Accessibility of the resources of near Earth space using multi-impulse transfers

Most future concepts for exploration and exploitation of space require a large initial mass in low Earth orbit. Delivering this mass requires overcoming Earth's natural gravity well, which imposes a distinct obstacle to space-faring. An alternative for future space progress is to search for resources in-situ among the near Earth asteroid population. This paper examines the scenario of future utilization of asteroid resources. The near Earth asteroid resources that could be transferred to a bound Earth orbit are determined by integrating the probability of finding asteroids inside the Keplerian orbital element space of the set of transfers with an specific energy smaller than a given threshold. Transfers are defined by a series of impulsive maneuvers and computed using the patched-conic approximation. The results show that even moderately low energy transfers enable access to a large mass of resources

Students’ Perception of Mind Mapping in Learning Vocabulary

This research deals with the sixth year students’ perception of mind mapping in learning vocabulary at PalopoCokroaminoto University. The population of this research was the primary school teacher education study program in PalopoCokroaminoto University in academic year 2021/2022. The total number of population was 10 students. The researcher used the purposive sampling. Based on the findings and discussion in the previous chapter, the researcher concludes that the English students give positive perception mind mapping in PalopoCokroaminoto University. It is supported by students’ answer about mind mapping that “mind mapping is good and appropriate to be used in learning vocabulary

Impact hazard protection efficiency by a small kinetic impactor

In this paper the ability of a small kinetic impactor spacecraft to mitigate an Earth-threatening asteroid is assessed by means of a novel measure of efficiency. This measure estimates the probability of a space system to deflect a single randomly-generated Earth-impacting object to a safe distance from the Earth. This represents a measure of efficiency that is not biased by the orbital parameters of a test-case object. A vast number of virtual Earth-impacting scenarios are investigated by homogenously distributing in orbital space a grid of 17,518 Earth impacting trajectories. The relative frequency of each trajectory is estimated by means Opik’s theory and Bottke’s near Earth objects model. A design of the entire mitigation mission is performed and the largest deflected asteroid computed for each impacting trajectory. The minimum detectable asteroid can also be estimated by an asteroid survey model. The results show that current technology would likely suffice against discovered airburst and local damage threats, whereas larger space systems would be necessary to reliably tackle impact hazard from larger threats. For example, it is shown that only 1,000 kg kinetic impactor would suffice to mitigate the impact threat of 27.1% of objects posing similar threat than that posed by Apophis

Diversity of morphological characters of 30 local torch ginger accessions from Pangandaran of West Java of Indonesia

Torch ginger (Etlingera spp.) is one of the herbal plants native to Indonesia that has long been known and used as medicines. Exploration on torch ginger plant needs to be done to conservate and determine genetic diversity. Study of genetic diversity torch ginger in the district of Pangandaran is important because as long as there has been no study in depth the potential of genetic diversity and phylogenetic relationship germplasm of torch ginger Genetic diversity based on this research had a proportion of 47% of the total of 100% in the PC1-PC3 was based on the analysis Principal Component Analysis (PCA) with the character influencing that form clumps, line leaf midrib, plant height, stem diameter, leaf length, color scales rhizome, stem color, rhizome and the leaf base forms. Based on the results of the genetic diversity cluster analysis found that narrow torch ginger euclidean indicated by coefficient of 0.79 and was divided into six clusters. Accession which had the closest kinship i.e. accession N1 from Cikadu subdistrict of Cintakarya and accession N2 from Cikoang subdistrict of Cintakarya, while accession with the farthest kinship namely accession N29 from Jangraga subdistrict of Mangunjaya with range euclidean of 0.79

Teachers Perceptions of Lesson Study Implementation at Bua Secondary School

This research is descriptive research with a qualitative approach. It aims to find out how the teachers’ perception regarding the implementation of lesson study. There were 4 teachers of Bua Secondary School who were involved as model teachers in LS activities as respondents in this study. The instruments used questionnaire to gain data of the students’ perception and observation sheet for lesson study activities to support the data. The result of this research shows that through lesson study their students be more active, they become innovative and creative to design and implement differentiation learning, and lots of input or suggestion from observers can improve quality of learning, Moreover, they state that by lesson study they got benefit such as: they can design fun and innovative learning, provide fun learning to students, elaboration occurs in the learning strategy, and through lesson study activities can improve the quality of learning so that it is more meaningful and pro-students. Based on the result, it can be concluded that all the respondents have good perception towards the implementation of lesson study at Bua Secondary School

A search for L dwarf binary systems

We present analysis of HST Planetary Camera images of twenty L dwarfs identified in the course of the Two Micron All-Sky Survey. Four of the targets have faint, red companions at separations between 0.07 and 0.29 arcseconds (1.6 to 7.6 AU). In three cases, the bolometric magnitudes of the components differ by less than 0.3 magnitudes. Since the cooling rate for brown dwarfs is a strong function of mass, similarity in luminosities implies comparable masses. The faint component in the 2M0850 system, however, is over 1.3 magnitudes fainter than the primary in the I-band, and ~0.8 magnitudes fainter in M(bol). Indeed, 2M0850B is ~0.8 magnitudes fainter in I than the lowest luminosity L dwarf currently known, while the absolute magnitude we deduce at J is almost identical with M_J for Gl 229B. Theoretical models indicate a mass ratio of \~0.75. The mean separation of the L dwarf binaries in the current sample is smaller by a factor of two than amongst M dwarfs. We discuss the implications of these results for the temperature scale in the L/T transition region and for the binary frequency amongst L dwarfs.Comment: 38 pages, 11 figures; accepted for A

Analisis dan perancangan arsitektur sistem aplikasi layanan informasi lokasi berbasis IoT

UIN SGD Bandung memiliki banyak mahasiswa berasal dari berbagai kota di Indonesia. Setiap tahun calon mahasiswa atau mahasiswa baru datang bersama orang tua atau saudara mereka untuk mendaftar atau registrasi sambil melihat-lihat lokasi kampus. Mereka akan merasa senang dan bangga jika kampus dilengkapi dengan perangkat yang dapat memudahkan mereka untuk mengetahui suasana lingungan kampus, paling tidak lokasi-lokasi di dalam kampus. Makalah ini berbicara tentang proses analisis, usulan sistem dan perancangan arsitektur sistem perangkat lunak aplikasi mobile layanan informasi lokasi secara otomatis. Notifikasi akan dikirm oleh perangkat bluetooth eksternal ketika pengguna tiba di suatu tempat di dalam suatu kampus. Aplikasi akan berkomunikasi dengan perangkat bluetooth ksternal yang dipasang di tiap lokasi. Metode perancangan perangkat lunak menggunakan metode berorientasi obyek dengan notasi UML. Hasil dari perancangan adalah arsitektur sistem yang terdiri dari arsitektur jaringan, arsitektur komputasi, dan arsitektur aplikas

A Hubble Space Telescope ACS Search for Brown Dwarf Binaries in the Pleiades Open Cluster

We present the results of a high-resolution imaging survey for brown dwarf binaries in the Pleiades open cluster. The observations were carried out with the Advance Camera for Surveys onboard the Hubble Space Telescope. Our sample consists of 15 bona-fide brown dwarfs. We confirm 2 binaries and detect their orbital motion, but we did not resolve any new binary candidates in the separation range between 5.4AU and 1700AU and masses in the range 0.035--0.065~Msun. Together with the results of our previous study (Martin et al., 2003), we can derive a visual binary frequency of 13.3$^{+13.7}_{-4.3}$\% for separations greater than 7~AU masses between 0.055--0.065~M_{\sun} and mass ratios between 0.45--0.9$<q<$1.0. The other observed properties of Pleiades brown dwarf binaries (distributions of separation and mass ratio) appear to be similar to their older counterparts in the field.Comment: 29 pages, 7 figures, 6 tables, accepted for publication in Ap

Elevation and plant species identity jointly shape a diverse arbuscular mycorrhizal fungal community in the High Arctic

Knowledge about the distribution and local diversity patterns of arbuscular mycorrhizal (AM) fungi are limited for extreme environments such as the Arctic, where most studies have focused on spore morphology or root colonization. We here studied the joint effects of plant species identity and elevation on AM fungal distribution and diversity. We sampled roots of 19 plant species in 18 locations in Northeast Greenland, using next generation sequencing to identify AM fungi. We studied the joint effect of plant species, elevation and selected abiotic conditions on AM fungal presence, richness and composition. We identified 29 AM fungal virtual taxa (VT), of which six represent putatively new VT. Arbuscular mycorrhizal fungal presence increased with elevation, and as vegetation cover and the active soil layer decreased. Arbuscular mycorrhizal fungal composition was shaped jointly by elevation and plant species identity. We demonstrate that the Arctic harbours a relatively species-rich and nonrandomly distributed diversity of AM fungi. Given the high diversity and general lack of knowledge exposed herein, we encourage further research into the diversity, drivers and functional role of AM fungi in the Arctic. Such insight is urgently needed for an area with some of the globally highest rates of climate change