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Hubble's universe : greatest discoveries and latest images
\"Building on the first edition, this book features 330 high resolution celestial portraits selected by bestselling astronomy writer Terence Dickinson, a four-page fold-out of the Andromeda Galaxy and an illuminating narrative that brings to life Hubble's journey and the fascinating forces at work in the universe.\"-- Provided by publisher.
Book
Overview of deep space laser communication
The deep space probe is a vital technology for observing and exploring the universe. It is thus intensifying as an aerospace research focus on an international scale. Despite improving the frequency band, the conventional microwave communication technique has difficulty satisfying the increased demand for the enormous volume of scientific data returning to the Earth. With a carrier frequency that is several orders of magnitude higher than the microwave, free-space optical communication is a robust and promising method for achieving both high bit rates and long distances in deep space communication. In this article, the history of this technology is summarized and the objective laws are formulated, while key techniques and development trends are analyzed. Finally, useful concepts and suggestions are proposed for the development of deep space laser communication in China.
Journal Article
Advances in Drill-Based Sampling Technology for Extraterrestrial Bodies
The sampling of extraterrestrial bodies is a critical technology in deep space exploration. Analyzing these samples allows researchers to uncover valuable information about the composition, structure, and evolutionary history of these celestial bodies. Compared to alternative sampling methods such as shoveling and grinding, drilling offers the advantage of obtaining larger sample volumes while preserving sample integrity. Furthermore, it enables sampling at various depths and terrains, making it an essential approach for acquiring samples from extraterrestrial environments. However, drill-based sampling devices are versatile, and their working principles and methods vary across different exploration missions and celestial bodies’ environments. This paper provides a comprehensive investigation into the progress made in drill-based sampling devices for extraterrestrial bodies. It begins by introducing the environmental and geological characteristics of the target celestial bodies, analyzing how these factors impact the structural design and operational parameters of sampling devices. The research then reviews drill-based sampling devices used in previous extraterrestrial exploration missions and examines the latest advancements in drill-based sampling technology. Based on different drilling depths, this study categorizes drill-based sampling devices into seven groups: small drills, pneumatic surface drills, single-rod drills, multi-rod drills, pneumatic deep probes, cable-based drills, and terrestrial ice penetration drills. It also provides an analysis of the operational characteristics, advantages and disadvantages of these seven types of drill-based sampling devices. The paper further outlines the technical difficulties and challenges encountered during the sampling of extraterrestrial bodies and concludes by presenting prospects for the future development of drill-based sampling technology for extraterrestrial bodies.
Journal Article
Optimization Design of an Airbreathing Satellite Based on In-Situ Utilization of Atmospheric Resources in Mars Very Low Orbit
This study systematically investigates the feasibility of applying airbreathing electric propulsion (ABEP) satellites for deep space missions based on in-situ utilization of the atmospheric environment in low Mars orbit. First, a detailed analysis of the Martian low-orbit atmosphere is conducted, examining the variations in number densities of different gas species across various orbital altitudes. Due to the presence of atomic oxygen in recent orbital datasets, the impact of wall surface roughness on gas intake performance must be considered. Against this background, a gas dynamics model of the intake chamber is established using the Direct Simulation Monte Carlo (DSMC) method to quantitatively analyze the influence of wall reflection coefficients (ranging from 0.2 to 0.8) on gas collection efficiency. Finally, a thrust-drag coupling analysis model is applied to calculate the thrust-to-drag ratio at different altitudes in Mars orbit, identifying the theoretically optimal operational altitude for ABEP systems. With strong engineering relevance, the results demonstrate that the optimized ABEP system exhibits promising technical feasibility at specific orbital altitudes around Mars.
Journal Article
Seven wonders of the Milky Way
Blast off to the oldest star in our galaxy, zoom around planetary nebulae dubbed \"the butterflies of space,\" circle past humongous, ringed exoplanets, and close in on newly discovered orbs that just might support alien life. David Aguilar, former Director of Science Information at the Harvard Smithsonian Center for Astrophysics, and creator of Cosmic Catastrophes and Seven Wonders of the Solar System, takes us on a unique space journey through the Milky Way.
Book
Two-layer Lagrange-based relay network topology and trajectory design for solar system explorations
Exploration targeting outer planets and even the edge of the solar system is an emerging direction for the deep-space exploration in the next decades. To address this challenge, a novel two-layer Lagrange-based relay network topology is proposed in this study. Specifically, we utilize the Sun-Mars and Sun-Saturn Lagrange points (LPs) L4 and L5 to build a two-layer backbone relay network, which ensures continuous and high-efficiency communication capability for the exploration of the solar system. Furthermore, we utilize the planetary gravity assist and design the transfer trajectory of backbone relays with the help of planetary celestial body motion equations and Kepler’s laws. Moreover, we conduct link budget analysis for multihop relay transmission under Gamma-Gamma distribution, shadowed Rician fading, and additive white Gaussian noise channels in several typical exploration scenarios and validate that the LP relays can effectively support future deep-space exploration missions.
Journal Article
RockSeg: A Novel Semantic Segmentation Network Based on a Hybrid Framework Combining a Convolutional Neural Network and Transformer for Deep Space Rock Images
Rock detection on the surface of celestial bodies is critical in the deep space environment for obstacle avoidance and path planning of space probes. However, in the remote and complex deep environment, rocks have the characteristics of irregular shape, being similar to the background, sparse pixel characteristics, and being easy for light and dust to affect. Most existing methods face significant challenges to attain high accuracy and low computational complexity in rock detection. In this paper, we propose a novel semantic segmentation network based on a hybrid framework combining CNN and transformer for deep space rock images, namely RockSeg. The network includes a multiscale low-level feature fusion (MSF) module and an efficient backbone network for feature extraction to achieve the effective segmentation of the rocks. Firstly, in the network encoder, we propose a new backbone network (Resnet-T) that combines the part of the Resnet backbone and the transformer block with a multi-headed attention mechanism to capture the global context information. Additionally, a simple and efficient multiscale feature fusion module is designed to fuse low-level features at different scales to generate richer and more detailed feature maps. In the network decoder, these feature maps are integrated with the output feature maps to obtain more precise semantic segmentation results. Finally, we conduct experiments on two deep space rock datasets: the MoonData and MarsData datasets. The experimental results demonstrate that the proposed model outperforms state-of-the-art rock detection algorithms under the conditions of low computational complexity and fast inference speed.
Journal Article