scholarly journals Hayabusa2’s superior solar conjunction mission operations: planning and post-operation results

Astrodynamics ◽  
2020 ◽  
Vol 4 (4) ◽  
pp. 265-288 ◽  
Author(s):  
Stefania Soldini ◽  
Hiroshi Takeuchi ◽  
Sho Taniguchi ◽  
Shota Kikuchi ◽  
Yuto Takei ◽  
...  
Keyword(s):  
Communication Link ◽  
Time Data ◽  
Operations Planning ◽  
The Earth ◽  
Post Operation ◽  
A Minor ◽  
Operation Results ◽  
The Hill ◽  
First Time ◽  
Mission Operations

AbstractIn late 2018, the asteroid Ryugu was in the Sun’s shadow during the superior solar conjunction phase. As the Sun-Earth-Ryugu angle decreased to below 3°, the Hayabusa2 spacecraft experienced 21 days of planned blackout in the Earth-probe communication link. This was the first time a spacecraft had experienced solar conjunction while hovering around a minor body. For the safety of the spacecraft, a low energy transfer trajectory named Ayu was designed in the Hill reference frame to increase its altitude from 20 to 110 km. The trajectory was planned with the newly developed optNEAR tool and validated with real time data. This article shows the results of the conjunction operation, from planning to flight data.

scholarly journals Hayabusa2’s Superior Solar Conjunction Phase

2020 ◽  
Vol 216 (6) ◽  
Author(s):  
Stefania Soldini ◽  
Tomohiro Yamaguchi ◽  
Yuichi Tsuda ◽  
Saiki Takanao ◽  
Satoru Nakazawa
Keyword(s):  
Covariance Analysis ◽  
Communication Link ◽  
Home Position ◽  
The Earth ◽  
Before And After ◽  
Wide Angle Camera ◽  
Navigation Planning ◽  
The Hill ◽  
First Time ◽  
Full Body

Abstract Hayabusa2 is the ongoing JAXA’s sample and return mission to the asteroid Ryugu. In late 2018, Ryugu was in superior solar conjunction with the Earth. It is the first time that a spacecraft experiences the blackouts in the communication link with the Earth while hovering around a small celestial body. In this article, the design of the nominal conjunction trajectory flown by the Hayabusa2’s spacecraft is presented. The requirements for the conjunction trajectory were (1) to guarantee a low fuel consumption, (2) to ensure the visibility of the asteroid by the spacecraft’s wide angle camera ($60^{\circ }$ 60 ∘ FoV), and (3) to increase the spacecraft altitude to a safety location ($\sim109~\mbox{km}$ ∼ 109 km ) from the nominal BOX-A operation of 20 km (Home Position - HP). Finally, (4) to return at BOX-A after the conjunction phase. Given the mission constraints, the designed conjunction trajectory appears to have a fish-shape in the Hill coordinates therefore we renamed it as “ayu” (sweetfish in Japanese) trajectory. The optNEAR tool was developed for the guidance ($\Delta V\mbox{s}$ Δ V s planning) and navigation design of the Hayabusa2’s conjunction mission phase. A preliminary sensitivity analysis in the Hill reference frame proved that the ayu trajectory is a good candidate for the conjunction operation of hovering satellite. The solution in the Hill coordinates is refined in the full-body planetary dynamics (optNEAR Tool) before flight. The ayu conjunction trajectory requires (a) two deterministic $\Delta V\mbox{s}$ Δ V s at the Conjunction Orbit Insertion (COI) point and at the Home-position Recovery Maneuver (HRM) point respectively. (b) Two stochastic $\Delta V\mbox{s}$ Δ V s , known as Trajectory Correction Manoeuvres (TCMs), before and after the deep conjunction phase are also required. The constraint linear covariance analysis in the full-body dynamics is here derived and used for the preliminary guidance and navigation planning. The results of the covariance analysis were validated in a nonlinear sense with a Monte Carlo approach which proved the validity of the semi-analytic method for the stochastic $\Delta V\mbox{s}$ Δ V s planning derived in this paper.

scholarly journals Homopiperazine (Hexahydro-1,4-diazepine)

Molbank ◽  
10.3390/m1200 ◽  
2021 ◽  
Vol 2021 (2) ◽  
pp. M1200
Author(s):  
R. Alan Aitken ◽  
Dheirya K. Sonecha ◽  
Alexandra M. Z. Slawin
Keyword(s):  
13C Nmr ◽  
Title Compound ◽  
Coupling Constants ◽  
15N Nmr ◽  
Time Data ◽  
Nmr Spectrum ◽  
X Ray ◽  
First Time

The X-ray structure of the title compound has been determined for the first time. Data on its 1H–13C-NMR coupling constants and 15N-NMR spectrum are also given.

Alexander and the Mongols

1979 ◽  
Vol 111 (2) ◽  
pp. 123-136 ◽  
Author(s):  
John Andrew Boyle
Keyword(s):  
Eighth Century ◽  
Alexander The Great ◽  
The Caucasus ◽  
The North ◽  
The Earth ◽  
Four Corners ◽  
Book Of Genesis ◽  
First Time

The association of Alexander the Great with the Mongols begins with the identification of the latter with the peoples of Gog and Magog. The evolution of this legend, which has its origin in the Book of Genesis, is curious in the extreme. In Genesis Magog is mentioned as one of the sons of Japhet, his name occurring between those of Gomer and Madai. Since Madai is clearly intended as the eponym of the Medes and Gomer has been located in Cappadocia and Phrygia it has been plausibly suggested that Magog at this stage corresponded to the territory in between, i.e. the region immediately south of the Caucasus in Eastern and Northern Armenia. In Ezekiel we hear for the first time of Gog “of the land of Magog”, who will come from his place out of the uttermost parts of the north, he and many peoples with him, “all of them riding on horses, a great company and a mighty army.” It will be seen that the “land of Magog” can no longer be located south of the Caucasus, and indeed Ezekiel's prophecy of the invasion of Gog has been interpreted as an echo of the invasions of the Cimmerians, who came southwards from the steppes through the Darial pass towards the end of the eighth century B.C.; or more probably of the invasion of the Scythians which took place in the following century by way of Darband. Finally we are told in Revelation that “when the thousand years are finished, Satan shall be loosed out of his prison, and shall come forth to deceive the nations which are in the four corners of the earth, Gog and Magog, to gather them together to the war; the number of whom is as the sand of the sea”.

scholarly journals Deservingness for "Family 500 +" Benefit in Poland: Qualitative Study of Internet Debates

2021 ◽  
Author(s):  
Piotr Michoń
Keyword(s):  
Future Research ◽  
Online Forums ◽  
Time Data ◽  
Social Surveys ◽  
Cash Benefit ◽  
Internet Forums ◽  
Welfare Attitudes ◽  
New Criterion ◽  
First Time ◽  
The Relationship

AbstractThe need for qualitative research of deservingness perception is strongly emphasised in the literature. This article studies the perception of deservingness for a "Family 500 +"—cash benefit in Poland. For the first time, data from online forums was used in the studies of deservingness and welfare attitudes. It allowed to avoid numerous limitations associated with social surveys. The qualitative analysis showed how participants of Internet debates perceive the criteria of deservingness: control, attitude, reciprocity, identity, need, and what are the relations between the criteria. The impurity of all deservingness criteria was indicated and a new criterion “adequacy” was proposed. Moreover due to the fact that the study concerned a concrete, non-abstract family cash benefit addressed the relationship between the perceived deservingness of children and their parents was pointed out. The vast majority of posts on Internet forums referred to deservingness of parents, not children. This is particularly evident in relation to the criteria of control and reciprocity. Presenting the hypothesis of jealousy and scapegoat strategy, the article also shows the direction of future research on deservingness.

Intensifiers on Tyneside

2010 ◽  
Vol 31 (3) ◽  
pp. 252-287 ◽  
Author(s):  
Katie Barnfield ◽  
Isabelle Buchstaller
Keyword(s):  
Real Time ◽  
Longitudinal Analysis ◽  
Developmental Trajectories ◽  
Time Data ◽  
Longitudinal Changes ◽  
Real Time Data ◽  
Quantitative Development ◽  
First Time

We report on longitudinal changes in the system of intensification in an innovative corpus that spans five decades of dialectal speech. Our analyses allow us — for the first time in a British context — to trace the quantitative development in the variable across four generations. Longitudinal analysis across real and apparent time determines the effect of extralinguistic and intralinguistic variables on intensification in Tyneside and tests to what extent real time data corroborates trends reported from previous apparent time analyses. Long-term competition within the variable manifests itself in distinctive developmental trajectories: expansion — both proportionally within the variable as well as across adjectival categories — tends to follow one of three types of patterns, exemplified, respectively, by really, so and dead. Variant retraction, however, follows only one schema. Importantly, numerical decline in the system does not necessarily go hand in hand with a reduction in breadth of application.

On the Electrochemical Insertion of Mg2+in Na7V4(P2O7)4(PO4) and Na3V2(PO4)3 Host Materials

2021 ◽  
Author(s):  
Saustin Dongmo ◽  
Fabio Maroni ◽  
Cornelius Gauckler ◽  
Mario Marinaro ◽  
Margret Wohlfahrt-Mehrens
Keyword(s):  
Energy Storage ◽  
Research And Development ◽  
Cathode Materials ◽  
Fast Kinetics ◽  
The Earth ◽  
Host Materials ◽  
High Potentials ◽  
Phosphate Phase ◽  
Storage Technologies ◽  
First Time

Abstract Next generation energy storage technologies need to be more sustainable and cheaper. Among Post-Li chemistries, Mg batteries are emerging as a possible alternative with desirable features like abundance of Mg on the Earth`s crust and a doubled volumetric capacity with respect to the current Li metal. However, research and development of Mg-batteries is still in its infancy stage and still many hurdles are to be understood and solved. For instance, cathode materials showing high capacities, operating at high potentials and with sufficient fast kinetics need to be designed and developed. Polyanionic materials are a class of sustainable and environmentally friendly materials that emerged as possible Mg2+ hosts. In this work the insertion of Mg cations inside the NASICON Na3V2(PO4)3 and, for the first time, in the mixed phosphate phase Na7V4(P2O7)4(PO4), is reported, structurally and electrochemically characterized.

Cosmic Deer as an Archaic Symbol in the Narratives and Rituals of the Tungus-Manchus

2020 ◽  
pp. 112-121
Author(s):  
Татьяна Юрьевна Сем
Keyword(s):  
Bronze Age ◽  
The Sun ◽  
Time Model ◽  
Space And Time ◽  
The Earth ◽  
Cosmic Scale ◽  
First Time ◽  
The Universe ◽  
The Bronze Age

Статья посвящена мифологическому образу космического оленя в традиционной культуре тунгусо-маньчжуров. В работе рассматриваются материалы фольклора, шаманства, промысловых и календарных ритуалов, а также искусства. Впервые систематизированы материалы по всем тунгусо-маньчжурским народам. Образ космического оленя в фольклоре эвенов имеет наиболее близкие аналогии с амурскими народами, которые представляют его с рогами до небес. Он сохранился в сказочном фольклоре с мифологическими и эпическими элементами. В эвенском мифе образ оленя имеет космические масштабы: из тела его происходит земля и всё живущее на ней. У народов Амура образ оленя нашел отражение в космогенезе, отделении неба от земли. Своеобразие сюжета космической охоты характеризует общесибирскую мифологию, относящуюся к ранней истории. В ней наиболее ярко проявляется мотив смены старого и нового солнца, хода времени, смены времен года, календарь тунгусо-маньчжуров. В результате анализа автор пришел к выводу, что олень в тунгусо-маньчжурской традиции моделирует пространство и время Вселенной, характеризует образ солнца и хода времени. Космический олень является архетипичным символом культуры тунгусо-маньчжуров, сохранившим свое значение до настоящего времени в художественной культуре This article is devoted to the mythological image of cosmic deer in traditional Tungus-Manchu culture. It examines materials of folklore, shamanism, trade and calendar rituals as well as art and for the first time systematizes materials from all of the Tungus-Manchu peoples. The image of cosmic deer in the folklore of the Evens has its closest analogy in that of the Amur peoples, reflected in the image of a deer with horns reaching up to the sky. This image is preserved in fairytales with mythological and epic elements. In the Even myth, the image of a deer is on a cosmic scale, as the cosmos issues from its body. Among the Amur peoples, the image of a deer is also related to cosmogenesis, to the separation of the earth from the sky. The plot of a cosmic hunt is reflected in pan-Siberian mythology, dating back to the Bronze Age. It clearly illustrates the motif of the change of the old and new sun, the passage of time, the change of seasons, the Tungus-Manchu calendar. The author comes to the conclusion that deer in the Tungus-Manchu tradition, in depicting the image of the sun and the passage of time, model the space and time of the Universe. The cosmic deer is an archetypal symbol of Tungus-Manchu culture, which has retained its significance in artistic culture to the present day.

The Strait of Magellan—a Gateway to New Worlds

2021 ◽  
Author(s):  
Mauricio Onetto Pavez
Keyword(s):  
Global Scale ◽  
Modern World ◽  
American Continent ◽  
The Earth ◽  
Starting Point ◽  
Strait Of Magellan ◽  
The World ◽  
The Strait Of Magellan ◽  
History Of ◽  
First Time

The year 2020 marks the five hundredth anniversary of the “discovery” of the Strait of Magellan. The unveiling of this passage between 1519 and 1522 allowed the planet to be circumnavigated for the first time in the history of humanity. All maritime routes could now be connected, and the idea of the Earth, in its geographical, cosmographic, and philosophical dimensions, gained its definitive meaning. This discovery can be considered one of the founding events of the modern world and of the process of globalization that still continues today. This new connectivity awoke an immediate interest in Europe that led to the emergence of a political consciousness of possession, domination, and territorial occupation generalized on a global scale, and the American continent was the starting point for this. This consciousness also inspired a desire for knowledge about this new form of inhabiting the world. Various fields of knowledge were redefined thanks to the new spaces and measurements produced by the discovery of the southern part of the Americas, which was recorded in books on cosmography, natural history, cartography, and manuscripts, circulating mainly between the Americas and Europe. All these processes transformed the Strait of Magellan into a geopolitical space coveted by Europeans during the 16th century. As an interoceanic connector, it was used to imagine commercial routes to the Orient and political projects that could sustain these dynamics. It was also conceived as a space to speculate on the potential wealth in the extreme south of the continent. In addition, on the Spanish side, some agents of the Crown considered it a strategic place for imperial projections and the defense of the Americas.

scholarly journals Improving the inverse modeling of a trace isotope: how precisely can radium-228 fluxes toward the ocean and submarine groundwater discharge be estimated?

2017 ◽  
Vol 14 (13) ◽  
pp. 3171-3189 ◽  
Author(s):  
Guillaume Le Gland ◽  
Laurent Mémery ◽  
Olivier Aumont ◽  
Laure Resplandy
Keyword(s):  
Ocean Circulation ◽  
Inverse Modeling ◽  
Submarine Groundwater Discharge ◽  
Groundwater Discharge ◽  
Radioactive Decay ◽  
The Arctic ◽  
Time Data ◽  
Global Estimate ◽  
Submarine Groundwater ◽  
First Time

Abstract. Radium-228 (228Ra), an almost conservative trace isotope in the ocean, supplied from the continental shelves and removed by a known radioactive decay (T1∕2 = 5. 75 years), can be used as a proxy to constrain shelf fluxes of other trace elements, such as nutrients, iron, or rare earth elements. In this study, we perform inverse modeling of a global 228Ra dataset (including GEOSECS, TTO and GEOTRACES programs, and, for the first time, data from the Arctic and around the Kerguelen Islands) to compute the total 228Ra fluxes toward the ocean, using the ocean circulation obtained from the NEMO 3.6 model with a 2° resolution. We optimized the inverse calculation (source regions, cost function) and find a global estimate of the 228Ra fluxes of 8.01–8. 49 × 1023 atoms yr−1, more precise and around 20 % lower than previous estimates. The largest fluxes are in the western North Atlantic, the western Pacific and the Indian Ocean, with roughly two-thirds in the Indo-Pacific Basin. An estimate in the Arctic Ocean is provided for the first time (0.43–0.50  ×  1023 atoms yr−1). Local misfits between model and data in the Arctic, the Gulf Stream and the Kuroshio regions could result from flaws of the ocean circulation in these regions (resolution, atmospheric forcing). As radium is enriched in groundwater, a large part of the 228Ra shelf sources comes from submarine groundwater discharge (SGD), a major but poorly known pathway for terrestrial mineral elements, including nutrients, to the ocean. In contrast to the 228Ra budget, the global estimate of SGD is rather unconstrained, between 1.3 and 14. 7 × 1013 m3 yr−1, due to high uncertainties on the other sources of 228Ra, especially diffusion from continental shelf sediments. Better precision on SGD cannot be reached by inverse modeling until a proper way to separate the contributions of SGD and diffusive release from sediments at a global scale is found.

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