designated as 2015 PDC - created as an example asteroid risk exercise for the 2015 Planetary Defence Conference, is used as a reference target asteroid to demonstrate the effectiveness and applicability of computational tools being developed for impact risk assessment and planetary defense mission planning for a hazardous asteroid or comet.

Bayesian modeling of the mass and density of asteroids

NASA Astrophysics Data System (ADS)

Dotson, Jessie L.; Mathias, Donovan

2017-10-01

Mass and density are two of the fundamental properties of any object. In the case of near earth asteroids, knowledge about the mass of an asteroid is essential for estimating the risk due to (potential) impact and planning possible mitigation options. The density of an asteroid can illuminate the structure of the asteroid. A low density can be indicative of a rubble pile structure whereas a higher density can imply a monolith and/or higher metal content. The damage resulting from an impact of an asteroid with Earth depends on its interior structure in addition to its total mass, and as a result, density is a key parameter to understanding the risk of asteroid impact. Unfortunately, measuring the mass and density of asteroids is challenging and often results in measurements with large uncertainties. In the absence of mass / density measurements for a specific object, understanding the range and distribution of likely values can facilitate probabilistic assessments of structure and impact risk. Hierarchical Bayesian models have recently been developed to investigate the mass - radius relationship of exoplanets (Wolfgang, Rogers & Ford 2016) and to probabilistically forecast the mass of bodies large enough to establish hydrostatic equilibrium over a range of 9 orders of magnitude in mass (from planemos to main sequence stars; Chen & Kipping 2017). Here, we extend this approach to investigate the mass and densities of asteroids. Several candidate Bayesian models are presented, and their performance is assessed relative to a synthetic asteroid population. In addition, a preliminary Bayesian model for probablistically forecasting masses and densities of asteroids is presented. The forecasting model is conditioned on existing asteroid data and includes observational errors, hyper-parameter uncertainties and intrinsic scatter.

Deflection by kinetic impact: Sensitivity to asteroid properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bruck Syal, Megan; Michael Owen, J.; Miller, Paul L.

Impacting an asteroid with a spacecraft traveling at high speed delivers an impulsive change in velocity to the body. In certain circumstances, this strategy could be used to deflect a hazardous asteroid, moving its orbital path off of an Earth-impacting course. However, the efficacy of momentum delivery to asteroids by hypervelocity impact is sensitive to both the impact conditions (particularly velocity) and specific characteristics of the target asteroid. We numerically model asteroid response to kinetic impactors under a wide range of initial conditions, using an Adaptive Smoothed Particle Hydrodynamics code. Impact velocities spanning 1–30 km/s were investigated, yielding, for amore » particular set of assumptions about the modeled target material, a power-law dependence consistent with a velocity-scaling exponent of μ = 0.44. Target characteristics including equation of state, strength model, porosity, rotational state, and shape were varied, and corresponding changes in asteroid response were documented. Moreover, the kinetic-impact momentum-multiplication factor, β, decreases with increasing asteroid cohesion and increasing porosity. Although increased porosity lowers β, larger porosities result in greater deflection velocities, as a consequence of reduced target masses for asteroids of fixed size. Porosity also lowers disruption risk for kinetic impacts near the threshold of disruption. Including fast (P = 2.5 h) and very fast (P = 100 s) rotation did not significantly alter β but did affect the risk of disruption by the impact event. Asteroid shape is found to influence the efficiency of momentum delivery, as local slope conditions can change the orientation of the crater ejecta momentum vector. Our results emphasize the need for asteroid characterization studies to bracket the range of target conditions expected at near-Earth asteroids while also highlighting some of the principal uncertainties associated with the kinetic-impact deflection strategy.« less

Asteroid mass estimation with Markov-chain Monte Carlo

NASA Astrophysics Data System (ADS)

Siltala, Lauri; Granvik, Mikael

2017-10-01

Estimates for asteroid masses are based on their gravitational perturbations on the orbits of other objects such as Mars, spacecraft, or other asteroids and/or their satellites. In the case of asteroid-asteroid perturbations, this leads to a 13-dimensional inverse problem at minimum where the aim is to derive the mass of the perturbing asteroid and six orbital elements for both the perturbing asteroid and the test asteroid by fitting their trajectories to their observed positions. The fitting has typically been carried out with linearized methods such as the least-squares method. These methods need to make certain assumptions regarding the shape of the probability distributions of the model parameters. This is problematic as these assumptions have not been validated. We have developed a new Markov-chain Monte Carlo method for mass estimation which does not require an assumption regarding the shape of the parameter distribution. Recently, we have implemented several upgrades to our MCMC method including improved schemes for handling observational errors and outlier data alongside the option to consider multiple perturbers and/or test asteroids simultaneously. These upgrades promise significantly improved results: based on two separate results for (19) Fortuna with different test asteroids we previously hypothesized that simultaneous use of both test asteroids would lead to an improved result similar to the average literature value for (19) Fortuna with substantially reduced uncertainties. Our upgraded algorithm indeed finds a result essentially equal to the literature value for this asteroid, confirming our previous hypothesis. Here we show these new results for (19) Fortuna and other example cases, and compare our results to previous estimates. Finally, we discuss our plans to improve our algorithm further, particularly in connection with Gaia.

Sensitivity of Asteroid Impact Risk to Uncertainty in Asteroid Properties and Entry Parameters

NASA Astrophysics Data System (ADS)

Wheeler, Lorien; Mathias, Donovan; Dotson, Jessie L.; NASA Asteroid Threat Assessment Project

2017-10-01

A central challenge in assessing the threat posed by asteroids striking Earth is the large amount of uncertainty inherent throughout all aspects of the problem. Many asteroid properties are not well characterized and can range widely from strong, dense, monolithic irons to loosely bound, highly porous rubble piles. Even for an object of known properties, the specific entry velocity, angle, and impact location can swing the potential consequence from no damage to causing millions of casualties. Due to the extreme rarity of large asteroid strikes, there are also large uncertainties in how different types of asteroids will interact with the atmosphere during entry, how readily they may break up or ablate, and how much surface damage will be caused by the resulting airbursts or impacts.In this work, we use our Probabilistic Asteroid Impact Risk (PAIR) model to investigate the sensitivity of asteroid impact damage to uncertainties in key asteroid properties, entry parameters, or modeling assumptions. The PAIR model combines physics-based analytic models of asteroid entry and damage in a probabilistic Monte Carlo framework to assess the risk posed by a wide range of potential impacts. The model samples from uncertainty distributions of asteroid properties and entry parameters to generate millions of specific impact cases, and models the atmospheric entry and damage for each case, including blast overpressure, thermal radiation, tsunami inundation, and global effects. To assess the risk sensitivity, we alternately fix and vary the different input parameters and compare the effect on the resulting range of damage produced. The goal of these studies is to help guide future efforts in asteroid characterization and model refinement by determining which properties most significantly affect the potential risk.

Deflection by kinetic impact: Sensitivity to asteroid properties

DOE PAGES

Bruck Syal, Megan; Michael Owen, J.; Miller, Paul L.

2016-05-01

Impacting an asteroid with a spacecraft traveling at high speed delivers an impulsive change in velocity to the body. In certain circumstances, this strategy could be used to deflect a hazardous asteroid, moving its orbital path off of an Earth-impacting course. However, the efficacy of momentum delivery to asteroids by hypervelocity impact is sensitive to both the impact conditions (particularly velocity) and specific characteristics of the target asteroid. We numerically model asteroid response to kinetic impactors under a wide range of initial conditions, using an Adaptive Smoothed Particle Hydrodynamics code. Impact velocities spanning 1–30 km/s were investigated, yielding, for amore » particular set of assumptions about the modeled target material, a power-law dependence consistent with a velocity-scaling exponent of μ = 0.44. Target characteristics including equation of state, strength model, porosity, rotational state, and shape were varied, and corresponding changes in asteroid response were documented. Moreover, the kinetic-impact momentum-multiplication factor, β, decreases with increasing asteroid cohesion and increasing porosity. Although increased porosity lowers β, larger porosities result in greater deflection velocities, as a consequence of reduced target masses for asteroids of fixed size. Porosity also lowers disruption risk for kinetic impacts near the threshold of disruption. Including fast (P = 2.5 h) and very fast (P = 100 s) rotation did not significantly alter β but did affect the risk of disruption by the impact event. Asteroid shape is found to influence the efficiency of momentum delivery, as local slope conditions can change the orientation of the crater ejecta momentum vector. Our results emphasize the need for asteroid characterization studies to bracket the range of target conditions expected at near-Earth asteroids while also highlighting some of the principal uncertainties associated with the kinetic-impact deflection strategy.« less

Spectral evidence of size dependent space weathering processes on asteroid surfaces

NASA Technical Reports Server (NTRS)

Gaffey, M. J.; Bell, J. F.; Brown, R. H.; Burbine, T. H.; Piatek, J. L.; Reed, K. L.; Chaky, D. A.

1993-01-01

Most compositional characterizations of the minor planets are derived from analysis of visible and near-infrared reflectance spectra. However, such spectra are derived from light which has only interacted with a very thin surface layer. Although regolith processes are assumed to mix all near-surface lithologic units into this layer, it has been proposed that space weathering processes can alter this surface layer to obscure the spectral signature of the bedrock lithology. It has been proposed that these spectral alteration processes are much less pronounced on asteroid surfaces than on the lunar surface, but the possibility of major spectral alteration of asteroidal optical surfaces has been invoked to reconcile S-asteroids with ordinary chondrites. The reflectance spectra of a large subset of the S-asteroid population have been analyzed in a systematic investigation of the mineralogical diversity within the S-class. In this sample, absorption band depth is a strong function of asteroid diameter. The S-asteroid band depths are relatively constant for objects larger than 100 km and increase linearly by factor of two toward smaller sizes (approximately 40 km). Although the S-asteroid surface materials includes a diverse variety of silicate assemblages, ranging from dunites to basalts, all compositional subtypes of the S-asteroids conform to this trend. The A-, R-, and V-type asteroids which are primarily silicate assemblages (as opposed to the metal-silicate mixtures of most S-asteroids) follow a parallel but displaced trend. Some sort of textural or regolith equilibrium appears to have been attained in the optical surfaces of asteroids larger than about 100 km diameter but not on bodies below this size. The relationships between absorption band depth, spectral slope, surface albedo and body size provide an intriguing insight into the nature of the optical surfaces of the S-asteroids and space weathering on these objects.

"Prospecting Asteroids: Indirect technique to estimate overall density and inner composition"

NASA Astrophysics Data System (ADS)

Such, Pamela

2016-07-01

Spectroscopic studies of asteroids make possible to obtain some information on their composition from the surface but say little about the innermost material, porosity and density of the object. In addition, spectroscopic observations are affected by the effects of "space weathering" produced by the bombardment of charged particles for certain materials that change their chemical structure, albedo and other physical properties, partly altering their chances of identification. Data such as the mass, size and density of the asteroids are essential at the time to propose space missions in order to determine the best candidates for space exploration and is of great importance to determine a priori any of them remotely from Earth. From many years ago its determined masses of largest asteroids studying the gravitational effects they have on smaller asteroids when they approach them (see Davis and Bender, 1977; Schubart and Matson, 1979; School et al 1987; Hoffman, 1989b, among others), but estimates of the masses of the smallest objects is limited to the effects that occur in extreme close encounters to other asteroids of similar size. This paper presents the results of a search for approaches of pair of asteroids that approximate distances less than 0.0004 UA (50,000 km) of each other in order to study their masses through the astrometric method and to estimate in a future their densities and internal composition. References Davis, D. R., and D. F. Bender. 1977. Asteroid mass determinations: search for futher encounter opportunities. Bull. Am. Astron. Soc. 9, 502-503. Hoffman, M. 1989b. Asteroid mass determination: Present situation and perspectives. In asteroids II (R. P. Binzel, T. Gehreis, and M. S. Matthews, Eds.), pp 228-239. Univ. Arizona Press, Tucson. School, H. L. D. Schmadel and S. Roser 1987. The mass of the asteroid (10) Hygiea derived from observations of (829) Academia. Astron. Astrophys. 179, 311-316. Schubart, J. And D. L. Matson 1979. Masses and densities of asteroids. In Asteroids (T. Gehrels, Ed.), pp.

Discovery of a New Super-Fast Rotator

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2015-07-01

Recent observations of asteroid (335433) 2005 UW163 have added a new member to the mysterious category of "super-fast rotators" — asteroids that rotate faster than should be possible, given current theories of asteroid composition. Asteroids come in sizes of a few meters to a few hundred kilometers, and can spin at rates from 0.1 to nearly 1000 revolutions per day. Current theories suggest that asteroids smaller than 150m are mostly monolithic (made up of a single rock), whereas asteroids larger than 150m are usually what's known as a "rubble pile" — a collection of rock fragments from past collisions, bound together into a clump by gravity. "Rubble pile" asteroids have an important structural limitation: they can't spin faster than once every 2.2 hours without flying apart as the centripetal force overcomes the force of gravity. Asteroid 2005 UW163 violates this rule: its diameter is 690m, but it rotates once every 1.29 hours. This discovery was made by a team of scientists using telescopes at the Palomar Observatory in California to conduct a large survey of the rotation rates of nearby asteroids. The group, led by Chan-Kao Chang of Taiwan's National Central University, discovered 11 super-fast rotator candidates — of which asteroid 2005 UW163 is the first to have its rotation rate confirmed by additional observations. The category of super-fast rotators poses an interesting problem: how are they able to spin so quickly without flying apart? Either the density of these asteroids is unexpectedly high (roughly four times the density of typical "rubble pile" asteroids), or else there must be additional forces besides gravity at work to help hold the asteroid together, such as bonds between the rocks. Future observations of super-fast rotators will help us better understand the peculiar structure of these rocky neighbors. Citation: Chan-Kao Chang et al. 2014 ApJ 791 L35 doi:10.1088/2041-8205/791/2/L35

78 FR 51750 - NASA Asteroid Initiative Idea Synthesis Workshop

Federal Register 2010, 2011, 2012, 2013, 2014

2013-08-21

... NATIONAL AERONAUTICS AND SPACE ADMINISTRATION [Notice: 13-096] NASA Asteroid Initiative Idea... Conference to examine ideas in response to the recent RFI for the agency's Asteroid Initiative. SUMMARY: The... Agency's Asteroid Initiative planning and to enable feedback and discussion from the global community and...

Capturing asteroids into bound orbits around the earth: Massive early return on an asteroid terminal defense system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hills, J.G.

1992-02-06

Nuclear explosives may be used to capture small asteroids (e.g., 20--50 meters in diameter) into bound orbits around the earth. The captured objects could be used for construction material for manned and unmanned activity in Earth orbit. Asteroids with small approach velocities, which are the ones most likely to have close approaches to the Earth, require the least energy for capture. They are particularly easy to capture if they pass within one Earth radius of the surface of the Earth. They could be intercepted with intercontinental missiles if the latter were retrofit with a more flexible guiding and homing capability.more » This asteroid capture-defense system could be implemented in a few years at low cost by using decommissioned ICMs. The economic value of even one captured asteroid is many times the initial investment. The asteroid capture system would be an essential part of the learning curve for dealing with larger asteroids that can hit the earth.« less

Prospects for asteroid mass determination from close encounters between asteroids: ESA's Gaia space mission and beyond

NASA Astrophysics Data System (ADS)

Ivantsov, Anatoliy; Hestroffer, Daniel; Eggl, Siegfried

2018-04-01

We present a catalog of potential candidates for asteroid mass determination based on mutual close encounters of numbered asteroids with massive perturbers (D>20 km). Using a novel geometric approach tuned to optimize observability, we predict optimal epochs for mass determination observations. In contrast to previous studies that often used simplified dynamical models, we have numerically propagated the trajectories of all numbered asteroids over the time interval from 2013 to 2023 using relativistic equations of motion including planetary perturbations, J2 of the Sun, the 16 major asteroid perturbers and the perturbations due to non-sphericities of the planets. We compiled a catalog of close encounters between asteroids where the observable perturbation of the sky plane trajectory is greater than 0.5 mas so that astrometric measurements of the perturbed asteroids in the Gaia data can be leveraged. The catalog v1.0 is available at ftp://dosya.akdeniz.edu.tr/ivantsov.

Asteroid Size-Frequency Distribution

NASA Technical Reports Server (NTRS)

Tedesco, Edward F.

2001-01-01

A total of six deep exposures (using AOT CAM01 with a 6 inch PFOV) through the ISOCAM LW10 filter (IRAS Band 1, i.e. 12 micron) were obtained on an approximately 15 arcminute square field centered on the ecliptic plane. Point sources were extracted using the technique described. Two known asteroids appear in these frames and 20 sources moving with velocities appropriate for main belt asteroids are present. Most of the asteroids detected have flux densities less than 1 mJy, i,e., between 150 and 350 times fainter than any of the asteroids observed by IRAS. These data provide the first direct measurement of the 12 pm sky-plane density for asteroids on the ecliptic equator. The median zodiacal foreground, as measured by ISOCAM during this survey, is found to be 22.1 +/- 1.5 mJy per pixel, i.e., 26.2 +/- 1.7 MJy/sr. The results presented here imply that the actual number of kilometer-sized asteroids is significantly greater than previously believed and in reasonable agreement with the Statistical Asteroid Model.

Sample Return Science by Hayabusa Near-Earth Asteroid Mission

NASA Technical Reports Server (NTRS)

Fujiwara, A.; Abe, M.; Kato, M.; Kushiro, I.; Mukai, T.; Okada, T.; Saito, J.; Sasaki, S.; Yano, H.; Yeomans, D.

2004-01-01

Assigning the material species to each asteroid spectral type and finding out the corresponding meteorite category is crucial to make the global material map in the whole asteroid belt and to understand the evolution of the asteroid belt. Recent direct observations by spacecrafts are revealing new intriguing aspects of asteroids which cannot be obtained solely from ground-based observations or meteorite studies. However identification of the real material species constituting asteroids and their corresponding meteorite analogs are still ambiguous. Space weathering makes difficult to identify the true material, and there is still a great gap between the remote sensing data on the global surface and the local microscopic data from meteorites. Sample return from asteroids are inevitable to solve these problems. For this purpose sample return missions to asteroids belonging to various spectral classes are required. The HAYABUSA spacecraft (prelaunch name is MUSESC) launched last year is the first attempt on this concept. This report presents outline of the mission with special stress on its science.

Meteoritic and other constraints on the internal structure and impact history of small asteroids

NASA Astrophysics Data System (ADS)

Scott, Edward R. D.; Wilson, Lionel

2005-03-01

Studies of the internal structure of asteroids, which are crucial for understanding their impact history and for hazard mitigation, appear to be in conflict for the S-type asteroids, Eros, Gaspra, and Ida. Spacecraft images and geophysical data show that they are fractured, coherent bodies, whereas models of catastrophic asteroidal impacts, family and satellite formation, and studies of asteroid spin rates, and other diverse properties of asteroids and planetary craters suggest that such asteroids are gravitationally bound aggregates of rubble. These conflicting views may be reconciled if 10-50 km S-type asteroids formed as rubble piles, but were later consolidated into coherent bodies. Many meteorites are breccias that testify to a long history of impact fragmentation and consolidation by alteration, metamorphism, igneous and impact processes. Ordinary chondrites, which are the best analogs for S asteroids, are commonly breccias. Some may have formed in cratering events, but many appear to have formed during disruption and reaccretion of their parent asteroids. Some breccias were lithified during metamorphism, and a few were lithified by injected impact melt, but most are regolith and fragmental breccias that were lithified by mild or moderate shock, like their lunar analogs. Shock experiments show that porous chondritic powders can be consolidated during mild shock by small amounts of silicate melt that glues grains together, and by friction and pressure welding of silicate and metallic Fe,Ni grains. We suggest that the same processes that converted impact debris into meteorite breccias also consolidated asteroidal rubble. Internal voids would be partly filled with regolith by impact-induced seismic shaking. Consolidation of this material beneath large craters would lithify asteroidal rubble to form a more coherent body. Fractures on Ida that were created by antipodal impacts and are concentrated in and near large craters, and small positive gravity anomalies associated with the Psyche and Himeros craters on Eros, are consistent with this concept. Spin data suggest that smaller asteroids 0.6-6 km in size are unconsolidated rubble piles. C-type asteroids, which are more porous than S-types, and their analogs, the volatile-rich carbonaceous chondrites, were probably not lithified by shock.

Results of the 2015 Mexican Asteroid Photometry Campaign

NASA Astrophysics Data System (ADS)

Sada, Pedro V.; Navarro-Meza, Samuel; Reyes-Ruiz, Mauricio; Olguin, Lorenzo L.; Saucedo, Julio C.; Loera-Gonzalez, Pablo

2016-04-01

The 2015 Mexican Asteroid Photometry Campaign was organized at the 2nd National Planetary Astrophysics Workshop held in 2015 March at the Universidad Autónoma de Nuevo León in Monterrey, México. Three asteroids were selected for coordinated observations from several Mexican observatories. We report full lightcurves for the main-belt asteroid 1084 Tamariwa (P = 6.195 ± 0.001 h) and near-Earth asteroid (NEA) 4055 Magellan (P = 7.479 ± 0.001 h). Asteroid 1466 Mundleria was also observed on eight nights but no lightcurve was obtained because of its faintness, a crowded field-of-view, and low amplitude (<0.03 mag).

The Large Super-Fast Rotators and Asteroidal Spin-Rate Distributions With Large Sky-Field Surveys Using iPTF

NASA Astrophysics Data System (ADS)

Chang, Chan-Kao; Lin, Hsing-Wen; Ip, Wing-Huen; iPTF Team

2016-10-01

In order to look for kilometer-sized super-fast rotators (large SFRs) and understand the spin-rate distributions of small (i.e. D of several kilometers) asteroids, we have been conducting asteroid rotation period surveys of large sky area using intermediate Palomar Transient Factory (iPTF) since 2014. So far, we have observed 261 deg2 with 20 min cadence, 188 deg2 with 10 min cadence, and 65 deg2 with 5 min cadence. From these surveys, we found that the spin-rate distributions of small asteroids at different locations in the main-belt are very similar. Moreover, the distributions of asteroids with 3 < D < 15 km show number decrease along with increase of spin rate for frequency > 5 rev/day, and that of asteroids with D < 3 km have a significant number drop at frequency = 5 rev/day. However, we only discover two new large SFRs and 24 candidates. Comparing with the ordinary asteroids, the population of large SFR seems to be far less than the whole asteroid population. This might indicate a peculiar group of asteroid for large SFRs.

Optimised low-thrust mission to the Atira asteroids

NASA Astrophysics Data System (ADS)

Di Carlo, Marilena; Romero Martin, Juan Manuel; Ortiz Gomez, Natalia; Vasile, Massimiliano

2017-04-01

Atira asteroids are recently-discovered celestial bodies characterised by orbits lying completely inside the heliocentric orbit of the Earth. The study of these objects is difficult due to the limitations of ground-based observations: objects can only be detected when the Sun is not in the field of view of the telescope. However, many asteroids are expected to exist in the inner region of the Solar System, many of which could pose a significant threat to our planet. In this paper, a small, low-cost, mission to visit the known Atira asteroids and to discover new Near Earth Asteroids (NEA) is proposed. The mission is realised using electric propulsion. The trajectory is optimised to maximise the number of visited asteroids of the Atira group using the minimum propellant consumption. During the tour of the Atira asteroids an opportunistic NEA discovery campaign is proposed to increase our knowledge of the asteroid population. The mission ends with a transfer to an orbit with perihelion equal to Venus's orbit radius. This orbit represents a vantage point to monitor and detect asteroids in the inner part of the Solar System and provide early warning in the case of a potential impact.

Capture orbits around asteroids by hitting zero-velocity curves

NASA Astrophysics Data System (ADS)

Wang, Wei; Yang, Hongwei; Zhang, Wei; Ma, Guangfu

2017-12-01

The problem of capturing a spacecraft from a heliocentric orbit into a high parking orbit around binary asteroids is investigated in the current study. To reduce the braking Δ V, a new capture strategy takes advantage of the three-body gravity of the binary asteroid to lower the inertial energy before applying the Δ V. The framework of the circular restricted three-body problem (CR3BP) is employed for the binary asteroid system. The proposed capture strategy is based on the mechanism by which inertial energy can be decreased sharply near zero-velocity curves (ZVCs). The strategy has two steps, namely, hitting the target ZVC and raising the periapsis by a small Δ V at the apoapsis. By hitting the target ZVC, the positive inertial energy decreases and becomes negative. Using a small Δ V, the spacecraft inserts into a bounded orbit around the asteroid. In addition, a rotating mass dipole model is employed for elongated asteroids, which leads to dynamics similar to that of the CR3BP. With this approach, the proposed capture strategy can be applied to elongated asteroids. Numerical simulations validate that the proposed capture strategy is applicable for the binary asteroid 90 Antiope and the elongated asteroid 216 Kleopatra.

Asteroid (457175) 2008 GO98: a quasi-Hilda comet. (Italian Title: Asteroide (457175) 2008 GO98:una cometa "quasi-Hilda")

NASA Astrophysics Data System (ADS)

Bacci, P.

2017-12-01

Cometary activity in the asteroid (457175) 2008 GO98 was observed at San Marcello Observatory, highlighting an extended coma and a tail of 36 arcseconds. The asteroid should be classified as a quasi-Hilda comet.

LCA in space - current status and future development

NASA Astrophysics Data System (ADS)

Ko, Nathanael; Betten, Thomas; Schestak, Isabel; Gantner, Johannes

2018-06-01

This paper represents the first stage of extending the scope of LCA to space and is intended as a discussion starter. Based on the assumption, that the future and outlast of humanity lies within the exploration and colonisation of space, the LCA methodology as of today, is discussed with regards to its capabilities to cover the impact of human activities in space. Based on this assessment, ideas whether and how LCA can be extended are outlined. Initially, an understanding of additional environmental impacts which occur in space compared to Earth is built up by the means of literature research. The state of the art of space regulations and availability of LCAs in space and for astronautics is clarified as well. Further literature research was conducted on the LCA subtopic of regionalization. Based on this and assumptions regarding future space travel, the suitability of LCA as an assessment method is validated. Afterwards, different potential development phases of LCA towards its applicability in space are defined. For activities in space, the regarded environmental impacts have to be expanded (e.g. space debris, extra-terrestrial life toxicity, etc.). Space regulations, if in place, cover only impacts of space activities on Earth so far. LCAs for space activities are not widespread yet. One reason for this is that the state of the art LCA methodology has not been expanded and existing regionalisation approaches are not easily transferable to space. Critical issues are faced in all phases of an LCA and include widening of boundaries, definition of space regions, finding suitable reference units and ethical problems. As a result, four LCA development phases are suggested: Earth-bound, solar system-bound, transition phase and intergalactic. Each phase involves different activities and goals, which result in different system boundaries and impact categories and widen the scope of LCA subsequently. It is a long way for humanity to populate space and so, it is for enabling LCA to assess these activities. The methodology of LCA is flexible and capable to make this adaptation. This paper can be seen as a starting point of a discussion opening up many questions. Some of these questions can only be answered in the future with more certainty about the development of space colonialization.

The Near Earth Asteroid Medical Conditions List

NASA Technical Reports Server (NTRS)

Barr, Yael R.; Watkins, S. D.

2011-01-01

Purpose: The Exploration Medical Capability (ExMC) element is one of six elements within NASA s Human Research Program (HRP) and is responsible for addressing the risk of "the inability to adequately recognize or treat an ill or injured crewmember" for exploration-class missions. The Near Earth Asteroid (NEA) Medical Conditions List, constructed by ExMC, is the first step in addressing the above-mentioned risk for the 13-month long NEA mission. The NEA mission is being designed by NASA's Human Space Flight Architecture Team (HAT). The purpose of the conditions list is to serve as an evidence-based foundation for determining which medical conditions could affect a crewmember during the NEA mission, which of those conditions would be of concern and require treatment, and for which conditions a gap in knowledge or technology development exists. This information is used to focus research efforts and technology development to ensure that the appropriate medical capabilities are available for exploration-class missions. Scope and Approach: The NEA Medical Conditions List is part of a broader Space Medicine Exploration Medical Conditions List (SMEMCL), which incorporates various exploration-class design reference missions (DRMs). The conditions list contains 85 medical conditions which could occur during space flight and which are derived from several sources: Long-Term Surveillance of Astronaut Health (LSAH) in-flight occurrence data, The Space Shuttle (STS) Medical Checklist, The International Space Station (ISS) Medical Checklist, and subject matter expert opinion. Each medical condition listed has been assigned a clinical priority and a clinical priority rationale based on incidence, consequence, and mitigation capability. Implementation: The conditions list is a "living document" and as such, new conditions can be added to the list, and the priority of conditions on the list can be adjusted as the DRM changes, and as screening, diagnosis, or treatment capabilities change. The NEA medical conditions list was used recently as the basis for identifying gaps in in-flight medical evaluation (screening) capabilities. Learning Objectives: The audience will become familiar with the approach taken by NASA's Exploration Medical Capability element in addressing the risk of inability to recognize and treat medical conditions in the setting of a Near Earth Asteroid mission. Which one of the following statements is incorrect? a) The Near Earth Asteroid (NEA) medical conditions list includes 85 medical conditions which could occur during space flight. b) Each condition on the NEA medical conditions list has been assigned a clinical priority and a clinical priority rationale. c) The NEA medical conditions list targets a mission to Mars. d) The NEA medical conditions list should be viewed as a "living document" where new conditions can be added and clinical priorities adjusted to address changes in the design reference mission or medical capabilities. The incorrect answer is c). The NEA medical conditions list targets a mission to a Near Earth Asteroid.

Small Main-Belt Asteroid Lightcurve Survey

NASA Technical Reports Server (NTRS)

Binzel, Richard P.; Xu, Shui; Bus, Schelte J.; Bowell, Edward

1992-01-01

The Small Main-Belt Asteroid Lightcurve Survey is the first to measure main-belt asteroid lightcurve properties for bodies with diameters smaller than 5 km. Attention is given to CCD lightcurves for 32 small main-belt asteroids. The objects of this sample have a mean rotational frequency which is faster than that of larger main-belt asteroids. All lightcurves were investigated for nonperiodic variations ascribable to free precession; no conclusive detection of this phenomenon has been made, however.

Asteroid Initiative Industry and Partner Day

NASA Image and Video Library

2013-06-18

NASA Associate Administrator Robert Lightfoot, talks during the Asteroid Initiative Industry and Partner Day at NASA Headquarters on Tuesday, June 18, 2013 in Washington. During the event NASA Deputy Administrator Lori Garver and other senior NASA officials discussed the progress being made on NASA's mission to capture, redirect, and explore an asteroid. NASA also announced an Asteroid Grand Challenge focused on finding all asteroid threats to human populations and knowing what to do about them. Photo Credit: (NASA/Bill Ingalls)

Compositional Variegation of Large-Diameter Low-Albedo Asteroids

NASA Astrophysics Data System (ADS)

Vilas, F.; Jarvis, K. S.; Anz-Meador, T. D.; Thibault, C. A.; Sawyer, S. R.; Fitzsimmons, A.

1997-07-01

Asteroids showing signs of aqueous alteration and thermal metamorphism in visible/near IR spectroscopy and photometry (C, G, F, B, and P classes) ranging from 0.37 - 0.90mu m dominate the asteroid population at heliocentric distances of 2.6 - 3.5 AU. Age dating of meteorites indicates that the Solar System was subjected to a major heating event 4.5 Gyr ago. Recent meteoritic research has produced evidence of a carbonaceous chondrite subjected to two separate aqueous alteration events with a metamorphic heating inbetween (Krot et al., 1997, submitted). Models of the effects of heating by electromagnetic induction or decay of short-lived radionuclides combined with models of the early collisional history of the Solar System after Jupiter's formation indicate that asteroids observed today can be divided into two groups by diameter. Those asteroids having diameters greater than 100 km were mixed by multiple collisions but remain as gravitationally bound rubble piles. Asteroids with diameters less than 100 km should show more compositional diversity. Vilas and Sykes (1996, Icarus, v. 124, 483) have shown using ECAS photometry that this compositional difference exists. Those asteroids having diameters greater than 100 km should be individually homogeneous, with spectral differences showing the combined effects of a primordial compositional gradient in the asteroid belt with thermal metamorphism. We address the significance of spatially-resolved spectra of 42 asteroids to the collective origin of these asteroids.

Reconstructing the size distribution of the primordial Main Belt

NASA Astrophysics Data System (ADS)

Tsirvoulis, G.; Morbidelli, A.; Delbo, M.; Tsiganis, K.

2018-04-01

In this work we aim to constrain the slope of the size distribution of main-belt asteroids, at their primordial state. To do so we turn out attention to the part of the main asteroid belt between 2.82 and 2.96 AU, the so-called "pristine zone", which has a low number density of asteroids and few, well separated asteroid families. Exploiting these unique characteristics, and using a modified version of the hierarchical clustering method we are able to remove the majority of asteroid family members from the region. The remaining, background asteroids should be of primordial origin, as the strong 5/2 and 7/3 mean-motion resonances with Jupiter inhibit transfer of asteroids to and from the neighboring regions. The size-frequency distribution of asteroids in the size range 17 < D(km) < 70 has a slope q ≃ - 1 . Using Monte-Carlo methods, we are able to simulate, and compensate for the collisional and dynamical evolution of the asteroid population, and get an upper bound for its size distribution slope q = - 1.43 . In addition, applying the same 'family extraction' method to the neighboring regions, i.e. the middle and outer belts, and comparing the size distributions of the respective background populations, we find statistical evidence that no large asteroid families of primordial origin had formed in the middle or pristine zones.

THE ORIGIN OF ASTEROID 162173 (1999 JU{sub 3})

DOE Office of Scientific and Technical Information (OSTI.GOV)

Campins, Humberto; De Leon, Julia; Morbidelli, Alessandro

Near-Earth asteroid (162173) 1999 JU{sub 3} (henceforth JU{sub 3}) is a potentially hazardous asteroid and the target of the Japanese Aerospace Exploration Agency's Hayabusa-2 sample return mission. JU{sub 3} is also a backup target for two other sample return missions: NASA's OSIRIS-REx and the European Space Agency's Marco Polo-R. We use dynamical information to identify an inner-belt, low-inclination origin through the {nu}{sub 6} resonance, more specifically, the region with 2.15 AU < a < 2.5 AU and i < 8 Degree-Sign . The geometric albedo of JU{sub 3} is 0.07 {+-} 0.01, and this inner-belt region contains four well-defined low-albedomore » asteroid families (Clarissa, Erigone, Polana, and Sulamitis), plus a recently identified background population of low-albedo asteroids outside these families. Only two of these five groups, the background and the Polana family, deliver JU{sub 3}-sized asteroids to the {nu}{sub 6} resonance, and the background delivers significantly more JU{sub 3}-sized asteroids. The available spectral evidence is also diagnostic; the visible and near-infrared spectra of JU{sub 3} indicate it is a C-type asteroid, which is compatible with members of the background, but not with the Polana family because it contains primarily B-type asteroids. Hence, this background population of low-albedo asteroids is the most likely source of JU{sub 3}.« less

Geotechnical Tests on Asteroid Simulant Orgueil

NASA Technical Reports Server (NTRS)

Garcia, Alexander D'marco

2017-01-01

In the last 100 years, the global population has more than quadrupled to over seven billion people. At the same time, the demand for food and standard of living has been increasing which has amplified the global water use by nearly eight times from approximately 500 to 4000 cu km per yr from 1900 to 2010. With the increasing concern to sustain the growing population on Earth it is necessary to seek other approaches to ensure that our planet will have resources for generations to come. In recent years, the advancement of space travel and technology has allowed the idea of mining asteroids with resources closer to becoming a reality. During the duration of the internship at NASA Kennedy Space Center, several geotechnical tests were conducted on BP-1 lunar simulant and asteroid simulant Orgueil. The tests that were conducted on BP-1 was to practice utilizing the equipment that will be used on the asteroid simulant and the data from those tests will be omitted from report. Understanding the soil mechanics of asteroid simulant Orgueil will help provide basis for future technological advances and prepare scientists for the conditions they may encounter when mining asteroids becomes reality in the distant future. Distinct tests were conducted to determine grain size distribution, unconsolidated density, and maximum density. Once the basic properties are known, the asteroid simulant will be altered to different levels of compaction using a vibrator table to see how compaction affects the density. After different intervals of vibration compaction, a miniature vane shear test will be conducted. Laboratory vane shear testing is a reliable tool to investigate strength anisotropy in the vertical and horizontal directions of a very soft to stiff saturated fine-grained clayey soil. This test will provide us with a rapid determination of the shear strength on the undisturbed compacted regolith. The results of these tests will shed light on how much torque is necessary to drill through the surface of an asteroid. Most of the known asteroids are believed to be left over material during the formation of the solar system that never accreted to form planets. Asteroids can be found in several groups such as Trojan Asteroids, Near Earth Asteroids (NEAs) and the main asteroid belt. The Trojan Asteroids orbit the 4th and 5th Lagrange points of major planets in the Solar System while the NEA's have orbits that are close to and sometimes intersect with Earths orbit and the Main Asteroid Belt which is found between the orbit of Mars and Jupiter. Gravitational perturbations can alter the orbit of asteroids in the Main Asteroid Belt causing them to move closer to earth causing them to become in the NEA class.

Main-belt asteroid exploration - Mission options for the 1990s

NASA Technical Reports Server (NTRS)

Yen, C.-W. L.

1982-01-01

Mission configurations, propulsion systems, and target bodies for possible NASA asteroid exploration projects are examined. Noting that an announced delay in the development of a solar electric propulsion system has led to a consideration of chemical rocket systems, asteroid missions are grouped in terms of five potential areas for investigation, each successively further from the sun. The Shuttle-launched IUS is suggested as the prime candidate for boosting probes into trajectories for asteroid rendezvous with a number of the 3000 known asteroids. Planetary swingbys are mentioned as the only suitable method for satisfying the large energy requirements of the asteroid missions. Performance analyses are presented of the IUS 2-stage/Star-48 and Centaur vehicles, and sample missions to Fortuna, Anahita, and Urania in 1990 and further missions to the middle, outer, and Trojans asteroids are outlined.

Targeting an asteroid: The DSPSE encounter with asteroid 1620 Geographos

NASA Technical Reports Server (NTRS)

Yeomans, Donald K.

1993-01-01

Accurate targeting of the Deep Space Program Science Experiment (DSPSE) spacecraft to achieve a 100 km sunward flyby of asteroid 1620 Geographos will require that the ground-based ephemeris of Geographos be well known in advance of the encounter. Efforts are underway to ensure that precision optical and radar observations are available for the final asteroid orbit update that takes place several hours prior to the DSPSE flyby. Because the asteroid passes very close to the Earth six days prior to the DSPSE encounter, precision ground-based optical and radar observations should be available. These ground-based data could reduce the asteroid's position uncertainties (1-sigma) to about 10 km. This ground-based target ephemeris error estimate is far lower than for any previous comet or asteroid that has been under consideration as a mission target.

Lightcurve survey of V-type asteroids in the inner asteroid belt

NASA Astrophysics Data System (ADS)

Hasegawa, Sunao; Miyasaka, Seidai; Mito, Hiroyuki; Sarugaku, Yuki; Ozawa, Tomohiko; Kuroda, Daisuke; Nishihara, Setsuko; Harada, Akari; Yoshida, Michitoshi; Yanagisawa, Kenshi; Shimizu, Yasuhiro; Nagayama, Shogo; Toda, Hiroyuki; Okita, Kichi; Kawai, Nobuyuki; Mori, Machiko; Sekiguchi, Tomohiko; Ishiguro, Masateru; Abe, Takumi; Abe, Masanao

2014-06-01

We observed the lightcurves of 13 V-type asteroids [(1933) Tinchen, (2011) Veteraniya, (2508) Alupka, (3657) Ermolova, (3900) Knezevic, (4005) Dyagilev, (4383) Suruga, (4434) Nikulin, (4796) Lewis, (6331) 1992 FZ1, (8645) 1998 TN, (10285) Renemichelsen, and (10320) Reiland]. Using these observations we determined the rotational rates of the asteroids, with the exception of Nikulin and Renemichelsen. The distribution of rotational rates of 59 V-type asteroids in the inner main belt, including 29 members of the Vesta family, which are regarded as being ejecta from the asteroid (4) Vesta, is inconsistent with the best-fit Maxwellian distribution. This inconsistency may be due to the effect of thermal radiation Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) torques, which implies that the collision event that formed V-type asteroids is sub-billion to several billion years in age.

ASTEROID SIZING BY RADIOGALAXY OCCULTATION AT 5 GHZ

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lehtinen, K.; Muinonen, K.; Poutanen, M.

Stellar occultations by asteroids observed at visual wavelengths have been an important tool for studying the size and shape of asteroids and for revising the orbital parameters of asteroids. At radio frequencies, a shadow of an asteroid on the Earth is dominated by diffraction effects. Here, we show, for the first time, that a single observation of an occultation of a compact radio source at a frequency of 5 GHz can be used to derive the effective size of the occulting object and to derive the distance between the observer and the center of the occultation path on the Earth.more » The derived diameter of the occulting object, asteroid (115) Thyra, is 75 ± 6 km. The observed occultation profile shows features that cannot be explained by diffraction of a single asteroid.« less

Radar Movie of Asteroid 2011 UW158

NASA Image and Video Library

2015-07-23

Scientists using two giant, Earth-based radio telescopes bounced radar signals off passing asteroid 2011 UW158 to create images for this animation showing the rocky body's fast rotation. The passing asteroid made its closest approach to Earth on July 19, 2015 at 7:37 a.m. PST (4:37 a.m. EST) at a distance of about 1.5 million miles (2.4 million kilometers, or 6 times the distance from Earth to the moon). The close proximity during the pass made 2011 UW158 one of the best asteroid flybys of 2015 for imaging from Earth using radar. The radar images reveal that the shape of the asteroid is extremely irregular and quite elongated. Prominent parallel, linear features run along the length of the object that cause a large increase in brightness of the radar images as they rotate into view. Scientists note that the asteroid appears to be fairly unusual. Its fast rotation suggests the object has greater mechanical strength than other asteroids its size. A fast-rotating asteroid with lower mechanical strength would tend to split apart. To obtain the views, researchers paired the 230-foot- (70-meter-) wide Deep Space Network antenna at Goldstone, California, in concert with the National Radio Astronomy Observatory's 330-foot (100-meter) Green Bank Telescope. Using this technique, the Goldstone antenna beams a radar signal at an asteroid and Green Bank receives the reflections. The technique, referred to as a bi-static observation, dramatically improves the amount of detail that can be seen in radar images. The new views obtained with the technique show features as small as about 24 feet (7.5 meters) wide. The 171 individual images used in the movie were generated from data collected on July 18. They show the asteroid is approximately 2000 by 1000 feet (600 by 300 meters) across. The observations also confirm earlier estimates by astronomers that the asteroid rotates quickly, completing one spin in just over half an hour. The movie spans a period of about an hour and 45 minutes. The trajectory of asteroid 2011 UW158 is well understood. This flyby was the closest approach the asteroid will make to Earth for at least the next 93 years. Asteroid 2011 UW158 was discovered on October 25, 2011, by the PanSTARRS 1 telescope, located on the summit of Haleakala on Maui, Hawaii. Managed by the University of Hawaii, the PanSTARRS survey receives NASA funding. Radar is a powerful technique for studying an asteroid's size, shape, rotation state, surface features and surface roughness, and for improving the calculation of asteroid orbits. Radar measurements of asteroid distances and velocities often enable computation of asteroid orbits much further into the future than if radar observations weren't available. http://photojournal.jpl.nasa.gov/catalog/PIA19644

The 1986 DA and 1986 EB: M-class asteroids in near-Earth orbits

NASA Technical Reports Server (NTRS)

Gradie, Jonathan; Tedesco, Edward

1987-01-01

The Earth-approaching asteroid population is composed of asteroids in orbits with short lifetimes compared with the age of the solar system. These objects which are comprised of Aten, Apollo, and Amor asteroids must be replenished from either cometary or mainbelt asteroid sources since lifetimes against collision with or ejection by a planet are on the order of 10 to 100 million years. The physical study of Earth-approaching asteroids is constrained by the generally long period between favorable apparitions and poorly known orbits. Broadband spectrophotometry on the Johnson UBVR system and the Eight-Color Asteroid Survey system were obtained at Kitt Peak National Observatory and on the Johnson JHK system and at 10 and 20 microns at the NASA Infrared Telescope Facility at Mauna Kea Observatory. These observations were used to determine the absolute visual magnitudes and to derive the visual geometric albedos and diameters on the IRAS system. The spectral reflectance properties and geometric albedos of the M-class asteroids are consistent compositions analogous to the iron nickel meteorites or the enstatite-metal assemblages of the enstatite chondrites. The issue of the source(s) of the near-Earth asteroids population was examined by comparing the classifications on the scheme employed by Gradie and Tedesco of 38 such asteroids. Most of the near-Earth objects is indeed the asteroid belt as the observations suggest, then a method for removing extinct nuclei of short period comets must be found since the rate of production of short period comets from the long period comets is relatively large.

Photometric Observations of Main-belt Asteroids 1968 Mehltretter 2681 Ostrovskij & 3431 Nakano

NASA Astrophysics Data System (ADS)

Brincat, Stephen M.; Galdies, Charles

2018-07-01

Lightcurves for three mid-belt asteroids were obtained from Flarestar Observatory (MPC171) and Znith Observatory in 2017 and 2018. These asteroids were selected from the Collaborative Asteroid Lightcurve Link (CALL) website. No reported observations were available to deduce their rotation periods prior to this research.

Studies of Asteroids and Comets

NASA Technical Reports Server (NTRS)

Bowell, Edward L. G.

1998-01-01

Research under this grant was carried out between 1989 and 1998. It comprised observational, theoretical, and computational research, mainly on asteroids. Two principal areas of research, centering on astrometry and photometry, were interrelated in their aim to study the overall structure of the asteroid belt and the orbital and physical properties of individual asteroids.

Asteroid collisions, craters, regoliths, and lifetimes

NASA Technical Reports Server (NTRS)

Chapman, C. R.

1978-01-01

Laboratory experiments and computer modeling are used to predict the development of regoliths on all asteroids more than a few tens of kilometers in diameter, allowing for a wide range in the intrinsic strength of asteroidal surface materials. The high frequency of interasteroid collisions requires nearly all asteroids to be fragments of precursors.

Analysis of the Environmental Impact Assessment (EIA) Directive and the EIA decision in Turkey

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bilgin, Ayla

The Environmental Impact Assessment (EIA) Directive first entered into force in the United States in 1969, and began to be implemented in many other countries by 1990. The first Environmental Impact Assessment (EIA) Directive in Turkey was published on February 7, 1993, under the Environmental Law No. 2872. The EIA Directive was revised seven times on June 23, 1997, June 6, 2002, December 16, 2003, July 17, 2008, October 3, 2013, and November 25, 2014. Several amendments were made during this process. The first EIA Directive dated 1993 was narrow in scope and its procedure was long, while the amendmentsmore » in 2003, 2008, 2013, and 2014 widened the scope of the EIA, and shortened the EIA assessment procedures. In this study, the amendments to the Turkish EIA Directive were analysed, and their effect on the number of EIA decisions made was addressed. It was concluded that the uncertainties in EIA procedures were removed, procedures were shortened, and as a result, the number of EIA decisions increased thanks to the revisions made in line with harmonisation with European Union (EU) acquis. - Highlights: • Demonstrates the Environmental Impact Assessment practices in Turkey. • Demonstrates the application of the EIA in Turkey by sector. • Demonstrates the amendments of the EIA by-laws in Turkey. • Demonstrates the changes in EIA practices and EIA decisions.« less

Social work at the Chinese Medicine system in Hong Kong: opportunities and challenges.

PubMed

Chan, Kai-fong; Ng, Yat-nam; Bian, Zhao-xiang; Shi, Yan; Lee, Siu-ping; Ng, Ka-ying

2008-01-01

Dealing with health and disease is an area of concern for social workers. The establishment of medical social service in a health setting has more than 100 years of history in the USA and more than 60 years in Hong Kong. Despite the increasing popularity of Chinese Medicine (CM) used by the Hong Kong people, there has been no medical social service presence in the CM system. A pilot project demonstrated a successful interdisciplinary collaboration model between social work and CM irrespective of different social work methods, that is, individual work, groupwork, and community-based services. In this article, we will relate the opportunities and difficulties that we encountered in setting up the first medical social service in the CM system. Drawing on our experience, we found that both professions benefited from the interdisciplinary collaboration. CM was able to expand its scope of service to increase the service quality and promote primary health care in the community with the support of social work. Conversely, social workers found that CM is a good resource for providing innovative services to meet the various needs of the people in the community. There was also a ripple effect of incorporating CM elements into social service. The interface between the disciplines of social work and CM can widen the scope of their contributions on health. Implications for CM social service in social work will also be examined.

PHARMACEUTICALS IN THE ENVIRONMENT: OVERVIEW ...

EPA Pesticide Factsheets

Pharmaceuticals and personal care products (PPCPs) comprise large, diverse arrays of chemicals that can occur in the environment as unregulated pollutants. They originate largely from the combined activities and actions of multitudes of individuals as well as from veterinary and agricultural use; the wide spectrum of sources and origins of PPCPs. Concerted research that began in Europe about two decades ago, and in the U.S. in the late 1990s, has been rapidly expanding in the last few years, as reflected by an escalation in publications. Investigations that were originally limited to studying the sources, origins, and occurrence of PPCPs (mainly in waters) were led primarily by analytical chemists. The scope of this research has expanded, now accommodating more dimensions of the risk assessment paradigm. The scope has widened to encompass not just occurrence over a wider spectrum of environmental matrices but also to address the complexities involved with assessing the range of unanticipated and subtle effects that might occur from chronic, low-dose exposure of non-target organisms (Daughton 2003a; Daughton and Ternes 1999). Risk management options designed around the principles of pollution prevention and environmental stewardship are also under discussion in the many sectors of the healthcare community and by various state and local legislatures The research focused on in the subtasks is the development and application of state-of the-art technologies to meet

A Scoping Review of Health Game Research: Past, Present, and Future

PubMed Central

Lu, Amy Shirong; Gharghabi, Fardad; Coleman, Whitney

2012-01-01

Abstract Health game research has flourished over the last decade. The number of peer-reviewed scientific publications has surged as the clinical application of health games has diversified. In response to this growth, several past literature reviews have assessed the effectiveness of health games in specific clinical subdomains. The past literature reviews, however, have not provided a general scope of health games independent of clinical context. The present systematic review identified 149 publications. All sources were published before 2011 in a peer-reviewed venue. To be included in this review, publications were required (1) to be an original research, (2) to focus on health, (3) to utilize a sound research design, (4) to report quantitative health outcomes, and (5) to target healthcare receivers. Initial findings showed certain trends in health game publications: Focus on younger male demographics, relatively low number of study participants, increased number of controlled trials, short duration of intervention periods, short duration and frequency of user–game interaction, dominance of exercise and rehab games, lack of underlying theoretical frameworks, and concentration on clinical contexts such as physical activity and nutrition. The review concludes that future research should (1) widen the demographics to include females and elderly, (2) increase the number of participants in controlled trials, (3) lengthen both the intervention period and user–game interaction duration, and (4) expand the application of health games in new clinical contexts. PMID:24416638

Asteroid Pond Mineralogy: View from a Cognate Clast in LL3 NWA 8330

NASA Technical Reports Server (NTRS)

Zolensky, M.; Le, L.

2017-01-01

All asteroids surfaces imaged at the cm-scale reveal the presence of pond deposits. These ponds are important because it is likely all asteroid sample return missions will sample them, being the safest (very flat) places to touch down. Therefore, it is essential to understand the differences between the material at the pond surfaces and the host asteroid. Fortunately, some fine-grained cognate lithologies in chondrites show sedimentary features indicating that they sample asteroid ponds.

Asteroids in three-body mean motion resonances with planets

NASA Astrophysics Data System (ADS)

Smirnov, Evgeny A.; Dovgalev, Ilya S.; Popova, Elena A.

2018-04-01

We have identified all asteroids in three-body mean-motion resonances in all possible planets configurations. The identification was done dynamically: the orbits of the asteroids were integrated for 100,000 yrs and the set of the resonant arguments was numerically analyzed. We have found that each possible planets configuration has a lot of the resonant asteroids. In total 65,972 resonant asteroids (≈14.1% of the total number of 467,303 objects from AstDyS database) have been identified.

CCD reflectance spectra of selected asteroids. I - Presentation and data analysis considerations

NASA Technical Reports Server (NTRS)

Vilas, Faith; Mcfadden, Lucy A.

1992-01-01

Narrowband reflectance spectra have been acquired which contribute to the library of asteroid data in the visible and near-IR spectral regions. The spectra support the existence of aqueous alteration products on asteroids located in the outer part of the main asteroid belt out to at least 4 AU. No evidence for features similar to the spectral features of ordinary chondrite meteorites was found in the spectra of asteroids located near the 3:1 Kirkwood Gap chaotic zone.

Diogenite-like Features in the Spitzer IRS (5-35 micrometers) Spectrum of 956 ELISA

NASA Technical Reports Server (NTRS)

Lim, Lucy F.; Emery, Joshua P.; Moskovitz, Nicholas A.

2009-01-01

We report preliminary results from the Spitzer Infrared Spectrograph (IRS) observations of the V-type asteroid 956 Elisa. Elisa was observed as part of a campaign to measure the 5.2-38 micron spectra of small basaltic asteroids with the Spitzer IRS. Targets include members of the dynamical family of the unique large differentiated asteroid 4 Vesta ("Vesroids"), several outer-main-belt basaltic asteroids whose orbits exclude them from originating on 4 Vesta, and the basaltic near-Earth asteroid 4055 Magellan.

Asteroid Initiative Industry and Partner Day

NASA Image and Video Library

2013-06-18

NASA Associate Administrator for Human Exploration and Operations, William Gerstenmaier, talks during the Asteroid Initiative Industry and Partner Day at NASA Headquarters on Tuesday, June 18, 2013 in Washington. During the event NASA Deputy Administrator Lori Garver and other senior NASA officials discussed the progress being made on NASA's mission to capture, redirect, and explore an asteroid. NASA also announced an Asteroid Grand Challenge focused on finding all asteroid threats to human populations and knowing what to do about them. Photo Credit: (NASA/Bill Ingalls)

Asteroid Initiative Industry and Partner Day

NASA Image and Video Library

2013-06-18

Jenn Gustetic, Prizes Program Executive, NASA Office of the Chief Technologist moderates the Asteroid Initiative Industry and Partner Day at NASA Headquarters on Tuesday, June 18, 2013 in Washington. During the event NASA Deputy Administrator Lori Garver and other senior NASA officials discussed the progress being made on NASA's mission to capture, redirect, and explore an asteroid. NASA also announced an Asteroid Grand Challenge focused on finding all asteroid threats to human populations and knowing what to do about them. Photo Credit: (NASA/Bill Ingalls)

Asteroid Initiative Industry and Partner Day

NASA Image and Video Library

2013-06-18

NASA Associate Administrator Science John Grunsfeld, Ph.D, talks during the Asteroid Initiative Industry and Partner Day at NASA Headquarters on Tuesday, June 18, 2013 in Washington. During the event NASA Deputy Administrator Lori Garver and other senior NASA officials discussed the progress being made on NASA's mission to capture, redirect, and explore an asteroid. NASA also announced an Asteroid Grand Challenge focused on finding all asteroid threats to human populations and knowing what to do about them. Photo Credit: (NASA/Bill Ingalls)

Asteroid Initiative Industry and Partner Day

NASA Image and Video Library

2013-06-18

NASA Associate Administrator for Space Technology, Mike Gazarik, Ph.D, talks during the Asteroid Initiative Industry and Partner Day at NASA Headquarters on Tuesday, June 18, 2013 in Washington. During the event NASA Deputy Administrator Lori Garver and other senior NASA officials discussed the progress being made on NASA's mission to capture, redirect, and explore an asteroid. NASA also announced an Asteroid Grand Challenge focused on finding all asteroid threats to human populations and knowing what to do about them. Photo Credit: (NASA/Bill Ingalls)

Asteroid Initiative Industry and Partner Day

NASA Image and Video Library

2013-06-18

NASA Associate Administrator Robert Lightfoot, listens as other NASA senior leadership talk during the Asteroid Initiative Industry and Partner Day at NASA Headquarters on Tuesday, June 18, 2013 in Washington. During the event NASA Deputy Administrator Lori Garver and other senior NASA officials discussed the progress being made on NASA's mission to capture, redirect, and explore an asteroid. NASA also announced an Asteroid Grand Challenge focused on finding all asteroid threats to human populations and knowing what to do about them. Photo Credit: (NASA/Bill Ingalls)

Asteroid Initiative Industry and Partner Day

NASA Image and Video Library

2013-06-18

Jason Kessler, Special Projects Program Executive, NASA Office of the Chief Technologist, talks during the Asteroid Initiative Industry and Partner Day at NASA Headquarters on Tuesday, June 18, 2013 in Washington. During the event NASA Deputy Administrator Lori Garver and other senior NASA officials discussed the progress being made on NASA's mission to capture, redirect, and explore an asteroid. NASA also announced an Asteroid Grand Challenge focused on finding all asteroid threats to human populations and knowing what to do about them. Photo Credit: (NASA/Bill Ingalls)

Trojan and Hilda asteroid lightcurves. I - Anomalously elongated shapes among Trojans (and Hildas?)

NASA Technical Reports Server (NTRS)

Hartmann, William K.; Binzel, Richard P.; Tholen, David J.; Cruikshank, Dale P.; Goguen, Jay

1988-01-01

A comparison of the available sample of lightcurves for 26 Trojan and Hilda asteroids with belt asteroid lightcurves shows the former to be distinguished by a higher incidence of high amplitudes rgan belt asteroids of comparable size, suggesting more elongated shapes; they currently have, moreover, only a few percent of the main-belt asteroids' collision frequency. A more modest collisional evolution that may have affected the relative degree of fragmentation of these bodies, and thus their shapes, is inferred.

The 1990 MB: The first Mars Trojan

NASA Technical Reports Server (NTRS)

Bowell, Edward

1991-01-01

Asteroid 1990 MB was discovered during the course of the Mars and Earth-crossing Asteroid and Comet Survey. An orbit based on a 9-day arc and the asteroid's location near Mars L5 longitude led to speculation that it might be in 1:1 resonance with Mars, analogous to the Trojan asteroids of Jupiter. Subsequent observations strengthened the possibility, and later calculations confirmed it. The most recent orbit shows that the asteroid's semimajor axis is very similar to that of Mars.

Blending Learning: Widening Participation in Higher Education

ERIC Educational Resources Information Center

Jones, Norah; Lau, Alice Man Sze

2010-01-01

Widening participation has increased in emphasis in Higher Education over recent years. While there has been some progress in making higher education more accessible to students who have traditionally been excluded, widening participation is still being described as one of the major challenges facing Higher Education Institutions. Likewise…

Multiple main-belt asteroid mission options for a Mariner Mark II spacecraft

NASA Astrophysics Data System (ADS)

Sauer, Carl G., Jr.; Yen, Chen-Wan L.

This paper presents the trajectory options available for a MMII spacecraft mission to asteroids and introduces systematic methods of uncovering attractive mission opportunities. The analysis presented considers multiple synchronous gravity assists of Mars and introduces a terminal resonant or phasing orbit; a concept useful for both increasing the number of asteroid rendezvous targets attainable during a launch opportunity, and also in increasing the number of potential asteroid flybys. Systematic examinations of the requirements for superior asteroidal alignments are made and a comprehensive set of asteroid rendezvous opportunities for the 1998 to 2010 period are presented. Examples of candidate missions involving one or more rendezvous and several flybys are also presented.

Dynamical properties of Watsonia asteroid family

NASA Astrophysics Data System (ADS)

Tsirvoulis, Georgios; Novaković, Bojan; Knežević, Zoran; Cellino, Alberto

2014-07-01

In recent years, a rare class of asteroids has been discovered by Cellino et al. (2006), with its distinguishing characteristic being the anomalous polarimetric properties of its members. Named Barbarians, after (234) Barbara, the prototype of the class, these asteroids show negative polarization at unusually high phase-angles compared to normal asteroids. Motivated by the fact that some of the few discovered Barbarians seemed to be related to the Watsonia asteroid family, Cellino et al. (2014) performed a search for more Barbarians among its members. A positive result of this search led to the conclusion that Watsonia is indeed an important repository of Barbarian asteroids. Based on these findings, we decided to analyze this family in detail.

Evidence for a near-Earth asteroid belt

NASA Technical Reports Server (NTRS)

Rabinowitz, D. L.; Gehrels, T.; Scotti, J. V.; Mcmillan, R. S.; Perry, M. L.; Wisniewski, W.; Larson, S. M.; Howell, E. S.; Mueller, B. E. A.

1993-01-01

In January 1991, the 0.9-m Spacewatch telescope made the first observation of an asteroid outside Earth's atmosphere but in the neighborhood of the Earth-moon system. Since then, more than 40 Earth-approaching asteroids have been discovered, including 13 smaller than 50 m. Using these data, one of us has shown that there is an excess of Earth-approaching asteroids with diameters less than 50 m, relative to the population inferred from the distribution of larger objects. Here we argue that these smaller objects - characterized by low eccentricities, widely ranging inclinations and unusual spectral properties - form a previously undetected asteroid belt concentrated near Earth. The recent discovery of additional small Earth-approaching asteroids supports this conclusion.

Multiple main-belt asteroid mission options for a Mariner Mark II spacecraft

NASA Technical Reports Server (NTRS)

Sauer, Carl G., Jr.; Yen, Chen-Wan L.

1990-01-01

This paper presents the trajectory options available for a MMII spacecraft mission to asteroids and introduces systematic methods of uncovering attractive mission opportunities. The analysis presented considers multiple synchronous gravity assists of Mars and introduces a terminal resonant or phasing orbit; a concept useful for both increasing the number of asteroid rendezvous targets attainable during a launch opportunity, and also in increasing the number of potential asteroid flybys. Systematic examinations of the requirements for superior asteroidal alignments are made and a comprehensive set of asteroid rendezvous opportunities for the 1998 to 2010 period are presented. Examples of candidate missions involving one or more rendezvous and several flybys are also presented.

Distribution of taxonomic classes and the compositional structure of the asteroid belt

NASA Technical Reports Server (NTRS)

Gradie, Jonathan C.; Chapman, Clark R.; Tedesco, Edward F.

1989-01-01

This paper reviews previous studies on the distribution of the asteroid taxonomic classes and analyzes the techniques, results, and interpretations of these studies, with special attention given to the strong and weak points of these studies and the important caveat for their interpretation. It is concluded that, in spite of the differences in class definition, the rather ordered heliocentric distribution of the composition is real and must be due to either primordial, evolutionary, or dynamical processes, or to a combination of all three. In general, the distribution of asteroid taxonomic classes is characterized by moderate-albedo asteroids dominant in the inner asteroid belt, and low-albedo asteroids prevalent in the outer belt and beyond.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brown, M. E.; Rhoden, A. R., E-mail: mbrown@caltech.edu, E-mail: Alyssa.Rhoden@jhuapl.edu

We present a medium resolution spectrum of Jupiter's irregular satellite Himalia covering the critical 3 μm spectral region. The spectrum shows no evidence for aqueously altered phyllosilicates, as had been suggested from the tentative detection of a 0.7 μm absorption, but instead shows a spectrum strikingly similar to the C/CF type asteroid 52 Europa. 52 Europa is the prototype of a class of asteroids generally situated in the outer asteroid belt between less distant asteroids which show evidence for aqueous alteration and more distant asteroids which show evidence for water ice. The spectral match between Himalia and this group of asteroids ismore » surprising and difficult to reconcile with models of the origin of the irregular satellites.« less

Orbital and Landing Operations at Near-Earth

NASA Technical Reports Server (NTRS)

Scheeres, D. J.

1995-01-01

Orbital and landing operations about near-Earth asteroids are different than classical orbital operations about large bodies. The major differences lie with the small mass of the asteroid, the lower orbital velocities, the larger Solar tide and radiation pressure perturbations, the irregular shape of the asteroid and the potential for non-uniform rotation of the asteroid. These differences change the nature of orbits about an asteroid to where it is often common to find trajectories that evolve from stable, near-circular orbits to crashing or escaping orbits in a matter of days. The understanding and control of such orbits is important if a human or robotic presence at asteroids is to be commonplace in the future.

Mineralogy and Temperature-induced Spectral Investigations of A-type Asteroids 246 Asporina and 446 Aeternitas

NASA Technical Reports Server (NTRS)

Reddy, V.; Hardersen, P. S.; Gaffey, M. J.; Abell, P. A.

2005-01-01

A-type asteroids are a relatively rare taxonomic class with no more than 17 known objects. They were first identified as a separate group of R-type asteroids based on broadband spectrophotometry by, and were later classified based on ECAS data by Tholen (1984). These asteroids have moderately high albedos (0.13-0.39), extremely reddish slopes shortward of 0.7 m and a strong absorption feature centered at approx. 1.05 m. More recent surveys like the Small Main-Belt Asteroid Spectroscopic Survey (SMASS) and SMASS II have expanded the taxonomic classes including the A-type, adding 12 new asteroids to the original five.

Confusion Noise Due To Asteroids: From Mid-infrared To Millimetre Wavelengths

NASA Astrophysics Data System (ADS)

Kelemen, Janos; Kiss, C.; Pal, A.; Muller, T.; Abraham, P.

2006-12-01

We developed a statistical model for the asteroid component of the infrared sky for wavelengths 5 μm <= λ <= 1000 μm based on the Statistical Asteroid Model (Tedesco et al., 2005). Far-infrared fluxes of 1.9 million asteroids -derived with the help of the Standard Thermal Model -are used to calculate confusion noise values and expected asteroid counts for infrared space instruments in operation or in the near future (e.g. Akari, Herschel and Planck). Our results show that the confusion noise due to asteroids will not increase the detection threshold for most of the sky. However, there are specific areas near the ecliptic plane where the effect of asteroids can be comparable to the contribution of Galactic cirrus emission and that of the extragalactic background. This work was supported by the European Space Agency (PECS #98011) and by the Hungarian Space Office (TP286)

Asteroids as Calibration Standards in the Thermal Infrared -- Applications and Results from ISO

NASA Astrophysics Data System (ADS)

Müller, T. G.; Lagerros, J. S. V.

Asteroids have been used extensively as calibration sources for ISO. We summarise the asteroid observational parameters in the thermal infrared and explain the important modelling aspects. Ten selected asteroids were extensively used for the absolute photometric calibration of ISOPHOT in the far-IR. Additionally, the point-like and bright asteroids turned out to be of great interest for many technical tests and calibration aspects. They have been used for testing the calibration for SWS and LWS, the validation of relative spectral response functions of different bands, for colour correction and filter leak tests. Currently, there is a strong emphasis on ISO cross-calibration, where the asteroids contribute in many fields. Well known asteroids have also been seen serendipitously in the CAM Parallel Mode and the PHT Serendipity Mode, allowing for validation and improvement of the photometric calibration of these special observing modes.

A record of planet migration in the main asteroid belt.

PubMed

Minton, David A; Malhotra, Renu

2009-02-26

The main asteroid belt lies between the orbits of Mars and Jupiter, but the region is not uniformly filled with asteroids. There are gaps, known as the Kirkwood gaps, in distinct locations that are associated with orbital resonances with the giant planets; asteroids placed in these locations will follow chaotic orbits and be removed. Here we show that the observed distribution of main belt asteroids does not fill uniformly even those regions that are dynamically stable over the age of the Solar System. We find a pattern of excess depletion of asteroids, particularly just outward of the Kirkwood gaps associated with the 5:2, the 7:3 and the 2:1 Jovian resonances. These features are not accounted for by planetary perturbations in the current structure of the Solar System, but are consistent with dynamical ejection of asteroids by the sweeping of gravitational resonances during the migration of Jupiter and Saturn approximately 4 Gyr ago.

Asteroid exploration and utilization

NASA Technical Reports Server (NTRS)

Radovich, Brian M.; Carlson, Alan E.; Date, Medha D.; Duarte, Manny G.; Erian, Neil F.; Gafka, George K.; Kappler, Peter H.; Patano, Scott J.; Perez, Martin; Ponce, Edgar

1992-01-01

The Earth is nearing depletion of its natural resources at a time when human beings are rapidly expanding the frontiers of space. The resources possessed by asteroids have enormous potential for aiding and enhancing human space exploration as well as life on Earth. Project STONER (Systematic Transfer of Near Earth Resources) is based on mining an asteroid and transporting raw materials back to Earth. The asteroid explorer/sample return mission is designed in the context of both scenarios and is the first phase of a long range plan for humans to utilize asteroid resources. Project STONER is divided into two parts: asteroid selection and explorer spacecraft design. The spacecraft design team is responsible for the selection and integration of the subsystems: GNC, communications, automation, propulsion, power, structures, thermal systems, scientific instruments, and mechanisms used on the surface to retrieve and store asteroid regolith. The sample return mission scenario consists of eight primary phases that are critical to the mission.

Chang'e-2 spacecraft observations of asteroid 4179 Toutatis

NASA Astrophysics Data System (ADS)

Ji, Jianghui; Jiang, Yun; Zhao, Yuhui; Wang, Su; Yu, Liangliang

2016-01-01

On 13 December 2012, Chang'e-2 completed a successful flyby of the near-Earth asteroid 4179 Toutatis at a closest distance of 770 meters from the asteroid's surface. The observations show that Toutatis has an irregular surface and its shape resembles a ginger-root of a smaller lobe (head) and a larger lobe (body). Such bilobate shape is indicative of a contact binary origin for Toutatis. In addition, the high-resolution images better than 3 meters provide a number of new discoveries about this asteroid, such as an 800-meter depression at the end of the large lobe, a sharply perpendicular silhouette near the neck region, boulders, indicating that Toutatis is probably a rubble-pile asteroid. Chang'e-2 observations have significantly revealed new insights into the geological features and the formation and evolution of this asteroid. In final, we brief the future Chinese asteroid mission concept.

Asteroidal-meteoric complexes.

NASA Astrophysics Data System (ADS)

Shestaka, I. S.

1994-12-01

Fourteen asteroidal-meteoric complexes were identified by means of the criterion of similarity of quasistationary parameters μ, ν and Tisserand's invariant Ti. Each of these complexes consists of several meteor swarms and one or several asteroids. The existence of such complexes confirms the possibility of formation of meteor swarms by means of disintegration of asteroids and their fragments.

Asteroid Redirection Mission Evaluation Using Multiple Landers

NASA Astrophysics Data System (ADS)

Bazzocchi, Michael C. F.; Emami, M. Reza

2018-06-01

In this paper, a low-thrust tugboat redirection method is assessed using multiple spacecraft for a target range of small near-Earth asteroids. The benefits of a landed configuration of tugboat spacecraft in formation are examined for the redirection of a near-Earth asteroid. The tugboat method uses a gimballed thruster with a highly collimated ion beam to generate a thrust on the asteroid. The target asteroid range focuses on near-Earth asteroids smaller than 150 m in diameter, and carbonaceous (C-type) asteroids, due to the volatiles available for in-situ utilization. The assessment focuses primarily on the three key parameters, i.e., the asteroid mass redirected, the timeframe for redirection, and the overall system cost. An evaluation methodology for each parameter is discussed in detail, and the parameters are employed to determine the expected return and feasibility of the redirection mission. The number of spacecraft employed is optimized along with the electrical power needed for each spacecraft to ensure the highest possible return on investment. A discussion of the optimization results and the benefits of spacecraft formation for the tugboat method are presented.

Lightcurves of the Karin family asteroids

NASA Astrophysics Data System (ADS)

Yoshida, Fumi; Ito, Takashi; Dermawan, Budi; Nakamura, Tsuko; Takahashi, Shigeru; Ibrahimov, Mansur A.; Malhotra, Renu; Ip, Wing-Huen; Chen, Wen-Ping; Sawabe, Yu; Haji, Masashige; Saito, Ryoko; Hirai, Masanori

2016-05-01

The Karin family is a young asteroid family formed by an asteroid breakup 5.8 Myr ago. Since the members of this family probably have not experienced significant orbital or collisional evolution yet, it is possible that they still preserve properties of the original family-forming event in terms of their spin state. We carried out a series of photometric observations of the Karin family asteroids, and here we report on the analysis of the lightcurves including the rotation period of eleven members. The mean rotation rate of the Karin family members turned out to be much lower than those of near-Earth asteroids or small main belt asteroids (diameter D < 12 km), and even lower than that of large main belt asteroids (D > 130 km). We investigated a correlation between the peak-to-trough variation and the rotation period of the eleven Karin family asteroids, and found a possible trend that elongated members have lower spin rates, and less elongated members have higher spin rates. However, this trend has to be confirmed by another series of future observations.

Speckle interferometry applied to asteroids and other solar system objects

NASA Technical Reports Server (NTRS)

Drummond, J. D.; Hege, E. K.

1986-01-01

Speckle interferometry is a high angular resolution technique that allows study of resolved asteroids. By following the changing size, shape, and orientation of minor planets, and with a few general assumptions (e.g., geometric scattering, triaxial ellipsoid figures, no albedo features), it is possible to directly measure an asteroid's true dimensions and the direction of its spin axis in one or two nights. A particular subset of triaxial ellipsoid figures are equilibrium shapes, and would imply that some asteroids are thoroughly fractured. Such shapes if they exist among the asteroids would allow a determination of bulk density since there is a unique relation among spin period, size, shape, and density. The discovery of even a single rubble pile, (just as the finding of even one binary asteroid by speckle interferometric techniques) would drastically alter the notion of asteroids as small solid planets. The Pluto/Charon system was studied to aid in improving the orbital elements necessary to predict the eclipse/occultation season currently in progress. Four asteroids were reduced to their size, shape, and pole direction: 433 Eros, 532 Herculina, 511 Davida, and 2 Pallas.

Japanese Studies of Asteroids Following the Discovery of the Hirayama Families

NASA Astrophysics Data System (ADS)

Nakamura, Tsuko

This paper reviews studies relating to asteroids conducted by Japanese astronomers since the discovery of asteroid families by Kiyotsugu Hirayama in 1918. First, the situation is mentioned that it took quite some time for the concept of an `asteroid family' to be understood correctly by the astronomical community worldwide. It is no wonder that some eminent researches on the dynamics of asteroids based on secular perturbation theories appeared in Japan after WWII, as represented by the `Kozai mechanism' (1962), which probably was influenced by Hirayama's monumental discovery. As for studies of the physical nature of asteroids, we must note the pioneering work by M. Kitamura in 1959 when the observed colors of about 40 asteroids were compared with reflectance spectra of several meteorites measured in the laboratory, even though this result unfortunately was not pursued further at the time. Modern impact experiments initiated by A. Fujiwara in 1975 soon became an important means of investigating the origin of asteroid families, and of the ubiquitous craters seen on the surfaces of airless Solar System bodies.

Size-dependent modification of asteroid family Yarkovsky V-shapes

NASA Astrophysics Data System (ADS)

Bolin, B. T.; Morbidelli, A.; Walsh, K. J.

2018-04-01

Context. The thermal properties of the surfaces of asteroids determine the magnitude of the drift rate cause by the Yarkovsky force. In the general case of Main Belt asteroids, the Yarkovsky force is indirectly proportional to the thermal inertia, Γ. Aim. Following the proposed relationship between Γ and asteroid diameter D, we find that asteroids' Yarkovsky drift rates might have a more complex size dependence than previous thought, leading to a curved family V-shape boundary in semi-major axis, a, vs. 1/D space. This implies that asteroids are drifting faster at larger sizes than previously considered decreasing on average the known ages of asteroid families. Methods: The V-Shape curvature is determined for >25 families located throughout the Main Belt to quantify the Yarkovsky size-dependent drift rate. Results: We find that there is no correlation between family age and V-shape curvature. In addition, the V-shape curvature decreases for asteroid families with larger heliocentric distances suggesting that the relationship between Γ and D is weaker in the outer MB possibly due to homogenous surface roughness among family members.

A census of the asteroid belt

NASA Technical Reports Server (NTRS)

Tedesco, E. F.; Veeder, G. J.

1991-01-01

Observations obtained by the Infrared Astronomical Satellite (IRAS) during its ten month mission in 1983 were originally processed by the Asteroid Data Analysis System (ADAS) to search for 3453 asteroids with known orbital elements as of September 1985. A total of 1811 had one or more observations of sufficient reliability to be accepted. These results were released in October 1986. Recently IRAS data were reprocessed to increase both the number of recognized asteroid observations and their reliability. As input 7311 asteroids were used with known orbital elements as of December 1990. This processor is referred to as the IRAS Minor Planet Survey (IMPS). As of April 1991 approximately 3000 asteroids had been identified with one or more acceptable observations. These results were used to derive the total number of asteroids with diameters greater than 1 km. In addition to being an interesting piece of information in itself these size-frequency distributions produce bias-correction factors which, for example, will be used in investigations of the physical properties of asteroid dynamical families and to estimate the distribution of the taxonomic classes as a function of heliocentric distance.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kasuga, Toshihiro; Shirahata, Mai; Usui, Fumihiko

Most outer main-belt asteroids have low albedos because of their carbonaceouslike bodies. However, infrared satellite surveys have revealed that some asteroids have high albedos, which may suggest the presence of unusual surface minerals for those primitive objects. We present new near-infrared (1.1–2.5 μm) spectra of four outer main-belt asteroids with albedos ≥ 0.1. The C-complex asteroids (555) Norma and (2542) Calpurnia are featureless and have (50%–60%) amorphous Mg pyroxenes that might explain the high albedos. Asteroids (701) Oriola (which is a C-complex asteroid) and (2670) Chuvashia (a D/T-type or M-type asteroid) show possible broad absorption bands (1.5–2.1 μm). The featuremore » can be reproduced by either Mg-rich amorphous pyroxene (with 50%–60% and 80%–95% Mg, respectively) or orthopyroxene (crystalline silicate), which might be responsible for the high albedos. No absorption features of water ice (near 1.5 and 2.0 μm) are detected in the objects. We discuss the origin of high albedo components in the outer main-belt asteroids and their physical relations to comets.« less

Asteroids and Comets Outreach Compilation

NASA Technical Reports Server (NTRS)

1999-01-01

Contents include various different animations in the area of Asteroids and Comets. Titles of the short animated clips are: STARDUST Mission; Asteroid Castallia Impact Simulation; Castallia, Toutatis and the Earth; Simulation Asteroid Encounter with Earth; Nanorover Technology Task; Near Earth Asteroid Tracking; Champollian Anchor Tests; Early Views of Comets; Exploration of Small Bodies; Ulysses Resource Material from ESA; Ulysses Cometary Plasma Tail Animation; and various discussions on the Hale-Bopp Comet. Animation of the following are seen: the Stardust aerogel collector grid collecting cometary dust particles, comet and interstellar dust analyzer, Wiper-shield and dust flux monitor, a navigation camera, and the return of the sample to Earth; a comparison of the rotation of the Earth to the Castallia and Tautatis Asteroids; an animated land on Tautatis and the view of the motion of the sky from its surface; an Asteroid collision with the Earth; the USAF Station in Hawaii; close-up views of asteroids; automatic drilling of the Moon; exploding Cosmic Particles; and the dropping off of the plasma tail of a comet as it travels near the sun.

Asteroid Redirection Mission Evaluation Using Multiple Landers

NASA Astrophysics Data System (ADS)

Bazzocchi, Michael C. F.; Emami, M. Reza

2018-01-01

In this paper, a low-thrust tugboat redirection method is assessed using multiple spacecraft for a target range of small near-Earth asteroids. The benefits of a landed configuration of tugboat spacecraft in formation are examined for the redirection of a near-Earth asteroid. The tugboat method uses a gimballed thruster with a highly collimated ion beam to generate a thrust on the asteroid. The target asteroid range focuses on near-Earth asteroids smaller than 150 m in diameter, and carbonaceous (C-type) asteroids, due to the volatiles available for in-situ utilization. The assessment focuses primarily on the three key parameters, i.e., the asteroid mass redirected, the timeframe for redirection, and the overall system cost. An evaluation methodology for each parameter is discussed in detail, and the parameters are employed to determine the expected return and feasibility of the redirection mission. The number of spacecraft employed is optimized along with the electrical power needed for each spacecraft to ensure the highest possible return on investment. A discussion of the optimization results and the benefits of spacecraft formation for the tugboat method are presented.

Round-trip missions to low delta-V asteroids and implications for material retrieval

NASA Technical Reports Server (NTRS)

Bender, D. F.; Dunbar, R. S.; Ross, D. J.

1979-01-01

Low-delta-V asteroids are to be found among those which have perihelia near 1 AU. From the 50 known asteroids with perihelia less than 1.5 AU, 10 candidates for asteroid retrieval missions were selected on the basis of low eccentricity and inclination. To estimate the ranges of orbital elements for which capture in earth orbit may be feasible, a survey was made of 180 deg transfer from a set of orbits having elements near those of the earth to the earth. For 2 of the 10 low-delta-V asteroids and for an additional one with elements more earth-like than any yet known, direct ballistic round trips in the 1980's were computed. A stay time of several months at the asteroid was used. The results show that the total delta V, including that for rendezvous with earth upon return, for the known asteroids is above 14 km/sec. But if asteroids are found similar to the strawman considered, the total delta V could be as low as 10 km/sec.

The IRAS Minor Planet Survey

NASA Technical Reports Server (NTRS)

Tedesco, Edward F.; Veeder, Glenn J.; Fowler, John W.; Chillemi, Joseph R.

1992-01-01

This report documents the program and data used to identify known asteroids observed by the Infrared Astronomical Satellite (IRAS) and to compute albedos and diameters from their IRAS fluxes. It also presents listings of the results obtained. These results supplant those in the IRAS Asteroid and Comet Survey, 1986. The present version used new and improved asteroid orbital elements for 4679 numbered asteroids and 2632 additional asteroids for which at least two-opposition elements were available as of mid-1991. It employed asteroid absolute magnitudes on the International Astronomical Union system adopted in 1991. In addition, the code was modified to increase the reliability of associating asteroids with IRAS sources and rectify several shortcomings in the final data products released in 1986. Association reliability was improved by decreasing the position difference between an IRAS source and a predicted asteroid position required for an association. The shortcomings addressed included the problem of flux overestimation for low SNR sources and the systematic difference in albedos and diameters among the three wavelength bands (12, 25, and 60 micrometers). Several minor bugs in the original code were also corrected.

Mine Planning for Asteroid Orebodies

NASA Astrophysics Data System (ADS)

Gertsch, L. S.; Gertsch, R. E.

2000-01-01

Given that an asteroid (or comet) has been determined to contain sufficient material of value to be potentially economic to exploit, a mining method must be selected and implemented. This paper discusses the engineering necessary to bring a mine online, and the opportunities and challenges inherent in asteroid mineral prospects. The very important step of orebody characterization is discussed elsewhere. The mining methods discussed here are based on enclosing the asteroid within a bag in some fashion, whether completely or partially. In general, asteroid mining methods based on bags will consist of the following steps. Not all will be required in every case, nor necessarily in this particular sequence. Some steps will be performed simultaneously. Their purpose is to extract the valuable material from the body of the asteroid in the most efficient, cost-effective manner possible. In approximate order of initiation, if not of conclusion, the steps are: 1. Tether anchoring to the asteroid. 2. Asteroid motion control. 3. Body/fragment restraint system placement. 4. Operations platform construction. 5. Bag construction. 6. Auxiliary and support equipment placement. 7. Mining operations. 8. Processing operations. 9. Product transport to markets.

Widening Access, Widening Participation, Widening Success: An Indian Case Study

ERIC Educational Resources Information Center

Thornton, Mary

2006-01-01

Multiple deprivations are widespread in rural India. Literacy levels remain stubbornly low, albeit gradually improving. Caste, class, religion, gender, age and disability all impact on access to education, participation and successful completion. The education of girls remains problematic given the higher value attached to sons, especially in…

P and n-type microcrystalline semiconductor alloy material including band gap widening elements, devices utilizing same

DOEpatents

Guha, Subhendu; Ovshinsky, Stanford R.

1988-10-04

An n-type microcrystalline semiconductor alloy material including a band gap widening element; a method of fabricating p-type microcrystalline semiconductor alloy material including a band gap widening element; and electronic and photovoltaic devices incorporating said n-type and p-type materials.

Joining the Dots between Teacher Education and Widening Participation in Higher Education

ERIC Educational Resources Information Center

Duckworth, Vicky; Thomas, Liz; Bland, Derek

2016-01-01

In England and Australia, higher education institutions are required to widen participation in higher education by including students from under-represented and non-traditional groups. Widening participation is most effective when it starts early--during compulsory education and other forms of pre-tertiary education. Higher education institutions…

Introducing Widening Participation Policies in Higher Education: The Influence of Institutional Culture

ERIC Educational Resources Information Center

Greenbank, Paul

2007-01-01

This paper examines the role of culture in the development of higher education institution (HEI) policy on widening participation. The study involved documentary research and interviews with senior and middle managers. It suggests that a culture of widening participation is often not embedded throughout institutions. Therefore, widening…

Thermal fatigue as the origin of regolith on small asteroids.

PubMed

Delbo, Marco; Libourel, Guy; Wilkerson, Justin; Murdoch, Naomi; Michel, Patrick; Ramesh, K T; Ganino, Clément; Verati, Chrystele; Marchi, Simone

2014-04-10

Space missions and thermal infrared observations have shown that small asteroids (kilometre-sized or smaller) are covered by a layer of centimetre-sized or smaller particles, which constitute the regolith. Regolith generation has traditionally been attributed to the fall back of impact ejecta and by the break-up of boulders by micrometeoroid impact. Laboratory experiments and impact models, however, show that crater ejecta velocities are typically greater than several tens of centimetres per second, which corresponds to the gravitational escape velocity of kilometre-sized asteroids. Therefore, impact debris cannot be the main source of regolith on small asteroids. Here we report that thermal fatigue, a mechanism of rock weathering and fragmentation with no subsequent ejection, is the dominant process governing regolith generation on small asteroids. We find that thermal fragmentation induced by the diurnal temperature variations breaks up rocks larger than a few centimetres more quickly than do micrometeoroid impacts. Because thermal fragmentation is independent of asteroid size, this process can also contribute to regolith production on larger asteroids. Production of fresh regolith originating in thermal fatigue fragmentation may be an important process for the rejuvenation of the surfaces of near-Earth asteroids, and may explain the observed lack of low-perihelion, carbonaceous, near-Earth asteroids.

Developing space weathering on the asteroid 25143 Itokawa.

PubMed

Hiroi, Takahiro; Abe, Masanao; Kitazato, Kohei; Abe, Shinsuke; Clark, Beth E; Sasaki, Sho; Ishiguro, Masateru; Barnouin-Jha, Olivier S

2006-09-07

Puzzlingly, the parent bodies of ordinary chondrites (the most abundant type of meteorites) do not seem to be abundant among asteroids. One possible explanation is that surfaces of the parent bodies become optically altered, to become the S-type asteroids which are abundant in the main asteroid belt. The process is called 'space weathering'-it makes the visible and near-infrared reflectance spectrum of a body darker and redder. A recent survey of small, near-Earth asteroids suggests that the surfaces of small S asteroids may have developing stages of space weathering. Here we report that a dark region on a small (550-metre) asteroid-25143 Itokawa-is significantly more space-weathered than a nearby bright region. Spectra of both regions are consistent with those of LL5-6 chondrites after continuum removal. A simple calculation suggests that the dark area has a shorter mean optical path length and about 0.04 per cent by volume more nanophase metallic iron particles than the bright area. This clearly shows that space-weathered materials accumulate on small asteroids, which are likely to be the parent bodies of LL chondrites. We conclude that, because LL meteorites are the least abundant of ordinary (H, L, and LL) chondrites, there must be many asteroids with ordinary-chondrite compositions in near-Earth orbits.

Pairs of Asteroids Probably of a Common Origin

NASA Astrophysics Data System (ADS)

Vokrouhlický, David; Nesvorný, David

2008-07-01

We report the first observational evidence for pairs of main-belt asteroids with bodies in each pair having nearly identical orbits. The existence of ~60 pairs identified here cannot be reconciled with random fluctuations of the asteroid orbit density and rather suggests a common origin of the paired objects. We propose that the identified pairs formed by (i) collisional disruptions of km-sized and larger parent asteroids, (ii) Yarkovsky-O'Keefe-Radzievski-Paddack (YORP)-induced spin-up and rotational fission of fast-rotating objects, and/or (iii) splitting of unstable asteroid binaries. In case (i), the pairs would be parts of compact collisional families with many km- and sub-km-size members that should be found by future asteroid surveys. Our dynamical analysis suggests that most identified pairs formed within the past lsim1 Myr, in several cases even much more recently. For example, paired asteroids (6070) Rheinland and (54827) 2001 NQ8 probably separated from their common ancestor only 16.5-19 kyr ago. Given their putatively very recent formation, the identified objects are prime candidates for astronomical observations. The title paraphrases that of Hirayama's 1918 paper "Groups of asteroids probably of a common origin," where the first evidence was given for groups of asteroid fragments produced by disruptive collisions.

A Unified Model for Repeating and Non-repeating Fast Radio Bursts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bagchi, Manjari, E-mail: manjari@imsc.res.in

The model that fast radio bursts (FRBs) are caused by plunges of asteroids onto neutron stars can explain both repeating and non-repeating bursts. If a neutron star passes through an asteroid belt around another star, there would be a series of bursts caused by a series of asteroid impacts. Moreover, the neutron star would cross the same belt repetitively if it were in a binary with the star hosting the asteroid belt, leading to a repeated series of bursts. I explore the properties of neutron star binaries that could lead to the only known repeating FRB so far (FRB121102). Inmore » this model, the next two epochs of bursts are expected around 2017 February 27 and 2017 December 18. On the other hand, if the asteroid belt is located around the neutron star itself, then a chance fall of an asteroid from that belt onto the neutron star would lead to a non-repeating burst. Even a neutron star grazing an asteroid belt can lead to a non-repeating burst caused by just one asteroid plunge during the grazing. This is possible even when the neutron star is in a binary with the asteroid-hosting star, if the belt and the neutron star orbit are non-coplanar.« less

AIDA: The Asteroid Impact & Deflection Assessment Mission

NASA Astrophysics Data System (ADS)

Galvez, A.; Carnelli, I.; Michel, P.; Cheng, A. F.; Reed, C.; Ulamec, S.; Biele, J.; Abell, P.; Landis, R.

2013-09-01

The Asteroid Impact and Deflection Assessment (AIDA) mission, a joint effort of ESA, JHU/APL, NASA, OCA, and DLR, is the first demonstration of asteroid deflection and assessment via kinetic impact. AIDA consists of two independent but mutually supporting mission elements, one of which is the asteroid kinetic impactor and the other is the characterization spacecraft. These two missions are, respectively, JHU/APL's Double Asteroid Redirection Test (DART) and the European Space Agency's Asteroid Investigation Mission (AIM) missions. As in the separate DART and AIM studies, the target of this mission is the binary asteroid [65803] Didymos in October, 2022. For a successful joint mission, one spacecraft, DART, would impact the secondary of the Didymos system while AIM would observe and measure any change in the relative orbit. AIM will be the first probe to characterise a binary asteroid, especially from the dynamical point of view, but also considering its interior and subsurface composition. The mission concept focuses on the monitoring aspects i.e., the capability to determine in-situ the key physical properties of a binary asteroid playing a role in the system's dynamic behavior. DART will be the first ever space mission to deflect the trajectory of an asteroid in a measurable way.- It is expected that the deflection can be measured as a change in the relative orbit period with a precision better than 10%. The joint AIDA mission will return vital data to determine the momentum transfer efficiency of the kinetic impact [1,2].

On the metal-rich surfaces of (16) Psyche and other M-type asteroids from interferometric observations in the thermal infrared

NASA Astrophysics Data System (ADS)

Delbo, Marco; Matter, A.; Gundlach, B.; Blum, J.

2013-10-01

Asteroids belonging to the spectroscopic M-type exhibit a quasi featureless and moderately red reflectance spectrum and a geometric visible albedo between 0.1 and 0.3. These asteroids were initially thought to be metallic cores of differentiated asteroids that were exposed to space by a catastrophic disruption by impacts. Later, this view has been challenged by the detection of silicates and hydration spectroscopic bands on these bodies. Unveiling the physical properties of the surfaces of these asteroids, and identifying their meteorite analogs is a challenge from remote-sensing observations. Nevertheless, these are crucial problems, important for estimating the number of asteroids that underwent differentiation in the early phases of the formation of our solar system. The thermal inertia is a sensitive indicator for the presence of metal in the regolith on the surfaces of asteroids. We developed a new thermophysical model that allow us to derive the value of the thermal inertia from interferometric observations in the thermal infrared. We report on our investigation of the thermal inertia of M-type asteroids, including the asteroids (16) Psyche, for which we obtained a thermal inertia value anomalously high compared to the thermal inertia values of other asteroids in the same size range. From the thermal inertia and model of heat conductivity that accounts for different values of the packing fraction (a measure of the degree of compaction of the regolith particles) the regolith grain size is derived.

Scale-dependent measurements of meteorite strength: Implications for asteroid fragmentation

NASA Astrophysics Data System (ADS)

Cotto-Figueroa, Desireé; Asphaug, Erik; Garvie, Laurence A. J.; Rai, Ashwin; Johnston, Joel; Borkowski, Luke; Datta, Siddhant; Chattopadhyay, Aditi; Morris, Melissa A.

2016-10-01

Measuring the strengths of asteroidal materials is important for developing mitigation strategies for potential Earth impactors and for understanding properties of in situ materials on asteroids during human and robotic exploration. Studies of asteroid disruption and fragmentation have typically used the strengths determined from terrestrial analog materials, although questions have been raised regarding the suitability of these materials. The few published measurements of meteorite strength are typically significantly greater than those estimated from the stratospheric breakup of meter-sized meteoroids. Given the paucity of relevant strength data, the scale-varying strength properties of meteoritic and asteroidal materials are poorly constrained. Based on our uniaxial failure studies of centimeter-sized cubes of a carbonaceous and ordinary chondrite, we develop the first Weibull failure distribution analysis of meteorites. This Weibull distribution projected to meter scales, overlaps the strengths determined from asteroidal airbursts and can be used to predict properties of to the 100 m scale. In addition, our analysis shows that meter-scale boulders on asteroids are significantly weaker than small pieces of meteorites, while large meteorites surviving on Earth are selected by attrition. Further, the common use of terrestrial analog materials to predict scale-dependent strength properties significantly overestimates the strength of meter-sized asteroidal materials and therefore is unlikely well suited for the modeling of asteroid disruption and fragmentation. Given the strength scale-dependence determined for carbonaceous and ordinary chondrite meteorites, our results suggest that boulders of similar composition on asteroids will have compressive strengths significantly less than typical terrestrial rocks.

VESTOIDS, PART II: THE BASALTIC NATURE AND HED METEORITE ANALOGS FOR EIGHT V{sub p}-TYPE ASTEROIDS AND THEIR ASSOCIATIONS WITH (4) VESTA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hardersen, Paul S.; Reddy, Vishnu; Roberts, Rachel, E-mail: Hardersen@space.edu

Improving the constraints on the abundance of basaltic asteroids in the main asteroid belt is necessary for better understanding the thermal and collisional environment in the early solar system, for more rigorously identifying the genetic family for (4) Vesta, for determining the effectiveness of Yarkovsky/YORP in dispersing asteroid families, and for better quantifying the population of basaltic asteroids in the outer main belt (a > 2.5 AU) that is likely unrelated to (4) Vesta. Near-infrared (NIR) spectral observations in this work were obtained for the V{sub p}-type asteroids (2011) Veteraniya, (5875) Kuga, (8149) Ruff, (9147) Kourakuen, (9553) Colas, (15237) 1988 RL{sub 6},more » (31414) Rotaryusa, and (32940) 1995 UW{sub 4} during 2014 August/September utilizing the SpeX spectrograph at the NASA Infrared Telescope Facility, Mauna Kea, Hawaii. Spectral band parameter (band centers, band area ratios) and mineralogical analysis (pyroxene chemistry) for each average asteroid NIR reflectance spectrum suggest a howardite–eucrite–diogenite meteorite analog for each asteroid. (5875) Kuga is most closely associated with the eucrite meteorites, (31414) Rotaryusa is most closely associated with the diogenites, and the remaining other six asteroids are most closely associated with the howardite meteorites. Along with their orbital locations in the inner main belt and in the vicinity of (4) Vesta, the existing evidence suggests that these eight V{sub p}-type asteroids are also likely Vestoids.« less

Spin Rate Distribution of Small Asteroids Shaped by YORP Effect

NASA Astrophysics Data System (ADS)

Pravec, Petr

2008-09-01

We studied a distribution of spin rates of main belt/Mars crossing (MB/MC) asteroids with diameters 3-15 km using data obtained within the Photometric Survey of Asynchronous Binary Asteroids (Pravec et al. 2008). We found that the spin distribution of the small asteroids is uniform in the range from f = 1 to 9.5 d-1, and there is an excess of slow rotators with f < 1 d-1. The observed distribution appears to be controlled by the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect. The magnitude of the excess of slow rotators is related to the residence time of slowed down asteroids in the excess and the rate of spin rate change outside the excess. We estimated a median YORP spin rate change of 0.022 d-1/Myr for asteroids in our sample (i.e., a median time in which the spin rate changes by 1 d-1 is 45 Myr), thus the residence time of slowed down asteroids in the excess is 110 Myr. The spin rate distribution of near-Earth asteroids (NEAs) with sizes in the range 0.2-3 km ( 5-times smaller in median diameter than the MB/MC asteroids sample) shows a similar excess of slow rotators, but there is also a concentration of NEAs at fast spin rates with f = 9-10 d-1. The concentration at fast spin rates is correlated with a narrower distribution of spin rates of primaries of binary systems among NEAs; the difference may be due to the apparently more evolved population of binaries among MB/MC asteroids. Reference: Pravec, P., and 30 colleagues, 2008. Spin rate distribution of small asteroids. Icarus, in press. DOI: http://dx.doi.org/10.1016/j.icarus.2008.05.012

Scattering V-type asteroids during the giant planet instability: a step for Jupiter, a leap for basalt

NASA Astrophysics Data System (ADS)

Brasil, P. I. O.; Roig, F.; Nesvorný, D.; Carruba, V.

2017-06-01

V-type asteroids are a taxonomic class whose surface is associated with a basaltic composition. The only known source of V-type asteroids in the Main Asteroid Belt is (4) Vesta, which is located in the inner part of the Main Belt. However, many V-type asteroids cannot be dynamically linked to Vesta, in particular, those asteroids located in the middle and outer parts of the Main Belt. Previous works have failed to find mechanisms to transport V-type asteroids from the inner to the middle and outer belts. In this work, we propose a dynamical mechanism that could have acted on primordial asteroid families. We consider a model of the giant planet migration known as the jumping Jupiter model with five planets. Our study is focused on the period of 10 Myr that encompasses the instability phase of the giant planets. We show that, for different hypothetical Vesta-like paleo-families in the inner belt, the perturbations caused by the ice giant that is scattered into the asteroid belt before being ejected from the Solar system are able to scatter V-type asteroids to the middle and outer belts. Based on the orbital distribution of V-type candidates identified from the Sloan Digital Sky Survey and the VISTA Survey colours, we show that this mechanism is efficient enough provided that the hypothetical paleo-family originated from a 100 to 500 km crater excavated on the surface of (4) Vesta. This mechanism is able to explain the currently observed V-type asteroids in the middle and outer belts, with the exception of (1459) Magnya.

Discovery and dynamical characterization of the Amor-class asteroid 2012 XH16

NASA Astrophysics Data System (ADS)

Wlodarczyk, I.; Cernis, K.; Boyle, R. P.; Laugalys, V.

2014-03-01

The near-Earth asteroid belt is continuously replenished with material originally moving in Amor-class orbits. Here, the orbit of the dynamically interesting Amor-class asteroid 2012 XH16 is analysed. This asteroid was discovered with the Vatican Advanced Technology Telescope (VATT) at the Mt Graham International Observatory as part of an ongoing asteroid survey focused on astrometry and photometry. The orbit of the asteroid was computed using 66 observations (57 obtained with VATT and 9 from the Lunar and Planetary Laboratory-Spacewatch II project) to give a = 1.63 au, e = 0.36, i = 3.76°. The absolute magnitude of the asteroid is 22.3 which translates into a diameter in the range 104-231 m, assuming the average albedos of S-type and C-type asteroids, respectively. We have used the current orbit to study the future dynamical evolution of the asteroid under the perturbations of the planets and the Moon, relativistic effects, and the Yarkovsky force. Asteroid 2012 XH16 is locked close to the strong 1:2 mean motion resonance with the Earth. The object shows stable evolution and could survive in near-resonance for a relatively long period of time despite experiencing frequent close encounters with Mars. Moreover, results of our computations show that the asteroid 2012 XH16 can survive in the Amor region at most for about 200-400 Myr. The evolution is highly chaotic with a characteristic Lyapunov time of 245 yr. Jupiter is the main perturber but the effects of Saturn, Mars and the Earth-Moon system are also important. In particular, secular resonances with Saturn are significant.

Asteroid Impact & Deflection Assessment mission: Kinetic impactor

NASA Astrophysics Data System (ADS)

Cheng, A. F.; Michel, P.; Jutzi, M.; Rivkin, A. S.; Stickle, A.; Barnouin, O.; Ernst, C.; Atchison, J.; Pravec, P.; Richardson, D. C.; AIDA Team

2016-02-01

The Asteroid Impact & Deflection Assessment (AIDA) mission will be the first space experiment to demonstrate asteroid impact hazard mitigation by using a kinetic impactor to deflect an asteroid. AIDA is an international cooperation, consisting of two mission elements: the NASA Double Asteroid Redirection Test (DART) mission and the ESA Asteroid Impact Mission (AIM) rendezvous mission. The primary goals of AIDA are (i) to test our ability to perform a spacecraft impact 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 near-Earth asteroid (65803) Didymos, with the deflection experiment to occur in late September, 2022. The DART impact on the secondary member of the binary at 7 km/s is expected to alter the binary orbit period by about 4 minutes, assuming a simple transfer of momentum to the target, and this period change will be measured by Earth-based observatories. The AIM spacecraft will characterize the asteroid target and monitor results of the impact in situ at Didymos. The DART mission is a full-scale kinetic impact to deflect a 150 m diameter asteroid, with known impactor conditions and with target physical properties characterized by the AIM mission. Predictions for the momentum transfer efficiency of kinetic impacts are given for several possible target types of different porosities, using Housen and Holsapple (2011) crater scaling model for impact ejecta mass and velocity distributions. Results are compared to numerical simulation results using the Smoothed Particle Hydrodynamics code of Jutzi and Michel (2014) with good agreement. The model also predicts that the ejecta from the DART impact may make Didymos into an active asteroid, forming an ejecta coma that may be observable from Earth-based telescopes. The measurements from AIDA of the momentum transfer from the DART impact, the crater size and morphology, and the evolution of an ejecta coma will substantially advance understanding of impact processes on asteroids.

BAOBAB (Big And Outrageously Bold Asteroid Belt) Project

NASA Technical Reports Server (NTRS)

Mcfadden, L. A.; Thomas, C. A; Englander, J. A.; Ruesch, O.; Hosseini, S.; Goossens, S. J.; Mazarico, E. M.; Schmerr, N.

2017-01-01

One of the intriguing results of NASA's Dawn mission is the composition and structure of the Main Asteroid Belt's only known dwarf planet, Ceres [1]. It has a top layer of dehydrated clays and salts [2] and an icy-rocky mantle [3,4]. It is widely known that the asteroid belt failed to accrete as a planet by resonances between the Sun and Jupiter. About 20-30 asteroids >100 km diameter are probably differentiated protoplanets [5]. 1) how many more and which ones are fragments of protoplanets? 2) How many and which ones are primordial rubble piles left over from condensation of the solar nebula? 3) How would we go about gaining better and more complete characterization of the mass, interior structure and composition of the Main Belt asteroid population? 4) What is the relationship between asteroids and ocean worlds? Bulk parameters such as the mass, density, and porosity, are important to characterize the structure of any celestial body, and for asteroids in particular, they can shed light on the conditions in the early solar system. Asteroid density estimates exist but currently they are often based on assumed properties of taxonomic classes, or through astronomical survey data where interactions with asteroids are weak at best resulting in large measurement uncertainty. We only have direct density estimates from spacecraft encounters for a few asteroids at this time. Knowledge of the asteroids is significant not only to understand their role in solar system workings, but also to assess their potential as space resources, as impact hazards on Earth, or even as harboring life forms. And for the distant future, we want to know if the idea put forth in a contest sponsored by Physics Today, to surface the asteroids into highly reflecting, polished surfaces and use them as a massively segmented mirror for astrophysical exploration [6], is feasible.

Reanalysis of Asteroid Families Structure Through Visible Spectroscopy

NASA Astrophysics Data System (ADS)

Mothé-Diniz, T.; Carvano, J.; Roig, F.; Lazzaro, D.

In this work we re-analyse the presence of interlopers in asteroid families based on a larger spectral database and on a family determination which makes use of a larger set of proper elements. The asteroid families were defined using the HCM method (Zappalà et al. 1995) on the set of proper elements for 110,000 asteroids available at the Asteroid Dynamic Site (AstDyS http://hamilton.dm.unipi.it/astdys )). The spectroscopic analysis is performed using spectra on the 0.44-0.92 μ m range observed by the SMASS Xu et al. 1995, SMASSII (Bus and Binzel, 2002) and 3OS2 (Lazzaro et al. 2002) surveys, which together total around 2140 asteroids with observed spectra. The asteroid taxonomy used is the Bus taxonomy (Bus et al. 2000). A total of 22 two families were analysed . The families of Vesta, Eunomia, Hoffmeister, Dora, Merxia, Agnia, and Koronis were found to be spectrally homogeneous, which confirms previous studies. The Veritas family, on the other hand, which is quoted in the literature as an heterogeneous family was found to be quite homogeneous in the present work. The Eos family is noteworthy for being at one time spectrally heterogeneous and quite different from the background population. References Bus, S. J., and R. P. Binzel 2002. Phase II of the Small Main-Belt Asteroid Spectroscopic Survey - The Observations. Icarus 158, 106-145. Bus, S. J., R. P. Binzel, and T. H. Burbine 2000. A New Generation of Asteroid Taxonomy. Meteoritics and Planetary Science, vol. 35, Supplement, p.A36 35, 36 +. Lazzaro, D., C. A. Angeli, T. Mothe-Diniz, J. M. Carvano, R. Duffard, and M. Florczak 2002. The superficial characterization of a large sample of asteroids: the S3OS2. Bulletin of the American Astronomical Society 34, 859 +. Xu, S., R. P. Binzel, T. H. Burbine, and S. J. Bus 1995. Small main-belt asteroid spectroscopic survey: Initial results. Icarus 115, 1-35. Zappala, V., P. Bendjoya, A. Cellino, P. Farinella, and C. Froeschle 1995. Asteroid families: Search of a 12,487-asteroid sample using two different clustering techniques. Icarus 116, 291-314.

Colors and spin period distributions of sub-km main belt asteroids

NASA Astrophysics Data System (ADS)

Yoshida, Fumi; Lin, Hsing-Wen; Chen, Ying-Tung; Souami, Damya; Bouquillon, Sebastien; Ip, Wing-Huen; Chang, Chan-Kao; Nakamura, Tsuko; Dermawan, Budi; Yagi, Masafumi; Souchay, Jean

2014-11-01

The size dependency of space weathering on asteroid’s surface and collisional lifetimes suggest that small asteroids are younger than large asteroids. Therefore, the studies of smaller asteroid provide us new information about asteroid composition on fresh surface and their collisional evolution. We performed a color observation using 4 filters and lightcurve observation using 2 filters on different nights, using the 8.2m Subaru telescope/Suprime-Cam, for investigating the color and spin period distributions of sub-km main-belt asteroids (MBAs) that could not be seen before by middle class telescopes. In a lightcurve observation on Sep. 2, 2002, we kept taking images of a single sky field at near the opposition and near the ecliptic plane. Taking advantage of the wide field view of Suprime-Cam, this observation was planned to obtain lightcurves of 100 asteroids at the same time. Actually, we detected 112 MBAs and obtained their lightcurves by using a modified GAIA-GBOT PIPELINE. For the period analysis, we defined a criterion for judging whether an obtained rotational period is robust or not. Although Dermawan et al. (2011) have suggested that there are many fast rotators (FR) in MBAs, we noticed that many MBAs have long spin periods. Therefore, we could determine the rotation period of only 22 asteroids. We found one FR candidate (P=2.02 hr). We could measure the B-R color of 16 asteroids among the 22 MBAs. We divided them into S-like and C-like asteroids by the B-R color. The average rotational periods of C-like and S-like asteroids are 4.3 hr and 7.6 hr, respectively. C-like asteroids seem to rotate faster than S-like ones. We carried out a multi-color survey on Aug. 9 and 10, 2004 and then detected 154 MBAs. We classified them into several taxonomic types. Then we noticed that there are only very few Q-type candidates (non-weathered S-type) unlike the near Earth asteroid (NEAs) population, in which Q-type is a main component. This may indicate that most of Q-type NEAs did not originated from Q-type MBAs. They are probably objects subjected to resurfacing process (by peeling surface regolith, the outer layer of asteroid changes from S-type to Q-type) due to the tidal effect during their planetary encounters.

Physical properties of asteroids in comet-like orbits in the infrared asteroidal survey catalogs

NASA Astrophysics Data System (ADS)

Kim, Y.; Ishiguro, M.; Usui, F.

2014-07-01

Dormant comet and Infrared Asteroidal Survey Catalogs. Comet nucleus is a solid body consisting of dark refractory material and ice. Cometary volatiles sublimate from subsurface layer by solar heating, leaving behind large dust grains on the surface. Eventually, the appearance could turn into asteroidal rather than cometary. It is, therefore, expected that there would be ''dormant comets'' in the list of known asteroids. Over past decade, several ground-based studies have been performed to dig out such dormant comets. One common approach is applying a combination of optical and dynamical properties learned from active comet nucleus to the list of known asteroids. Typical comet nucleus has (i) Tisserand parameter with respect to Jupiter, T_{J}<3, (ii) low geometric albedo, p_{v}<0.1 and (iii) reddish or neutral spectra, similar to P, D, C-type asteroids. Following past ground-based surveys, infrared space missions gave us an opportunity to work on further study of dormant comets. To the present, three infrared asteroidal catalogs taken with IRAS[1], AKARI[2] and WISE[3] are available, providing information of sizes and albedos which are useful to study the physical properties of dormant comets as well as asteroids. Usui et al. (2014) merged three infrared asteroidal catalogs with valid sizes and albedos into single catalog, what they called I-A-W[4]. We applied a huge dataset of asteroids in I-A-W to investigate the physical properties of asteroids in comet-like orbits (ACOs, whose orbits satisfy Q>4.5 au and T_{J}<3). Here we present a study of ACOs in infrared asteroidal catalogs taken with AKARI, IRAS and WISE. In this presentation, we aim to introduce albedo and size properties of ACOs in infrared asteroidal survey catalogs, in combination with orbital and spectral properties from literature. Results and Implications. We summarize our finding and implication as followings: - are 123 ACOs (Q>4.5 au and T_J<3) in I-A-W catalog after rejection of objects with large orbital uncertainties. - Majority (˜80 %) of ACOs have low albedo (p_{v}<0.1), showing similar albedo distribution to active comet nuclei. - Low-albedo ACOs have the cumulative size distribution shallower than that of active comet nuclei. - High-albedo (p_{v}≥0.1) ACOs consist of small (D<3 km) bodies are concentrated in near-Earth space. - We suggest that such high-albedo, small near-Earth asteroids are susceptible to Yarkovsky effect and injected into comet-like orbits.

New infrared spectral data for 27 asteroids: An investigation of meteorite- asteroid relationships by using the modified Gaussian model

NASA Astrophysics Data System (ADS)

Gietzen, Katherine M.

2009-09-01

Asteroids provide unique insights into the origin and early history of the solar system. Since asteroids are considered to be fairly pristine, studying them provides opportunities to learn more about the primordial solar system, its materials, processes and history. Since the discovery in 1801 of the first asteroid, Ceres, during the era when everyone was searching for the "missing planet", astronomers have been trying to understand what they are, where they came from, why they exist and what they can tell us about how our solar system formed and evolved. Within the asteroid population are a number of sub-populations, the primary division is due to the locations of the asteroids. There are the Main Belt Asteroid (MBA) population that resides between the orbits of Mars and Jupiter (1.8 - 3.5 AU) and the Near-Earth Asteroid (NEA) population whose orbits have an aphelion <= 1.3 AU. Within both the MBA and NEA populations are further subdivisions (taxonomic classes) based on physical properties of the asteroids such as albedo, spectral curve and probable composition. There have been a number of taxonomic classification schemes, the most current iteration splits the asteroids into three complexes (C, S, and X) that combined are comprised of twenty-six distinct taxonomic classes. Since the lifetimes of the NEAs are short (10 6 - 10 7 yrs), it is thought that the NEA population is and continues to be populated by the MBA population through various mechanisms like resonances and thermal forces. We have conducted a statistical comparison of the two populations as a whole, by complexes and individual taxonomic classes and found significant differences as well as similarities. On the surface, it appears that the NEA population is not representative of the MBA population. There are voids and relatively small numbers in taxonomic classes that exist in the NEA when compared to the MBA population and there are some important similarities. There are, however, biases that this analysis does not address that may explain our findings. The asteroid taxonomy classification schemas are based on visible wavelength spectra. There are ~2500 classified asteroids of which only a very small percentage have spectra in the infrared wavelength ranges. Here we demonstrate, using asteroid 1989 ML, the need for more asteroid spectra in the near-infrared wavelength range which contains much compositional information. We show that in the visible wavelengths spectra of several meteorites of very different types match the spectrum of 1989 ML. Finally, we examine twenty-seven S and possible S Complex asteroid spectra. We find that most contain pyroxenes in the monoclinic form (clinopyroxene). Clinopyroxenes can contain calcium; however, there are some that do not. The cases of Ca-free clinopyroxenes are rare on Earth, but are readily found in the type 3 unequilibrated ordinary chondrites. Analyses of the asteroids and ordinary chondrites were conducted using the Modified Gaussian Model (MGM) and the Band Area Ratio. We also examined two terrestrial Ca-free clinopyroxenes using the MGM. From our results we conclude that the surfaces of S Complex asteroids are consistent with the type 3 unequilibrated ordinary chondrites.

Could G Asteroids be the Parent Bodies of the CM Chondrites?

NASA Astrophysics Data System (ADS)

Burbine, T. H.; Binzel, R. P.

1995-09-01

Since almost all meteorites are believed to be derived from asteroidal source bodies, the comparison of asteroid and meteorite spectra should allow for possible meteorite parent bodies to be identified. However only two asteroids with unique spectral characteristics, 4 Vesta with the basaltic achondrites [1] and near-Earth asteroid 3103 Eger with the aubrites [2], have been convincingly linked with any meteorite type. Farinella et al. [3] has done a study of 2355 numbered main-belt asteroids to determine which asteroids have the highest probability of having their fragments injected into the 3:1 mean motion and the nu6 secular resonance regions. Interestingly, asteroids with the third (19 Fortuna), tenth (1 Ceres) and eleventh (13 Egeria) highest theoretical total fragment delivery efficiencies are G-asteroids, a moderately rare type of asteroid with approximately ten known members. (Vesta has the fifth highest theoretical total fragment delivery efficiency.) G-asteroids tend to have the strongest ultraviolet, 0.7 micrometers and 3 micrometers absorption features of all C-type (B, C, F and G) asteroids, appearing to indicate that G-asteroids are at the upper range of the aqueous alteration sequence in the asteroid population. (The 0.7 micrometers feature is apparently due to iron oxides in hydrated silicates and the 3 micrometers feature is apparently due to hydrated minerals.) Meteorites that have reflectance spectra with a 3 micrometers feature of comparable intensity to those of the G-asteroids are the CI, CM and CR chondrites. However, G-asteroids (like all C-types) have ultraviolet absorption features that are weaker than previously measured meteorite spectra. Comparisons of reflectance spectra between Ceres and meteorite samples appear to indicate that Ceres is compositionally different from almost all known carbonaceous chondrites. Both Fortuna and Egeria have an absorption feature centered around 0.7 micrometers [4] that is similar in structure and strength to those found in many CM chondrites. The visible and near-infrared spectrum of Fortuna [5] matches very well the spectra of CM chondrites Murchison (bulk powder) [6] and LEW90500 (particle sizes less than 100 micrometers) [7]. However, the ultraviolet absorption feature is still weaker in Fortuna's spectrum. A spectrum of a bulk powder of LEW90500 does have an ultraviolet feature that matches Fortuna's feature, but this spectrum is substantially bluer than Fortuna in the near-infrared. Egeria's ultraviolet absorption feature also matches very well the ultraviolet feature in LEW90500Us (bulk powder) spectrum, but this spectrum is slightly redder than Egeria [5] in the near-infrared. The question is how unique is any postulated linkage between the CM chondrites and the G-asteroids. The problem is that approximately two-thirds of all C-type asteroids have 3 micrometers absorption features [8] and approximately three-fourths have 0.7 micrometers absorption features [4]. However of all observed C-type asteroids, Fortuna and Egeria appear to be two of the best spectral matches for the CM chondrites. Coupled with the high probability that these two asteroids are injecting large numbers of fragments into meteorite-supplying resonances, G-asteroids Fortuna and Egeria appear to be possible CM chondrite parent bodies. Acknowledgments: This research is supported by NASA Grant Number NAGW-2049. References: [1] Binzel R. P. and Xu S. (1993) Science, 260, 186-191. [2] Gaffey M. J. et al. (1992) Icarus, 100, 95-109. [3] Farinella P. et al. (1993) Icarus, 101, 174-187. [4] Sawyer S. R. (1991) Ph.D. thesis, Univ. of Texas, Austin. [5] Bell J. F. et al. (1988) LPS XIX, 57-58. [6] Gaffey M. J. (1976) JGR, 81, 905-920. [7] Hiroi T. et al. (1993) Science, 261, 1016-1018. [8] Jones T. D. et al. (1990) Icarus, 88,172-192.

Aqueous alteration on main-belt asteroids

NASA Astrophysics Data System (ADS)

Fornasier, S.; Lantz, C.; Barucci, M.; Lazzarin, M.

2014-07-01

The study of aqueous alteration is particularly important for unraveling the processes occurring during the earliest times in Solar System history, as it can give information both on the thermal processes and on the localization of water sources in the asteroid belt, and for the associated astrobiological implications. The aqueous alteration process produces the low temperature (< 320 K) chemical alteration of materials by liquid water which acts as a solvent and produces materials like phyllosilicates, sulphates, oxides, carbonates, and hydroxides. This means that liquid water was present in the primordial asteroids, produced by the melting of water ice by heating sources, very probably by ^{26}Al decay. Hydrated minerals have been found mainly on Mars surface, on primitive main-belt asteroids (C, G, B, F, and P-type, following the classification scheme by Tholen, 1984) and possibly also on few transneptunian objects. Reflectance spectroscopy of aqueous altered asteroids shows absorption features in the 0.6-0.9 and 2.5-3.5-micron regions, which are diagnostic of, or associated with, hydrated minerals. In this work, we investigate the aqueous alteration process on a large sample of 600 visible spectra of C-complex asteroids available in the literature. We analyzed all these spectra in a similar way to characterize the absorption-band parameters (band center, depth, and width) and spectral slope, and to look for possible correlations between the aqueous alteration process and the asteroids taxonomic classes, orbital elements, heliocentric distances, albedo, and sizes. We find that 4.6 % of P, 7.7 % of F, 9.8 % of B, 50.5 % of C, and 100 % of the G-type asteroids have absorption bands in the visible region due to hydrated silicates. Our analysis shows that the aqueous alteration sequence starts from the P-type objects, practically unaltered, and increases through the P → F → B → C → G asteroids, these last being widely aqueously altered, strengthening thus the results previously obtained by Vilas (1994). We confirm the strong correlation between the 0.7-μm band and the 3-μ m band, the deepest feature associated with hydrated minerals, as 95 % of the asteroids showing the 0.7-μ m band have also the 3-μ m feature. 45 % of the asteroids belonging to the C-complex (the F, B, C, and G classes) have signatures of aqueously altered materials in the visible range. It must be noted that this percentage represents a lower limit in the number of hydrated asteroids, simply because the 3-μ m band, the main absorption feature produced by hydrated silicates, may be present in the spectra of primitive asteroids when no bands are detected in the visible range. All this considered, we estimate that 70 % of the C-complex asteroids might have the 3-μ m signature in the IR range and thus were affected by the aqueous alteration process in the past. We find that the aqueous alteration process dominates in primitive asteroids located between 2.3 and 3.1 au, that is, at smaller heliocentric distances than previously suggested by Vilas et al. (1993). The percentage of hydrated asteroids is strongly correlated with their size (Fornasier et al. 2014). The aqueous alteration process is less effective for bodies smaller than 50 km, while it dominates in the 50-240-km sized primitive asteroids. No correlation is found between the aqueous alteration process and the asteroid albedo or orbital elements. Aqueously altered asteroids are the plausible parent bodies of CM2 meteorites. Nevertheless, we see a systematic difference in the 0.7-μ m band center position, the CM2 meteorites having a band centered at longer wavelengths (0.71-0.75 μ m) compared to that of hydrated asteroids. Moreover, the hydrated asteroids are more clustered in spectral slope and band depth than the CM meteorites. All these spectral differences may be attributed to different mineral abundances (CM2 meteorites being more serpentine rich than the asteroids), and/or to grain-size effects, or simply to the fact the CM2 collected on the Earth might not be representative of the whole population of aqueously altered asteroids.

Double Asteroid Redirection Test (DART) element of AIDA mission

NASA Astrophysics Data System (ADS)

Cheng, A.; Michel, P.; Rivkin, A.; Barnouin, O.; Stickle, A.; Miller, P.; Chesley, S.; Richardson, D.

2017-09-01

The AIDA mission, an international cooperation between NASA and ESA, will be the first demonstration of a kinetic impactor spacecraft to deflect an asteroid. AIDA will perform the first hypervelocity impact on an asteroid where the impact conditions are fully known and the target properties are also characterized. AIDA will reduce risks for any future asteroid hazard mitigation.

The Nature of C Asteroid Regolith from Meteorite Observations

NASA Technical Reports Server (NTRS)

Zolensky, M.; Mikouchi, T.; Hagiya, K.; Ohsumi, K.; Komatsu, M.; Jenniskens, P.; Le, L.; Yin, Q.-Z; Kebukawa, Y.; Fries, M.

2013-01-01

Regolith from C (and related) asteroid bodies are a focus of the current missions Dawn at Ceres, Hayabusa 2 and OSIRIS REx. An asteroid as large as Ceres is expected to be covered by a mature regolith, and as Hayabusa demonstrated, flat and therefore engineeringly-safe ponded deposits will probably be the sampling sites for both Hayabusa 2 and OSIRIS REx. Here we examine what we have learned about the mineralogy of fine-grained asteroid regolith from recent meteorite studies and the examination of the samples harvested from asteroid Itokawa by Hayabusa.

First spacecraft encounter with an asteroid approaches

NASA Technical Reports Server (NTRS)

Tholen, David J.

1991-01-01

During the course of the Galileo spacecraft's journey to Jupiter it will make two excursions through the steroid belt situated between Mars and Jupiter. The first excursion involves an encounter with the asteroid 951 Gaspra, which will take place on October 29, 1991. Gaspra is a small (about 15 km diameter) asteroid near the outer edge of the main asteroid belt. It's spectral classification is S, suggesting a composition similar to those of stony-iron meteorites. A figure is given showing the brightness of this asteroid as a function of time.

Photometric geodesy of main-belt asteroids. II - Analysis of lightcurves for poles, periods, and shapes

NASA Technical Reports Server (NTRS)

Drummond, J. D.; Weidenschilling, S. J.; Chapman, C. R.; Davis, D. R.

1988-01-01

The assumption that asteroids can be modeled as smooth, featureless, triaxial ellipsoids that rotate about their shortest axes is presently used to study all but one of the 26 asteroids treated in the Weidenschilling et al. (1987) 'photometric geodesy' program. Rotational poles derived from three independent methods are used to determine each asteroid's sidereal period and triaxial ellipsoid axial ratios, together with their associated photometric parameters. The asteroids appear to have rotational poles that do not lie along their orbital planes.

Collision rates and impact velocities in the Main Asteroid Belt

NASA Technical Reports Server (NTRS)

Farinella, Paolo; Davis, Donald R.

1992-01-01

Wetherill's (1967) algorithm is presently used to compute the mutual collision probabilities and impact velocities of a set of 682 asteroids with large-than-50-km radius representative of a bias-free sample of asteroid orbits. While collision probabilities are nearly independent of eccentricities, a significant decrease is associated with larger inclinations. Collisional velocities grow steeply with orbital eccentricity and inclination, but with curiously small variation across the asteroid belt. Family asteroids are noted to undergo collisions with other family members 2-3 times more often than with nonmembers.

The first retrograde Trojan asteroid

NASA Astrophysics Data System (ADS)

Wiegert, Paul; Connors, Martin; Veillet, Christian

2018-04-01

There are about six thousand asteroids which share Jupiter's orbit around the Sun. Called the 'Trojan asteroids', they co-exist easily with this giant planet because they travel in the same direction as it ('direct' or 'prograde' motion), and remain roughly 60 degrees ahead of or behind it in its orbit. Newly discovered asteroid 2015 BZ509 is on a retrograde orbit, but is nonetheless in a state dynamically analogous to that of the prograde Trojans. The discovery circumstances and the nature of the motion of this curious asteroid -the first of its kind- will be outlined.

Asteroid rotation rates - Distributions and statistics

NASA Technical Reports Server (NTRS)

Binzel, Richard P.; Farinella, Paolo; Zappala, Vincenzo; Cellino, Alberto

1989-01-01

An analysis of asteroid rotation rates and light-curve amplitudes disclosed many significant correlations between these rotation parameters and asteroid diameter, with distinct changes occurring near 125 km, a diameter above which self-gravity may become important. It is suggested that this size range may represent a division between surviving primordial asteroids and collisional fragments. A comparison of rotational parameters between family and nonfamily asteroids showed that the Koronis and Eos families exhibit noticeable differences, considered to be due to different impact conditions and/or to a relatively younger age for the Koronis family.

Asteroid Initiative Industry and Partner Day

NASA Image and Video Library

2013-06-18

Tom Kalil, Deputy Director for Technology and Innovation, White House Office of Science and Technology Policy, talks during the Asteroid Initiative Industry and Partner Day at NASA Headquarters on Tuesday, June 18, 2013 in Washington. During the event NASA Deputy Administrator Lori Garver and other senior NASA officials discussed the progress being made on NASA's mission to capture, redirect, and explore an asteroid. NASA also announced an Asteroid Grand Challenge focused on finding all asteroid threats to human populations and knowing what to do about them. Photo Credit: (NASA/Bill Ingalls)

Radar investigation of asteroids

NASA Technical Reports Server (NTRS)

Ostro, S. J.

1981-01-01

Software to support all stages of asteroid radar observation and data analysis is developed. First-order analysis of all data in hand is complete. Estimates of radar cross sections, circular polarization ratios, and limb-to-limb echo spectral bandwidths for asteroids 7 Iris, 16 Psyche, 97 Klotho, 1862 Apollo, and 1915 Quetzalcoatl are reported. Radar observations of two previously unobserved asteroids were conducted. An Aten asteroid, 2100 Ra-Shalom, with the smallest known semimajor axis (0.83) was detected. Preliminary data reduction indicates a circular polarization ratio comparable to those of Apollo, Quetzalcoatl, and Toro.

Asteroid Initiative Industry and Partner Day

NASA Image and Video Library

2013-06-18

NASA Associate Administrator for Space Technology, Mike Gazarik, Ph.D, listens to a question from the audience during the Asteroid Initiative Industry and Partner Day at NASA Headquarters on Tuesday, June 18, 2013 in Washington. During the event NASA Deputy Administrator Lori Garver and other senior NASA officials discussed the progress being made on NASA's mission to capture, redirect, and explore an asteroid. NASA also announced an Asteroid Grand Challenge focused on finding all asteroid threats to human populations and knowing what to do about them. Photo Credit: (NASA/Bill Ingalls)

Asteroid Initiative Industry and Partner Day

NASA Image and Video Library

2013-06-18

NASA Associate Administrator Robert Lightfoot, left, talks as NASA Associate Administrator Science John Grunsfeld, Ph.D, listens, during the Asteroid Initiative Industry and Partner Day at NASA Headquarters on Tuesday, June 18, 2013 in Washington. During the event NASA Deputy Administrator Lori Garver and other senior NASA officials discussed the progress being made on NASA's mission to capture, redirect, and explore an asteroid. NASA also announced an Asteroid Grand Challenge focused on finding all asteroid threats to human populations and knowing what to do about them. Photo Credit: (NASA/Bill Ingalls)

Asteroid Initiative Industry and Partner Day

NASA Image and Video Library

2013-06-18

NASA Associate Administrator Robert Lightfoot, left, talks as NASA Associate Administrator Science John Grunsfeld, Ph.D, listens during the Asteroid Initiative Industry and Partner Day at NASA Headquarters on Tuesday, June 18, 2013 in Washington. During the event NASA Deputy Administrator Lori Garver and other senior NASA officials discussed the progress being made on NASA's mission to capture, redirect, and explore an asteroid. NASA also announced an Asteroid Grand Challenge focused on finding all asteroid threats to human populations and knowing what to do about them. Photo Credit: (NASA/Bill Ingalls)

Asteroid Initiative Industry and Partner Day

NASA Image and Video Library

2013-06-18

NASA Associate Administrator for Human Exploration and Operations, William Gerstenmaier, listens to a question from the audience during the Asteroid Initiative Industry and Partner Day at NASA Headquarters on Tuesday, June 18, 2013 in Washington. During the event NASA Deputy Administrator Lori Garver and other senior NASA officials discussed the progress being made on NASA's mission to capture, redirect, and explore an asteroid. NASA also announced an Asteroid Grand Challenge focused on finding all asteroid threats to human populations and knowing what to do about them. Photo Credit: (NASA/Bill Ingalls)

How Many Ch-Class NEOs Do We Expect?

NASA Astrophysics Data System (ADS)

Rivkin, A. S.; DeMeo, F. E.

2017-09-01

The Ch spectral class is thought to contain objects that have water in their minerals, and they are of great interest to scientists and the nascent asteroid mining industry. We use models of asteroid delivery to near-Earth space and measurements of the different compositions of asteroids to estimate there should be at least 20 Ch asteroids larger than 100 m that are more accessible than the Moon, though we note that there are some untested assumptions that lead to that number. Further work must be done to identify the specific Ch asteroids.

Asteroid differentiation - Pyroclastic volcanism to magma oceans

NASA Technical Reports Server (NTRS)

Taylor, G. J.; Keil, Klaus; Mccoy, Timothy; Haack, Henning; Scott, Edward R. D.

1993-01-01

A summary is presented of theoretical and speculative research on the physics of igneous processes involved in asteroid differentiation. Partial melting processes, melt migration, and their products are discussed and explosive volcanism is described. Evidence for the existence of asteroidal magma oceans is considered and processes which may have occurred in these oceans are examined. Synthesis and inferences of asteroid heat sources are discussed under the assumption that asteroids are heated mainly by internal processes and that the role of impact heating is small. Inferences of these results for earth-forming planetesimals are suggested.

Search techniques for near-earth asteroids

NASA Technical Reports Server (NTRS)

Helin, E. F.; Dunbar, R. S.

1990-01-01

Knowledge of the near-earth asteroids (Apollo, Amor, and Aten groups) has increased enormously over the last 10 to 15 years. This has been due in large part to the success of programs that have systematically searched for these objects. These programs have been motivated by the apparent relationships of the near-earth asteroids to terrestrial impact cratering, meteorites, and comets, and their relative accessibility for asteroid missions. Discovery of new near-earth asteroids is fundamental to all other studies, from theoretical modeling of their populations to the determination of their physical characteristics by various remote-sensing techniques. The methods that have been used to find these objects are reviewed, and ways in which the search for near-earth asteroids can be expanded are discussed.

Innovations in Mission Architectures for Human and Robotic Exploration Beyond Low Earth Orbit

NASA Technical Reports Server (NTRS)

Cooke, Douglas R.; Joosten, B. Kent; Lo, Martin W.; Ford, Ken; Hansen, Jack

2002-01-01

Through the application of advanced technologies, mission concepts, and new ideas in combining capabilities, architectures for missions beyond Earth orbit have been dramatically simplified. These concepts enable a stepping stone approach to discovery driven, technology enabled exploration. Numbers and masses of vehicles required are greatly reduced, yet enable the pursuit of a broader range of objectives. The scope of missions addressed range from the assembly and maintenance of arrays of telescopes for emplacement at the Earth-Sun L2, to Human missions to asteroids, the moon and Mars. Vehicle designs are developed for proof of concept, to validate mission approaches and understand the value of new technologies. The stepping stone approach employs an incremental buildup of capabilities; allowing for decision points on exploration objectives. It enables testing of technologies to achieve greater reliability and understanding of costs for the next steps in exploration.

Widening Participation: What Works?

ERIC Educational Resources Information Center

Gorard, Stephen

2007-01-01

In this brief article, the author talks about what--other than money--works to widen higher education (HE) participation for adult learners. He also discusses the problems in trying to discover what works to widen participation for adults. One problem is that the decision to participate in any formal learning episode, including HE, is not a simple…

Integrated Blowoff and Breakup Calculations for Asteroid Deflection by Nuclear Ablation

NASA Astrophysics Data System (ADS)

Bruck Syal, M.; Owen, M.; Dearborn, D. S.; Miller, P. L.

2016-12-01

When the warning timing is short, hazardous asteroids or comets can only be deflected off of an Earth-impacting trajectory by a nuclear device [1]. Here we model asteroid response to a standoff nuclear explosion, a problem which requires sub-millimeter spatial resolution at the body's surface to fully capture x-ray energy deposition. The first stage of the calculation focuses on modeling blowoff momentum from vaporized material, using a problem domain confined to the uppermost surface of the asteroid. Once the blowoff momentum transfer process is complete, the problem is remapped into a coarser resolution and the remainder of the asteroid body is added to the calculation, so that asteroid response can be tracked over longer timescales. This two-stage approach enables an integrated assessment of both the efficacy of momentum delivery and damage incurred by the bulk of the asteroid. Investigating the degree of post-ablation fracture, fragmentation, and fragment dispersion is necessary for modeling the outcomes of cases intended to fully fragment and disperse the body (disruption), as well as cases where the bulk of the asteroid should remain intact (deflection). We begin with 500-m spherical asteroids but also extend our analysis to radar-derived asteroid shape models. [1] Dearborn, D.S.P., Miller, P.L., 2014. Deflecting or Disrupting a Threatening Object, in: Pelton, J.N., Allahdadi, F. (Eds.), Handbook of Cosmic Hazards and Planetary Defense, Springer. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52- 07NA27344. LLNL-ABS-699631.

Meteoroid Impact Ejecta Detection by Nanosatellites for Asteroid Surface Characterization

NASA Astrophysics Data System (ADS)

Lee, N.; Close, S.; Goel, A.

2015-12-01

Asteroids are constantly bombarded by much smaller meteoroids at extremely high speeds, which results in erosion of the material on the asteroid surface. Some of this material is vaporized and ionized, forming a plasma that is ejected into the environment around the asteroid where it can be detected by a constellation of closely orbiting nanosatellites. We present a concept to leverage this natural phenomenon and to analyze this excavated material using low-power plasma sensors on nanosatellites in order to determine the composition of the asteroid surface. This concept would enable a constellation of nanosatellites to provide useful data complementing existing techniques such as spectroscopy, which require larger and more power-hungry sensors. Possible mission architectures include precursor exploratory missions using nanosatellites to survey and identify asteroid candidates worthy of further study by a large spacecraft, or simultaneous exploration by a nanosatellite constellation with a larger parent spacecraft to decrease the time required to cover the entire asteroid surface. The use of meteoroid impact plasma to analyze the surface composition of asteroids will not only produce measurements that have not been previously obtained, including the molecular composition of the surface, but will also yield a better measurement of the meteoroid flux in the vicinity of the asteroid. Current meteoroid models are poorly constrained beyond the orbit of Mars, due to scarcity of data. If this technology is used to survey asteroids in the main belt, it will offer a dramatic increase in the availability of meteoroid flux measurements in deep space, identifying previously unknown meteoroid streams and providing additional data to support models of solar system dust dynamics.

A cheaper, faster, better way to detect water of hydration on Solar System bodies

NASA Technical Reports Server (NTRS)

Vilas, Faith

1994-01-01

The 3.0-micrometers water of hydration absorption feature observed in the IR photometry of many low-albedo and some medium-albedo asteroids strongly correlates with the 0.7-micrometers Fe(+2) to Fe(+3) oxidized iron absorption feature observed in narrowband spectrophotometry of these asteroids. Using this relationship, an empirical algorithm for predicting the presence of water of hydration in the surface material of a Solar System body using photometry obtained through the Eight-Color Asteroid Survey nu (0.550 micrometers), w (0.701 micrometers), and x (0.853 micrometers) filters was developed and applied to the ECAS photometry of asteroids and outer planet satellites. The percentage of objects in low-albedo, outer main-belt asteroid classes that test positively for water of hydration increases from P to B to C to G class and correlates linearly with the increasing mean albedos of those objects testing positively. The medium-albedo M-class asteroids do not test positively in large number using this algorithm. Aqueously altered asteroids dominate the Solar System population between heliocentric distances of 2.6 to 3.5 AU, bracketing the Solar System region where the aqueous alteration mechanism operated most strongly. One jovian satellite, J VI Himalia, and one saturnian satellite. Phoebe, tested positively for water of hydration, supporting the hypothesis that these may be captured C-class asteroids from a postaccretional dispersion. The proposed testing technique could be applied to an Earth-based survey of asteroids or a space-probe study of an asteroid's surface characteristic in order to identify a potential water source.

A cheaper, faster, better way to detect water of hydration on Solar System bodies

NASA Astrophysics Data System (ADS)

Vilas, Faith

1994-10-01

The 3.0-micrometers water of hydration absorption feature observed in the IR photometry of many low-albedo and some medium-albedo asteroids strongly correlates with the 0.7-micrometers Fe(+2) to Fe(+3) oxidized iron absorption feature observed in narrowband spectrophotometry of these asteroids. Using this relationship, an empirical algorithm for predicting the presence of water of hydration in the surface material of a Solar System body using photometry obtained through the Eight-Color Asteroid Survey nu (0.550 micrometers), w (0.701 micrometers), and x (0.853 micrometers) filters was developed and applied to the ECAS photometry of asteroids and outer planet satellites. The percentage of objects in low-albedo, outer main-belt asteroid classes that test positively for water of hydration increases from P to B to C to G class and correlates linearly with the increasing mean albedos of those objects testing positively. The medium-albedo M-class asteroids do not test positively in large number using this algorithm. Aqueously altered asteroids dominate the Solar System population between heliocentric distances of 2.6 to 3.5 AU, bracketing the Solar System region where the aqueous alteration mechanism operated most strongly. One jovian satellite, J VI Himalia, and one saturnian satellite. Phoebe, tested positively for water of hydration, supporting the hypothesis that these may be captured C-class asteroids from a postaccretional dispersion. The proposed testing technique could be applied to an Earth-based survey of asteroids or a space-probe study of an asteroid's surface characteristic in order to identify a potential water source.

The Binary Asteroid in-situ Explorer (BASiX) Mission

NASA Astrophysics Data System (ADS)

Dissly, Richard; Scheeres, D. J.; Nilsen, E.; Roark, S.; Frazier, W.; Bank, T.; Rosing, D.; Jordan, E.; BASiX Science Team

2010-10-01

The Binary Asteroid in-situ Explorer (BASiX) Mission represents the next phase of asteroid exploration, carrying out geophysical experiments by active engagement with an asteroid in a controlled and repeatable manner. BASiX will address new and timely scientific goals that address unresolved issues at the heart of our understanding of these bodies and which serve as barriers to their future exploration. A primary objective of the BASiX Mission is to determine the fundamental mechanical and strength properties of an asteroid through the creation of craters on the asteroid surface using calibrated charges. BASiX also takes advantage of these experiments to further understand the weathering and seismic properties of an asteroid. By carrying out these experiments at a binary Near Earth Asteroid (NEA), BASiX also advances our understanding of these ubiquitous bodies in the small asteroid population. BASiX is an efficient and simple mission concept that can deliver revolutionary science with its threshold mission and adds substantial enhancements with its baseline mission. BASiX assembles an international team of top small body scientists and astronomers and is led by PI Dan Scheeres (University of Colorado). BASiX is managed by JPL, which is also where mission and science operations will be based. The BASiX Spacecraft is built by Ball Aerospace & Technologies Corp. Instruments are built by JPL and Ball with additional contributed instruments from CNES.

Asteroid Euphrosyne as Seen by WISE

NASA Image and Video Library

2015-08-03

The asteroid Euphrosyne glides across a field of background stars in this time-lapse view from NASA's WISE spacecraft. WISE obtained the images used to create this view over a period of about a day around May 17, 2010, during which it observed the asteroid four times. Because WISE (renamed NEOWISE in 2013) is an infrared telescope, it senses heat from asteroids. Euphrosyne is quite dark in visible light, but glows brightly at infrared wavelengths. This view is a composite of images taken at four different infrared wavelengths: 3.4 microns (color-coded blue), 4.6 microns (cyan), 12 microns (green) and 22 microns (red). The moving asteroid appears as a string of red dots because it is much cooler than the distant background stars. Stars have temperatures in the thousands of degrees, but the asteroid is cooler than room temperature. Thus the stars are represented by shorter wavelength (hotter) blue colors in this view, while the asteroid is shown in longer wavelength (cooler) reddish colors. The WISE spacecraft was put into hibernation in 2011 upon completing its goal of surveying the entire sky in infrared light. WISE cataloged three quarters of a billion objects, including asteroids, stars and galaxies. In August 2013, NASA decided to reinstate the spacecraft on a mission to find and characterize more asteroids. http://photojournal.jpl.nasa.gov/catalog/PIA19645

Evolutionary Pathways for Asteroid Satellites

NASA Astrophysics Data System (ADS)

Jacobson, Seth Andrew

2015-08-01

The YORP-induced rotational fission hypothesis is a proposed mechanism for the creation of small asteroid binaries, which make up approximately 1/6-th of the near-Earth asteroid and small Main Belt asteroid populations. The YORP effect is a radiative torque that rotationally accelerates asteroids on timescales of thousands to millions of years. As asteroids rotationally accelerate, centrifugal accelerations on material within the body can match gravitational accelerations holding that material in place. When this occurs, that material goes into orbit. Once in orbit that material coalesces into a companion that undergoes continued dynamical evolution.Observations with radar, photometric and direct imaging techniques reveal a diverse array of small asteroid satellites. These systems can be sorted into a number of morphologies according to size, multiplicity of members, dynamical orbit and spin states, and member shapes. For instance, singly synchronous binaries have short separation distances between the two members, rapidly rotating oblate primary members, and tidally locked prolate secondary members. Other confirmed binary morphologies include doubly synchronous, tight asynchronous and wide asynchronous binaries. Related to these binary morphologies are unbound paired asteroid systems and bi-lobate contact binaries.A critical test for the YORP-induced rotational fission hypothesis is whether the binary asteroids produced evolve to the observed binary and related systems. In this talk I will review how this evolution is believed to occur according to gravitational dynamics, mutual body tides and the binary YORP effect.

New candidates for active asteroids: Main-belt (145) Adeona, (704) Interamnia, (779) Nina, (1474) Beira, and near-Earth (162,173) Ryugu

NASA Astrophysics Data System (ADS)

Busarev, Vladimir V.; Makalkin, Andrei B.; Vilas, Faith; Barabanov, Sergey I.; Scherbina, Marina P.

2018-04-01

For the first time, spectral signs of subtle coma activity were observed for four main-belt primitive asteroids (145) Adeona, (704) Interamnia, (779) Nina, and (1474) Beira around their perihelion distances in September 2012, which were interpreted as manifestations of the sublimation of H2O ice in/under the surface matter (Busarev et al., 2015a, 2015b). We confirm the phenomenon for Nina when it approached perihelion in September 2016. At the same time, based on results of spectral observations of near-Earth asteroid (162,173) Ryugu (Vilas, 2008) being a target of Japan's Hayabusa 2 space mission, we suspected a periodic similar transient activity on the Cg-type asteroid. However, unlike the main-belt primitive asteroids demonstrating sublimation of ices close to their perihelion distances, the effect on Ryugu was apparently registered near aphelion. To explain the difference, we calculated the subsolar temperature depending on heliocentric distance of the asteroids, considered qualitative models of internal structure of main-belt and near-Earth primitive asteroids including ice and performed some analytical estimations. Presumed temporal sublimation/degassing activity of Ryugu is a sign of a residual frozen core in its interior. This could be an indication of a relatively recent transition of the asteroid from the main asteroid belt to the near-Earth area.

Momentum harvesting techniques for solar system travel

NASA Technical Reports Server (NTRS)

Willoughby, Alan J.

1990-01-01

Astronomers are lately estimating there are 400,000 Earth visiting asteroids larger than 100 meters in diameter. These asteroids are accessible sources of building materials, propellants, oxygen, water, and minerals which also constitute a huge momentum reserve, potentially usable for travel throughout the solar system. To use this momentum, these stealthy objects must be tracked and the extraction of the momentum wanted must be learned. Momentum harvesting by momentum transfer from asteroid to spacecraft, and by using the momentum of the extraterrestrial material to help deliver itself to the destination are discussed. A net and tether concept is the suggested means of asteroid capture, the basic momentum exchange process. The energy damping characteristics of the tether will determine the velocity mismatch that can be tolerated, and hence the amount of momentum that can be harvested per capture. As it plays out of its reel, drag on the tether steadily accelerates the spacecraft. A variety of concepts for riding and using the asteroid after capture are discussed. The hitchhiker uses momentum transfer only. The beachcomber, the caveman, the swinger, the prospector, and the rock wrecker also take advantage of raw asteroidal materials. The chemist and the hijacker go further, they process the asteroid into propellant. Or, an 'asteroid railway system' could evolve with each hijacked asteroid becoming a scheduled train. Travelers could board the space railway system assured that water, oxygen, and propellants await them.

Solar Power at Play

NASA Astrophysics Data System (ADS)

2007-03-01

For the very first time, astronomers have witnessed the speeding up of an asteroid's rotation, and have shown that it is due to a theoretical effect predicted but never seen before. The international team of scientists used an armada of telescopes to discover that the asteroid's rotation period currently decreases by 1 millisecond every year, as a consequence of the heating of the asteroid's surface by the Sun. Eventually it may spin faster than any known asteroid in the solar system and even break apart. ESO PR Photo 11a/07 ESO PR Photo 11a/07 Asteroid 2000 PH5 "The Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect is believed to alter the way small bodies in the Solar System rotate," said Stephen Lowry (Queens University Belfast, UK), lead-author of one of the two companion papers in which this work is reported [1, 2]. "The warming caused by sunlight hitting the surfaces of asteroids and meteoroids leads to a gentle recoil effect as the heat is released," he added. "By analogy, if one were to shine light on a propeller over a long enough period, it would start spinning." Although this is an almost immeasurably weak force, its effect over millions of years is far from negligible. Astronomers believe the YORP effect may be responsible for spinning some asteroids up so fast that they break apart, perhaps leading to the formation of double asteroids. Others may be slowed down so that they take many days to complete a full turn. The YORP effect also plays an important role in changing the orbits of asteroids between Mars and Jupiter, including their delivery to planet-crossing orbits, such as those of near-Earth asteroids. Despite its importance, the effect has never been seen acting on a solar system body, until now. Using extensive optical and radar imaging from powerful Earth-based observatories, astronomers have directly observed the YORP effect in action on a small near-Earth asteroid, known as (54509) 2000 PH5. Shortly after its discovery in 2000, it was realised that asteroid 2000 PH5 would be the ideal candidate for such a YORP detection. With a diameter of just 114 metres, it is relatively small and so more susceptible to the effect. Also, it rotates very fast, with one 'day' on the asteroid lasting just over 12 Earth minutes, implying that the YORP effect may have been acting on it for some time. With this in mind, the team of astronomers undertook a long term monitoring campaign of the asteroid with the aim of detecting any tiny changes in its rotation speed. Over a 4-year time span, Stephen Lowry, Alan Fitzsimmons and colleagues took images of the asteroid at a range of telescope sites including ESO's 8.2-m Very Large Telescope array and 3.5-m New Technology Telescope in Chile, the 3.5-m telescope at Calar Alto, Spain, along with a suite of other telescopes from the Czech Republic, the Canary Islands, Hawaii, Spain and Chile. With these facilities the astronomers measured the slight brightness variations as the asteroid rotated. ESO PR Photo 11b/07 ESO PR Photo 11b/07 Radar Images of 2000 PH5 Over the same time period, the radar team led by Patrick Taylor and Jean-Luc Margot of Cornell University employed the unique capabilities of the Arecibo Observatory in Puerto Rico and the Goldstone radar facility in California to observe the asteroid by 'bouncing' a radar pulse off the asteroid and analysing its echo. "With this technique we can reconstruct a 3-D model of the asteroid's shape, with the necessary detail to allow a comparison between the observations and theory," said Taylor. After careful analysis of the optical data, the asteroid's spin rate was seen to steadily increase with time, at a rate that can be explained by the YORP theory. Critically, the effect was observed year after year, for more than 4 years. Furthermore, this number was elegantly supported via analysis of the combined radar and optical data, as it was required that the asteroid is increasing its spin rate at exactly this rate in order for a satisfactory 3-D shape model to be determined. ESO PR Video 11/07 ESO PR Video 11c/07 Watch the Asteroid Move! To predict what will happen to the asteroid in the future, Lowry and his colleagues performed detailed computer simulations using the measured strength of the YORP effect and the detailed shape model. They found that the orbit of the asteroid about the Sun could remain stable for up to the next 35 million years, allowing the rotation period to be reduced by a factor of 36, to just 20 seconds, faster than any asteroid whose rotation has been measured until now. "This exceptionally fast spin-rate could force the asteroid to reshape itself or even split apart, leading to the birth of a new double system," said Lowry.

Ultrastructure of myocardial widened Z bands and endocardial cells in two teleostean species.

PubMed

Leknes, I L

1981-01-01

Widened myocardial Z bands and endocardial cells are described in two teleostean species Cichlasoma meeki and Corydoras aeneus. Widened Z bands containing mainly amorphous and electron-dense material were seen in a number of myocardial cells. Further, similar material may occur in large amounts beneath the sarcolemma and at intercellular junctions. Occasionally, we observed continuity between the latter material and that in expanded Z bands. In C. meeki the ventricular endocardial layer consists of two structurally different cell types, whereas in C. aeneus only one cell type was seen. The functional aspects of widened Z bands are discussed.

Injecting asteroid fragments into resonances

NASA Technical Reports Server (NTRS)

Farinella, Paolo; Gonczi, R.; Froeschle, Christiane; Froeschle, Claude

1992-01-01

We have quantitatively modeled the chance insertion of asteroid collisional fragments into the 3:1 and g = g(sub 6) resonances, through which they can achieve Earth-approaching orbits. Although the results depend on some poorly known parameters, they indicate that most meteorites and near-earth asteroids probably come from a small and non-representative sample of asteroids, located in the neighborhood of the two resonances.

Abstracts for the International Conference on Asteroids, Comets, Meteors 1991

NASA Technical Reports Server (NTRS)

1991-01-01

Topics addressed include: chemical abundances; asteroidal belt evolution; sources of meteors and meteorites; cometary spectroscopy; gas diffusion; mathematical models; cometary nuclei; cratering records; imaging techniques; cometary composition; asteroid classification; radio telescopes and spectroscopy; magnetic fields; cosmogony; IUE observations; orbital distribution of asteroids, comets, and meteors; solar wind effects; computerized simulation; infrared remote sensing; optical properties; and orbital evolution.

Most stony meteorites come from the asteroid belt

NASA Technical Reports Server (NTRS)

Anders, E.

1978-01-01

The presence of trapped solar gas in stony meteorites places their origin in the regoliths of asteroidal-type bodies. The most plausible sources are the C (carbonaceous) and S (siliceous) asteroids, in spite of the differences between the spectra of S asteroids and ordinary chondrites. This problem is a central one for the interpretation of both astronomical observations and dynamical theory.

Did Earth-approaching asteroids 3551, 3908, or 4055 produce meteorites?

NASA Technical Reports Server (NTRS)

Gustafson, Bo A. S.; Williams, I. P.

1992-01-01

Orbital integrations show that Amor asteroid 3908 could have ejected one out of four plausible groups of meteorite producing fireballs during a collision in the asteroid belt. It was suggested by others that such a collision may also have split asteroids 3551 and 3908. A member of this group of fireballs is listed as one of the better possibilities for recovery.

The Palomar planet-crossing asteroid survey, 1973-1978

USGS Publications Warehouse

Helin, E.F.; Shoemaker, E.M.

1979-01-01

Photographic coverage of about 80,000 deg2 of sky with the Palomar 46-cm Schmidt camera has yielded 12 new planet-crossing asteroids as well as many objects in the main asteroid belt. The estimated population of planet-crossing asteroids includes ???100 Atens, 700 ?? 300 Apollos, 1000-2000 Amors, 10,000 ?? 5000 Mars crossers, and ???5000 Mars grazers. ?? 1979.

Geography of the asteroid belt

NASA Technical Reports Server (NTRS)

Zellner, B. H.

1978-01-01

The CSM classification serves as the starting point on the geography of the asteroid belt. Raw data on asteroid types are corrected for observational biases (against dark objects, for instance) to derive the distribution of types throughout the belt. Recent work on family members indicates that dynamical families have a true physical relationship, presumably indicating common origin in the breakup of a parent asteroid.

Evolution of the orbit of asteroid 4179 Toutatis over 11,550 years.

NASA Astrophysics Data System (ADS)

Zausaev, A. F.; Pushkarev, A. N.

1994-05-01

The Everhart method is used to study evolution of the orbit of the asteroid 4179 Toutatis, a member of the Apollo group, over the time period 9300 B.C. to 2250 A.D. Minimum asteroid-Earth distances during the evolution process are calculated. It is shown that the asteroid presents no danger to the Earth over the interval studied.

Identification and Calculation of the Three-Dimensional Orbit of an Asteroid

ERIC Educational Resources Information Center

Pereira, Vincent; Millan, Justin; Martin, Emerick

2013-01-01

Asteroids are clumps of rock, the sizes of which range from less than a kilometer to a few hundred kilometers in diameter. They are generally found in the unusually large gap between Mars and Jupiter. There are probably more than 40,000 asteroids in this gap called the "asteroid belt." In this paper we describe our efforts in confirming…

Deflection by Kinetic Impact or Nuclear Ablation: Sensitivity to Asteroid Properties

NASA Astrophysics Data System (ADS)

Bruck Syal, M.

2015-12-01

Impulsive deflection of a threatening asteroid can be achieved by deploying either a kinetic impactor or a standoff nuclear device to impart a modest velocity change to the body. Response to each of these methods is sensitive to the individual asteroid's characteristics, some of which may not be well constrained before an actual deflection mission. Numerical simulations of asteroid deflection, using both hypervelocity impacts and nuclear ablation of the asteroid's surface, provide detailed information on asteroid response under a range of initial conditions. Here we present numerical results for the deflection of asteroids by both kinetic and nuclear methods, focusing on the roles of target body composition, strength, porosity, rotational state, shape, and internal structure. These results provide a framework for evaluating the planetary defense-related value of future asteroid characterization missions and capture some of the uncertainty that may be present in a real threat scenario. Part of this work was funded by the Laboratory Directed Research and Development Program at LLNL under project tracking code 12-ERD-005, performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-675914.

Catching a Rolling Stone: Dynamics and Control of a Spacecraft and an Asteroid

NASA Technical Reports Server (NTRS)

Roithmayr, Carlos M.; Shen, Haijun; Jesick, Mark C; Cornelius, David M

2013-01-01

In a recent report, a robotic spacecraft mission is proposed for the purpose of collecting a small asteroid, or a small part of a large one, and transporting it to an orbit in the Earth-Moon system. Such an undertaking will require solutions to many of the engineering problems associated with deflection of an asteroid that poses a danger to Earth. In both cases, it may be necessary for a spacecraft to approach an asteroid from a nearby position, hover for some amount of time, move with the same angular velocity as the asteroid, descend, perhaps ascend, and finally arrest the angular velocity of the asteroid. Dynamics and control in each of these activities is analyzed in order to determine the velocity increments and control torque that must be provided by a reaction control system, and the mass of the propellant that will be consumed. Two attitude control algorithms are developed, one to deal with synchronizing the spacecraft s angular velocity with that of the asteroid, and the other to arrest the asteroid s angular velocity. A novel approach is proposed for saving fuel in the latter case.

Multiple-hopping trajectories near a rotating asteroid

NASA Astrophysics Data System (ADS)

Shen, Hong-Xin; Zhang, Tian-Jiao; Li, Zhao; Li, Heng-Nian

2017-03-01

We present a study of the transfer orbits connecting landing points of irregular-shaped asteroids. The landing points do not touch the surface of the asteroids and are chosen several meters above the surface. The ant colony optimization technique is used to calculate the multiple-hopping trajectories near an arbitrary irregular asteroid. This new method has three steps which are as follows: (1) the search of the maximal clique of candidate target landing points; (2) leg optimization connecting all landing point pairs; and (3) the hopping sequence optimization. In particular this method is applied to asteroids 433 Eros and 216 Kleopatra. We impose a critical constraint on the target landing points to allow for extensive exploration of the asteroid: the relative distance between all the arrived target positions should be larger than a minimum allowed value. Ant colony optimization is applied to find the set and sequence of targets, and the differential evolution algorithm is used to solve for the hopping orbits. The minimum-velocity increment tours of hopping trajectories connecting all the landing positions are obtained by ant colony optimization. The results from different size asteroids indicate that the cost of the minimum velocity-increment tour depends on the size of the asteroids.

Rotational Study of Ambiguous Taxonomic Classified Asteroids

NASA Astrophysics Data System (ADS)

Linder, Tyler R.; Sanchez, Rick; Wuerker, Wolfgang; Clayson, Timothy; Giles, Tucker

2017-01-01

The Sloan Digital Sky Survey (SDSS) moving object catalog (MOC4) provided the largest ever catalog of asteroid spectrophotometry observations. Carvano et al. (2010), while analyzing MOC4, discovered that individual observations of asteroids which were observed multiple times did not classify into the same photometric-based taxonomic class. A small subset of those asteroids were classified as having both the presence and absence of a 1um silicate absorption feature. If these variations are linked to differences in surface mineralogy, the prevailing assumption that an asteroid’s surface composition is predominantly homogenous would need to be reexamined. Furthermore, our understanding of the evolution of the asteroid belt, as well as the linkage between certain asteroids and meteorite types may need to be modified.This research is an investigation to determine the rotational rates of these taxonomically ambiguous asteroids. Initial questions to be answered:Do these asteroids have unique or nonstandard rotational rates?Is there any evidence in their light curve to suggest an abnormality?Observations were taken using PROMPT6 a 0.41-m telescope apart of the SKYNET network at Cerro Tololo Inter-American Observatory (CTIO). Observations were calibrated and analyzed using Canopus software. Initial results will be presented at AAS.

Laser Simulations of the Destructive Impact of Nuclear Explosions on Hazardous Asteroids

NASA Astrophysics Data System (ADS)

Aristova, E. Yu.; Aushev, A. A.; Baranov, V. K.; Belov, I. A.; Bel'kov, S. A.; Voronin, A. Yu.; Voronich, I. N.; Garanin, R. V.; Garanin, S. G.; Gainullin, K. G.; Golubinskii, A. G.; Gorodnichev, A. V.; Denisova, V. A.; Derkach, V. N.; Drozhzhin, V. S.; Ericheva, I. A.; Zhidkov, N. V.; Il'kaev, R. I.; Krayukhin, A. A.; Leonov, A. G.; Litvin, D. N.; Makarov, K. N.; Martynenko, A. S.; Malinov, V. I.; Mis'ko, V. V.; Rogachev, V. G.; Rukavishnikov, A. N.; Salatov, E. A.; Skorochkin, Yu. V.; Smorchkov, G. Yu.; Stadnik, A. L.; Starodubtsev, V. A.; Starodubtsev, P. V.; Sungatullin, R. R.; Suslov, N. A.; Sysoeva, T. I.; Khatunkin, V. Yu.; Tsoi, E. S.; Shubin, O. N.; Yufa, V. N.

2018-01-01

We present the results of preliminary experiments at laser facilities in which the processes of the undeniable destruction of stony asteroids (chondrites) in space by nuclear explosions on the asteroid surface are simulated based on the principle of physical similarity. We present the results of comparative gasdynamic computations of a model nuclear explosion on the surface of a large asteroid and computations of the impact of a laser pulse on a miniature asteroid simulator confirming the similarity of the key processes in the fullscale and model cases. The technology of fabricating miniature mockups with mechanical properties close to those of stony asteroids is described. For mini-mockups 4-10 mm in size differing by the shape and impact conditions, we have made an experimental estimate of the energy threshold for the undeniable destruction of a mockup and investigated the parameters of its fragmentation at a laser energy up to 500 J. The results obtained confirm the possibility of an experimental determination of the criteria for the destruction of asteroids of various types by a nuclear explosion in laser experiments. We show that the undeniable destruction of a large asteroid is possible at attainable nuclear explosion energies on its surface.

Near Earth Asteroid redirect missions based on gravity assist maneuver

NASA Astrophysics Data System (ADS)

Ledkov, Anton; Shustov, Boris M.; Eismont, Natan; Boyarsky, Michael; Nazirov, Ravil; Fedyaev, Konstantin

During last years several events attracted world community attention to the hazards of hitting the Earth by sky objects. One of these objects is Apophis asteroid what was expected with nonzero probability to hit the Earth in 2036. Luckily after more precise measurements this event is considered as practically improbable. But the other object has really reached the Earth, entered the atmosphere in the Chelyabinsk area and caused vast damages. After this the hazardous near Earth objects problem received practical confirmation of the necessity to find the methods of its resolution. The methods to prevent collision of the dangerous sky object with the Earth proposed up to now look not practical enough if one mentions such as gravitational tractor or changing the reflectivity of the asteroid surface. Even the method supposing the targeting of the spacecraft to the hazardous object in order to deflect it from initial trajectory by impact does not work because its low mass as compared with the mass of asteroid to be deflected. For example the mass of the Apophis is estimated to be about 40 million tons but the spacecraft which can be launched to intercept the asteroid using contemporary launchers has the mass not more than 5 tons. So the question arises where to find the heavier projectile which is possible to direct to the dangerous object? The answer proposed in our paper is very simple: to search it among small near Earth asteroids. As small ones we suppose those which have the cross section size not more than 12-15 meters and mass not exceeding 1500 -1700 tons. According to contemporary estimates the number of such asteroids is not less than 100000. The other question is how to redirect such asteroid to the dangerous one. In the paper the possibilities are studied to use for that purpose gravity assist maneuvers near Earth. It is shown that even among asteroids included in contemporary catalogue there are the ones which could be directed to the trajectory of the gravity assist maneuver near Earth resulted by following impact with dangerous asteroid. As example of the last one the Apophis was chosen. The required delta-V pulse to be applied to the candidate projectile asteroid to fulfill mentioned change of initial trajectory was confirmed to be comparatively small: not exceeding 10 m/s, and the smallest is about 2 m/s. To fulfilled this maneuver it is necessary to land and to mount on the surface of the asteroid projectile the spacecraft with sufficient amount of propellant onboard. The possible trajectories and demanded maneuvers were explored and it was confirmed that for contemporary space technology it is doable for the small asteroids belonging to the determined by our studies list of candidates supposing some reservations, namely the mass of the found asteroids. This was not considered as decisive obstacle because up to now only about 1% of small enough asteroids are included in catalogue so the list of the appropriate ones is far from to be closed. The studies have been fulfilled aimed to develop the methods to reached required accuracies of asteroid projectile trajectory parameters determination. With existing methods used for the usual spacecraft the limits of achievable accuracies demand the corrections delta-V maneuvers which may exceed the nominal ones. As a result the proposed conception of hazardous asteroids deflection becomes problematic. To overcome this obstacle in the paper new method of trajectory parameters determination is proposed and explored. Practically it is radio interferometer method when one transponder is placed on the asteroid target and two others together with the asteroid projectile form tetrahedron. This system begins to operate in vicinity of target asteroid in autonomous regime and expected to allow reaching the demanded low enough correction maneuver values. Paper gives the estimations of the accuracy of these three bodies relative motion parameters and expected limit values of correction maneuvers needed for hitting the target object. As additional option of planetary defense system construction the idea to redirect small near Earth asteroids onto the orbits resonance with the Earth orbit is explored. It is shown that it is possible to reach it by the use gravity assist maneuvers as it was described above by applying small velocity impulses to the asteroids. At least 11 asteroids were found demanded small enough delta-V for transferring them on such trajectories. After executing these maneuvers one can receive the system of asteroids approaching to the Earth practically each month with a possibility to use them as projectiles or for the purposes of delivering to the Earth their soil samples.

Simulations of hypervelocity impacts for asteroid deflection studies

NASA Astrophysics Data System (ADS)

Heberling, T.; Ferguson, J. M.; Gisler, G. R.; Plesko, C. S.; Weaver, R.

2016-12-01

The possibility of kinetic-impact deflection of threatening near-earth asteroids will be tested for the first time in the proposed AIDA (Asteroid Impact Deflection Assessment) mission, involving two independent spacecraft, NASAs DART (Double Asteroid Redirection Test) and ESAs AIM (Asteroid Impact Mission). The impact of the DART spacecraft onto the secondary of the binary asteroid 65803 Didymos, at a speed of 5 to 7 km/s, is expected to alter the mutual orbit by an observable amount. The velocity imparted to the secondary depends on the geometry and dynamics of the impact, and especially on the momentum enhancement factor, conventionally called beta. We use the Los Alamos hydrocodes Rage and Pagosa to estimate beta in laboratory-scale benchmark experiments and in the large-scale asteroid deflection test. Simulations are performed in two- and three-dimensions, using a variety of equations of state and strength models for both the lab-scale and large-scale cases. This work is being performed as part of a systematic benchmarking study for the AIDA mission that includes other hydrocodes.

BILLIARDS: A Demonstration Mission for Hundred-Meter Class Near Earth Asteroid Disruption

NASA Technical Reports Server (NTRS)

Marcus, Matthew; Sloane, Joshua; Ortiz, Oliver; Barbee, Brent W.

2015-01-01

Currently, no planetary defense demonstration mission has ever been flown. While Nuclear Explosive Devices (NEDs) have significantly more energy than a kinetic impactor launched directly from Earth, they present safety and political complications, and therefore may only be used when absolutely necessary. The Baseline Instrumented Lithology Lander, Inspector, and Asteroid Redirection Demonstration System (BILLIARDS) is a demonstration mission for planetary defense, which is capable of delivering comparable energy to the lower range of NED capabilities in the form of a safer kinetic impactor. A small asteroid (<10m) is captured by a spacecraft, which greatly increases the mass available as a kinetic impactor, without the need to bring all of the mass out of Earth's gravity well. The small asteroid is then deflected onto a collision course with a larger (approx. 100m) asteroid. This collision will deflect or disrupt the larger asteroid. To reduce the cost and complexity, an asteroid pair which has a natural close approach is selected.

Hydrated Minerals on Asteroids: The Astronomical Record

NASA Technical Reports Server (NTRS)

Rivkin, A. S.; Howell, E. S.; Vilas, F.; Lebofsky, L. A.

2002-01-01

Knowledge of the hydrated mineral inventory on the asteroids is important for deducing the origin of Earth's water, interpreting the meteorite record, and unraveling the processes occurring during the earliest times in solar system history. Reflectance spectroscopy shows absorption features in both the 0.6-0.8 and 2.5-3.5 micrometers regions, which are diagnostic of or associated with hydrated minerals. Observations in those regions show that hydrated minerals are common in the mid-asteroid belt, and can be found in unexpected spectral groupings, as well. Asteroid groups formerly associated with mineralogies assumed to have high temperature formation, such as M- and E-class asteroids, have been observed to have hydration features in their reflectance spectra. Some asteroids have apparently been heated to several hundred degrees Celsius, enough to destroy some fraction of their phyllosilicates. Others have rotational variation suggesting that heating was uneven. We summarize this work, and present the astronomical evidence for water- and hydroxyl-bearing minerals on asteroids.

Near-Earth object intercept trajectory design for planetary defense

NASA Astrophysics Data System (ADS)

Vardaxis, George; Wie, Bong

2014-08-01

Tracking the orbit of asteroids and planning for asteroid missions have ceased to be a simple exercise, and become more of a necessity, as the number of identified potentially hazardous near-Earth asteroids increases. Several software tools such as Mystic, MALTO, Copernicus, SNAP, OTIS, and GMAT have been developed by NASA for spacecraft trajectory optimization and mission design. However, this paper further expands upon the development and validation of an Asteroid Mission Design Software Tool (AMiDST), through the use of approach and post-encounter orbital variations and analytic keyhole theory. Combining these new capabilities with that of a high-precision orbit propagator, this paper describes fictional mission trajectory design examples of using AMiDST as applied to a fictitious asteroid 2013 PDC-E. During the 2013 IAA Planetary Defense Conference, the asteroid 2013 PDC-E was used for an exercise where participants simulated the decision-making process for developing deflection and civil defense responses to a hypothetical asteroid threat.

Rotation Studies of Jovian Trojan Asteroids

NASA Astrophysics Data System (ADS)

French, Linda M.; Stephens, Robert D.; Wasserman, Lawrence H.; Lederer, Susan M.; Rohl, Derrick A.

2011-08-01

The Jovian Trojan asteroids appear to be fundamentally different from main belt asteroids. They formed further from the sun, they are of different composition, and their collisional history is different. Lightcurve studies provide information about the distribution of rotation frequencies of a group of asteroids. For main belt asteroids larger than about 40 km in diameter, the distribution of rotation frequencies is Maxwellian (Pravec et al. 2000). This suggests that collisions determine their rotation properties. Smaller main belt asteroids, however, show a predominance of both fast and slow rotators, with the observed spin distribution apparently controlled by the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect (Pravec et al. 2008). The Trojans larger than 100 km in diameter have been almost completely sampled, but lightcurves for smaller Trojans have been less well studied due to their low albedos and greater solar distances. We propose to investigate the rotation periods of 4-6 small (D < 50 km) Trojan asteroids and 6-9 Trojans in the 50-100 km size range.

Ground-based observation of near-Earth asteroids

NASA Technical Reports Server (NTRS)

Gaffey, Michael J.

1992-01-01

An increased ground-based observation program is an essential component of any serious attempt to assess the resource potential of near-Earth asteroids. A vigorous search and characterization program could lead to the discovery and description of about 400 to 500 near-Earth asteroids in the next 20 years. This program, in conjunction with meteorite studies, would provide the data base to ensure that the results of a small number of asteroid-rendezvous and sample-return missions could be extrapolated with confidence into a geological base map of the Aten, Apollo, and Amor asteroids. Ground-based spectral studies of nearly 30 members of the Aten/Apollo/Amor population provide good evidence that this class includes bodies composed of silicates, metal-silicates, and carbonaceous assemblages similar to those found in meteorites. The instruments that are being used or could be used to search for near-Earth asteroids are listed. Techniques useful in characterizing asteroids and the types of information obtainable using these techniques are listed.

Potential Mission Scenarios Post Asteroid Crewed Mission

NASA Technical Reports Server (NTRS)

Lopez, Pedro, Jr.; McDonald, Mark A.

2015-01-01

A deep-space mission has been proposed to identify and redirect an asteroid to a distant retrograde orbit around the moon, and explore it by sending a crew using the Space Launch System and the Orion spacecraft. The Asteroid Redirect Crewed Mission (ARCM), which represents the third segment of the Asteroid Redirect Mission (ARM), could be performed on EM-3 or EM-4 depending on asteroid return date. Recent NASA studies have raised questions on how we could progress from current Human Space Flight (HSF) efforts to longer term human exploration of Mars. This paper will describe the benefits of execution of the ARM as the initial stepping stone towards Mars exploration, and how the capabilities required to send humans to Mars could be built upon those developed for the asteroid mission. A series of potential interim missions aimed at developing such capabilities will be described, and the feasibility of such mission manifest will be discussed. Options for the asteroid crewed mission will also be addressed, including crew size and mission duration.

Dynamical Evolution of Asteroids and Meteoroids Using the Yarkovsky Effect

NASA Technical Reports Server (NTRS)

Bottke, William F., Jr.; Vokrouhlicky, David; Rubincam, David P.; Broz, Miroslav; Smith, David E. (Technical Monitor)

2001-01-01

The Yarkovsky effect is a thermal radiation force which causes objects to undergo semimajor axis drift and spin up/down as a function of their spin, orbit, and material properties. This mechanism can be used to (i) deliver asteroids (and meteoroids) with diameter D < 20 km from their parent bodies in the main belt to chaotic resonance zones capable of transporting this material to Earth-crossing orbits, (ii) disperse asteroid families, with drifting bodies jumping or becoming trapped in mean-motion and secular resonances within the main belt, and (iii) modify the rotation rates of asteroids a few km in diameter or smaller enough to explain the excessive number of very fast and very slow rotators among the small asteroids. Accordingly, we suggest that nongravitational forces, which produce small but meaningful effects on asteroid orbits and rotation rates over long timescales, should now be considered as important as collisions and gravitational perturbations to our overall understanding of asteroid evolution.

Aqueous alteration on main belt primitive asteroids: Results from visible spectroscopy

NASA Astrophysics Data System (ADS)

Fornasier, S.; Lantz, C.; Barucci, M. A.; Lazzarin, M.

2014-05-01

This work focuses on the study of the aqueous alteration process which acted in the main belt and produced hydrated minerals on the altered asteroids. Hydrated minerals have been found mainly on Mars surface, on main belt primitive asteroids and possibly also on few TNOs. These materials have been produced by hydration of pristine anhydrous silicates during the aqueous alteration process, that, to be active, needed the presence of liquid water under low temperature conditions (below 320 K) to chemically alter the minerals. The aqueous alteration is particularly important for unraveling the processes occurring during the earliest times of the Solar System history, as it can give information both on the asteroids thermal evolution and on the localization of water sources in the asteroid belt. To investigate this process, we present reflected light spectral observations in the visible region (0.4-0.94 μm) of 80 asteroids belonging to the primitive classes C (prevalently), G, F, B and P, following the Tholen (Tholen, D.J. [1984]. Ph.D. Dissertation, University of Arizona, Tucson). classification scheme. We find that about 65% of the C-type and all the G-type asteroids investigated reveal features suggesting the presence of hydrous materials, mainly a band centered around 0.7 μm, while we do not find evidence of hydrated materials in the other low albedo asteroids (B, F, and P) investigated. We combine the present observations with the visible spectra of asteroids available in the literature for a total of 600 primitive main belt asteroids. We analyze all these spectra in a similar way to characterize the absorption band parameters (band center, depth and width) and spectral slope, and to look for possible correlations between the aqueous alteration process and the asteroids taxonomic classes, orbital elements, heliocentric distances, albedo and sizes. Our analysis shows that the aqueous alteration sequence starts from the P-type objects, practically unaltered, and increases through the P → F → B → C → G asteroids, these last being widely aqueous altered, strengthening thus the results previously obtained by Vilas (Vilas, F. [1994]. Icarus 111, 456-467). Around 50% of the observed C-type asteroids show absorption feature in the visible range due to hydrated silicates, implying that more than ∼70% of them will have a 3 μm absorption band and thus hydrated minerals on their surfaces, based on correlations between those two absorptions (Howell, E.S. et al. [2011]. EPSC-DPS Joint Meeting 2011, vol. 6. Abstracts, 637). We find that the aqueous alteration process dominates in primitive asteroids located between 2.3 and 3.1 AU, that is at smaller heliocentric distances than previously suggested by Vilas et al. (Vilas, F., Hatch, E.C., Larson, S.M., Sawyer, S.R., Gaffey, M.J. [1993]. Icarus 102, 225-231). The percentage of hydrated asteroids is strongly correlated with their size. The aqueous alteration process is less effective for bodies smaller than 50 km, while it dominates in the 50-240 km sized primitive asteroids. No correlation is found between the aqueous alteration process and the asteroids albedo or orbital elements. Comparing the ∼0.7 μm band parameters of hydrated silicates and CM2 carbonaceous chondrites, the meteorites that have aqueous altered asteroids as parent bodies, we see that the band center of meteorites is at longer wavelengths than that of asteroids. This difference on center positions may be attributed to different minerals abundances, and to the fact that CM2 available on Earth might not be representative of the whole aqueous altered asteroids population.

Planetary geology: Impact processes on asteroids

NASA Technical Reports Server (NTRS)

Chapman, C. R.; Davis, D. R.; Greenberg, R.; Weidenschilling, S. J.

1982-01-01

The fundamental geological and geophysical properties of asteroids were studied by theoretical and simulation studies of their collisional evolution. Numerical simulations incorporating realistic physical models were developed to study the collisional evolution of hypothetical asteroid populations over the age of the solar system. Ideas and models are constrained by the observed distributions of sizes, shapes, and spin rates in the asteroid belt, by properties of Hirayama families, and by experimental studies of cratering and collisional phenomena. It is suggested that many asteroids are gravitationally-bound "rubble piles.' Those that rotate rapidly may have nonspherical quasi-equilibrium shapes, such as ellipsoids or binaries. Through comparison of models with astronomical data, physical properties of these asteroids (including bulk density) are determined, and physical processes that have operated in the solar system in primordial and subsequent epochs are studied.

Sensitivity of the Asteroid Redirect Robotic Mission (ARRM) to Launch Date and Asteroid Stay Time

NASA Technical Reports Server (NTRS)

Mcguire, Melissa L.; Burke, Laura M.; McCarty, Steven L.; Strange, Nathan J.; Qu, Min; Shen, Haijun; Vavrina, Matthew A.

2017-01-01

National Aeronautics and Space Administrations (NASAs) proposed Asteroid Redirect Mission (ARM) is being designed to robotically capture and then redirect an asteroidal boulder into a stable orbit in the vicinity of the moon, where astronauts would be able to visit and study it. The current reference trajectory for the robotic portion, ARRM, assumes a launch on a Delta-IV H in the end of the calendar year 2021, with a return for astronaut operations in cislunar space in 2026. The current baseline design allocates 245 days of stay time at the asteroid for operations and boulder collection. This paper outlines analysis completed by the ARRM mission design team to understand the sensitivity of the reference trajectory to launch date and asteroid stay time.

Sensitivity of the Asteroid Redirect Robotic Mission (ARRM) to Launch Date and Asteroid Stay Time

NASA Technical Reports Server (NTRS)

Mcguire, Melissa L.; Burke, Laura M.; McCarty, Steven L.; Strange, Nathan J.; Qu, Min; Shen, Haijun; Vavrina, Matthew A.

2017-01-01

National Aeronautics and Space Administrations (NASAs) proposed Asteroid Redirect Mission (ARM) is being designed to robotically capture and then redirect an asteroidal boulder mass into a stable orbit in the vicinity of the moon, where astronauts would be able to visit and study it. The current reference trajectory for the robotic portion, ARRM, assumes a launch on a Delta IV H in the end of the calendar year 2021, with a return for astronaut operations in cislunar space in 2026. The current baseline design allocates 245 days of stay time at the asteroid for operations and boulder collection. This paper outlines analysis completed by the ARRM mission design team to understand the sensitivity of the reference trajectory to launch date and asteroid stay time.

Volatiles in asteroids

NASA Astrophysics Data System (ADS)

Campins, H.

2014-07-01

For more than three decades, hydrated minerals have been identified in asteroids. The distribution of these minerals among asteroid spectral types and heliocentric distance has been somewhat unexpected, and there is also diversity in the composition of these hydrated minerals (e.g., Takir and Emery 2012). In addition, water ice and organic molecules have been detected on two asteroids (Campins et al. 2010; Rivkin and Emery 2010; Licandro et al. 2011) and water vapor is emanating from (1) Ceres (Küppers et al. 2014). These discoveries have important implications on current views of primitive asteroids, the nature of active asteroids or main-belt comets, the dynamics of the early Solar System, and the delivery of water and organic molecules to the Earth. They are also relevant to several space missions, including Dawn, Gaia, Hayabusa2, OSIRIS-REx ,and WISE.

Taxonomy of asteroids. [according to polarimetric, spectrophotometric, radiometric, and UBV photometric data

NASA Technical Reports Server (NTRS)

Bowell, E.; Chapman, C. R.; Gradie, J. C.; Zellner, B.; Morrison, D.

1978-01-01

A taxonomic system for asteroids is discussed which is based on seven directly observable parameters from polarimetry, spectrophotometry, radiometry, and UBV photometry. The classification scheme is entirely empirical and independent of specific mineralogical interpretations. Five broad classes (designated C, S, M, E, and R), as well as an 'unclassifiable' designation, are defined on the basis of observational data for 523 asteroids. Computer-generated type classifications and derived diameters are given for the 523 asteroids, and the application of the classification procedure is illustrated. Of the 523 asteroids classified, 190 are identified as C objects, 141 as S type, 13 as type M, three as type E, three as type R, 55 as unclassifiable, and 118 as ambiguous. The present taxonomic system is compared with several other asteroid classification systems.

Visual and near-IR spectrophotometry of asteroids

NASA Technical Reports Server (NTRS)

Lebofsky, Larry A.

1991-01-01

We have been continuing our studies of the spectral properties of dark asteroids in the solar system. From these studies we expect to learn about the distribution of volatile materials, such as water in clay materials (water of hydration) and how the asteroids may relate to the comets. Our most recent work has been concentrating on simultaneous visual and near infrared photometry near Earth, main belt, and trojan asteroids. We have made observations of some unusual asteroids such as Chiron, which has recently shown cometary activity, and 944 Hidalgo, which has a comet-like orbit. We have also begun studies of the small, dark satellites of Mars and Jupiter in order to understand better how they may relate to the steroids. Could they actually be captured asteroids or comets?

Hungaria asteroid region telescopic spectral survey (HARTSS) I: Stony asteroids abundant in the Hungaria background population

NASA Astrophysics Data System (ADS)

Lucas, Michael P.; Emery, Joshua P.; Pinilla-Alonso, Noemi; Lindsay, Sean S.; Lorenzi, Vania

2017-07-01

The Hungaria asteroids remain as survivors of late giant planet migration that destabilized a now extinct inner portion of the primordial asteroid belt and left in its wake the current resonance structure of the Main Belt. In this scenario, the Hungaria region represents a ;purgatory; for the closest, preserved samples of the asteroidal material from which the terrestrial planets accreted. Deciphering the surface composition of these unique samples may provide constraints on the nature of the primordial building blocks of the terrestrial planets. We have undertaken an observational campaign entitled the Hungaria Asteroid Region Telescopic Spectral Survey (HARTSS) to record near-infrared (NIR) reflectance spectra in order to characterize their taxonomy, surface mineralogy, and potential meteorite analogs. The overall objective of HARTSS is to evaluate the compositional diversity of asteroids located throughout the Hungaria region. This region harbors a collisional family of Xe-type asteroids, which are situated among a background (i.e., non-family) of predominantly S-complex asteroids. In order to assess the compositional diversity of the Hungaria region, we have targeted background objects during Phase I of HARTSS. Collisional family members likely reflect the composition of one original homogeneous parent body, so we have largely avoided them in this phase. We have employed NIR instruments at two ground-based telescope facilities: the NASA Infrared Telescope Facility (IRTF), and the Telescopio Nazionale Galileo (TNG). Our data set includes the NIR spectra of 42 Hungaria asteroids (36 background; 6 family). We find that stony S-complex asteroids dominate the Hungaria background population (29/36 objects; ∼80%). C-complex asteroids are uncommon (2/42; ∼5%) within the Hungaria region. Background S-complex objects exhibit considerable spectral diversity as band parameter measurements of diagnostic absorption features near 1- and 2-μm indicate that several different S-subtypes are represented therein, which translates to a variety of surface compositions. We identify the Gaffey S-subtype (Gaffey et al. [1993]. Icarus 106, 573-602) and potential meteorite analogs for 24 of these S-complex background asteroids. Additionally, we estimate the olivine and orthopyroxene mineralogy for 18 of these objects using spectral band parameter analysis established from laboratory-based studies of ordinary chondrite meteorites. Nine of the asteroids have band parameters that are not consistent with ordinary chondrites. We compared these to the band parameters measured from laboratory VIS+NIR spectra of six primitive achondrite (acapulcoite-lodranite) meteorites. These comparisons suggest that two main meteorite groups are represented among the Hungaria background asteroids: unmelted, nebular L- (and possibly LL-ordinary chondrites), and partially-melted primitive achondrites of the acapulcoite-lodranite meteorite clan. Our results suggest a source region for L chondrite like material from within the Hungarias, with delivery to Earth via leakage from the inner boundary of the Hungaria region. H chondrite like mineralogies appear to be absent from the Hungaria background asteroids. We therefore conclude that the Hungaria region is not a source for H chondrite meteorites. Seven Hungaria background asteroids have spectral band parameters consistent with partially-melted primitive achondrites, but the probable source region of the acapulcoite-lodranite parent body remains inconclusive. If the proposed connection with the Hungaria family to fully-melted enstatite achondrite meteorites (i.e., aubrites) is accurate (Gaffey et al. [1992]. Icarus 100, 95-109; Kelley and Gaffey [2002]. Meteorit. Planet. Sci. 37, 1815-1827), then asteroids in the Hungaria region exhibit a full range of petrologic evolution: from nebular, unmelted ordinary chondrites, through partially-melted primitive achondrites, to fully-melted igneous aubrite meteorites.

Images of an Activated Asteroid

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2016-08-01

In late April of this year, asteroid P/2016 G1 (PANSTARRS) was discovered streaking through space, a tail of dust extending behind it. What caused this asteroids dust activity?Asteroid or Comet?Images of asteroid P/2016 G1 at three different times: late April, late May, and mid June. The arrow in the center panel points out an asymmetric feature that can be explained if the asteroid initially ejected material in a single direction, perhaps due to an impact. [Moreno et al. 2016]Asteroid P/2016 G1 is an interesting case: though it has the orbital elements of a main-belt asteroid it orbits at just under three times the EarthSun distance, with an eccentricity of e ~ 0.21 its appearance is closer to that of a comet, with a dust tail extending 20 behind it.To better understand the nature and cause of this unusual asteroids activity, a team led by Fernando Moreno (Institute of Astrophysics of Andalusia, in Spain) performed deep observations of P/2016 G1 shortly after its discovery. The team used the 10.4-meter Great Canary Telescope to image the asteroid over the span of roughly a month and a half.A Closer Look at P/2016 G1P/2016 G1 lies in the inner region of the main asteroid belt, so it is unlikely to have any ices that suddenly sublimated, causing the outburst. Instead, Moreno and collaborators suggest that the asteroids tail may have been caused by an impact that disrupted the parent body.To test this idea, the team used computer simulations to model their observations of P/2016 G1s dust tail. Based on their models, they demonstrate that the asteroid was likely activated on February 10 2016 roughly 350 days before it reached perihelion in its orbit and its activity was a short-duration event, lasting only ~24 days. The teams models indicate that over these 24 days, the asteroid lost around 20 million kilograms of dust, and at its maximum activity level, it was ejecting around 8 kg/s!Comparison of the observation from late May (panel a) and two models: one in which the emission is all isotropic (panel b), and one in which the emission is initially directed (panel c). The second model better fits the observations. [Adapted from Moreno et al. 2016]Activation By ImpactTo reproduce the observed asymmetric features in the asteroids tail, Moreno and collaborators show that the ejected material could not have been completely isotropically emitted. Instead, the observations can be reproduced if the material was initially ejected all in the same direction (away from the Sun) at the time of the asteroids activation.These conclusions support the idea that the asteroids parent body was impacted by another object. The initial impact caused a large ejection of material, and the subsequent activity is due to the partial or total disruption of the asteroid as a result of the impact.To further test this model for P/2016 G1, the next step is to obtain higher-resolution and higher-sensitivity imaging (as could be provided by Hubble) of this unusual object. Such images would allow scientists to search for smaller fragments of the parent body that could remain near the dust tail.CitationF. Moreno et al 2016 ApJ 826 L22. doi:10.3847/2041-8205/826/2/L22

Overview of Mission Design for NASA Asteroid Redirect Robotic Mission Concept

NASA Technical Reports Server (NTRS)

Strange, Nathan; Landau, Damon; McElrath, Timothy; Lantoine, Gregory; Lam, Try; McGuire, Melissa; Burke, Laura; Martini, Michael; Dankanich, John

2013-01-01

Part of NASA's new asteroid initiative would be a robotic mission to capture a roughly four to ten meter asteroid and redirect its orbit to place it in translunar space. Once in a stable storage orbit at the Moon, astronauts would then visit the asteroid for science investigations, to test in space resource extraction, and to develop experience with human deep space missions. This paper discusses the mission design techniques that would enable the redirection of a 100-1000 metric ton asteroid into lunar orbit with a 40-50 kW Solar Electric Propulsion (SEP) system.

Near-Earth and near-Mars asteroids: Prognosis of pyroxene types

NASA Technical Reports Server (NTRS)

Shestopalov, D. I.; Golubeva, L. F.

1991-01-01

The diagnostic signs of ferrous absorption band at 505nm and color index (u-x) found at main-belt asteroids and 6-parametric classification of light stone meteorites have been the basis of the work. The colorimetric data of light near-Earth and near-Mars asteroids from TRIAD and ECAS were analyzed. Composition fields of pyroxenes were obtained for these asteroids by the value of (u-x) and 505-nm ferrous absorption band position within the pyroxenes quadrilateral. Pyroxenes of the S-asteroids from Apollo-Amor which have spectral parameters similar to achondrites may be presented by the diopside series.

Post Deflection Impact Risk Analysis of the Double Asteroid Redirection Test (DART)

NASA Astrophysics Data System (ADS)

Eggl, S.; Hestroffer, D.

2017-09-01

Collisions between potentially hazardous near-Earth objects and our planet are among the few natural disasters that can be avoided by human intervention. The complexity of such an endeavor necessitates an asteroid orbit deflection test mission, however, ensuring all relevant knowledge is present when an asteroid on a collision course with the Earth is indeed discovered. The double asteroid redirection test (DART) mission concept currently investigated by NASA would serve such a purpose. The aim of our research is to make certain that DART does not turn a previously harmless asteroid into a potentially dangerous one.

Phyllosilicate absorption features in main-belt and outer-belt asteroid reflectance spectra.

PubMed

Vilas, F; Gaffey, M J

1989-11-10

Absorption features having depths up to 5% are identified in high-quality, high-resolution reflectance spectra of 16 dark asteroids in the main belt and in the Cybele and Hilda groups. Analogs among the CM2 carbonaceous chondrite meteorites exist for some of these asteroids, suggesting that these absorptions are due to iron oxides in phyllosilicates formed on the asteroidal surfaces by aqueous alteration processes. Spectra of ten additional asteroids, located beyond the outer edge of the main belt, show no discernible absorption features, suggesting that aqueous alteration did not always operate at these heliocentric distances.

Phyllosilicate absorption features in main-belt and outer-belt asteroid reflectance spectra

NASA Technical Reports Server (NTRS)

Vilas, Faith; Gaffey, Michael J.

1989-01-01

Absorption features having depths up to 5 percent are identified in high-quality, high-resolution reflectance spectra of 16 dark asteroids in the main belt and in the Cybele and Hilda groups. Analogs among the CM2 carbonaceous chondrite meteorites exist for some of these asteroids, suggesting that these absorptions are due to iron oxides in phyllosilicates formed on the asteroidal surfaces by aqueous alteration processes. Spectra of ten additional asteroids, located beyond the outer edge of the main belt, show no discernible absorption features, suggesting that aqueous alteration did not always operate at these heliocentric distances.

Photometric geodesy of main-belt asteroids. III - Additional lightcurves

NASA Technical Reports Server (NTRS)

Weidenschilling, S. J.; Chapman, C. R.; Davis, D. R.; Greenberg, R.; Levy, D. H.

1990-01-01

A total of 107 complete or partial lightcurves are presented for 59 different asteroids over the 1982-1989 period. Unusual lightcurves with unequal minima and maxima at large amplitudes are preferentially seen for M-type asteroids. Some asteroids, such as 16 Psyche and 201 Penelope, exhibit lightcurves combining large amplitude with very unequal brightness for both maxima and both minima, even at small phase angles. An M-type asteroid is believed to consist of a metal core of a differentiated parent body that has had its rocky mantle completely removed by one or more large impacts.

Asteroid Initiative Industry and Partner Day

NASA Image and Video Library

2013-06-18

NASA Associate Administrator Science John Grunsfeld, Ph.D, displays a fragment of the Pallasite meteorite from Chubut, Argentina found in 1951 and given to him by his daughter on Father's Day during the Asteroid Initiative Industry and Partner Day at NASA Headquarters on Tuesday, June 18, 2013 in Washington. During the event NASA Deputy Administrator Lori Garver and other senior NASA officials discussed the progress being made on NASA's mission to capture, redirect, and explore an asteroid. NASA also announced an Asteroid Grand Challenge focused on finding all asteroid threats to human populations and knowing what to do about them. Photo Credit: (NASA/Bill Ingalls)

Reflectance spectrophotometry (about 0.5-1.0 micron) of oute-belt asteroids - Implications for primitive, organic solar system material

NASA Technical Reports Server (NTRS)

Vilas, F.; Smith, B. A.

1985-01-01

The surface compositions of outer-belt asteroids were used to obtain information about the origin of these asteroids. High-resolution CCD reflectance spectra of 21 asteroids, primarily P class, were examined for compositional information. Distinct slope changes are observed that suggest that these asteroids are the remnants of a compositional gradation of planetesimals in the outer solar system, which were retained selectively in location when other material was ejected from the solar system. Other data suggest that this gradation could extend through the orbits of Uranus and Neptune.

The nature of C-class asteroids from 3-micron spectrophotometry

NASA Technical Reports Server (NTRS)

Feierberg, M. A.; Lebofsky, L. A.; Tholen, D. J.

1985-01-01

Narrowband spectrophotometry between 2.3 and 3.5 micrometers is presented for 14 main-belt C asteroids greater than 100 km in diameter. Absorption features at 3 micrometers due to water of hydration are present in the spectra of nine of the asteroids, with intensities ranging from 6 to 23 percent. The other five asteroids have no such absorption greater than 2 percent in intensity. The present C-asteroid population may be fragments of larger parent bodies with anhydrous C3-like cores and hydrated C1I- or C2M-like mantles.

The hierarchical stability of the seven known large size ratio triple asteroids using the empirical stability parameters.

PubMed

Liu, Xiaodong; Baoyin, Hexi; Marchis, Franck

In this study, the hierarchical stability of the seven known large size ratio triple asteroids is investigated. The effect of the solar gravity and primary's J 2 are considered. The force function is expanded in terms of mass ratios based on the Hill's approximation and the large size ratio property. The empirical stability parameters are used to examine the hierarchical stability of the triple asteroids. It is found that the all the known large size ratio triple asteroid systems are hierarchically stable. This study provides useful information for future evolutions of the triple asteroids.

Photometric geodesy of main-belt asteroids. III. Additional lightcurves

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weidenschilling, S.J.; Chapman, C.R.; Davis, D.R.

1990-08-01

A total of 107 complete or partial lightcurves are presented for 59 different asteroids over the 1982-1989 period. Unusual lightcurves with unequal minima and maxima at large amplitudes are preferentially seen for M-type asteroids. Some asteroids, such as 16 Psyche and 201 Penelope, exhibit lightcurves combining large amplitude with very unequal brightness for both maxima and both minima, even at small phase angles. An M-type asteroid is believed to consist of a metal core of a differentiated parent body that has had its rocky mantle completely removed by one or more large impacts. 39 refs.

Why Did the Black-White Dropout Gap Widen in the 2000s?

ERIC Educational Resources Information Center

Suh, Suhyun; Malchow, Ashley; Suh, Jingyo

2014-01-01

This research investigates causes of the widening Black-White gap in dropout rates during the 2000s using two cohorts of National Longitudinal Surveys of Youth, NLSY79 and NLSY97. The authors found four factors which contributed to the widening of the Black-White gap: school suspension policies, peer impact, fatherless households, and the…

Good Students, Bad Pupils: Constructions of "Aspiration", "Disadvantage" and Social Class in Undergraduate-Led Widening Participation Work

ERIC Educational Resources Information Center

Taylor, Yvette

2008-01-01

This C-SAP funded research explores undergraduate student involvement in widening participation initiatives at a traditional university and the ways that students promote and market their university and higher education more generally. It seeks to explore the widening participation messages disseminated by students in their work with pupils and…

Science case for the Asteroid Impact Mission (AIM): A component of the Asteroid Impact & Deflection Assessment (AIDA) mission

NASA Astrophysics Data System (ADS)

Michel, Patrick; Cheng, A.; Küppers, M.; Pravec, P.; Blum, J.; Delbo, M.; Green, S. F.; Rosenblatt, P.; Tsiganis, K.; Vincent, J. B.; Biele, J.; Ciarletti, V.; Hérique, A.; Ulamec, S.; Carnelli, I.; Galvez, A.; Benner, L.; Naidu, S. P.; Barnouin, O. S.; Richardson, D. C.; Rivkin, A.; Scheirich, P.; Moskovitz, N.; Thirouin, A.; Schwartz, S. R.; Campo Bagatin, A.; Yu, Y.

2016-06-01

The Asteroid Impact & Deflection Assessment (AIDA) mission is a joint cooperation between European and US space agencies that consists of two separate and independent spacecraft that will be launched to a binary asteroid system, the near-Earth asteroid Didymos, to test the kinetic impactor technique to deflect an asteroid. The European Asteroid Impact Mission (AIM) is set to rendezvous with the asteroid system to fully characterize the smaller of the two binary components a few months prior to the impact by the US Double Asteroid Redirection Test (DART) spacecraft. AIM is a unique mission as it will be the first time that a spacecraft will investigate the surface, subsurface, and internal properties of a small binary near-Earth asteroid. In addition it will perform various important technology demonstrations that can serve other space missions. The knowledge obtained by this mission will have great implications for our understanding of the history of the Solar System. Having direct information on the surface and internal properties of small asteroids will allow us to understand how the various processes they undergo work and transform these small bodies as well as, for this particular case, how a binary system forms. Making these measurements from up close and comparing them with ground-based data from telescopes will also allow us to calibrate remote observations and improve our data interpretation of other systems. With DART, thanks to the characterization of the target by AIM, the mission will be the first fully documented impact experiment at asteroid scale, which will include the characterization of the target's properties and the outcome of the impact. AIDA will thus offer a great opportunity to test and refine our understanding and models at the actual scale of an asteroid, and to check whether the current extrapolations of material strength from laboratory-scale targets to the scale of AIDA's target are valid. Moreover, it will offer a first check of the validity of the kinetic impactor concept to deflect a small body and lead to improved efficiency for future kinetic impactor designs. This paper focuses on the science return of AIM, the current knowledge of its target from ground-based observations, and the instrumentation planned to get the necessary data.

NEOCAM: Near Earth Object Chemical Analysis Mission: Bridging the Gulf between Telescopic Observations and the Chemical and Mineralogical Compositions of Asteroids or Diogenes A: Diagnostic Observation of the Geology of Near Earth Spectrally-Classified Asteroids

NASA Technical Reports Server (NTRS)

Nuth, Joseph A.

2009-01-01

Studies of meteorites have yielded a wealth of scientific information based on highly detailed chemical and isotopic studies possible only in sophisticated terrestrial laboratories. Telescopic studies have revealed an enormous (greater than 10(exp 5)) number of physical objects ranging in size from a few tens of meters to several hundred kilometers, orbiting not only in the traditional asteroid belt between Mars and Jupiter but also throughout the inner solar system. Many of the largest asteroids are classed into taxonomic groups based on their observed spectral properties and are designated as C, D. X, S or V types (as well as a wide range in sub-types). These objects are certainly the sources far the meteorites in our laboratories, but which asteroids are the sources for which meteorites? Spectral classes are nominally correlated to the chemical composition and physical characteristics of the asteroid itself based on studies of the spectral changes induced in meteorites due to exposure to a simulated space environment. While laboratory studies have produced some notable successes (e.g. the identification of the asteroid Vesta as the source of the H, E and D meteorite classes), it is unlikely that we have samples of each asteroidal spectral type in our meteorite collection. The correlation of spectral type and composition for many objects will therefore remain uncertain until we can return samples of specific asteroid types to Earth for analyses. The best candidates for sample return are asteroids that already come close to the Earth. Asteroids in orbit near 1 A.U. have been classified into three groups (Aten, Apollo & Amor) based on their orbital characteristics. These Near Earth Objects (NEOs) contain representatives of virtually all spectral types and sub-types of the asteroid population identified to date. Because of their close proximity to Earth, NEOs are prime targets for asteroid missions such as the NEAR-Shoemaker NASA Discovery Mission to Eros and the Japanese Hyabusa Mission to Itokawa. Also due to their close proximity to Earth, NEOs constitute the most likely set of celestial objects that will impact us in the relatively near future.

Seven Near-Earth Asteroids at Asteroids Observers (OBAS) - MMPD: 2017 Jan-May

NASA Astrophysics Data System (ADS)

Fornas, Gonzalo; Carreño, Alfonso; Arce, Enrique; Flores, Angel; Mas, Vincente; Rodrigo, Onofre; Brines, Pedro; Fornas, Alvaro; Herrero, David; Lozano, Juan

2018-01-01

We report on the photometric analysis result of seven near-Earth asteroids (NEA) by Asteroides Observers (OBAS). This work is part of the Minor Planet Photometric Database effort that was initiated by a group of Spanish amateur astronomers. We have managed to obtain a number of accurate and complete lightcurves as well as some additional incomplete lightcurves to help analysis at future oppositions.

Experiments on asteroids using hard landers

NASA Technical Reports Server (NTRS)

Turkevich, A.; Economou, T.

1978-01-01

Hard lander missions to asteroids are examined using the Westphal penetrator study as a basis. Imagery and chemical information are considered to be the most significant science to be obtained. The latter, particularly a detailed chemical analysis performed on an uncontaminated sample, may answer questions about the relationships of asteroids to meteorites and the place of asteroids in theories of the formation of the solar system.

Asteroid Detection Results Using the Space Surveillance Telescope

DTIC Science & Technology

2015-10-18

Distribution Statement A: Approved for public release, distribution unlimited. Asteroid Detection Results Using the Space Surveillance Telescope...issued a series of directives to the National Air and Space Administration (NASA), setting Near-Earth Asteroid (NEA) search and discovery targets in...order to protect the Earth and its inhabitants from the threat of asteroid impact. The focus of the original 1998 Congressional mandate was to catalog

Spin vectors of asteroids 21 Lutetia, 196 Philomela, 250 Bettina, 337 Devosa, and 804 Hispania

NASA Technical Reports Server (NTRS)

Michalowski, Tadeusz

1992-01-01

Such parameters as shape, orientation of spin axis, prograde or retrograde rotation are important for understanding the collisional evolution of asteroids since the primordial epochs of solar system history. These parameters remain unknown for most asteroids and poorly constrained for all but a few. This work presents results for five asteroids: 21, 196, 250, 337, and 804.

Planetary astronomy program

NASA Technical Reports Server (NTRS)

Chapman, C. R.; Hartmann, W. K.

1978-01-01

Observations and analyses of asteroids, Trojans and cometary nuclei are presented. Spectrophotometry was used to observe the cometary nuclei. The spectra are plotted as a function of semimajor axis and eccentricity. Trojans and other asteroids at great solar distances show a variety of spectra, many of them quite red despite the low measured albedoes for many of these asteroids. The asteroid spectra are grouped according to diameter and taxonomic class.

Asteroid Lightcurve Analysis at CS3-Palmer Divide Station: 2017 April thru June

NASA Astrophysics Data System (ADS)

Warner, Brian D.

2017-10-01

Lightcurves for 16 main-belt asteroids were obtained at the Center for Solar System Studies-Palmer Divide Station (CS3-PDS) from 2017 April thru June. Many of the asteroids were “strays” in the field of planned targets, demonstrating a good reason for data mining images. Analysis shows that the Hungaria asteroid (45878) 2000 WX29 may be binary.

Figure of Merit for Asteroid Regolith Simulants

NASA Astrophysics Data System (ADS)

Metzger, P.; Britt, D.; Covey, S.; Lewis, J. S.

2017-09-01

High fidelity asteroid simulant has been developed, closely matching the mineral and elemental abundances of reference meteorites representing the target asteroid classes. The first simulant is a CI class based upon the Orgueil meteorite, and several other simulants are being developed. They will enable asteroid mining and water extraction tests, helping mature the technologies for space resource utilization for both commercial and scientific/exploration activities in space.

Asteroid Lightcurve Analysis at CS3-Palmer Divide Station: 2016 December thru 2017 March

NASA Astrophysics Data System (ADS)

Warner, Brian D.

2017-07-01

Lightcurves for 18 main-belt asteroids were obtained at the Center for Solar System Studies-Palmer Divide Station (CS3-PDS) from 2016 December thru 2017 March. Many of the asteroids were “strays” in the field of planned targets, demonstrating a good reason for data mining images. Analysis shows that the Hungaria asteroid (45878) 2000 WX29 may be binary.

Laboratory Simulations of Space Weathering of Asteroid Surfaces by Solar Wind Ions.

NASA Astrophysics Data System (ADS)

Miller, Kenneth A.; De Ruette, Nathalie; Harlow, George; Domingue, Deborah L.; Savin, Daniel Wolf

2014-06-01

Studies into the formation of the terrestrial planets rely on the analysis of asteroids and meteorites. Asteroids are solar system remnants from the planetary formation period. By characterizing their mineralogical composition we can better constrain the formation and evolution of the inner planets.Remote sensing is the primary means for studying asteroids. Sample return missions, such as Hayabusa, are complex and expensive, hence we rely on asteroid reflectance spectra to determine chemical composition. Links have been made and debated between meteorite classes and asteroid types [1, 2]. If such relationships can be confirmed, then meteorites would provide a low cost asteroid sample set for study. However, a major issue in establishing this link is the spectral differences between meteorite samples and asteroid surfaces. The most commonly invoked explanation for these differences is that the surfaces of asteroids are space weathered [2, 3]. The dominant mechanism for this weathering is believed to be solar-wind ion irradiation [2, 4, 5]. Laboratory simulations of space weathering have demonstrated changes in the general direction required to alter spectra from unweathered meteorite samples to asteroid observations [3, 6 -10], but many open questions remain and we still lack a comprehensive understanding. We propose to explore the alleged connection of ordinary chondrite (OC) meteorites to S-type asteroids through a series of systematic laboratory simulations of solar-wind space weathering of asteroid surface materials. Here we describe the issue in more detail and describe the proposed apparatus. [1] Chapman C. R. (1996) Meteorit. Planet. Sci., 31, 699-725. [2] Chapman C. R. (2004), Annu. Rev. Earth Planet. Sci., 32, 539-567. [3] Hapke B. (2001) J. Ge-ophys. Res., 106, 10039-10074. [4] Pieters C.M. et al. (2000) Meteorit. Planet. Sci., 35, 1101-1107. [5] Ver-nazza P. et al. (2009) Nature, 458, 993-995. [6] Stra-zulla G. et al. (2005) Icarus, 174, 31-35 (2005). [7] Brunetto R and Strazzulla G (2005) Icarus, 179, 265-273. [8] Marchi S et al. (2005) Astron. Astrophys., 443, 769-775. [9] Loeffler M. J. et al. (2009) J. Geo-phys. Res., 114, E03003. [10] Fu X. et al. (2012) Ica-rus, 219, 630-640

DOE Office of Scientific and Technical Information (OSTI.GOV)

Usui, Fumihiko; Hasegawa, Sunao; Matsuhara, Hideo

We present an analysis of the albedo properties of main belt asteroids (MBAs) detected by the All-Sky Survey of the infrared astronomical satellite AKARI. The characteristics of 5120 asteroids detected by the survey, including their sizes and albedos, were cataloged in the Asteroid Catalog Using AKARI (AcuA). Size and albedo measurements were based on the standard thermal model, using inputs of infrared fluxes and absolute magnitudes measured at optical wavelengths. MBAs, which account for 4722 of the 5120 AcuA asteroids, have semimajor axes of 2.06-3.27 AU, except for the near-Earth asteroids. AcuA provides a complete data set of all MBAsmore » brighter than the absolute magnitude of H < 10.3, which corresponds to the diameter of d > 20 km. We confirmed that the albedo distribution of the MBAs is strongly bimodal as was already known from the past observations, and that the bimodal distribution occurs not only in the total population, but also within inner, middle, and outer regions of the main belt. The bimodal distribution in each group consists of low-albedo components in C-type asteroids and high-albedo components in S-type asteroids. We found that the small asteroids have much more variety in albedo than the large asteroids. In spite of the albedo transition process like space weathering, the heliocentric distribution of the mean albedo of asteroids in each taxonomic type is nearly flat. The mean albedo of the total, on the other hand, gradually decreases with an increase in semimajor axis. This can be explained by the compositional ratio of taxonomic types; that is, the proportion of dark asteroids such as C- and D-types increases, while that of bright asteroids such as S-type decreases, with increasing heliocentric distance. The heliocentric distributions of X-subclasses: E-, M-, and P-types, which can be divided based on albedo values, are also examined. P-types, which are the major component in X-types, are distributed throughout the main belt regions, and the abundance of P-types increases beyond 3 AU. This distribution is similar to that of C- or D-types.« less

Building Blocks of the Terrestrial Planets: Mineralogy of Hungaria Asteroids

NASA Astrophysics Data System (ADS)

Lucas, Michael; Emery, J. P.

2013-10-01

Deciphering the mineralogy of the Hungaria asteroids has the potential to place constraints on the material from which the terrestrial planets accreted. Among asteroids with semi-major axes interior to the main-belt (e.g., Hungarias, Mars-crossers, and near-Earth asteroids), only the Hungarias are located in relatively stable orbital space. Hungaria asteroids have likely resided in this orbital space since the planets completed their migration to their current orbits. The accretion and igneous differentiation of primitive asteroids appears to be a function of chronology and heliocentric distance. However, differentiated bodies that originated in the terrestrial planet region were either accreted or scattered out of this region early in solar system history. Thus, the Hungaria asteroids represent the closest reservoir of in situ material to the terrestrial planet region from early in solar system history. We present VISNIR 0.45-2.45 µm) and NIR spectra 0.65-2.45 µm) spectra of 24 Hungaria group (objects in similar orbital space) asteroids. Our NIR data (17 objects) were acquired using the InfraRed Telescope Facility and was supplemented with available visible data. Spectra of seven objects were obtained from the MIT-UH-IRTF survey. We distinguish our sample between Hungaria family (presumed fragments of parent 434 Hungaria; 2 objects) and Hungaria background (group minus family 22 objects) asteroids using proper orbital elements. The classification of each asteroid is determined using the taxonomy of Bus-DeMeo. We find that S- and S-subtypes are prevalent among the Hungaria background population (17/22). Spectral band parameters measurements (i.e., Band I and Band II centers and depths, and Band Area Ratio) indicate that eight of these S-types are analogous with undifferentiated ordinary chondrites (SIV “boot” of S-subtypes plot). Mafic silicate mineral abundances and compositions derived for these SIV asteroids mainly correlate with L chondrites. However, one object is an SIII subtype (possible ureilite analog), while two asteroids are SVI subtypes (possible primitive achondrite analog). Family member 6447 Terrycole is a Xe-type, consistent with the taxonomic classification of the parent 434 Hungaria.

Water in the Early Solar System: Infrared Studies of Aqueously Altered and Minimally Processed Asteroids

NASA Astrophysics Data System (ADS)

McAdam, Margaret M.

This thesis investigates connections between low albedo asteroids and carbonaceous chondrite meteorites using spectroscopy. Meteorites and asteroids preserve information about the early solar system including accretion processes and parent body processes active on asteroids at these early times. One process of interest is aqueous alteration. This is the chemical reaction between coaccreted water and silicates producing hydrated minerals. Some carbonaceous chondrites have experienced extensive interactions with water through this process. Since these meteorites and their parent bodies formed close to the beginning of the Solar System, these asteroids and meteorites may provide clues to the distribution, abundance and timing of water in the Solar nebula at these times. Chapter 2 of this thesis investigates the relationships between extensively aqueously altered meteorites and their visible, near and mid-infrared spectral features in a coordinated spectral-mineralogical study. Aqueous alteration is a parent body process where initially accreted anhydrous minerals are converted into hydrated minerals in the presence of coaccreted water. Using samples of meteorites with known bulk properties, it is possible to directly connect changes in mineralogy caused by aqueous alteration with spectral features. Spectral features in the mid-infrared are found to change continuously with increasing amount of hydrated minerals or degree of alteration. Building on this result, the degrees of alteration of asteroids are estimated in a survey of new asteroid data obtained from SOFIA and IRTF as well as archived the Spitzer Space Telescope data. 75 observations of 73 asteroids are analyzed and presented in Chapter 4. Asteroids with hydrated minerals are found throughout the main belt indicating that significant ice must have been present in the disk at the time of carbonaceous asteroid accretion. Finally, some carbonaceous chondrite meteorites preserve amorphous iron-bearing materials that formed through disequilibrium condensation in the disk. These materials are readily destroyed in parent body processes so their presence indicates the meteorite/asteroid has undergone minimal parent body processes since the time of accretion. Presented in Chapter 3 is the spectral signature of meteorites that preserve significant amorphous iron-bearing materials and the identification of an asteroid, (93) Minerva, that also appears to preserve these materials.

Guided asteroid deflection by kinetic impact: Mapping keyholes to an asteroid's surface

NASA Astrophysics Data System (ADS)

Chesley, S.; Farnocchia, D.

2014-07-01

The kinetic impactor deflection approach is likely to be the optimal deflection strategy in most real-world cases, given the likelihood of decades of warning time provided by asteroid search programs and the probable small size of the next confirmed asteroid impact that would require deflection. However, despite its straightforward implementation, the kinetic impactor approach can have its effectiveness limited by the astrodynamics that govern the impactor spacecraft trajectory. First, the deflection from an impact is maximized when the asteroid is at perihelion, while an impact near perihelion can in some cases be energetically difficult to implement. Additionally, the asteroid change in velocity Δ V should aligned with the target's heliocentric velocity vector in order to maximize the deflection at a potential impact some years in the future. Thus the relative velocity should be aligned with or against the heliocentric velocity, which implies that the impactor and asteroid orbits should be tangent at the point of impact. However, for natural bodies such as meteorites colliding with the Earth, the relative velocity vectors tend to cluster near the sunward or anti- sunward directions, far from the desired direction. This is because there is generally a significant crossing angle between the orbits of the impactor and target and an impact at tangency is unusual. The point is that hitting the asteroid is not enough, but rather we desire to hit the asteroid at a point when the asteroid and spacecraft orbits are nearly tangent and when the asteroid is near perihelion. However, complicating the analysis is the fact that the impact of a spacecraft on an asteroid would create an ejecta plume that is roughly normal to the surface at the point of impact. This escaping ejecta provides additional momentum transfer that generally adds to the effectiveness of a kinetic deflection. The ratio β between the ejecta momentum and the total momentum (ejecta plus spacecraft) can range from around 1 for a porous, compressible body producing negligible ejecta, to 2 when the ejecta momentum matches the spacecraft momentum, and as high as 5--10 for rocky bodies that produce large, high-velocity ejecta fragments. If the impactor hits the centerpoint of a spherical asteroid the momentum of the escaping ejecta directly adds to the momentum of the impacting asteroid, but if the impact is oblique then the ejecta and spacecraft momenta are added to the asteroid in vector sum. This suggests the possibility that for a given intercept trajectory the asteroid deflection could include guidance by targeting an oblique impact that could steer the asteroid Δ V to a more optimal direction that is different from the relative velocity direction of the spacecraft. An oblique impact decreases the net Δ V magnitude, and yet could significantly increase the net deflection at the time of the threatening Earth encounter. We use asteroid (101955) Bennu, which is the target of the OSIRIS-REx asteroid sample return mission and which has a series of potential Earth impacts in the years from 2175--2196, as an example to demonstrate the effectiveness of the oblique impact. These future potential impacts will occur if the asteroid passes through one of a series of keyholes when the asteroid passes the Earth at roughly the lunar distance from the Earth in 2135. To study the Bennu deflection problem we simulate a hypervelocity spacecraft impact on Bennu in March 2021, after the OSIRIS-REx mission is complete. In our example, the spacecraft arrives from approximately the sunward direction, and targeting ahead or behind the center of the asteroid allows non-negligible transverse accelerations for modest values of β. A given impact location on the asteroid surface yields a given Δ V vector, and our approach starts by mapping the net Δ V components on the surface for an assumed value of β. Knowing the mapping from impact location to Δ V and also the mapping from Δ V to the future Earth miss distance allows us to map the surface locations where a spacecraft impact would lead to an Earth impact 150--200 years later. In effect, we are able to project Earth impact trajectories, or keyholes, onto the asteroid surface and, for a given value of β, we can target our impactor spacecraft for an area on the surface that avoids potential Earth impacts. Of course, at the present time we have little information on what is the appropriate value or range of values for β in the case of asteroid Bennu, or any other asteroid for that matter. However, if this information is made known, either through a precursor mission or better inferences as to its nature we can develop a distribution of β that can be used to better design an impact deflection strategy. Specifically, we can compute a map of Earth impact probability density on the surface of the asteroid based on an assumed probability density function for β. If we target the lowest impact probability density regions then we maximize the chance of a successful deflection. This approach has the potential to allow more efficient kinetic impactor deflection, and therefore the deflection of larger bodies than would otherwise be possible.

Hydrodynamic Influence Dabanhu River Bridge Holes Widening Based on Two-Dimensional Finite Element Numerical Model

NASA Astrophysics Data System (ADS)

Li, Dong Feng; Bai, Fu Qing; Nie, Hui

2018-06-01

In order to analyze the influence of bridge holes widening on hydrodynamic such as water level, a two-dimensional mathematical model was used to calculate the hydrodynamic factors, river network flow velocity vector distribution is given, water level and difference of bridge widening before and after is calculated and charted, water surface gradient in seven different river sections near the upper reaches of bridges is counted and revealed. The results of hydrodynamic calculation indicate that The Maximum and the minimum deducing numerical value of the water level after bridge widening is 0.028m, and 0.018m respective. the seven sections water surface gradient becomes smaller until it becomes negative, the influence of bridge widening on the upstream is basically over, the range of influence is about 450m from the bridge to the upstream. reach

Hungaria Asteroid Region Telescopic Spectral Survey (HARTSS) II: Spectral Homogeneity Among Hungaria Family Asteroids

NASA Astrophysics Data System (ADS)

Lucas, Michael P.; Emery, Joshua; Pinilla-Alonso, Noemi; Lindsay, Sean S.; MacLennan, Eric M.; Cartwright, Richard; Reddy, Vishnu; Sanchez, Juan A.; Thomas, Cristina A.; Lorenzi, Vania

2017-10-01

Spectral observations of asteroid family members provide valuable information regarding parent body interiors, the source regions of near-Earth asteroids, and the link between meteorites and their parent bodies. Hungaria family asteroids constitute the closest samples to the Earth from a collisional family (~1.94 AU), permitting observations of smaller fragments than accessible for Main Belt families. We have carried out a ground-based observational campaign - Hungaria Asteroid Region Telescopic Spectral Survey (HARTSS) - to record reflectance spectra of these preserved samples from the inner-most primordial asteroid belt. During HARTSS phase one (Lucas et al. [2017]. Icarus 291, 268-287) we found that ~80% of the background population is comprised of stony S-complex asteroids that exhibit considerable spectral and mineralogical diversity. In HARTSS phase two, we turn our attention to family members and hypothesize that the Hungaria collisional family is homogeneous. We test this hypothesis through taxonomic classification, albedo estimates, and spectral properties.During phase two of HARTSS we acquired near-infrared (NIR) spectra of 50 new Hungarias (19 family; 31 background) with SpeX/IRTF and NICS/TNG. We analyzed X-type family spectra for NIR color indices (0.85-J J-K), and a subtle ~0.9 µm absorption feature that may be attributed to Fe-poor orthopyroxene. Surviving fragments of an asteroid collisional family typically exhibit similar taxonomies, albedos, and spectral properties. Spectral analysis of X-type Hungaria family members and independently calculated WISE albedo determinations for 428 Hungaria asteroids is consistent with this scenario. Furthermore, ~1/4 of the background population exhibit similar spectral properties and albedos to family X-types.Spectral observations of 92 Hungaria region asteroids acquired during both phases of HARTSS uncover a compositionally heterogeneous background and spectral homogeneity down to ~2 km for collisional family members. Taxonomy, albedos, and spectral properties reveal that the Hungaria family progenitor was an igneous body that formed under reduced conditions, and was compositionally consistent with the enstatite achondrite (i.e., aubrite) meteorite group.

ASTEROIDS: Living in the Kingdom of Chaos

NASA Astrophysics Data System (ADS)

Morbidelli, A.

2000-10-01

The existence of chaotic regions in the main asteroid belt, related with the lowest-order mean-motion and secular resonances, has long been known. However, only in the last decade have semi-analytic theories allowed a proper understanding of the chaotic behavior observed in numerical simulations which accurately incorporate the entire planetary system. The most spectacular result has been the discovery that the asteroids in some of these resonance may collide with the Sun on typical time scales of a few million year, their eccentricities being pumped to unity during their chaotic evolution. But the asteroid belt is not simply divided into violent chaotic zones and regular regions. It has been shown that the belt is criss-crossed by a large number of high-order mean-motion resonances with Jupiter or Mars, as well as by `three-body resonances' with Jupiter and Saturn. All these weak resonances cause the slow chaotic drift of the `proper' eccentricities and inclinations. The traces left by this evolution are visible, for example, in the structure of the Eos and Themis asteroid families. Weak chaos may also explain the anomalous dispersion of the eccentricities and inclinations observed in the Flora ``clan." Moreover, due to slow increases in their eccentricities, many asteroids start to cross the orbit of Mars, over a wide range of semimajor axes. The improved knowledge of the asteroid belt's chaotic structure provides, for the first time, an opportunity to build detailed quantitative models of the origin and the orbital distribution of Near-Earth Asteroids and meteorites. In turn, these models seem to imply that the semimajor axes of main-belt asteroids must also slowly evolve with time. For asteroids larger than about 20 km this is due mainly to encounters with Ceres, Pallas, and Vesta, while for smaller bodies the so-called Yarkovsky effect should dominate. Everything moves chaotically in the asteroid belt.

The Double Asteroid Redirection Test (DART)

NASA Astrophysics Data System (ADS)

Rivkin, A.; Cheng, A. F.; Stickle, A. M.; Richardson, D. C.; Barnouin, O. S.; Thomas, C.; Fahnestock, E.

2017-12-01

The Double Asteroid Redirection Test (DART) will be the first space experiment to demonstrate asteroid impact hazard mitigation by using a kinetic impactor. DART is currently in Preliminary Design Phase ("Phase B"), and is part of the Asteroid Impact and Deflection Assessment (AIDA), a joint ESA-NASA cooperative project. The AIDA target is the near-Earth binary asteroid 65803 Didymos, an S-class system that will make a close approach to Earth in fall 2022. The DART spacecraft is designed to impact the Didymos secondary at 6 km/s and demonstrate the ability to modify its trajectory through momentum transfer. The primary goals of AIDA are (1) perform a full-scale demonstration of the spacecraft kinetic impact technique for deflection of an asteroid; (2) measure the resulting asteroid deflection, by targeting the secondary member of a binary NEO and measuring the resulting changes of the binary orbit; and (3) study hyper-velocity collision effects on an asteroid, validating models for momentum transfer in asteroid impacts. The DART impact on the Didymos secondary will change the orbital period of the binary by several minutes, which can be measured by Earth-based optical and radar observations. The baseline DART mission launches in late 2020 to impact the Didymos secondary in 2022 near the time of its close pass of Earth, which enables an array of ground- and space-based observatories to participate in gathering data. The AIDA project will provide the first measurements of momentum transfer efficiency from hyper-velocity kinetic impact at full scale on an asteroid, where the impact conditions of the projectile are known, and physical properties and internal structures of the target asteroid are characterized or constrained. The DART kinetic impact is predicted to make a crater of 6 to 17 meters diameter, depending on target physical properties, but will also release a large volume of particulate ejecta that may be directly observable from Earth or even resolvable as a coma or an ejecta tail by ground-based telescopes.

OSIRIS-REx Asteroid Sample Return Mission Image Analysis

NASA Astrophysics Data System (ADS)

Chevres Fernandez, Lee Roger; Bos, Brent

2018-01-01

NASA’s Origins Spectral Interpretation Resource Identification Security-Regolith Explorer (OSIRIS-REx) mission constitutes the “first-of-its-kind” project to thoroughly characterize a near-Earth asteroid. The selected asteroid is (101955) 1999 RQ36 (a.k.a. Bennu). The mission launched in September 2016, and the spacecraft will reach its asteroid target in 2018 and return a sample to Earth in 2023. The spacecraft that will travel to, and collect a sample from, Bennu has five integrated instruments from national and international partners. NASA's OSIRIS-REx asteroid sample return mission spacecraft includes the Touch-And-Go Camera System (TAGCAMS) three camera-head instrument. The purpose of TAGCAMS is to provide imagery during the mission to facilitate navigation to the target asteroid, confirm acquisition of the asteroid sample and document asteroid sample stowage. Two of the TAGCAMS cameras, NavCam 1 and NavCam 2, serve as fully redundant navigation cameras to support optical navigation and natural feature tracking. The third TAGCAMS camera, StowCam, provides imagery to assist with and confirm proper stowage of the asteroid sample. Analysis of spacecraft imagery acquired by the TAGCAMS during cruise to the target asteroid Bennu was performed using custom codes developed in MATLAB. Assessment of the TAGCAMS in-flight performance using flight imagery was done to characterize camera performance. One specific area of investigation that was targeted was bad pixel mapping. A recent phase of the mission, known as the Earth Gravity Assist (EGA) maneuver, provided images that were used for the detection and confirmation of “questionable” pixels, possibly under responsive, using image segmentation analysis. Ongoing work on point spread function morphology and camera linearity and responsivity will also be used for calibration purposes and further analysis in preparation for proximity operations around Bennu. Said analyses will provide a broader understanding regarding the functionality of the camera system, which will in turn aid in the fly-down to the asteroid, as it will allow the pick of a suitable landing and sample location.

Visible spectroscopy of the Polana-Eulalia family complex: Spectral homogeneity

NASA Astrophysics Data System (ADS)

de León, J.; Pinilla-Alonso, N.; Delbo, M.; Campins, H.; Cabrera-Lavers, A.; Tanga, P.; Cellino, A.; Bendjoya, P.; Gayon-Markt, J.; Licandro, J.; Lorenzi, V.; Morate, D.; Walsh, K. J.; DeMeo, F.; Landsman, Z.; Alí-Lagoa, V.

2016-03-01

The Polana-Eulalia family complex is located in the inner part of the asteroid belt, bounded by the ν6 and the 3:1 resonances, where we can find another three collisional families of primitive asteroids (Erigone, Clarissa, and Sulamitis), and a low-albedo population of background objects. This region of the belt is believed to be the most likely origin of the two primitive near-Earth asteroids that are the current targets of two sample return missions: NASA's OSIRIS-REx and JAXA's Hayabusa 2 to Asteroids (101955) Bennu and (162173) Ryugu (also known as 1999 JU3), respectively. Therefore, understanding these families will enhance the scientific return of these missions. We present the results of a spectroscopic survey of asteroids in the region of the Polana-Eulalia family complex, and also asteroids from the background population of low-albedo, low-inclination objects. We obtained visible spectra of a total of 65 asteroids, using the 10.4 m Gran Telescopio Canarias (GTC) and the 3.6 m Telescopio Nazionale Galileo (TNG), both located at the El Roque de Los Muchachos Observatory, in the island of La Palma (Spain), and the 3.6 m New Technology Telescope (NTT), located at the European Southern Observatory of La Silla, in Chile. From the spectral analysis of our sample we found that, in spite of the presence of distinct dynamical groups, the asteroids in this region present spectral homogeneity at visible wavelengths, showing a continuum of spectral slopes, from blue to moderately red, typical of primitive asteroids classified as B- and C-types. We conclude that visible spectra cannot be used to distinguish between members of the Polana and the Eulalia families, or members of the background population. The visible spectra of the two targets of sample return missions, Asteroids Bennu and Ryugu, are compatible with the spectra of the asteroids in this region, supporting previous studies that suggested either the Polana family or the background population as the most likely origins of these NEAs.

Thermal Infrared Imager on Hayabusa2: Science and Development

NASA Astrophysics Data System (ADS)

Okada, Tatsuaki

2015-04-01

Thermal Infrared Imager TIR was developed and calibrated for Haya-busa2 asteroid explorer, aiming at the investigation of thermo-physical properties of C-class near-Earth sub-km sized asteroid (162173) 1999JU3. TIR is based on the 2D micro-bolometer array with germani-um lens to image the surface of asteroid in 8 to 12 μm wavelength (1), measuring the thermal emission off the asteroid surface. Its field of view is 16° x 12° with 328 x 248 pixels. At least 40 (up to 100) images will be taken during asteroid rotation once a week, mainly from the Home Position which is about 20km sunward from asteroid surface. Therefore TIR will image the whole asteroid with spatial resolution of < 20m per pixel, and the temperature profile of each site on the asteroid will be traced from dawn to dusk regions by asteroid rotation. The scien-tific objectives of TIR include the mapping of asteroid surface condi-tions (regional distribution of thermal inertia), since the surface physical conditions are strongly correlated with thermal inertia. It is so informa-tive on understanding the re-accretion or surface sedimentation process-es of the asteroid to be the current form. TIR data will be used for searching for those sites having the typical particle size of 1mm for best sample collection, and within the proper thermal condition for space-craft safe operation. After launch of Hayabusa2, TIR has been tested successfully, covering from -100 to 150 °C using a single parameter settings (2). This implies that TIR is actually able to map the surface other than the sunlit areas. Performance of TIR was found basically the same as those in the pre-launch test, when the temperature of TIR is well controlled. References: (1) Fukuhara T. et al., (2011) Earth Planet. Space 63, 1009-1018; (2) Okada T. et al., (2015) Lunar Planet. Sci. Conf. 46, #1331.

First results of the seven-color asteroid survey

NASA Astrophysics Data System (ADS)

Clark, Beth E.; Bell, Jeffrey F.; Fanale, Fraser P.; Lucey, Paul G.

1993-03-01

The new Seven-Color infrared filter system (SCAS), designed specifically to capture the essential mineralogical information present in asteroid spectra, is composed of seven broad-band filters which allow for IR observations of objects as faint as 17th magnitude. The first test of the SCAS system occurred in Jul. 1992. In four nights at the IRTF on Mauna Kea, Hawaii, over 67 objects were observed. Five of the observations were to test the new system for accuracy relative to previous observations with the high-resolution 52 Color Infrared Survey and with the Eight-Color Asteroid Survey (ECAS). In three cases, the match with previous data was good. In two cases, the match to previous observations was not as good. In addition, sixty S-Type asteroids were measured with the SCAS system. Forty of those asteroids were also observed with the ECAS system. Among the new observations is infrared data of 371 Bohemia, a main belt asteroid which was classified 'QSV' according to its UBV colors in the taxonomic system of D.J. Tholen. There are no corresponding ECAS data for 371. Q-type asteroids are of special interest as they are proposed to be the elusive parent bodies of the ordinary chondrite meteorites. Most Q-types are Earth-crossing asteroids and have not yet been observed in the infrared (except, perhaps, 371). Positive identification of a large main belt Q-type would be of major importance in the scheme of the geological structure of the asteroid belt. Without visible wavelength data, however, the classification of 371 Bohemia remains ambiguous. An attempt to conjoin Bohemia SCAS data with ECAS data of both a typical Q-Type asteroid and an average S-Type asteroid is shown. This figure thus illustrates the importance of visible wavelength data to the SCAS system. In other words, without ECAS data of 371 Bohemia we cannot use its spectral characteristics to identify it as a possible parent body of ordinary chondrite meteorites.

Near-Earth asteroids: Metals occurrence, extraction, and fabrication

NASA Astrophysics Data System (ADS)

Westfall, Richard

Near-earth asteroids occur in three principle types of orbits: Amor, Apollo, and Aten. Amor asteroids make relatively close (within 0.3 AU) approaches to the earth's orbit, but do not actually overlap it. Apollo asteroids spend most of their time outside the earth's orbital path, but at some point of close approach to the sun, they cross the orbit of the earth. Aten asteroids are those whose orbits remain inside the earth's path for the majority of their time, with semi-major axes less than 0.1 AU. Near-earth orbit asteroids include: stones, stony-irons, irons, carbonaceous, and super-carbonaceous. Metals within these asteroids include: iron, nickel, cobalt, the platinum group, aluminum, titanium, and others. Focus is on the extraction of ferrous and platinum group metals from the stony-iron asteroids, and the iron asteroids. Extraction of the metal fraction can be accomplished through the use of tunnel-boring-machines (TBM) in the case of the stony-irons. The metals within the story-iron asteroids occur as dispersed granules, which can be separated from the stony fraction through magnetic and gaseous digestion separation techniques. The metal asteroids are processes by drilling and gaseous digestion or by gaseous digestion alone. Manufacturing of structures, housings, framing networks, pressure vessels, mirrors, and other products is accomplished through the chemical vapor deposition (CVD) of metal coating on advanced composites and on the inside of contour-defining inflatables (CDI). Metal coatings on advanced composites provide: resistance to degradation in the hostile environments of space; superior optical properties; superior heat dissipation; service as wear coatings; and service as evidential coatings. Metal coatings on the inside of CDI produce metal load-bearing products. Fibers such as graphite, kevlar, glass, ceramic, metal, etc., can be incorporated in the metal coatings on the inside of CDI producing metal matrix products which exhibit high strength and resist crack propagation.

A Framework for Inferring Taxonomic Class of Asteroids.

NASA Technical Reports Server (NTRS)

Dotson, J. L.; Mathias, D. L.

2017-01-01

Introduction: Taxonomic classification of asteroids based on their visible / near-infrared spectra or multi band photometry has proven to be a useful tool to infer other properties about asteroids. Meteorite analogs have been identified for several taxonomic classes, permitting detailed inference about asteroid composition. Trends have been identified between taxonomy and measured asteroid density. Thanks to NEOWise (Near-Earth-Object Wide-field Infrared Survey Explorer) and Spitzer (Spitzer Space Telescope), approximately twice as many asteroids have measured albedos than the number with taxonomic classifications. (If one only considers spectroscopically determined classifications, the ratio is greater than 40.) We present a Bayesian framework that provides probabilistic estimates of the taxonomic class of an asteroid based on its albedo. Although probabilistic estimates of taxonomic classes are not a replacement for spectroscopic or photometric determinations, they can be a useful tool for identifying objects for further study or for asteroid threat assessment models. Inputs and Framework: The framework relies upon two inputs: the expected fraction of each taxonomic class in the population and the albedo distribution of each class. Luckily, numerous authors have addressed both of these questions. For example, the taxonomic distribution by number, surface area and mass of the main belt has been estimated and a diameter limited estimate of fractional abundances of the near earth asteroid population was made. Similarly, the albedo distributions for taxonomic classes have been estimated for the combined main belt and NEA (Near Earth Asteroid) populations in different taxonomic systems and for the NEA population specifically. The framework utilizes a Bayesian inference appropriate for categorical data. The population fractions provide the prior while the albedo distributions allow calculation of the likelihood an albedo measurement is consistent with a given taxonomic class. These inputs allows calculation of the probability an asteroid with a specified albedo belongs to any given taxonomic class.

Near-Earth asteroids: Metals occurrence, extraction, and fabrication

NASA Technical Reports Server (NTRS)

Westfall, Richard

1991-01-01

Near-earth asteroids occur in three principle types of orbits: Amor, Apollo, and Aten. Amor asteroids make relatively close (within 0.3 AU) approaches to the earth's orbit, but do not actually overlap it. Apollo asteroids spend most of their time outside the earth's orbital path, but at some point of close approach to the sun, they cross the orbit of the earth. Aten asteroids are those whose orbits remain inside the earth's path for the majority of their time, with semi-major axes less than 0.1 AU. Near-earth orbit asteroids include: stones, stony-irons, irons, carbonaceous, and super-carbonaceous. Metals within these asteroids include: iron, nickel, cobalt, the platinum group, aluminum, titanium, and others. Focus is on the extraction of ferrous and platinum group metals from the stony-iron asteroids, and the iron asteroids. Extraction of the metal fraction can be accomplished through the use of tunnel-boring-machines (TBM) in the case of the stony-irons. The metals within the story-iron asteroids occur as dispersed granules, which can be separated from the stony fraction through magnetic and gaseous digestion separation techniques. The metal asteroids are processes by drilling and gaseous digestion or by gaseous digestion alone. Manufacturing of structures, housings, framing networks, pressure vessels, mirrors, and other products is accomplished through the chemical vapor deposition (CVD) of metal coating on advanced composites and on the inside of contour-defining inflatables (CDI). Metal coatings on advanced composites provide: resistance to degradation in the hostile environments of space; superior optical properties; superior heat dissipation; service as wear coatings; and service as evidential coatings. Metal coatings on the inside of CDI produce metal load-bearing products. Fibers such as graphite, kevlar, glass, ceramic, metal, etc., can be incorporated in the metal coatings on the inside of CDI producing metal matrix products which exhibit high strength and resist crack propagation.

Two Years of NEOWISE Asteroid Data

NASA Image and Video Library

2016-04-04

NASA's asteroid hunting NEOWISE survey uses infrared to detect and characterize asteroids and comets. Since the mission was restarted in December 2013, NEOWISE has discovered 72 near-Earth objects and characterized 439 others.

Volumes and bulk densities of forty asteroids from ADAM shape modeling

NASA Astrophysics Data System (ADS)

Hanuš, J.; Viikinkoski, M.; Marchis, F.; Ďurech, J.; Kaasalainen, M.; Delbo', M.; Herald, D.; Frappa, E.; Hayamizu, T.; Kerr, S.; Preston, S.; Timerson, B.; Dunham, D.; Talbot, J.

2017-05-01

Context. Disk-integrated photometric data of asteroids do not contain accurate information on shape details or size scale. Additional data such as disk-resolved images or stellar occultation measurements further constrain asteroid shapes and allow size estimates. Aims: We aim to use all the available disk-resolved images of approximately forty asteroids obtained by the Near-InfraRed Camera (Nirc2) mounted on the W.M. Keck II telescope together with the disk-integrated photometry and stellar occultation measurements to determine their volumes. We can then use the volume, in combination with the known mass, to derive the bulk density. Methods: We downloaded and processed all the asteroid disk-resolved images obtained by the Nirc2 that are available in the Keck Observatory Archive (KOA). We combined optical disk-integrated data and stellar occultation profiles with the disk-resolved images and use the All-Data Asteroid Modeling (ADAM) algorithm for the shape and size modeling. Our approach provides constraints on the expected uncertainty in the volume and size as well. Results: We present shape models and volume for 41 asteroids. For 35 of these asteroids, the knowledge of their mass estimates from the literature allowed us to derive their bulk densities. We see a clear trend of lower bulk densities for primitive objects (C-complex) and higher bulk densities for S-complex asteroids. The range of densities in the X-complex is large, suggesting various compositions. We also identified a few objects with rather peculiar bulk densities, which is likely a hint of their poor mass estimates. Asteroid masses determined from the Gaia astrometric observations should further refine most of the density estimates.

Momentum harvesting techniques for solar system travel

NASA Technical Reports Server (NTRS)

Willoughby, Alan J.

1991-01-01

Astronomers are lately estimating there are 400,000 earth visiting asteroids larger than 100 meters in diameter. These asteroids are uniquely accessible sources of building materials, propellants, oxygen, water, and minerals. They also constitute a huge momentum reserve, potentially usable for travel throughout the solar system. To use this momentum, these stealthy objects must be tracked and the ability to extract the desired momentum obtained. Momentum harvesting by momentum transfer from asteroid to spacecraft, and by using the momentum of the extraterrestrial material to help deliver itself to its destination is discussed. The purpose is neither to quantify nor justify the momentum exchange processes, but to stimulate collective imaginations with some intriguing possibilities which emerge when momentum as well as material is considered. A net and tether concept is the suggested means of asteroid capture, the basic momentum exchange process. The energy damping characteristics of the tether determines the velocity mismatch that can be tolerated, and hence the amount of momentum that can be harvested per capture. As the tether plays out of its reel, drag on the tether steadily accelerates the spacecraft and dilutes, in time, the would-be collision. A variety of concepts for riding and using asteroids after capture are introduced. The hitchhiker uses momentum transfer only. The beachcomber, the caveman, the swinger, the prospector, and the rock wrecker also take advantage of raw asteroid materials. The chemist and the hijacker go further, they process the asteroid into propellants. Or, an asteroid railway system could be constructed with each hijacked asteroid becoming a scheduled train. Travelers could board this space railway system assured that water, oxygen propellants, and shielding await them. Austere space travel could give way to comforts, with a speed and economy impossible without nature's gift of earth visiting asteroids.

DAMIT: a database of asteroid models

NASA Astrophysics Data System (ADS)

Durech, J.; Sidorin, V.; Kaasalainen, M.

2010-04-01

Context. Apart from a few targets that were directly imaged by spacecraft, remote sensing techniques are the main source of information about the basic physical properties of asteroids, such as the size, the spin state, or the spectral type. The most widely used observing technique - time-resolved photometry - provides us with data that can be used for deriving asteroid shapes and spin states. In the past decade, inversion of asteroid lightcurves has led to more than a hundred asteroid models. In the next decade, when data from all-sky surveys are available, the number of asteroid models will increase. Combining photometry with, e.g., adaptive optics data produces more detailed models. Aims: We created the Database of Asteroid Models from Inversion Techniques (DAMIT) with the aim of providing the astronomical community access to reliable and up-to-date physical models of asteroids - i.e., their shapes, rotation periods, and spin axis directions. Models from DAMIT can be used for further detailed studies of individual objects, as well as for statistical studies of the whole set. Methods: Most DAMIT models were derived from photometric data by the lightcurve inversion method. Some of them have been further refined or scaled using adaptive optics images, infrared observations, or occultation data. A substantial number of the models were derived also using sparse photometric data from astrometric databases. Results: At present, the database contains models of more than one hundred asteroids. For each asteroid, DAMIT provides the polyhedral shape model, the sidereal rotation period, the spin axis direction, and the photometric data used for the inversion. The database is updated when new models are available or when already published models are updated or refined. We have also released the C source code for the lightcurve inversion and for the direct problem (updates and extensions will follow).

Momentum transfer in asteroid impacts. I. Theory and scaling

NASA Astrophysics Data System (ADS)

Holsapple, Keith A.; Housen, Kevin R.

2012-11-01

When an asteroid experiences an impact, its path is changed. How much it changes is important to know for both asteroid evolution studies and for attempts to prevent an asteroid from impacting the Earth. In an impact process the total momentum of the material is conserved. However, not all of the material is of interest, but only that remaining with the asteroid. The ratio of the change of momentum of the remaining asteroid to that of the impactor is called the momentum multiplication factor; and is commonly given the symbol β. It has been known for some time that β can be greater than unity, and in some cases far greater. That could be a significant factor in attempts to deflect an asteroid with an impact, and can also be important in the stirring of objects in the asteroid belt due to mutual impacts. The escaping crater ejecta are the source of the momentum multiplication. Housen and Holsapple (Housen, K.R., Holsapple, K.A. [2011a]. Icarus 211, 856-875) have given a recent summary of ejecta characteristics and scaling. Here we use those ejecta results to determine how β depends on the impactor properties, on the asteroid size and composition, and establish the paths and time of flight of all of the ejecta particles. The approach is to add the contribution of each element of ejected mass accounting for its initial velocity, its trajectory and whether it escapes the asteroid. The goal in this paper is to provide a theoretical framework of the fundamental results which can be used as a test of the veracity of experiments and detailed numerical calculations of impacts. A subsequent paper will present direct laboratory results and numerical simulations of momentum multiplication in various geological materials.

The Composition of M-type Asteroids: Synthesis of Spectroscopic and Radar Observations.

NASA Astrophysics Data System (ADS)

Bell, Maureen; Clark, B. E.; Shepard, M. K.; Issacs, R. A.; Cloutis, E. A.; Fornasier, S.; Bus, S. J.

2010-10-01

We have conducted a radar-driven observational campaign of 22 main-belt asteroids (MBAs) focused on Bus-DeMeo Xc- and Xk-type objects (Tholen X and M class asteroids) using the Arecibo radar and NASA Infrared Telescope Facilities (IRTF). Sixteen of our targets were near-simultaneously observed with radar. We find that most of the highest metal-content asteroids, as suggested by radar, tend to exhibit silicate absorption features at both 0.9 and 1.9 microns, and the lowest metal-content asteroids tend to exhibit either no bands or only the 0.9 microns band. Eleven of the asteroids were observed at several rotational longitudes in the near-infrared and significant variations in continuum slope were found for nine in the spectral regions 1.1-1.45 microns and 1.6-2.3 microns. Compositional evidence is derived from our target asteroid spectra using two different methods: 1) a Chi-squared search for spectral matches in the RELAB database, and 2) parametric comparisons with meteorites. We find that for four of the seven asteroids with the highest iron abundances, our spectral results are consistent with each other and with the radar evidence pointing to an iron meteorite composition (16 Psyche, 216 Kleopatra, 347 Pariana, and 779 Nina). Four asteroids have radar analogs consistent with either our parametric comparison or our RELAB analog type (21 Lutetia, 135 Hertha, 497 Iva, and 758 Mancunia ). The remaining eight asteroids (22 Kalliope, 97 Klotho, 110 Lydia, 129 Antigone, 224 Oceana, 678 Fredegundis, 771 Libera, and 785 Zwetana) have ambiguous compositional interpretations when comparing the spectral analogs to the radar analogs.

Asteroid spin-rate studies using large sky-field surveys

NASA Astrophysics Data System (ADS)

Chang, Chan-Kao; Lin, Hsing-Wen; Ip, Wing-Huen; Prince, Thomas A.; Kulkarni, Shrinivas R.; Levitan, David; Laher, Russ; Surace, Jason

2017-12-01

Eight campaigns to survey asteroid rotation periods have been carried out using the intermediate Palomar Transient Factory in the past 3 years. 2780 reliable rotation periods were obtained, from which we identified two new super-fast rotators (SFRs), (335433) 2005 UW163 and (40511) 1999 RE88, and 23 candidate SFRs. Along with other three known super-fast rotators, there are five known SFRs so far. Contrary to the case of rubble-pile asteroids (i.e., bounded aggregations by gravity only), an internal cohesion, ranging from 100 to 1000 Pa, is required to prevent these five SFRs from flying apart because of their super-fast rotations. This cohesion range is comparable with that of lunar regolith. However, some candidates of several kilometers in size require unusually high cohesion (i.e., a few thousands of Pa). Therefore, the confirmation of these kilometer-sized candidates can provide important information about asteroid interior structure. From the rotation periods we collected, we also found that the spin-rate limit of C-type asteroids, which has a lower bulk density, is lower than for S-type asteroids. This result is in agreement with the general picture of rubble-pile asteroids (i.e., lower bulk density, lower spin-rate limit). Moreover, the spin-rate distributions of asteroids of 3< D < 15 km in size show a steady decrease along frequency for f > 5 rev/day, regardless of the location in the main belt. The YORP effect is indicated to be less efficient in altering asteroid spin rates from our results when compared with the flat distribution found by Pravec et al. (Icarus 197:497-504, 2008. doi: 10.1016/j.icarus.2008.05.012). We also found a significant number drop at f = 5 rev/day in the spin-rate distributions of asteroids of D < 3 km.

Secular Resonance Sweeping of the Main Asteroid Belt During Planet Migration

NASA Astrophysics Data System (ADS)

Minton, David A.; Malhotra, Renu

2011-05-01

We calculate the eccentricity excitation of asteroids produced by the sweeping ν6 secular resonance during the epoch of planetesimal-driven giant planet migration in the early history of the solar system. We derive analytical expressions for the magnitude of the eccentricity change and its dependence on the sweep rate and on planetary parameters; the ν6 sweeping leads to either an increase or a decrease of eccentricity depending on an asteroid's initial orbit. Based on the slowest rate of ν6 sweeping that allows a remnant asteroid belt to survive, we derive a lower limit on Saturn's migration speed of ~0.15 AU Myr-1 during the era that the ν6 resonance swept through the inner asteroid belt (semimajor axis range 2.1-2.8 AU). This rate limit is for Saturn's current eccentricity and scales with the square of its eccentricity; the limit on Saturn's migration rate could be lower if its eccentricity were lower during its migration. Applied to an ensemble of fictitious asteroids, our calculations show that a prior single-peaked distribution of asteroid eccentricities would be transformed into a double-peaked distribution due to the sweeping of the ν6 resonance. Examination of the orbital data of main belt asteroids reveals that the proper eccentricities of the known bright (H <= 10.8) asteroids may be consistent with a double-peaked distribution. If so, our theoretical analysis then yields two possible solutions for the migration rate of Saturn and for the dynamical states of the pre-migration asteroid belt: a dynamically cold state (single-peaked eccentricity distribution with mean of ~0.05) linked with Saturn's migration speed ~4 AU Myr-1 or a dynamically hot state (single-peaked eccentricity distribution with mean of ~0.3) linked with Saturn's migration speed ~0.8 AU Myr-1.

Scenarios for the Evolution of Asteroid Belts

NASA Image and Video Library

2012-11-01

This illustration shows three possible scenarios for the evolution of asteroid belts. At the top, a Jupiter-size planet migrates through the asteroid belt, scattering material and inhibiting the formation of life on planets.

Asteroid Redirect Mission: EVA and Sample Collection

NASA Technical Reports Server (NTRS)

Abell, Paul; Stich, Steve

2015-01-01

Asteroid Redirect Mission (ARM) Overview (1) Notional Development Schedule, (2) ARV Crewed Mission Accommodations; Asteroid Redirect Crewed Mission (ARCM) Mission Summary; ARCM Accomplishments; Sample collection/curation plan (1) CAPTEM Requirements; SBAG Engagement Plan

Near-infrared reflectance spectra-applications to problems in asteroid-meteorite relationships

NASA Technical Reports Server (NTRS)

Mcfadden, Lucy A.; Chamberlin, Alan; Vilas, Faith

1991-01-01

Near-infrared spectral reflectance data were collected at the Infrared Telescope Facility (IRTF) at Mauna Kea Observatories in 1985 and 1986 for the purpose of searching the region near the 3:1 Kirkwood gap for asteroids with the spectral signatures of ordinary chondrite parent bodies. Twelve reflectance spectra are observed. The presence of ordinary chondrite parent bodies among this specific set of observed asteroids is not obvious, though the sample is biased towards the larger asteroids in the region due to limitations imposed by detector sensitivity. The data set, which was acquired with the same instrumentation used for the 52-color asteroid survey (Bell et al., 1987), also presents some additional findings. The range of spectral characteristics that exist among asteroids of the same taxonomic type is noted. Conclusions based on the findings are discussed.

On the alleged collisional origin of the Kirkwood Gaps. [in asteroid belt

NASA Technical Reports Server (NTRS)

Heppenheimer, T. A.

1975-01-01

This paper examines two proposed mechanisms whereby asteroidal collisions and close approaches may have given rise to the Kirkwood Gaps. The first hypothesis is that asteroids in near-resonant orbits have markedly increased collision probabilities and so are preferentially destroyed, or suffer decay in population density, within the resonance zones. A simple order-of-magnitude analysis shows that this hypothesis is untenable since it leads to conclusions which are either unrealistic or not in accord with present understanding of asteroidal physics. The second hypothesis is the Brouwer-Jefferys theory that collisions would smooth an asteroidal distribution function, as a function of Jacobi constant, thus forming resonance gaps. This hypothesis is examined by direct numerical integration of 50 asteroid orbits near the 2:1 resonance, with collisions simulated by random variables. No tendency to form a gap was observed.

SPHERE Sheds New Light on the Collisional History of Main-belt Asteroids

NASA Astrophysics Data System (ADS)

Marsset, M.; Carry, B.; Pajuelo, M.; Viikinkoski, M.; Hanuš, J.; Vernazza, P.; Dumas, C.; Yang, B.

2017-09-01

The Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) instrument has unveiled unprecedented details of the three-dimensional shape, surface topography and cratering record of four medium-sized ( 200 km) asteroids, opening the prospect of a new era of ground-based exploration of the asteroid belt. Although two of the targets, (130) Elektra and (107) Camilla, have been observed extensively for more than fifteen years by the first-generation adaptive optics imagers, two new moonlets were discovered around these targets, illustrating the unique power of SPHERE. In the next two years SPHERE will continue to collect high- angular-resolution and high-contrast measurements of about 40 asteroids. These observations of a large number of asteroids will provide a unique dataset to better understand the collisional history and multiplicity rate of the asteroid belt.

A radar survey of M- and X-class asteroids

NASA Astrophysics Data System (ADS)

Shepard, Michael K.; Clark, Beth Ellen; Nolan, Michael C.; Howell, Ellen S.; Magri, Christopher; Giorgini, Jon D.; Benner, Lance A. M.; Ostro, Steven J.; Harris, Alan W.; Warner, Brian; Pray, Donald; Pravec, Petr; Fauerbach, Michael; Bennett, Thomas; Klotz, Alain; Behrend, Raoul; Correia, Horacio; Coloma, Josep; Casulli, Silvano; Rivkin, Andrew

2008-05-01

We observed ten M- and X-class main-belt asteroids with the Arecibo Observatory's S-band (12.6 cm) radar. The X-class asteroids were targeted based on their albedos or other properties which suggested they might be M-class. This work brings the total number of main-belt M-class asteroids observed with radar to 14. We find that three of these asteroids have rotation rates significantly different from what was previously reported. Based on their high radar albedo, we find that only four of the fourteen—16 Psyche, 216 Kleopatra, 758 Mancunia, and 785 Zwetana—are almost certainly metallic. 129 Antigone has a moderately high radar albedo and we suggest it may be a CH/CB/Bencubbinite parent body. Three other asteroids, 97 Klotho, 224 Oceana, and 796 Sarita have radar albedos significantly higher than the average main belt asteroid and we cannot rule out a significant metal content for them. Five of our target asteroids, 16 Psyche, 129 Antigone, 135 Hertha, 758 Mancunia, and 785 Zwetana, show variations in their radar albedo with rotation. We can rule out shape and composition in most cases, leaving variations in thickness, porosity, or surface roughness of the regolith to be the most likely causes. With the exception of 129 Antigone, we find no hydrated M-class asteroids (W-class; Rivkin, A.S., Howell, E.S., Lebofsky, L.A., Clark, B.E., Britt, D.T., 2000. Icarus 145, 351-368) to have high radar albedos.

The Widening Gender Gap and Its Influence on Contemporary Postsecondary Campuses: Perceptions of Senior Student Affairs Officers

ERIC Educational Resources Information Center

Schellpfeffer, Shane E.

2012-01-01

Throughout the past 30 years, a gender gap in postsecondary education in the United States has steadily widened. The widening postsecondary gender gap, described as the difference between the number of males and females in both enrollment and degree attainment in postsecondary education, has recently garnered significant attention. The purpose of…

Modeling of Fragmentation of Asteroids

NASA Technical Reports Server (NTRS)

Agrawal, Parul; Prabhu, Dinesh K.; Carlozzi, Alexander; Hart, Kenneth; Bryson, Katie; Sears, Derek

2015-01-01

The objective of this study is to understand fragmentation and fracture of a given asteroid and mechanisms of break-up. The focus of the present work is to develop modeling techniques for stony asteroids in 10m-100m range to answer two questions: 1) What is the role of material makeup of an asteroid in the stress distribution? 2)How is stress distribution altered in the presence of pre-existing defects?

The asteroid impact mission: testing laser communication in deep-space

NASA Astrophysics Data System (ADS)

Carnelli, I.; Mellab, K.; Heese, C.; Sodnik, Z.; Pesquita, V.; Gutierrez, B.

2017-09-01

In October 2022 the binary asteroid system 65803 Didymos will have an exceptionally close approach with the Earth flying by within only 0.088 AU. ESA is planning to leverage on this close encounter to launch a small mission of opportunity called Asteroid Impact Mission (AIM) to explore and demonstrate new technologies for future science and exploration missions while addressing planetary defence and performing asteroid scientific investigations.

Spectroscopy of asteroids in unusual orbits

NASA Technical Reports Server (NTRS)

Cochran, W. D.; Cochran, A. L.; Barker, E. S.

1986-01-01

Medium-resolution spectroscopy of a collection of nonmain-belt asteroids has been obtained in order to search for possible cometlike spectral features. The asteroids include nine earth approachers, two Trojans, and the unusual object 2060 Chiron. All spectra were obtained and reduced in the same manner as comet data in the McDonald Observatory Faint Comet Survey. No indication of cometary activity was found in any of the asteroids observed.

Twenty-one Asteroid Lightcurves at Asteroids Observers (OBAS) - MPPD: Nov 2016 - May 2017

NASA Astrophysics Data System (ADS)

Mas, Vicente; Fornas, G.; Lozano, Juan; Rodrigo, Onofre; Fornas, A.; Carreño, A.; Arce, Enrique; Brines, Pedro; Herrero, David

2018-01-01

We report on the analysis of photometric observations of 21 main-belt asteroids (MBA) done by Asteroids Observers (OBAS). This work is part of the Minor Planet Photometric Database task that was initiated by a group of Spanish amateur astronomers. We have managed to obtain a number of accurate and complete lightcurves as well as some additional incomplete lightcurves to help analysis at future oppositions.

Low-energy multiple rendezvous of main belt asteroids

NASA Technical Reports Server (NTRS)

Penzo, Paul A.; Bender, David F.

1992-01-01

An approach to multiple asteroid rendezvous missions to the main belt region is proposed. In this approach key information which consists of a launch date and delta V can be generated for all possible pairs of asteroids satisfying specific constraints. This information is made available on a computer file for 1000 numbered asteroids with reasonable assumptions, limitations, and approximations to limit the computer requirements and the size of the data file.

New shape models of asteroids reconstructed from sparse-in-time photometry

NASA Astrophysics Data System (ADS)

Durech, Josef; Hanus, Josef; Vanco, Radim; Oszkiewicz, Dagmara Anna

2015-08-01

Asteroid physical parameters - the shape, the sidereal rotation period, and the spin axis orientation - can be reconstructed from the disk-integrated photometry either dense (classical lightcurves) or sparse in time by the lightcurve inversion method. We will review our recent progress in asteroid shape reconstruction from sparse photometry. The problem of finding a unique solution of the inverse problem is time consuming because the sidereal rotation period has to be found by scanning a wide interval of possible periods. This can be efficiently solved by splitting the period parameter space into small parts that are sent to computers of volunteers and processed in parallel. We will show how this approach of distributed computing works with currently available sparse photometry processed in the framework of project Asteroids@home. In particular, we will show the results based on the Lowell Photometric Database. The method produce reliable asteroid models with very low rate of false solutions and the pipelines and codes can be directly used also to other sources of sparse photometry - Gaia data, for example. We will present the distribution of spin axis of hundreds of asteroids, discuss the dependence of the spin obliquity on the size of an asteroid,and show examples of spin-axis distribution in asteroid families that confirm the Yarkovsky/YORP evolution scenario.

Asteroid Secular Dynamics: Ceres’ Fingerprint Identified

NASA Astrophysics Data System (ADS)

Novaković, Bojan; Maurel, Clara; Tsirvoulis, Georgios; Knežević, Zoran

2015-07-01

Here we report on the significant role of a so far overlooked dynamical aspect, namely, a secular resonance between the dwarf planet Ceres and other asteroids. We demonstrate that this type of secular resonance can be the dominant dynamical factor in certain regions of the main asteroid belt. Specifically, we performed a dynamical analysis of the asteroids belonging to the (1726) Hoffmeister family. To identify which dynamical mechanisms are actually at work in this part of the main asteroid belt, i.e., to isolate the main perturber(s), we study the evolution of this family in time. The study is accomplished using numerical integrations of test particles performed within different dynamical models. The obtained results reveal that the post-impact evolution of the Hoffmeister asteroid family is a direct consequence of the nodal secular resonance with Ceres. This leads us to the conclusion that similar effects must exist in other parts of the asteroid belt. In this respect, the obtained results shed light on an important and entirely new aspect of the long-term dynamics of small bodies. Ceres’ fingerprint in asteroid dynamics, expressed through the discovered secular resonance effect, completely changes our understanding of the way in which perturbations by Ceres-like objects affect the orbits of nearby bodies.

Mineralogy and petrography of C asteroid regolith: The Sutter's Mill CM meteorite

NASA Astrophysics Data System (ADS)

Zolensky, Michael; Mikouchi, Takashi; Fries, Marc; Bodnar, Robert; Jenniskens, Peter; Yin, Qing-zhu; Hagiya, Kenji; Ohsumi, Kazumasa; Komatsu, Mutsumi; Colbert, Matthew; Hanna, Romy; Maisano, Jessie; Ketcham, Richard; Kebukawa, Yoko; Nakamura, Tomoki; Matsuoka, Moe; Sasaki, Sho; Tsuchiyama, Akira; Gounelle, Matthieu; Le, Loan; Martinez, James; Ross, Kent; Rahman, Zia

2014-11-01

Based upon our characterization of three separate stones by electron and X-ray beam analyses, computed X-ray microtomography, Raman microspectrometry, and visible-IR spectrometry, Sutter's Mill is a unique regolith breccia consisting mainly of various CM lithologies. Most samples resemble existing available CM2 chondrites, consisting of chondrules and calcium-aluminum-rich inclusion (CAI) set within phyllosilicate-dominated matrix (mainly serpentine), pyrrhotite, pentlandite, tochilinite, and variable amounts of Ca-Mg-Fe carbonates. Some lithologies have witnessed sufficient thermal metamorphism to transform phyllosilicates into fine-grained olivine, tochilinite into troilite, and destroy carbonates. One finely comminuted lithology contains xenolithic materials (enstatite, Fe-Cr phosphides) suggesting impact of a reduced asteroid (E or M class) onto the main Sutter's Mill parent asteroid, which was probably a C class asteroid. One can use Sutter's Mill to help predict what will be found on the surfaces of C class asteroids such as Ceres and the target asteroids of the OSIRIS-REx and Hayabusa 2 sample return missions (which will visit predominantly primitive asteroids). C class asteroid regolith may well contain a mixture of hydrated and thermally dehydrated indigenous materials as well as a significant admixture of exogenous material would be essential to the successful interpretation of mineralogical and bulk compositional data.

Hubble Witnesses an Asteroid Mysteriously Disintegrating

NASA Image and Video Library

2014-03-06

Though fragile comet nuclei have been seen falling apart as they near the Sun, nothing like the slow breakup of an asteroid has ever before been observed in the asteroid belt. A series of Hubble Space Telescope images shows that the fragments are drifting away from each other at a leisurely one mile per hour. This makes it unlikely that the asteroid is disintegrating because of a collision with another asteroid. A plausible explanation is that the asteroid is crumbling due to a subtle effect of sunlight. This causes the rotation rate to slowly increase until centrifugal force pulls the asteroid apart. The asteroid's remnant debris, weighing in at 200,000 tons, will in the future provide a rich source of meteoroids. Hubble Observation of P/2013 R3 - November 15, 2013 Credit: NASA, ESA, and D. Jewitt (University of California, Los Angeles) Read more: 1.usa.gov/1ig2E0x NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Extending the McDonald Observatory Serendipitous Survey of UV/Blue Asteroid Spectra

NASA Technical Reports Server (NTRS)

Vilas, Faith; Cochran, A. L.

1999-01-01

Moderate resolution asteroid spectra in the 350 - 650 nm spectral range acquired randomly over many years (Cochran and Vilas, Icarus v 127, 121, 1997) identified absorption features in spectra of some of the asteroids. A feature centered at 430 nm was identified in the spectra of some low-albedo asteroids (C class and subclass), similar to the feature identified by Vilas et al. (Icarus, v. 102, 225,1993) in other low-albedo asteroid spectra and attributed to a ferric iron spin-forbidden transition in iron alteration minerals such as jarosite. Features at 505 nm and 430 nm were identified in the spectrum of 4 Vesta. The 505-nm feature is highly diagnostic of the amount and form of calcium in pyroxenes. This suggested further research on the sharpness and spectral placement of this feature in the spectra of Vesta and Vestoids (e.g., Cochran and Vilas, Icarus v. 134, 207, 1998). In 1997 and 1998, additional UV/blue spectra were obtained at the 2.7-m Harlan J. Smith telescope with a facility cassegrain spectrograph. These included spectra of low-albedo asteroids, the R-class asteroid 349 Dembowska, and the M-class asteroid 135 Hertha. These spectra will be presented and identified features will be discussed.

Linear Covariance Analysis For Proximity Operations Around Asteroid 2008 EV5

NASA Technical Reports Server (NTRS)

Wright, Cinnamon A.; Bhatt, Sagar; Woffinden, David; Strube, Matthew; D'Souza, Chris

2015-01-01

The NASA initiative to collect an asteroid, the Asteroid Robotic Redirect Mission (ARRM), is currently investigating the option of retrieving a boulder from an asteroid, demonstrating planetary defense with an enhanced gravity tractor technique, and returning it to a lunar orbit. Techniques for accomplishing this are being investigated by the Satellite Servicing Capabilities Office (SSCO) at NASA GSFC in collaboration with JPL, NASA JSC, LaRC, and Draper Laboratory, Inc. Two critical phases of the mission are the descent to the boulder and the Enhanced Gravity Tractor demonstration. A linear covariance analysis is done for these phases to assess the feasibility of these concepts with the proposed design of the sensor and actuator suite of the Asteroid Redirect Vehicle (ARV). The sensor suite for this analysis includes a wide field of view camera, LiDAR, and an IMU. The proposed asteroid of interest is currently the C-type asteroid 2008 EV5, a carbonaceous chondrite that is of high interest to the scientific community. This paper presents an overview of the linear covariance analysis techniques and simulation tool, provides sensor and actuator models, and addresses the feasibility of descending to the surface of the asteroid within allocated requirements as well as the possibility of maintaining a halo orbit to demonstrate the Enhanced Gravity Tractor technique.

Trojan Asteroid Lightcurves: Probing Internal Structure and the Origins

NASA Astrophysics Data System (ADS)

Ryan, E. L.

2017-12-01

Studies of the small bodies of the solar system reveal important clues about the condensation and formation of planetesimal bodies, and ultimately planets in planetary systems. Dynamics of small bodies have been utilized to model giant planet migration within our solar system, colors have been used to explore compositional gradients within the protoplanetary disk, & studies of the size-frequency distribution of main belt asteroids may reveal compositional dependences on planetesimal strength limiting models of planetary growth from collisional aggregration. Studies of the optical lightcurves of asteroids also yield important information on shape and potential binarity of asteroidal bodies. The K2 mission has allowed for the unprecedented collection of Trojan asteroid lightcurves on a 30 minute cadence for baselines of 10 days, in both the L4 and L5 Trojan clouds. Preliminary results from the K2 mission suggest that Trojan asteroids have bulk densities of 1 g/cc and a binary fraction ≤ 33 percent (Ryan et al., 2017, Astronomical Journal, 153, 116), however Trojan lightcurve data is actively being collected via the continued K2 mission. We will present updated results of bulk density and binary fraction of the Trojan asteroids and compare these results to other small body populations, including Hilda asteroids, transNeptunian objects and comet nuclei to test dynamical models of the origins of these populations.

Towing Asteroids with Gravity Tractors Enhanced by Tethers and Solar Sails

NASA Technical Reports Server (NTRS)

Shen, Haijun; Roithmayr, Carlos M.

2015-01-01

Material collected from an asteroid's surface can be used to increase gravitational attraction between the asteroid and a Gravity Tractor (GT); the spacecraft therefore operates more effectively and is referred to as an Enhanced Gravity Tractor (EGT). The use of tethers and solar sails to further improve effectiveness and simplify operations is investigated. By employing a tether, the asteroidal material can be placed close to the asteroid while the spacecraft is stationed farther away, resulting in a better safety margin and improved thruster efficiency. A solar sail on a spacecraft can naturally provide radial offset and inter-spacecraft separation required for multiple EGTs.

Ferric iron in primitive asteroids - A 0.43-micron absorption feature

NASA Technical Reports Server (NTRS)

Vilas, Faith; Hatch, Erin C.; Larson, Stephen M.; Sawyer, Scott R.; Gaffey, Michael J.

1993-01-01

A search of reflectance spectra of C- P-, D- and S-class asteroids to hunt for the Soret band near 0.4 micron that is indicative of porphyrins yielded an identification of an 0.43 micron absorption feature in 11 primitive asteroids of the C, P, and G classes and in one S-class asteroid. It is proposed that the feature is an Fe(3+) spin-forbidden transition in aqueously altered material, possibly located near 0.43 micron due to an enhancement effect similar to the mechanism operating in jarosite. The significance of the feature for the aqueous alteration history of these asteroids is addressed.

Radar Image of Christmas Eve Asteroid 2003 SD2020

NASA Image and Video Library

2015-12-23

This image of an asteroid that is at least 3,600 feet (1,100 meters) long was taken on Dec. 17, 2015, by scientists using NASA's 230-foot (70-meter) DSS-14 antenna at Goldstone, California. This asteroid, named 2003 SD2020, will safely fly past Earth on Thursday, Dec. 24, at a distance of 6.8 million miles (11 million kilometers). At the time this image was taken, the asteroid was about 7.3 million miles (12 million kilometers) from Earth. In 2018, this asteroid will fly past Earth at a distance of 1.8 million miles (2.8 million kilometers). http://photojournal.jpl.nasa.gov/catalog/PIA20279

Oxygen isotope variation in stony-iron meteorites.

PubMed

Greenwood, R C; Franchi, I A; Jambon, A; Barrat, J A; Burbine, T H

2006-09-22

Asteroidal material, delivered to Earth as meteorites, preserves a record of the earliest stages of planetary formation. High-precision oxygen isotope analyses for the two major groups of stony-iron meteorites (main-group pallasites and mesosiderites) demonstrate that each group is from a distinct asteroidal source. Mesosiderites are isotopically identical to the howardite-eucrite-diogenite clan and, like them, are probably derived from the asteroid 4 Vesta. Main-group pallasites represent intermixed core-mantle material from a single disrupted asteroid and have no known equivalents among the basaltic meteorites. The stony-iron meteorites demonstrate that intense asteroidal deformation accompanied planetary accretion in the early Solar System.

Asteroid and comet surfaces

NASA Technical Reports Server (NTRS)

Mcfadden, Lucy-Ann

1988-01-01

Photometric and spectrophotometric studies of asteroids and comets are in progress to address questions about the mineralogical relationship between asteroids near the 3:1 Kirkwood gap and ordinary chondrite meteorites and between cometary nuclei and the surface of asteroids. Progress was made on a method to convert the measured excess UV flux in the spectrum of 2201 Oljato to column abundance of OH and CN. Spectral reflectance measurements of large asteroids near the 3:1 Kirkwood gap, which is expected to be the source of ordinary chondrite meteorites, were briefly examined and show no spectral signatures that are characteristic of ordinary chondrite meteorite powders measured in the lab.

Deflection Missions for Asteroid 2011 AG5

NASA Technical Reports Server (NTRS)

Grebow, Daniel; Landau, Damon; Bhaskaran, Shyam; Chodas, Paul; Chesley, Steven; Yeomans, Don; Petropoulos, Anastassios; Sims, Jon

2012-01-01

The recently discovered asteroid 2011 AG5 currently has a 1-in-500 chance of impacting Earth in 2040. In this paper, we discuss the potential of future observations of the asteroid and their effects on the asteroid's orbital uncertainty. Various kinetic impactor mission scenarios, relying on both conventional chemical as well as solar-electric propulsion, are presented for deflecting the course of the asteroid safely away from Earth. The times for the missions range from pre-keyhole passage (pre-2023), and up to five years prior to the 2040 Earth close approach. We also include a brief discussion on terminal guidance, and contingency options for mission planning.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baer, James; Chesley, Steven R.; Matson, Robert D., E-mail: jimbaer1@earthlink.net, E-mail: steve.chesley@jpl.nasa.gov

As an application of our recent observational error model, we present the astrometric masses of 26 main-belt asteroids. We also present an integrated ephemeris of 300 large asteroids, which was used in the mass determination algorithm to model significant perturbations from the rest of the main belt. After combining our mass estimates with those of other authors, we study the bulk porosities of over 50 main-belt asteroids and observe that asteroids as large as 300 km in diameter may be loose aggregates. This finding may place specific constraints on models of main-belt collisional evolution. Additionally, we observe that C-group asteroidsmore » tend to have significantly higher macroporosity than S-group asteroids.« less

Asteroid photometry

USGS Publications Warehouse

Li, Jian-Yang; Helfenstein, Paul; Buratti, Bonnie J.; Takir, Driss; Beth Ellen Clark,; Michel, Patrick; DeMeo, Francesca E.; Bottke, William F.

2015-01-01

Asteroid photometry has three major applications: providing clues about asteroid surface physical properties and compositions, facilitating photometric corrections, and helping design and plan ground-based and spacecraft observations. The most significant advances in asteroid photometry in the past decade were driven by spacecraft observations that collected spatially resolved imaging and spectroscopy data. In the mean time, laboratory measurements and theoretical developments are revealing controversies regarding the physical interpretations of models and model parameter values. We will review the new developments in asteroid photometry that have occurred over the past decade in the three complementary areas of observations, laboratory work, and theory. Finally we will summarize and discuss the implications of recent findings.

Are Adonis and Hephaistos "Extinct" Comets?

NASA Astrophysics Data System (ADS)

Babadzhanov, P. B.

The investigation of the evolution of Earth-approaching asteroids with the aim of revealing their meteor streams is one of the ways to determine if these asteroids are extinct comets. The orbital evolution of asteroids 2101 Adonis and 2212 Hephaistos studied, respectively, by AlfanGoryachev and Everhart methods shows that these asteroids cross the Earth's orbit four times. Their possible meteoroid swarms may therefore produce four meteor showers each. In this work, the theoretically predicted orbital elements and radiants of these streams are compared to the available observational data. In the cases of both Adonis and Hephaistos, all four meteor showers are shown to be active. Most likely, these asteroids are extinct comets.

Asteroid Initiative Industry and Partner Day

NASA Image and Video Library

2013-06-18

Tom Kalil, Deputy Director for Technology and Innovation, White House Office of Science and Technology Policy, and, NASA Deputy Administrator Lori Garver, listen as NASA Associate Administrator for Human Exploration and Operations, William Gerstenmaier, talks during the Asteroid Initiative Industry and Partner Day at NASA Headquarters on Tuesday, June 18, 2013 in Washington. During the event NASA Deputy Administrator Lori Garver and other senior NASA officials discussed the progress being made on NASA's mission to capture, redirect, and explore an asteroid. NASA also announced an Asteroid Grand Challenge focused on finding all asteroid threats to human populations and knowing what to do about them. Photo Credit: (NASA/Bill Ingalls)

Rotation parameters and shapes of 15 asteroids

NASA Astrophysics Data System (ADS)

Tungalag, N.; Shevchenko, V. G.; Lupishko, D. F.

2002-12-01

With the use of the combined method (the amplitude and magnitude method plus the epoch method) pole coordinates, sidereal rotation periods, and axial ratios of triaxial ellipsoid figures for asteroids 22 Kalliope, 75 Eurydike, 93 Minerva, 97 Klotho, 105 Artemis, 113 Amalthea, 119 Althaea, 201 Penelope, 270 Anahita, 338 Budrosa, 487 Venetia, 674 Rachele, 776 Berbericia, 887 Alinda, nd 951 Gaspra were determined. For eight of them (asteroids 75, 97, 105, 113, 119, 338, 674, and 887) these values were obtained for the first time. We used the numerical photometric asteroid model based on ellipsoidal asteroid shape, homogeneous albedo distribution over the surface, and Akimov's scattering law.

The origin of planetary impactors in the inner solar system.

PubMed

Strom, Robert G; Malhotra, Renu; Ito, Takashi; Yoshida, Fumi; Kring, David A

2005-09-16

Insights into the history of the inner solar system can be derived from the impact cratering record of the Moon, Mars, Venus, and Mercury and from the size distributions of asteroid populations. Old craters from a unique period of heavy bombardment that ended approximately 3.8 billion years ago were made by asteroids that were dynamically ejected from the main asteroid belt, possibly due to the orbital migration of the giant planets. The impactors of the past approximately 3.8 billion years have a size distribution quite different from that of the main belt asteroids but very similar to that of near-Earth asteroids.

Philosophy and updating of the asteroid photometric catalogue

NASA Technical Reports Server (NTRS)

Magnusson, Per; Barucci, M. Antonietta; Capria, M. T.; Dahlgren, Mats; Fulchignoni, Marcello; Lagerkvist, C. I.

1992-01-01

The Asteroid Photometric Catalogue now contains photometric lightcurves for 584 asteroids. We discuss some of the guiding principles behind it. This concerns both observers who offer input to it and users of the product.

Application of Close Encounters in Determining the Masses of Asteroids

NASA Astrophysics Data System (ADS)

Tang, H. J.; Li, F.; Fu, Y. N.

2017-11-01

Asteroids are important part of the solar system. So far, the number of known asteroids is more than seven hundred thousand, and the total number is probably more than one million. Among many events of encounters among asteroids, those very close ones can be used to improve the precision of the masses of asteroids. To achieve this, it's necessary to search for the latter events in advance by making an accurate assessment of the effectiveness of an encounter in the mass determination. In this context, the previous dynamical models and assessing indicators are not precise enough. By using a more realistic dynamical model and introducing a properly defined Signal-to-Noise ratio, we are able to estimate the precision of the mass determination based on observations made from the Earth. Moreover, the best observation time span can be quantitatively given, which is useful in collecting observational data and planning further observations. We search systematically for the useful asteroid encounters involving one of the 773 massive asteroids with equivalent diameter larger than 50 km, for which the searched time span is from the year 2000 to 2030.

Logistics Needs for Potential Deep Space Mission Scenarios Post Asteroid Crewed Mission

NASA Technical Reports Server (NTRS)

Lopez, Pedro, Jr.

2015-01-01

A deep-space mission has been proposed to identify and redirect an asteroid to a distant retrograde orbit around the moon, and explore it by sending a crew using the Space Launch System and the Orion spacecraft. The Asteroid Redirect Crewed Mission (ARCM), which represents the third segment of the Asteroid Redirect Mission (ARM), could be performed on EM-3 or EM-4 depending on asteroid return date. Recent NASA studies have raised questions on how we could progress from current Human Space Flight (HSF) efforts to longer term human exploration of Mars. This paper will describe the benefits of execution of the ARM as the initial stepping stone towards Mars exploration, and how the capabilities required to send humans to Mars could be built upon those developed for the asteroid mission. A series of potential interim missions aimed at developing such capabilities will be described, and the feasibility of such mission manifest will be discussed. Options for the asteroid crewed mission will also be addressed, including crew size and mission duration.

Trajectory of asteroid 2017 SB20 within the CRTBP

NASA Astrophysics Data System (ADS)

Tiwary, Rishikesh Dutta; Kushvah, Badam Singh; Ishwar, Bhola

2018-06-01

Regular monitoring the trajectory of asteroids to a future time is a necessity, because the variety of known probably unsafe near-Earth asteroids are increasing. The analysis is perform to avoid any incident or whether they would have a further future threat to the Earth or not. Recently a new Near Earth Asteroid (2017 SB20) has been observed to cross the Earth orbit. In view of this we obtain the trajectory of Asteroid in the circular restricted three body problem with radiation pressure and oblateness. We examine nature of Asteroid's orbit with Lyapunov Characteristic Exponents (LCEs) over a finite intervals of time. LCE of the system confirms that the motion of asteroid is chaotic in nature. With the effect of radiation pressure and oblateness the length of curve varies in both the planes. Oblateness factor is found to be more perturbative than radiation pressure. To see the precision of result obtain from numerical integration we show the error propagation and the numerical stability is assured around the singularity by applying regularized equations of motion for precise long-term study.

Asteroid 'Bites the Dust' Around Dead Star

NASA Technical Reports Server (NTRS)

2009-01-01

NASA's Spitzer Space Telescope set its infrared eyes upon the dusty remains of shredded asteroids around several dead stars. This artist's concept illustrates one such dead star, or 'white dwarf,' surrounded by the bits and pieces of a disintegrating asteroid. These observations help astronomers better understand what rocky planets are made of around other stars.

Asteroids are leftover scraps of planetary material. They form early on in a star's history when planets are forming out of collisions between rocky bodies. When a star like our sun dies, shrinking down to a skeleton of its former self called a white dwarf, its asteroids get jostled about. If one of these asteroids gets too close to the white dwarf, the white dwarf's gravity will chew the asteroid up, leaving a cloud of dust.

Spitzer's infrared detectors can see these dusty clouds and their various constituents. So far, the telescope has identified silicate minerals in the clouds polluting eight white dwarfs. Because silicates are common in our Earth's crust, the results suggest that planets similar to ours might be common around other stars.

Special issue on asteroids - Introduction

NASA Astrophysics Data System (ADS)

Novaković, Bojan; Hsieh, Henry H.; Gronchi, Giovanni F.

2018-04-01

The articles in this special issue are devoted to asteroids, small solar system bodies that primarily populate a region between the orbits of Mars and Jupiter, known as the asteroid belt, but can also be found throughout the Solar System. Asteroids are considered to be a key to understanding the formation and evolution of our planetary system. Their properties allow us to test current theoretical models and develop new theoretical concepts pertaining to evolutionary processes in the Solar System. There have been major advances in asteroid science in the last decade, and that trend continues. Eighteen papers accepted for this special issue cover a wide range of asteroid-related subjects, pushing the boundaries of our understanding of these intriguing objects even further. Here we provide the reader with a brief overview of these thrilling papers, with an invitation for interested scientists to read each work in detail for a better understanding of these recent cutting edge results. As many topics in asteroid science remain open challenges, we hope that this special issue will be an important reference point for future research on this compelling topic.

An age-colour relationship for main-belt S-complex asteroids.

PubMed

Jedicke, Robert; Nesvorný, David; Whiteley, Robert; Ivezić Z, Zeljko; Jurić, Mario

2004-05-20

Asteroid collisions in the main belt eject fragments that may eventually land on Earth as meteorites. It has therefore been a long-standing puzzle in planetary science that laboratory spectra of the most populous class of meteorite (ordinary chondrites, OC) do not match the remotely observed surface spectra of their presumed (S-complex) asteroidal parent bodies. One of the proposed solutions to this perplexing observation is that 'space weathering' modifies the exposed planetary surfaces over time through a variety of processes (such as solar and cosmic ray bombardment, micro-meteorite bombardment, and so on). Space weathering has been observed on lunar samples, in Earth-based laboratory experiments, and there is good evidence from spacecraft data that the process is active on asteroid surfaces. Here, we present a measurement of the rate of space weathering on S-complex main-belt asteroids using a relationship between the ages of asteroid families and their colours. Extrapolating this age-colour relationship to very young ages yields a good match to the colour of freshly cut OC meteorite samples, lending strong support to a genetic relationship between them and the S-complex asteroids.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kasuga, Toshihiro; Usui, Fumihiko; Hasegawa, Sunao

Primitive, outer-belt asteroids are generally of low albedo, reflecting carbonaceous compositions like those of CI and CM meteorites. However, a few outer-belt asteroids having high albedos are known, suggesting the presence of unusually reflective surface minerals or, conceivably, even exposed water ice. Here, we present near-infrared (1.1-2.5 {mu}m) spectra of four outer-belt C-complex asteroids with albedos {>=}0.1. We find no absorption features characteristic of water ice (near 1.5 and 2.0 {mu}m) in the objects. Intimate mixture models set limits to the water ice by weight {<=}2%. Asteroids (723) Hammonia and (936) Kunigunde are featureless and have (60%-95%) amorphous Mg pyroxenesmore » that might explain the high albedos. Asteroid (1276) Ucclia also shows a featureless reflection spectrum with (50%-60%) amorphous Mg pyroxenes. Asteroid (1576) Fabiola shows a possible weak, broad absorption band (1.5-2.1 {mu}m). The feature can be reproduced by (80%) amorphous Mg pyroxenes or orthopyroxene (crystalline silicate), either of which is likely to cause its high albedo. We discuss the origin of high-albedo components in primitive asteroids.« less

Spitzer IRS Spectra of Basaltic Asteroids: Preliminary Results

NASA Technical Reports Server (NTRS)

Lim, Lucy F.; Emery, Joshua P.; Moskovitz, Nick; Stewart, Heather; Marchis, Frank

2008-01-01

We present preliminary results of a Spitzer program to observe the 5.2--38 micron spectra of small basaltic asteroids using the Spitzer IRS (Infrared Spectrograph). Our targets include members of the dynamical family of the unique large differentiated asteroid 4 Vesta ("Vestoids"), four outer-main-belt basaltic asteroids whose orbits exclude them from originating on 4 Vesta, and the basaltic near-Earth asteroid (NEA) 4055 Magellan. We will compare the compositions and thermophysical properties of the non-Vestoid objects with those of the dynamical vestoids to provide insight on the extent of metal-silicate differentiation on planetsimals during the epoch of planet formation in the early Solar System. As of this writing, spectra of asteroids 10537 (1991 RY16) and 2763 Jeans have been returned. Analysis of these data are ongolng. Observations of 956 Elisa, 2653 Principia, 4215 Kamo, 7472 Kumakiri, and 1459 Magnya have been scheduled and are expected to be available by the time of the DPS meeting. NIR spectra and lightcurves o f the target asteroids are also being observed in support of this program.

Parameter-Study Of The Thermal Yarkovsky Effect Acting On Neas

NASA Astrophysics Data System (ADS)

Polishook, David; Prialnik, D.; Rosenberg, E.; Brosch, N.

2010-10-01

We study the relevant parameters for the thermal Yarkovsky effect acting on Near-Earth Asteroids (NEAs), specifically the rotation period and rotation axis. The study uses a quasi 3-D thermal model to derive the temperature map over the surface of the asteroid, and the thermal thrust is calculated. The model (Prialnik et al. 2004, Rosenberg and Prialnik 2006), uses an implicit scheme to numerically solve the equations that describe the asteroid and its thermal evolution. The results show how the thermal thrust is stronger for fast-rotating asteroids, as heat is emitted from their surface on the evening side, increasing the tangential component of the thermal thrust. Moreover, we show the differences in the thermal thrust between asteroids with different perihelion distances, and how this can explain the observed distribution of asteroids in the inner Solar System on the spin-perihelion plane. Our results suggest that many asteroids within the inner Solar System may have retrograde spins. Acknowledgements: D. Polishook is grateful for an Ilan Ramon doctoral scholarship from the Israeli Ministry of Science.

Reverse Asteroids: Searching for an Effective Tool to Combat Asteroid Belt Misconceptions

NASA Astrophysics Data System (ADS)

Summers, F.; Eisenhamer, B.

2014-12-01

The public 'knows' that asteroid belts are densely packed and dangerous for spaceships to cross. Visuals from "Star Wars" to, unfortunately, the recent "Cosmos" TV series have firmly established this astronomical misconception. However, even scientifically correct graphics, such as the Minor Planet Center's plot of the inner solar system, reinforces that view. Each pixel in the image is more than a million kilometers in width, making an accurate representation of the object density impossible.To address this widespread misconception, we are investigating an educational exercise built around a computer interactive that we call "Reverse Asteroids". In the arcade classic video game, the asteroids came to the player's spaceship. For our reverse implementation, we consider an inquiry-based activity in which the spaceship must go hunting for the asteroids, using a database of real objects in our solar system. Both 3D data visualization and basic statistical analysis play crucial roles in bringing out the true space density within the asteroid belt, and perhaps a reconciliation between imagination and reality. We also emphasize that a partnership of scientists and educators is fundamental to the success of such projects.

Asteroid resources

NASA Technical Reports Server (NTRS)

Lewis, John S.

1992-01-01

There are three types of possible asteroidal materials that appear to be attractive for exploitation: (1) volatiles, (2) free metals, and (3) bulk dirt. Because some of the near-Earth asteroids are energetically more accessible than the Moon (require a round-trip total change in velocity less than 9 km/sec, though the trip time would be measured in years not days), such an asteroid might be chosen as the source of any useful material, even if that material was also available on the Moon. Provided that the asteroid was minable, it might therefore be chosen as the source of bulk dirt needed for shielding in low Earth orbit (LEO) or elsewhere in near-Earth space. And the near-Earth asteroids may offer materials that are rare or absent on the surface of the Moon. The relationship between asteroids and meteorites is discussed. A brief overview of the entire range of meteorite compositions, with emphasis on the occurrence of interesting resources is presented. Focus is on materials useful in space, especially volatiles, metals, and raw dirt. Those few materials that may have sufficiently high market value to be worth returning to Earth will be mentioned.

AN ASTEROID BELT INTERPRETATION FOR THE TIMING VARIATIONS OF THE MILLISECOND PULSAR B1937+21

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shannon, R. M.; Cordes, J. M.; Metcalfe, T. S.

Pulsar timing observations have revealed companions to neutron stars that include other neutron stars, white dwarfs, main-sequence stars, and planets. We demonstrate that the correlated and apparently stochastic residual times of arrival from the millisecond pulsar B1937+21 are consistent with the signature of an asteroid belt having a total mass {approx}< 0.05 M{sub Circled-Plus }. Unlike the solar system's asteroid belt, the best fit pulsar asteroid belt extends over a wide range of radii, consistent with the absence of any shepherding companions. We suggest that any pulsar that has undergone accretion-driven spin-up and subsequently evaporated its companion may harbor orbitingmore » asteroid mass objects. The resulting timing variations may fundamentally limit the timing precision of some of the other millisecond pulsars. Observational tests of the asteroid belt model include identifying periodicities from individual asteroids, which are difficult; testing for statistical stationarity, which becomes possible when observations are conducted over a longer observing span; and searching for reflected radio emission.« less

Physical Characteristics of Asteroid-like Comet Nucleus C/2001 OG108 (LONEOS)

NASA Technical Reports Server (NTRS)

Abell, P. A.; Fernandez, Y. R.; Pravec, P.; French, L. M.; Farnham, T. L.; Gaffey, M. J.; Hardersen, P. S.; Kusnirak, P.; Sarounova, L.; Sheppard, S. S.

2003-01-01

For many years several investigators have suggested that some portion of the near-Earth asteroid population may actually be extinct cometary nuclei. Evidence used to support these hypotheses was based on: observations of asteroid orbits and associated meteor showers (e.g. 3200 Phaethon and the Geminid meteor shower); low activity of short period comet nuclei, which implied nonvolatile surface crusts (e.g. Neujmin 1, Arend-Rigaux); and detections of transient cometary activity in some near-Earth asteroids (e.g. 4015 Wilson-Harrington). Recent investigations have suggested that approximately 5-10% of the near- Earth asteroid population may be extinct comets. However if members of the near-Earth asteroid population are extinct cometary nuclei, then there should be some objects within this population that are near their final stages of evolution and so should demonstrate only low levels of activity. The recent detections of coma from near-Earth object 2001 OG108 have renewed interest in this possible comet-asteroid connection. This paper presents the first high quality ground-based near-infrared reflectance spectrum of a comet nucleus combined with detailed lightcurve and albedo measurements.

The distribution of compositional classes in the asteroid belt: A cosmochemical fingerprint?

NASA Technical Reports Server (NTRS)

Gradie, J.

1985-01-01

Studies of the physical properties of the asteroids show a nonrandom distribution of types across the belt for asteroid classes E, S, M, F, C, P, and D. The general trend is for asteroids in the inner belt to have higher albedos and stronger mafic silicate absorption features than those asteroids located further out in the belt. One interpretation of this trend is that the asteroids, which occupy the region between the silicate rich terrestrial planets and the volatile rich outer planets, have preserved in their heliocentric compositional distribution a cosmochemical fingerprint of the thermodynamic conditions present in the solar nebula at the time of their formation. This hypothesis predicts that the differences in the spectral properties among the low albedo classes (C, P, F, P, and D) are due to temperature controlled processes which formed carbonaceous opaques. If this is true then the exact composition of the opaque components could, in principle, be used to determine the thermodynamic conditions between the orbits of Mars and Jupiter during the formation of the asteroids.

Asteroids: A History

NASA Astrophysics Data System (ADS)

Britt, Dan

I finished reading Curtis Peebles' book Asteroids: A History with mixed emotions, but overall I was very disappointed. I enjoyed, with some reservations, the first few chapters, which describe the early days of asteroid astronomy. One thing that makes asteroid science enjoyable today is the rich collection of interesting and eccentric characters that share this profession.The 19th and early 20th centuries were no different. The story of these dedicated and sometimes strange individuals makes for lively reading. There was Hermann Goldschmidt, a German-born artist living over the Café Procope in Paris. In 1852, he caught the asteroid bug after attending a public lecture on astronomy, bought a telescope, and over the next 9 years discovered 14 asteroids by observing out of his apartment window with a 2-inch telescope! In those days, before astronomical photography, observers searched for asteroids by hand-drawing the starfield as seen through the telescope and then comparing it with another hand-drawn starfield done hours or nights later. Keen eyesight, steady hands, and the ability to draw accurately in the dark—and cold—were major advantages.

Sodium channel blockade with QRS widening after an escitalopram overdose.

PubMed

Schreffler, Susan M; Marraffa, Jeanna M; Stork, Christine M; Mackey, Jennifer

2013-09-01

Escitalopram is rarely associated with prolongation of the QTc interval; however, there are no reported cases of QRS complex widening associated with escitalopram overdose. We report a case of a patient who presented with both QRS complex widening and QTc interval prolongation after an escitalopram overdose. A 16-year-old girl presented to the emergency department after ingestion of escitalopram, tramadol/acetaminophen, and hydrocodone/acetaminophen. Laboratory results were significant for 4-hour acetaminophen 21.1 μg/mL. Serum electrolytes including potassium, magnesium, and calcium were all normal. Initial electrocardiogram (ECG) revealed a widened QRS with an incomplete right bundle branch pattern. After administration of 100-mEq sodium bicarbonate, a repeat ECG revealed narrowing of the QRS complex and a prolonged QTc interval. Magnesium sulfate 2 g intravenous and sodium bicarbonate drip were initiated. A repeat ECG, 1 hour after the second, revealed normalization of the QRS complex and QTc interval. Prolongation of the QTc interval is an expected effect of escitalopram. Both escitalopram and citalopram are metabolized to the cardiotoxic metabolite S-didesmethylcitalopram and didesmethylcitalopram, respectively, which have been implicated in numerous cardiac abnormalities including widening of the QRS complex. Although never previously described with escitalopram, this mechanism provides a reasonable explanation for the QRS complex widening and incomplete right bundle branch block that occurred in our patient. Both QRS complex widening and QTc interval prolongation should be monitored in cases of escitalopram and citalopram overdoses.

How to Tell the Size of An Asteroid

NASA Image and Video Library

2011-09-29

This chart based on data from NASA Wide-field Infrared Survey Explorer illustrates how infrared is used to more accurately determine an asteroid size; three asteroids of different sizes can look similar when viewed in visible-light.

Asteroid Bites the Dust Around Dead Star Artist Concept

NASA Image and Video Library

2009-01-05

NASA Spitzer Space Telescope set its infrared eyes upon the dusty remains of shredded asteroids around several dead stars. This artist concept illustrates a white dwarf, surrounded by the bits and pieces of a disintegrating asteroid.

Brazil Nuts on Eros: Size-Sorting of Asteroid Regolith

NASA Technical Reports Server (NTRS)

Asphaug, E.; King, P. J.; Swift, M. R.; Merrifield, M. R.

2001-01-01

We consider the hypothesis that frequent cratering produces size- or compositionally-sorted asteroid regolith, affecting the structure, texture, and in extreme cases the shape of asteroids. Additional information is contained in the original extended abstract.

Asteroid Studies: A 35-Year Forecast

NASA Astrophysics Data System (ADS)

Rivkin, A. S.; Denevi, B. W.; Klima, R. L.; Ernst, C. M.; Chabot, N. L.; Barnouin, O. S.; Cohen, B. A.

2017-02-01

We are in an active time for asteroid studies, which fall at the intersection of science, planetary defense, human exploration, and in situ resource utilization. We look forward and extrapolate what the future may hold for asteroid science.

Excluding interlopers from asteroid families

NASA Astrophysics Data System (ADS)

Radović, Viktor; Novaković, Bojan

2014-07-01

To study an asteroid family it is crucial to determine reliably the list of its members, i.e. to reduce the number of interlopers as much as possible. However, as the number of known asteroids increases fast it becomes more and more difficult to obtain robust list of members of an asteroid family. To cope with these challenges we are proposing a new approach that may help to significantly reduce presence of interlopers among the family members.

Asteroid Lightcurves from Xingming Observatory: 2017 - 2017 June

NASA Astrophysics Data System (ADS)

Tan, Hanjie; Yeh, Tingshuo; Li, Bin; Gao, Xing

2018-01-01

The lightcurves of main-belt asteroids 963, 1025, 2019, and 17814 and near-Earth asteroids (NEAs) 459872, 2014 JO25, and 2017 BS32 were obtained using Xingming Observatory (Code C42) from 2016 March to 2017 March. The absolute magnitudes of these asteroids range from H = 11.6 to 27.3, corresponding to a diameter range of 14 m to 14 km. The derived synodic rotation periods range between 0.1 to 10 h.

Solar System evolution from compositional mapping of the asteroid belt.

PubMed

DeMeo, F E; Carry, B

2014-01-30

Advances in the discovery and characterization of asteroids over the past decade have revealed an unanticipated underlying structure that points to a dramatic early history of the inner Solar System. The asteroids in the main asteroid belt have been discovered to be more compositionally diverse with size and distance from the Sun than had previously been known. This implies substantial mixing through processes such as planetary migration and the subsequent dynamical processes.

AO Images of Asteroids, Inverting their Lightcurves, and SSA

DTIC Science & Technology

2008-09-01

telescopes, we have recently obtained images of Main- Belt asteroids with adaptive optics (AO) on the Keck-II 10 meter telescope, the world’s largest...telescopes, we have recently obtained images of Main- Belt asteroids with adaptive optics (AO) on the Keck-II 10 meter telescope, the world’s largest...AO Images of Asteroids , Inverting their Lightcurves, and SSA Jack Drummond a and Julian Christoub,c aStarfire Optical Range, Directed Energy

Compositional structure of the asteroid belt.

PubMed

Gradie, J; Tedesco, E

1982-06-25

The distribution of compositional types among the asteroids is found to vary systematically with heliocentric distance. Seven distinct peaks in the relative proportion of the compositional types E, R, S, M, F, C, P, and D are found from 1.8 to 5.2 astronomical units. The inferred composition of the asteroids in each semimajor axis region is consistent with the theory that the asteroids accreted from the solar nebula at or near their present locations.

Killer rocks and the celestial police - The search for near-earth asteroids

NASA Technical Reports Server (NTRS)

Yeomans, Donald K.

1991-01-01

The discovery of asteroids near the earth as the result of search programs is detailed with attention given to methods for locating, tracking, and identifying asteroids. The concept of 'prediscovery' is discussed in which new asteroids are tracked backward in time through previous celestial observational data. The need for more comprehensive programs is identified in order to locate objects that present a clear danger of colliding with the earth.

Understanding asteroid collisional history through experimental and numerical studies

NASA Technical Reports Server (NTRS)

Davis, Donald R.; Ryan, Eileen V.; Weidenschilling, S. J.

1991-01-01

Asteroids can lose angular momentum due to so called splash effect, the analog to the drain effect for cratering impacts. Numerical code with the splash effect incorporated was applied to study the simultaneous evolution of asteroid sized and spins. Results are presented on the spin changes of asteroids due to various physical effects that are incorporated in the described model. The goal was to understand the interplay between the evolution of sizes and spins over a wide and plausible range of model parameters. A single starting population was used both for size distribution and the spin distribution of asteroids and the changes in the spins were calculated over solar system history for different model parameters. It is shown that there is a strong coupling between the size and spin evolution, that the observed relative spindown of asteroids approximately 100 km diameter is likely to be the result of the angular momentum splash effect.

Understanding asteroid collisional history through experimental and numerical studies

NASA Astrophysics Data System (ADS)

Davis, Donald R.; Ryan, Eileen V.; Weidenschilling, S. J.

1991-06-01

Asteroids can lose angular momentum due to so called splash effect, the analog to the drain effect for cratering impacts. Numerical code with the splash effect incorporated was applied to study the simultaneous evolution of asteroid sized and spins. Results are presented on the spin changes of asteroids due to various physical effects that are incorporated in the described model. The goal was to understand the interplay between the evolution of sizes and spins over a wide and plausible range of model parameters. A single starting population was used both for size distribution and the spin distribution of asteroids and the changes in the spins were calculated over solar system history for different model parameters. It is shown that there is a strong coupling between the size and spin evolution, that the observed relative spindown of asteroids approximately 100 km diameter is likely to be the result of the angular momentum splash effect.

UV Spectroscopy of Metallic Asteroid (16) Psyche

NASA Astrophysics Data System (ADS)

Cunningham, N. J.; Becker, T. M.; Retherford, K. D.; Roth, L.; Feaga, L. M.; Wahlund, J.-E.; Elkins-Tanton, L. T.

2017-09-01

Asteroid (16) Psyche is the largest M-type asteroid, and the planned destination of the NASA Discovery mission Psyche and the proposed ESA M5 mission Heavy Metal. Psyche is considered to be the exposed core of a differentiated asteroid, whose mantle has been stripped by collisions; but other histories have been proposed. We observed Psyche with the Space Telescope Imaging Spectrograph (STIS) and Cosmic Origins Spectrograph (COS) aboard the Hubble Space Telescope, to obtain a full ultraviolet (UV) spectrum of both of Psyche's hemispheres. We seek to test three possible scenarios for Psyche's origin: Is Psyche the exposed core of a differentiated asteroid? Is it an asteroid with high olivine content that has been space-weathered? Or did Psyche accrete as-is in a highly-reducing environment early in the history of the solar system? We will present the UV spectra and their implications for Psyche's history.

A Re-examination of the Lightcurves for Seven Hungaria Asteroids

NASA Astrophysics Data System (ADS)

Warner, Brian D.; Stephens, Robert, D.; Harris, Alan W.; Pravec, Petr

2009-10-01

During the course of a study of long period asteroids (f < 1/d) within the Hungaria asteroid population, the lightcurves for seven asteroids were re-examined using updated software and techniques. Several were found to have significantly different periods from those previously reported by two of the authors (Warner and Stephens). The most significant change was 2074 Shoemaker, which was initially reported to have a period of 57 h but now appears to be a binary asteroid with a primary period of 2.5328 ± 0.0004 h and a possible orbital period of 55.52 ± 0.01 h. The other asteroids that were re-examined were 1919 Clemence, 3043 San Diego, 3353 Jarvis, 4142 Dersu-Uzala, (20232) 1997 YK, and (101549) 1998 YY2. The reexamination showed once again the importance of placing data on at least an internal system to achieve accurate night-to-night calibrations.

Discovery of M class objects among the near-earth asteroid population

NASA Technical Reports Server (NTRS)

Tedesco, Edward F.; Gradie, Jonathan

1987-01-01

Broadband colorimetry, visual photometry, near-infrared photometry, and 10 and 20 micron radiometry of the near-earth asteroids (NEAs) 1986 DA and 1986 EB are used to show that these objects belong to the M class of asteroids. The similarity among the distributions of taxonomic classes among the 38 NEAs to the abundances found in the inner astoroid belt between the 3:1 and 5:2 resonances suggests that NEAs have their origins among asteroids in the vicinity of these resonances. The implied mineralogy of 1986 DA and 1986 EB is mostly nickel-iron metal; if this is indeed the case, then current models for meteorite production based on strength-related collisional processes on asteroidal surfaces predict that these two objects alone should produce about one percent of all meteorite falls. Iron meteorites derived from these near-earth asteroids should have low cosmic-ray exposure ages.

An automatic approach to exclude interlopers from asteroid families

NASA Astrophysics Data System (ADS)

Radović, Viktor; Novaković, Bojan; Carruba, Valerio; Marčeta, Dušan

2017-09-01

Asteroid families are a valuable source of information to many asteroid-related researches, assuming a reliable list of their members could be obtained. However, as the number of known asteroids increases fast it becomes more and more difficult to obtain a robust list of members of an asteroid family. Here, we are proposing a new approach to deal with the problem, based on the well-known hierarchical clustering method. An additional step in the whole procedure is introduced in order to reduce a so-called chaining effect. The main idea is to prevent chaining through an already identified interloper. We show that in this way a number of potential interlopers among family members is significantly reduced. Moreover, we developed an automatic online-based portal to apply this procedure, I.e. to generate a list of family members as well as a list of potential interlopers. The Asteroid Families Portal is freely available to all interested researchers.

The composition and origin of the C, P, and D asteroids - Water as a tracer of thermal evolution in the outer belt

NASA Technical Reports Server (NTRS)

Jones, Thomas D.; Lebofsky, Larry A.; Lewis, John S.; Marley, Mark S.

1990-01-01

A telescopic and laboratory investigation of water distribution among low albedo asteroids in the outer belt, using the 3-micron reflectance absorption of molecular H2O and structural OH ions (coincident with the 3-micron spectral signature of meteorite and asteroid hydrated silicates) shows that 66 percent of the C-class asteroids in the sample have hydrated silicate surfaces. In conjunction with the apparently anhydrous P and D surfaces, this pronounced hydration difference between C-class asteroids and the more distant P and D classes points to an original outer belt asteroid composition of anhydrous silicates, water ice, and complex organic material. Early solar-wind induction heating of protoasteroids, declining in intensity with distance from the sun, is conjectured to have produced the observed diminution of hydrated silicate abundance.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gould, Andrew; Yee, Jennifer C., E-mail: gould@astronomy.ohio-state.edu, E-mail: jyee@astronomy.ohio-state.edu

While of order of a million asteroids have been discovered, the number in rigorously controlled samples that have precise orbits and rotation periods, as well as well-measured colors, is relatively small. In particular, less than a dozen main-belt asteroids with estimated diameters D < 3 km have excellent rotation periods. We show how existing and soon-to-be-acquired microlensing data can yield a large asteroid sample with precise orbits and rotation periods, which will include roughly 6% of all asteroids with maximum brightness I < 18.1 and lying within 10 Degree-Sign of the ecliptic. This sample will be dominated by small andmore » very small asteroids, down to D {approx} 1 km. We also show how asteroid astrometry could turn current narrow-angle OGLE proper motions of bulge stars into wide-angle proper motions. This would enable one to measure the proper-motion gradient across the Galactic bar.« less

Planetary astronomy program

NASA Technical Reports Server (NTRS)

1977-01-01

A program was developed in which asteroids and two planets, namely, Saturn and Uranus, were investigated. This included: (1) asteroid spectrophotometry; (2) the nature of the Trojan asteroids; (3) an investigation to determine asteroid masses; (4) the photometry, structure, and dynamics of the rings surrounding the planet Saturn; and (5) aerosol distribution in the atmosphere of Uranus. Plans were finalized to obtain observations of the nucleus of the dying comet P/Arend-Rigaux. Further work was accomplished in asteroid data reduction. Data were entered into the TRIAD data file and a program generated classifications for over 560 different asteroids. A photoelectric area scanner was used to obtain UBV scans of the disk of the planet Saturn on several winter and spring nights in 1977. Intensity profiles show pronounced limb brightening in U, moderate limb brightening in B, and limb darkening in V. Narrow band photoelectric area-scanning photometry of the Uranus disk is also reported. Results are given.

Astrometric masses of 21 asteroids, and an integrated asteroid ephemeris

NASA Astrophysics Data System (ADS)

Baer, James; Chesley, Steven R.

2008-01-01

We apply the technique of astrometric mass determination to measure the masses of 21 main-belt asteroids; the masses of 9 Metis (1.03 ± 0.24 × 10-11 M⊙), 17 Thetis (6.17 ± 0.64 × 10-13 M⊙), 19 Fortuna (5.41 ± 0.76 × 10-12 M⊙), and 189 Phthia (1.87 ± 0.64 × 10-14 M⊙) appear to be new. The resulting bulk porosities of 11 Parthenope (12±4%) and 16 Psyche (46±16%) are smaller than previously-reported values. Empirical expressions modeling bulk density as a function of mean radius are presented for the C and S taxonomic classes. To accurately model the forces on these asteroids during the mass determination process, we created an integrated ephemeris of the 300 large asteroids used in preparing the DE-405 planetary ephemeris; this new BC-405 integrated asteroid ephemeris also appears useful in other high-accuracy applications.

Advanced Navigation Strategies for an Asteroid Sample Return Mission

NASA Technical Reports Server (NTRS)

Bauman, J.; Getzandanner, K.; Williams, B.; Williams, K.

2011-01-01

The proximity operations phases of a sample return mission to an asteroid have been analyzed using advanced navigation techniques derived from experience gained in planetary exploration. These techniques rely on tracking types such as Earth-based radio metric Doppler and ranging, spacecraft-based ranging, and optical navigation using images of landmarks on the asteroid surface. Navigation strategies for the orbital phases leading up to sample collection, the touch down for collecting the sample, and the post sample collection phase at the asteroid are included. Options for successfully executing the phases are studied using covariance analysis and Monte Carlo simulations of an example mission to the near Earth asteroid 4660 Nereus. Two landing options were studied including trajectories with either one or two bums from orbit to the surface. Additionally, a comparison of post-sample collection strategies is presented. These strategies include remaining in orbit about the asteroid or standing-off a given distance until departure to Earth.

THE PUZZLING MUTUAL ORBIT OF THE BINARY TROJAN ASTEROID (624) HEKTOR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marchis, F.; Cuk, M.; Durech, J.

Asteroids with satellites are natural laboratories to constrain the formation and evolution of our solar system. The binary Trojan asteroid (624) Hektor is the only known Trojan asteroid to possess a small satellite. Based on W. M. Keck adaptive optics observations, we found a unique and stable orbital solution, which is uncommon in comparison to the orbits of other large multiple asteroid systems studied so far. From lightcurve observations recorded since 1957, we showed that because the large Req = 125 km primary may be made of two joint lobes, the moon could be ejecta of the low-velocity encounter, which formedmore » the system. The inferred density of Hektor's system is comparable to the L5 Trojan doublet (617) Patroclus but due to their difference in physical properties and in reflectance spectra, both captured Trojan asteroids could have a different composition and origin.« less

Mass driver retrievals of earth-approaching asteroids. [earth orbit capture for mining purposes

NASA Technical Reports Server (NTRS)

Oleary, B.

1977-01-01

Mass driver tugs can be designed to move Apollo and Amor asteroids at opportunities of low velocity increment to the vicinity of the earth. The cost of transferring asteroids through a velocity interval of 3 km/sec by mass driver is about 16 cents per kilogram amortized over 10 years, about ten times less than that required to retrieve lunar resources during the early phases of a program of space manufacturing. About 22 per cent of a 200-meter diameter asteroid could be transferred to high earth orbit by an automated 100 megawatt solar-powered mass driver in a period of five years for a cost of approximately $1 billion. Estimates of the total investment of a space manufacturing program could be reduced twofold by using asteroidal instead of lunar resources; such a program could begin several years sooner with minimal concurrent development if asteroidal search programs and mass driver development are immediately accelerated.

4963 Kanroku: Asteroid with a possible precession of rotation axis

NASA Astrophysics Data System (ADS)

Sokova, Iraida A.; Marchini, Alessandro; Franco, Lorenzo; Papini, Riccardo; Salvaggio, Fabio; Palmas, Teodora; Sokov, Eugene N.; Garlitz, Joe; Knight, Carl R.; Bretton, Marc

2018-04-01

Based on photometric observations of 4963 Kanroku as part of a campaign to measure its light-curve, changes of the light-curve profile have been detected. These changes are of a periodic nature, i.e. the profiles change with a detected period P = 16.4032 h. Based on simulations of the shape of the asteroid and using observational data, we make the assumption that such changes of the light-curve of the asteroid could be caused by the existence of a precession force acting on the axis of rotation of the asteroid. Simulations of the 4963 Kanroku light-curve, taking into account the detected precession, and the parameters for the shape of the asteroid, the modeled light-curves are in good agreement with the light-curves obtained from the observation campaign. Thus, the detected precession force may indicate a possible satellite of the asteroid 4963 Kanroku.

The nature of Trojan asteroid 624 Hektor

NASA Technical Reports Server (NTRS)

Hartmann, W. K.; Cruikshank, D. P.

1978-01-01

Near-simultaneous visual and thermal IR (20-micron) photometry of the Trojan asteroid 624 Hektor is reported which was performed when the asteroid was observed nearly along its rotation axis. The results confirm and refine the low albedo and large size of this asteroid and confirm the general rotational-pole position and aspect angle predicted by Dunlap and Gehrels (1969). Hektor is found to be a truly extraordinary object in that it is larger and far more irregular in shape than other measured Trojans and far more irregular than other belt asteroids of comparable size. It is proposed that Hektor could be a partially coalesced pair of Trojan asteroids which collided with energy too low to cause complete fragmentation, thus forming a dumbbell-shaped object. A possible scenario is outlined according to which the two pre-Hektor objects were neighboring relatively large primitive spheroidal planetesimals trapped in Jupiter's Lagrangian cloud. Observational and theoretical tests of this model are suggested.

The composition of the Trojan asteroids

NASA Technical Reports Server (NTRS)

Gradie, J.; Veverka, J.

1980-01-01

Consideration is given to the composition of those Trojan asteroids, Hilda asteroids and 944 Hidalgo with very low albedos and spectral reddening between 0.4 and 1.1 microns with respect to the C asteroids, termed RD objects. It is proposed that the albedo and reddening of these objects can be explained by the presence of very opaque, very red, polymer-type organic compounds structurally similar to kerogen, presumably resulting from Fischer-Tropsch-type reactions in the early solar nebula. The spectra and various mixtures of powdered montmorillonite, magnetite, coal-tar residue containing kerogen substances and carbon black are shown to provide a good match to the RD asteroid spectral properties. It is suggested that the nonsoluble carbonaceous residue may have required lower temperatures for its formation and preservation than carbonaceous materials in the carbonaceous chondrites and C asteroids, and thus explain the absence of RD objects closer than 4 AU from the sun.

Asteroid masses with Gaia from ground and space-based observations

NASA Astrophysics Data System (ADS)

Ivantsov, Anatoliy; Hestroffer, Daniel; Thuillot, William; Bancelin, David

2013-04-01

Determination of masses of large asteroids is one of the expected scientific outputs from the future Gaia astrometric space mission. With the exception of binary asteroids or fly-by with a space probe, the error in mass determination depends on the size of perturbation effect produced on the motion of small asteroids. Considering the 5 years nominal duration of the Gaia mission, there will be mutual close encounters between asteroids occurring either close to the beginning or to the end of the mission. So that the maximum of deflection angle pertained to the perturbation maxima will not be observed directly by Gaia. Since astrometric data of the perturbed body before and after the encounter are mandatory to derive a perturber mass, the precision of mass determinations based solely on the Gaia observations will deteriorate in such cases. The possible way out consists in acquiring ground-based observations of high astrometric precision in time either before or after the Gaia operations, as it was suggested in [1]. By adding such data, it is expected to increase the number of derived asteroids masses [2]. This paper updates earlier predictions of encounters of large asteroids with smaller ones, e.g. [3], in terms of newly discovered asteroids and available ground-based observations. The method used consists in the computation of the offsets in right ascension and declination between the unperturbed and perturbed solutions fitted to the available observations for each small (perturbed) asteroid. For the purpose of decreasing CPU time, a special filter was applied based on the solution of the two-body problem and systematical search for close encounters, e.g. less than 0.1 A.U., of all known asteroids with the large (perturber) ones. The obtained list of asteroids-candidates was used as the input file for the mentioned above accurate calculations. Such a procedure was used for a few asteroids in [2]. The maximum visible offset corresponds to the dates when the complementary ground-based observations will be useful. [1] Hestroffer, D., Thuillot, W., Mouret, S., Colas, F., Tanga, P., Mignard, F., Delbo, M., Carry, B.: Ground-based observations of solar system bodies in complement to Gaia, SF2A-2008: Proceedings of the Annual meeting of the French Society of Astronomy and Astrophysics, 30 June - 4 July 2008, Paris, France, 2008. [2] Mouret, S., Hestroffer, D., and Mignard, F.: Asteroid masses and Gaia, Astronomy and Astrophysics, Vol. 472, pp. 1017-1027, 2007. [3] Mouret, S.: Investigations on the dynamics of minor planets with GAIA: orbits, masses and fundamental physics, PhD thesis, Paris Observatory, 2007. [4] Hilton, J.L., Seidelmann, P.K., and Middour, J.: Prospects for determining asteroid masses, Astronomical Journal, Vol. 112, pp. 2319-2329, 1996.

Working Group Reports and Presentations: Asteroids

NASA Technical Reports Server (NTRS)

Lewis, John

2006-01-01

The study and utilization of asteroids will be an economical way to enable exploration of the solar system and extend human presence in space. There are thousands of near-earth objects (NEOs) that we will be able to reach. They offer resources, transportation, and exploration platforms, but also present a potential threat to civilization. Asteroids play a catastrophic role in the history of the Earth. Geological records indicate a regular history of massive impacts, which astronomical observations confirm is likely to continue with potentially devastating consequences. However, study and exploration of near earth asteroids can significantly increase advanced warning of an Earth impact, and potentially lead to the technology necessary to avert such a collision. Efforts to detect and prevent cataclysmic events would tend to foster and likely require international cooperation toward a unified goal of self-preservation. Exploration of asteroids will help us to understand our history and perhaps save our future. Besides the obvious and compelling scientific and security drivers for asteroid research and exploration, there are numerous engineering and industrial applications for near-term asteroid exploration. We have strong evidence that some asteroids are metal rich. Some are water and organic rich. They can be reached with a very low fuel cost compared to other solar system destinations. Once we reach them, there are efficient, simple extraction technologies available that would facilitate utilization. In addition, the costs of returning extracted resources from asteroids will be a fraction of the cost to return similar resources from the moon to Low Earth Orbit (LEO). These raw materials, extracted and shipped at relatively low cost, can be used to manufacture structures, fuel, and products which could be used to foster mankind s further exploration of the solar system. Asteroids also have the potential to offer transport to several destinations in the solar system. In addition to Mars and the Asteroid belt, it is possible to nudge the orbits of NEOs to provide convenient transport to other destinations. Resources to support life on these long voyages may be gathered from the host asteroid itself. As asteroids travel over a wide range of inclinations and ranges, they offer possible platforms to perform scientific investigations. These include unique vantage point observations of the sun and planets. These observations can help us to understand solar activity and space weather. They also afford us an opportunity to see how the earth looks from afar with different perspectives. When we look for planets outside of our solar system, these observations will help us to calibrate our data. Asteroids may also be used as platforms to support very long baseline interferometry with unprecedented angular resolutions.

A mission concept for a Grand Tour of Multiple Asteroid Systems

NASA Astrophysics Data System (ADS)

Marchis, F.; Dankanich, J.; Tricarico, P.; Bellerose, J.

2009-12-01

In 1993, the Galileo spacecraft imaged the first companion of asteroid, Dactyl orbiting 243 Ida, a main-belt asteroid. Since then, discoveries have been accumulated thanks to the development of high angular resolution imaging on ground-based telescopes (adaptive optics), radar observations and accurate photometric light curve measurements. To date, 180 companions of small solar system bodies (SSSBs) are known in various populations, including 100 in the asteroid main belt, 33 Near Earth Asteroids, 4 Jupiter-Trojan asteroids and 44 in the Kuiper Belt. Multiple Asteroids have been shown to be complex worlds in their own with a wide range of morphologies, dynamical histories, and structural evolution. To the exception of 243 Ida, no spacecraft has visited any of them. Investigating binary asteroid systems can verify and validate current theories on their formation and on the influence of the sun in their formation (YORP effect) and evolution (space weathering). In particular, assessing the origin of the secondary satellite, if it is of common origin or capture, can provide clue of their formation. To a larger extend, the determination of their nature, scenario formation and evolution are key to understand how planet formation occurred but also to understand i) the population and compositional structure of the SSSB today ii) how the dynamics and collisions modify this structure over time iii) what the physical properties of asteroids are (density, porosity) iv) how the surface modification processes affect our ability to determine this structure (e.g. space weathering). In addition, being able to study these properties on closeby asteroids will give a relative scale accounting for the sizes, shape, rotation periods and cratering rate of these small and young bodies. In the framework of the NASA Discovery program, we propose a mission consisting of a Grand Tour of several multiple asteroid systems, including the flyby of a near earth binary asteroid and the rendezvous with several multiple asteroid systems located in the main belt. This mission concept uses the NASA's evolutionary Xenon Thruster (NEXT), the second generation of electric propulsion with 3 times more input power than the previous generation (NSTAR) of the Dawn mission. The mission objectives for each rendezvous asteroid are i) the characterization of the surface geology by direct imaging in visible and thermal infrared spectroscopy, ii) the characterization of the shape and gravity coupling visible observations with LIDAR ranging data, iii) the determination of the thermophysical properties of the surface, and iv) the identification of the surface composition by visible and near-infrared spectroscopy. The trajectory, science package and mission operations of the mission will be described. This work is supported by the National Science Foundation 05-608, "Astronomy and Astrophysics Research Grants (AAG)" No AST-0807468

Perspectives on the prevalence and treatment of personality disorder.

PubMed

Winship, G; Hardy, S

2007-04-01

Personality disorder (PD) is the most prevalent psychiatric disorder. A methodical literature search identified that PD is under researched compared with other mental health problems such as depression or schizophrenia. Social and psychotherapeutic approaches emerge as dominant treatment approaches with PD where there is good evidence of efficacy. Collaborative group-based therapeutic approaches appear to offer a therapeutic counterpoise to the anti-social traits often prevalent in PD. A retrospective analysis of formal group therapy on acute inpatient units (treating PD patients among other mental health disorders) reveals only one violent incident in over 40,000 treatment hours of formal group therapy. It is argued that group-based and social therapy should be the recommended treatment approach because these approaches have been shown to create a safe and contained milieu, establishing a good base for therapeutic gain with PD patients. The case for widening the scope of collaborative group and community-based therapies is considered and the merits and shortcomings of a key worker system with PD patients are critiqued.

Pulse EPR distance measurements to study multimers and multimerisation

NASA Astrophysics Data System (ADS)

Ackermann, Katrin; Bode, Bela E.

2018-06-01

Pulse dipolar electron paramagnetic resonance (PD-EPR) has become a powerful tool for structural biology determining distances on the nanometre scale. Recent advances in hardware, methodology, and data analysis have widened the scope to complex biological systems. PD-EPR can be applied to systems containing lowly populated conformers or displaying large intrinsic flexibility, making them all but intractable for cryo-electron microscopy and crystallography. Membrane protein applications are of particular interest due to the intrinsic difficulties for obtaining high-resolution structures of all relevant conformations. Many drug targets involved in critical cell functions are multimeric channels or transporters. Here, common approaches for introducing spin labels for PD-EPR cause the presence of more than two electron spins per multimeric complex. This requires careful experimental design to overcome detrimental multi-spin effects and to secure sufficient distance resolution in presence of multiple distances. In addition to obtaining mere distances, PD-EPR can also provide information on multimerisation degrees allowing to study binding equilibria and to determine dissociation constants.

Research methods from social science can contribute much to the health sciences.

PubMed

Wensing, Michel

2008-06-01

Research methods from social science, such as social network analysis, random coefficient modeling, and advanced measurement techniques, can contribute much to the health sciences. There is, however, a slow rate of transmission of social science methodology into the health sciences. This paper identifies some of the barriers for adoption and proposes ideas for the future. Commentary. Contributions of social science to the health sciences are not always recognized as such. It may help if the professional profile of social science in the health sciences would be higher and if its focus would be more on making useful predictions. Clinical epidemiologists may assume that their discipline includes all relevant methods and that social science is largely based on qualitative research. These perceptions need to be challenged in order to widen the scope of clinical epidemiology and include relevant methods from other sciences. New methods help to ask new research questions and to provide better to old questions. This paper has sketched challenges for both social science researchers and clinical epidemiologists.

Risk and safety concerns in anesthesiology practice: The present perspective

PubMed Central

Bajwa, Sukhminder Jit Singh; Kaur, Jasbir

2012-01-01

Newer developments and advancements in anesthesiology, surgical, and medical fields have widened the functional scope of anesthesiologist thus increasing his professional responsibilities and obligations. While at workplace, anesthesiologist is exposed to a wide array of potential hazards that can be detrimental to his overall health. Numerous risks and safety concerns have been mentioned in the literature, but the magnitude of challenges in anesthesiology practice are far greater than those cited and anticipated. Many times these challenging situations are unavoidable and the attending anesthesiologist has to deal with them on an individual basis. These hazards not only affect the general health but can be extremely threatening in various other ways that can increase the potential risks of morbidity and mortality. This article is an attempt to bring a general awareness among anesthesia fraternity about the various health hazards associated with anesthesia practice. Also, a genuine attempt has been made to enumerate the various preventive methods and precautions that should be adopted to make practice of anesthesiology safe and smooth. PMID:25885495

The development and organizing function of perversion: the example of transvestism.

PubMed

Meyer, Jon

2011-04-01

Perversion had been viewed as oedipally determined and in a reciprocal relationship with neurosis. In our widening scope, however, pre-oedipal and traumatic contributions have been increasingly emphasized. While both perspectives represent aspects of clinical reality, the tendency has been to overlook sexual and aggressive drive derivatives, with their related conflicts, object representations, and symbolic enactments, even though they may make significant contributions to the analytic situation. These latter, 'classical' patients have what I consider 'organized' perversions: complex, evolved, neurotic-level, stable psychopathological formations that may be distinguished from borderline or near psychotic syndromes enlisting perverse mechanisms to ward off disorganization. This paper will review Freud's work, briefly consider some recent trends in conceptualizing perversion and perverse mechanisms, characterize organized perversion, and present clinical material to illustrate its evolution, clinical manifestations, and analysis. Transsexualism, overtly similar to transvestism but not functioning as an organized perversion, will serve as a point of contrast. Copyright © 2011 Institute of Psychoanalysis.

Achievements and Limitations of Evidence-Based Medicine.

PubMed

Sheridan, Desmond J; Julian, Desmond G

2016-07-12

Evidence-based medicine (EBM) has a long history, but was revived in the early 1990s by a campaign mounted by a movement that took its name. The EBM movement focused attention on the need for greater objectivity in medical decision-making and led to the Cochrane Collaboration, which provides reviews of evidence on the basis of comparative research. Important limitations of EBM's effect on medicine have also emerged. Failure to acknowledge the limitations of clinical trials and systematic reviews has limited their applicability to individual patients' circumstances. An almost exclusive focus on drugs and devices has left vast areas of health care in an evidence vacuum. An overdependence on commissions for its research may have limited its independence in selecting what it investigates. EBM needs to widen its scope beyond drugs and devices to address many areas that often lack evidence at present, notably, health policy, management, and reforms. Copyright © 2016 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

CRISPR/Cas9 in Stem Cell Research: Current Application and Future Perspective.

PubMed

Patmanathan, Sathya Narayanan; Gnanasegaran, Nareshwaran; Lim, Moon Nian; Husaini, Roslina; Fakiruddin, Kamal Shaik; Zakaria, Zubaidah

2018-06-12

The clustered regularly interspaced short palindromic repeats-associated protein 9 or CRISPR/Cas9 system is one of the hottest topics discussed lately due to its robustness and effectiveness in genome editing. The technology has been widely used in life science research including microbial, plant, animal, and human cell studies. Combined with the pluripotency of stem cells, the technology represents a powerful tool to generate various cell types for disease modeling, drug screening, toxicology, and targeted therapies. Generally, the CRISPR/Cas9 system has been applied in genetic modification of pluripotent or multipotent stem cells, after which the cells are differentiated into specific cell types and used for functional analysis or even clinical transplantation. Recent advancement in CRISPR/Cas9 technology has widened the scope of stem cell research and its therapeutic application. This review provides an overview of the current application and the prospect of CRISPR/Cas9 technology, particularly in stem cell research and therapy. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Development and quality characteristics of shelf-stable soy-agushie: a residual by-product of soymilk production.

PubMed

Nti, Christina A; Plahar, Wisdom A; Annan, Nana T

2016-03-01

A process was developed for the production of a high-protein food ingredient, soy-agushie, from the residual by-product of soymilk production. The product, with a moisture content of about 6%, was evaluated for its quality characteristics and performance in traditional dishes. The protein content was about 26% with similar amino acids content as that of the whole soybean. Lysine remained high in the dehydrated product (6.57 g/16 g N). While over 60% of the original B vitamins content in the beans was extracted with the milk, high proportions of the minerals were found to be retained in the residual by-product. The process adequately reduced the trypsin inhibitor levels in the beans from 25 to 1.5 mg/g. High sensory scores were obtained for recipes developed with soy-agushie in traditional dishes. The scope of utilization of the soy-agushie could be widened to include several traditional foods and bakery products for maximum nutritional benefits.

Particle distributions in collisionless magnetic reconnection: An implicit Particle-In-Cell (PIC) description

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hewett, D.W.; Francis, G.E.; Max, C.E.

1990-06-29

Evidence from magnetospheric and solar flare research supports the belief that collisionless magnetic reconnection can proceed on the Alfven-wave crossing timescale. Reconnection behavior that occurs this rapidly in collisionless plasmas is not well understood because underlying mechanisms depend on the details of the ion and electron distributions in the vicinity of the emerging X-points. We use the direct implicit Particle-In-Cell (PIC) code AVANTI to study the details of these distributions as they evolve in the self-consistent E and B fields of magnetic reconnection. We first consider a simple neutral sheet model. We observe rapid movement of the current-carrying electrons awaymore » from the emerging X-point. Later in time an oscillation of the trapped magnetic flux is found, superimposed upon continued linear growth due to plasma inflow at the ion sound speed. The addition of a current-aligned and a normal B field widen the scope of our studies.« less

HUBBLE: ON THE ASTEROID TRAIL

NASA Technical Reports Server (NTRS)

2002-01-01

Astronomers Karl Stapelfeldt and Robin Evans have tracked down about 100 small asteroids by hunting through more than 28,000 archival images taken by the Hubble Space Telescope's Wide Field and Planetary Camera 2. Here is a sample of what they have found: four archival images that show the curved trails left by asteroids. [Top left]: Hubble captured a bright asteroid, with a visual magnitude of 18.7, roaming in the constellation Centaurus. Background stars are shown in white, while the asteroid trail is depicted in blue at top center. The trail has a length of 19 arc seconds. This asteroid has a diameter of one and one-quarter miles (2 kilometers), and was located 87 million miles from Earth and 156 million miles from the sun. Numerous orange and blue specks in this image and the following two images were created by cosmic rays, energetic subatomic particles that struck the camera's detector. [Top right]: Here is an asteroid with a visual magnitude of 21.8 passing a galaxy in the constellation Leo. The trail is seen in two consecutive exposures, the first shown in blue and the second in red. This asteroid has a diameter of half a mile (0.8 kilometers), and was located 188 million miles from Earth and 233 million miles from the sun. [Lower left]: This asteroid in the constellation Taurus has a visual magnitude of 23, and is one of the faintest seen so far in the Hubble archive. It moves from upper right to lower left in two consecutive exposures; the first trail is shown in blue and the second in red. Because of the asteroid's relatively straight trail, astronomers could not accurately determine its distance. The estimated diameter is half a mile (0.8 kilometers) at an Earth distance of 205 million miles and a sun distance of 298 million miles. [Lower right]: This is a broken asteroid trail crossing the outer regions of galaxy NGC 4548 in Coma Berenices. Five trail segments (shown in white) were extracted from individual exposures and added to a cleaned color image of the galaxy. The asteroid enters the image at top center and moves down toward the lower left. Large gaps in the trail occur because the telescope is orbiting the Earth and cannot continuously observe the galaxy. This asteroid has a visual magnitude of 20.8, a diameter of one mile (1.6 kilometers), and was seen at a distance of 254 million miles from Earth and 292 million miles from the sun. Credit: R. Evans and K. Stapelfeldt (Jet Propulsion Laboratory) and NASA

Tidal stress and failure in the moon of binary asteroid systems: Application to asteroid (65803) Didymos

NASA Astrophysics Data System (ADS)

Sophal Pou, Laurent; Garcia, Raphael F.; Mimoun, David; Murdoch, Naomi; Karatekin, Ozgur

2017-04-01

Rocky remnants left over from the early formation of the Solar System, asteroids are a target of choice for planetary science since much about the history of planetary formation and small body evolution processes can be learnt by studying them. Here we consider the case of the binary asteroid (65803) Didymos, the target of several mission proposals e.g., AIM [1] and DART [2]. A mission to Didymos would be a great opportunity for in-situ geophysical investigation, providing information on the surface and interior of asteroids. Such studies would improve our knowledge of binary asteroid formation and subsequent evolution of asteroids, thus of the history of the Solar System. As Didymos is a binary asteroid [3] with the main 800-meter diameter asteroid named Didymain and a 150-meter sized moon named Didymoon, both are subject to tidal stress. Recent investigations suggest that Didymoon is tidally locked and moves in a retrograde motion around Didymain along an elliptic orbit with a 0.03 eccentricity at most. In the case of an eccentric orbit, the tidal stress varies periodically and may be strong enough to cause tidal quakes on Didymoon at some points of the orbit. For this study, we modelled Didymoon as a spherical, layered body with different internal structures: a homogeneous model, and two models with a 1-meter and 10-meter regolith layer on top of a stronger internal core. Simulations show that, for a cohesionless body with an internal friction angle of 30°, tidal stress is strong enough to cause failure at the surface of Didymoon. A maximal stress is reached around the poles and for a mean anomaly of 90°. These results would mean that if tidal quakes occur on Didymoon, then they are likely to happen at these locations. An extension of these results to an ellipsoidal model of Didymoon is also presented for comparison with the spherical case and for application to other bodies. [1]: P. Michel et al., Science case for the asteroid impact mission (aim): A component of the asteroid impact and deflection assessment (aida) mission, Advances in Space Research 57 (12) (2016) 2529 - 2547. doi:http://dx.doi.org/10.1016/j.asr.2016.03.031. [2]: A. F. Cheng et al., Asteroid Impact & Deflection Assessment mission: Kinetic impactor, Planetary and Space Science 121 (2016) 27-35. doi:10.1016/j.pss.2015.12.004. [3]:"AIM-A Team", ASTEROID IMPACT MISSION: DIDYMOS REFERENCE MODEL v10, ESA document reference: AD3-AIMA.

Investigating the surface and subsurface properties of the Didymos binary asteroid with a landed CubeSat

NASA Astrophysics Data System (ADS)

Murdoch, Naomi; Cadu, Alexandre; Mimoun, David; Karatekin, Ozgur; Garcia, Raphael; Carrasco, José; Garcia de Quiros, Javier; Vasseur, Hugues; Ritter, Birgit; Eubanks, Marshall; Radley, Charles; Dehant, Veronique

2016-04-01

Despite the successes of recent space missions (e.g., Cheng et al., 1997; Fujiwara et al., 2006), there is still no clear understanding of the asteroid internal structure(s). Depending on their size, evolution and physical properties, many different asteroid internal structure models have been suggested from completely cohesive bodies, through to rubble pile objects. The Asteroid Geophysical Explorer (AGEX), a COPINS payload selected by ESA*, will land geophysical instrument packages on the surface of Didymoon; the secondary object in the (65803) Didymos (1996 GT) binary system (Karatekin et al 2016). The instruments will characterize the asteroid surface mechanical properties and probe, for the first time, the sub-surface structure of an asteroid. AGEX will be deployed from AIM on a ballistic transfer to the asteroid surface, several days before the MASCOT-2 package. We expect that AGEX will bounce multiple times before coming to rest on the surface of the asteroid thus providing a unique opportunity to study the asteroid surface properties, perhaps at several locations, using accelerometers. Once stationary, the seismological surface-monitoring phase, using a three-axis set of geophones, can begin. The high speed DART impact will be a major seismic source on Didymoon. However, the seismic payload may also be able to perform seismological investigations using natural seismic sources such as micrometeoroid impacts (e.g., Garcia et al., 2015), thermal cracks (e.g., Delbo et al., 2014), internal quakes due to tidal forces (e.g., Richardson et al. 1998) and other geophysical processes (see Murdoch et al., 2015). We will present the expected signal characteristics of the landing and also of the natural seismic sources that may occur on Didymoon. An understanding of the amplitude and frequency content of such signals is necessary in order to design the optimal geophysical payload for small body exploration using a CubeSat platform. [1.] Cheng, A. et al., Journal of Geophysical Research, 102, E10 (1997) [2.] Delbo, M., et al., Nature, 508, 233-236 (2014) [3.] Fujiwara, A. et al., Science 312, 1330 (2006) [4.] Garcia, R. F. et al., Icarus, 253, 159-168 (2015) [5.] Murdoch, N. et al., ASTEROIDS IV, University of Arizona Press Space Science Series, edited by P. Michel, F. DeMeo and W. Bottke, (2015) [6.] Richardson, D.C. et al., Icarus, 134, 47-79 (1998) [7.] Karatekin et al., The Asteroid Geophysical Explorer (AGEX); Proposal to explore the Didymos System using Cubesats, EGU (2016) *http://www.esa.int/Our_Activities/Space_Engineering_Technology/Asteroid_Impact_Mission/ CubeSat_companions_for_ESA_s_asteroid_mission

Velocity distributions among colliding asteroids

NASA Technical Reports Server (NTRS)

Bottke, William F., Jr.; Nolan, Michael C.; Greenberg, Richard; Kolvoord, Robert A.

1994-01-01

The probability distribution for impact velocities between two given asteroids is wide, non-Gaussian, and often contains spikes according to our new method of analysis in which each possible orbital geometry for collision is weighted according to its probability. An average value would give a good representation only if the distribution were smooth and narrow. Therefore, the complete velocity distribution we obtain for various asteroid populations differs significantly from published histograms of average velocities. For all pairs among the 682 asteroids in the main-belt with D greater than 50 km, we find that our computed velocity distribution is much wider than previously computed histograms of average velocities. In this case, the most probable impact velocity is approximately 4.4 km/sec, compared with the mean impact velocity of 5.3 km/sec. For cases of a single asteroid (e.g., Gaspra or Ida) relative to an impacting population, the distribution we find yields lower velocities than previously reported by others. The width of these velocity distributions implies that mean impact velocities must be used with caution when calculating asteroid collisional lifetimes or crater-size distributions. Since the most probable impact velocities are lower than the mean, disruption events may occur less frequently than previously estimated. However, this disruption rate may be balanced somewhat by an apparent increase in the frequency of high-velocity impacts between asteroids. These results have implications for issues such as asteroidal disruption rates, the amount/type of impact ejecta available for meteoritical delivery to the Earth, and the geology and evolution of specific asteroids like Gaspra.

Evaluating Different Scenarios for the Formation and Early Evolution of the Asteroid Belt

NASA Astrophysics Data System (ADS)

O'Brien, David P.; Walsh, Kevin J.

2014-11-01

The asteroid belt is dynamically excited, depleted in mass relative to the surface mass density of the rest of the Solar System, and contains numerous diverse taxonomic classes of asteroids that are partly, but not completely, radially mixed. In the 'classical' scenario of Solar System formation, the excitation, depletion and radial mixing of the asteroid belt is best explained by the effect of planetary embryos that are initially present in the primordial asteroid belt region [1-3]. In the more recent 'Grand Tack' scenario proposed by Walsh et al. [4], the early inward-then-outward migration of Jupiter in the gas disk initially depletes, then repopulates the asteroid belt with material scattered from both interior and exterior to Jupiter. Here we will examine in detail the model asteroid distributions resulting from these two scenarios for a range of parameters, and compare them to observational constraints on the current distribution of asteroids in the Solar System. We will also address the possible effects that late-stage planetesimal-driven migration and resonance-crossing of Jupiter and Saturn in the Nice Model [eg. 5,6] may have on the final asteroid distribution.[1] G.W. Wetherill, Icarus 100, 307-325 (1992)[2] J.-M. Petit et al., Icarus 153, 338-347 (2001)[3] D.P. O'Brien t al., Icarus 191, 434-452 (2007)[4] K.J. Walsh et al., Nature 475, 206-209 (2011)[5] K. Tsiganis et al., Nature 435, 459-461 (2005)[6] A. Morbidelli et al., AJ 140, 1391-1401 (2010)

Band of Rubble

NASA Technical Reports Server (NTRS)

2005-01-01

This artist's animation illustrates a massive asteroid belt in orbit around a star the same age and size as our Sun. Evidence for this possible belt was discovered by NASA's Spitzer Space Telescope when it spotted warm dust around the star, presumably from asteroids smashing together.

The view starts from outside the belt, where planets like the one shown here might possibly reside, then moves into to the dusty belt itself. A collision between two asteroids is depicted near the end of the movie. Collisions like this replenish the dust in the asteroid belt, making it detectable to Spitzer.

The alien belt circles a faint, nearby star called HD 69830 located 41 light-years away in the constellation Puppis. Compared to our own solar system's asteroid belt, this one is larger and closer to its star - it is 25 times as massive, and lies just inside an orbit equivalent to that of Venus. Our asteroid belt circles between the orbits of Mars and Jupiter.

Because Jupiter acts as an outer wall to our asteroid belt, shepherding its debris into a series of bands, it is possible that an unseen planet is likewise marshalling this belt's rubble. Previous observations using the radial velocity technique did not locate any large gas giant planets, indicating that any planets present in this system would have to be the size of Saturn or smaller.

Asteroids are chunks of rock from 'failed' planets, which never managed to coalesce into full-sized planets. Asteroid belts can be thought of as construction sites that accompany the building of rocky planets.

Analyzing Serendipitous Asteroid Observations in Imaging Data using PHOTOMETRYPIPELINE

NASA Astrophysics Data System (ADS)

Ard, Christopher; Mommert, Michael; Trilling, David E.

2016-10-01

Asteroids are nearly ubiquitous in the night sky, making them present in the majority of imaging data taken every night. Serendipitous asteroid observations represent a treasure trove to Solar System researchers: accurate positional measurements of asteroids provide important constraints on their sometimes highly uncertain orbits, whereas calibrated photometric measurements can be used to establish rotational periods, intrinsic colors, or photometric phase curves.We present an add-on to the PHOTOMETRYPIPELINE (PP, github.com/mommermi/photometrypipeline, see Poster presentation 123.42) that identifies asteroids that have been observed serendipitously and extracts astrometry and calibrated photometry for these objects. PP is an open-source Python 2.7 software suite that provides image registration, aperture photometry, photometric calibration, and target identification with only minimal human interaction.Asteroids are identified based on approximate positions that are pre-calculated for a range of dates. Using interpolated coordinates, we identify potential asteroids that might be in the observed field and query their exact positions and positional uncertainties from the JPL Horizons system. The method results in robust astrometry and calibrated photometry for all asteroids in the field as a function of time. Our measurements will supplement existing photometric databases of asteroids and improve their orbits.We present first results using this procedure based on imaging data from the Vatican Advanced Technology Telescope.This work was done in the framework of NAU's REU summer program that is supported by NSF grant AST-1461200. PP was developed in the framework of the "Mission Accessible Near-Earth Object Survey" (MANOS) and is supported by NASA SSO grants NNX15AE90G and NNX14AN82G.

The Big Splash: Tsunami from Large Asteroid and Comet Impacts

NASA Astrophysics Data System (ADS)

Hills, J.; Goda, M.

Asteroid and comet impacts produce a large range of damage. Tsunami may produce most of the economic damage in large asteroid impacts. Large asteroid impacts produce worldwide darkness lasting several months that may kill more people by mass starvation, especially in developing countries, than would tsunami, but the dust should not severely affect economic infrastructure. The tsunami may even kill more people in developed countries with large coastal populations, such as the United States, than the starvation resulting from darkness. We have been determining which regions of Earth are most susceptible to asteroid tsunami by simulating the effect of a large asteroid impact into mid-ocean. We have modeled the effect of midAtlantic and midPacific impacts that produce craters 300 to 150 km in diameter. A KT-size impactor would cause the larger of these craters. We used a computer code that has successfully determined the runup and inundation from historical earthquake-generated tsunami. The code has been progressively improved to eliminate previous problems at the domain boundaries, so it now runs until the tsunami inundation is complete. We find that the larger of these two midAtlantic impacts would engulf the entire Florida Peninsula. The smaller one would inundate the eastern third of the peninsula while a tsunami passing through the Gulf of Cuba would inundate the West Coast of Florida. Impacts at three different sites in the Pacific show the great vulnerability of Tokyo and its surroundings to asteroid tsunami. Mainland Asia is relatively protected from asteroid tsunami. In Europe, the Iberian Peninsula and the Atlantic Providences of France are highly vulnerable to asteroid tsunami.

Vesta Cratered Landscape: Double Crater and Craters with Bright Ejecta

NASA Image and Video Library

2011-11-23

This image from NASA Dawn spacecraft is dominated by a double crater which may have been formed by the simultaneous impact of a binary asteroid. Binary asteroids are asteroids that orbit their mutual center of mass.

Triple Asteroid System Triples Asteroid Observers Interest

NASA Image and Video Library

2009-08-06

NASA Deep Space Network, Goldstone radar images show triple asteroid 1994 CC, which consists of a central object approximately 700 meters 2,300 feet in diameter and two smaller moons that orbit the central body. Animation available at the Photojournal

Photometry of Main Belt and Trojan asteroids with K2

NASA Astrophysics Data System (ADS)

Szabó, Gyula; Kiss, Csaba; Pal, Andras; Szabo, Robert

2016-10-01

Due to the failure of the second reaction wheel, a new mission was conceived for the otherwise healthy Kepler space telescope. In the course of the K2 Mission, the telescope is staring at the plane of the Ecliptic, hence thousands of Solar System bodies cross the K2 fields, usually causing extra noise in the highly accurate photometric data.We could measure the first continuous asteroid light curves, covering several days wthout interruption, that has been unprecedented to date. We studied the K2 superstamps covering the M35 and Neptune/Nereid fields observed in the long cadence (29.4-min sampling) mode. Asteroid light curves are generated by applying elongated apertures. We investigated the photometric precision that the K2 Mission can deliver on moving Solar System bodies, and determined the first uninterrupted optical light curves of main-belt and Trojan asteroids. We use thed Lomb-Scargle method to find periodicities due to rotation.We derived K2 light curves of 924 main-belt asteroids in the M35 field, and 96 in the path of Neptune and Nereid. Due to the faintness of the asteroids and the high density of stars in the M35 field, 4.0% of the asteroids with at least 12 data points show clear periodicities or trend signalling a long rotational period, as opposed to 15.9% in the less crowded Neptune field. We found that the duty cycle of the observations had to reach ˜ 60% in order to successfully recover rotational periods.The derived period-amplitude diagram is consistent to the known distribution of Main Belt asteroids. For Trojan asteroids, the contribution of our 56 objects with newly determined precise period and amplitude is in the order of all previously known asteroids. The comparison with earth-based determinations showed a previous bias toward short periods and has also proven that asteroid periods >20 hour can be unreliable in a few cases because of daylight time and diurnal calibrations. These biases are avoided from the space. We present an unbiased sample of rotation periods and identify a higher rate of slow rotators. We also found multiple periods of large asteroids that has not been observed earlier and still needs explanation.

Harnessing Implementation Science to Increase the Impact of Health Equity Research.

PubMed

Chinman, Matthew; Woodward, Eva N; Curran, Geoffrey M; Hausmann, Leslie R M

2017-09-01

Health disparities are differences in health or health care between groups based on social, economic, and/or environmental disadvantage. Disparity research often follows 3 steps: detecting (phase 1), understanding (phase 2), and reducing (phase 3), disparities. Although disparities have narrowed over time, many remain. We argue that implementation science could enhance disparities research by broadening the scope of phase 2 studies and offering rigorous methods to test disparity-reducing implementation strategies in phase 3 studies. We briefly review the focus of phase 2 and phase 3 disparities research. We then provide a decision tree and case examples to illustrate how implementation science frameworks and research designs could further enhance disparity research. Most health disparities research emphasizes patient and provider factors as predominant mechanisms underlying disparities. Applying implementation science frameworks like the Consolidated Framework for Implementation Research could help disparities research widen its scope in phase 2 studies and, in turn, develop broader disparities-reducing implementation strategies in phase 3 studies. Many phase 3 studies of disparity-reducing implementation strategies are similar to case studies, whose designs are not able to fully test causality. Implementation science research designs offer rigorous methods that could accelerate the pace at which equity is achieved in real-world practice. Disparities can be considered a "special case" of implementation challenges-when evidence-based clinical interventions are delivered to, and received by, vulnerable populations at lower rates. Bringing together health disparities research and implementation science could advance equity more than either could achieve on their own.

Culturomics: A New Kid on the Block of OMICS to Enable Personalized Medicine.

PubMed

Kambouris, Manousos E; Pavlidis, Cristiana; Skoufas, Efthymios; Arabatzis, Michael; Kantzanou, Maria; Velegraki, Aristea; Patrinos, George P

2018-02-01

This innovation analysis highlights the underestimated and versatile potential of the new field of culturomics and examines its relation to other OMICS system sciences such as infectiomics, metabolomics, phenomics, and pharmacomicrobiomics. The advent of molecular biology, followed by the emergence of various disciplines of the genomics, and most importantly metagenomics, brought about the sharp decline of conventional microbiology methods. Emergence of culturomics has a natural synergy with therapeutic and clinical genomic approaches so as to realize personalized medicine. Notably, the concept of culturomics expands on that of phenomics and allows a reintroduction of the culture-based phenotypic characterization into the 21st century research repertoire, bolstered by robust technology for automated and massive execution, but its potential is largely unappreciated at present; the few available references show unenthusiastic pursuit and in narrow applications. This has not to be so: depending on the specific brand of culturomics, the scope of applications may extend to medicine, agriculture, environmental sciences, pharmacomicrobiomics, and biotechnology innovation. Moreover, culturomics may produce Big Data. This calls for a new generation of data scientists and innovative ways of harnessing and valorizing Big Data beyond classical genomics. Much more detailed and objective classification and identification of microbiota may soon be at hand through culturomics, thus enabling precision diagnosis toward truly personalized medicine. Culturomics may both widen the scope of microbiology and improve its contributions to diagnostics and personalized medicine, characterizing microbes and determining their associations with health and disease dynamics.

Ion Beam Deflection (AKA Push-Me/Pull-You)

NASA Technical Reports Server (NTRS)

Brophy, John

2013-01-01

The Ion Beam Deflection provides the following potential advantages over other asteroid deflection systems. Like the gravity tractor, it doesn't require despinning of the asteroid. Unlike the gravity tractor, it provides a significantly higher coupling force that is independent of the asteroid size. The concept could be tested as part of the baseline Asteroid Redirect Robotic Mission. The thrust and total impulse are entirely within the design of the SEP vehicle. The total impulse is potentially competitive with kinetic impactors and eliminates the need for a second rendezvous spacecraft.?Gridded ion thrusters provide beam divergence angles of a few degrees enabling long stand-off distances from the asteroid. Mitigating control issues. Minimizing back-sputter contamination risks

Dust motions in quasi-statically charged binary asteroid systems

NASA Astrophysics Data System (ADS)

Maruskin, Jared M.; Bellerose, Julie; Wong, Macken; Mitchell, Lara; Richardson, David; Mathews, Douglas; Nguyen, Tri; Ganeshalingam, Usha; Ma, Gina

2013-03-01

In this paper, we discuss dust motion and investigate possible mass transfer of charged particles in a binary asteroid system, in which the asteroids are electrically charged due to solar radiation. The surface potential of the asteroids is assumed to be a piecewise function, with positive potential on the sunlit half and negative potential on the shadow half. We derive the nonautonomous equations of motion for charged particles and an analytic representation for their lofting conditions. Particle trajectories and temporary relative equilibria are examined in relation to their moving forbidden regions, a concept we define and discuss. Finally, we use a Monte Carlo simulation for a case study on mass transfer and loss rates between the asteroids.