Space Systems Research Articles

Toward a Monte Carlo simulation of protein systems in amino-acid sequence space.

In this article, we present our strategy for studying amino-acid sequence dependences on protein structures. For this purpose, performing Metropolis Monte Carlo simulations in the amino-acid sequence space is necessary. We want to use a coarse-grained protein model with an accurate potential energy function. We introduce a method for optimizing potential-energy parameters based on the native protein structure database, Protein Data Bank.

Integrability of certain Hamiltonian systems in 2D variable curvature spaces

Integrability of certain Hamiltonian systems in 2D variable curvature spaces

On the incompleteness of the classification of quadratically integrable Hamiltonian systems in the three-dimensional Euclidean space

Abstract We present an example of an integrable Hamiltonian system with scalar potential in the three-dimensional Euclidean space whose integrals of motion are quadratic polynomials in the momenta, yet its Hamilton–Jacobi / Schrödinger equation cannot separate in any orthogonal coordinate system. This demonstrates a loophole in the derivation of the list of quadratically integrable Hamiltonian systems in Makarov et al (1967 Nuovo Cimento A 10 1061–84) where only separable systems were found, and the need for its revision.

The Assembly, Integration and Test of the DORA Telescope, a Deployable Optics System in Space for Remote Sensing Applications

The paper deals with the assembling, integration, and test (AIT) phase of the laboratory model of an innovative telescope in the framework of the project DORA (deployable optics for remote sensing applications). The telescope is a Cassegrain type of instrument, with an entrance pupil of ∅300 mm, f/16 aperture, and FOV of 0.16°. It has been designed to be mounted onboard a micro-satellite frame, allowing for switching between a stowed configuration during the launch phase and a deployed one once in orbit. The telescope is matched to an infrared Fourier spectrometer, operating in the spectral range of 5–25 μm, for the observation of terrestrial atmospheric phenomena, but it can also be adopted for planetary exploration missions. The telescope breadboard has been assembled in the INAF-IAPS premises and has undergone measurements for the determination of the accuracy and repeatability of the mechanism opening. The mechanical tests have demonstrated that the deployment mechanism adopted complies with the requirements imposed by the infrared Fourier spectrometer, guaranteeing a repositioning of the secondary mirror with respect to the primary mirror within 100 μm (in-plane displacement) and 0.01° (tilt) of the nominal position.

Urban Open Space Systems and Green Cities: History, Heritage, and All That

More than half the world’s population live in cities1. According to UN Habitat, we are rapidly approaching the time when five billion people will live in cities, and by 2050 this could be 7.5 billion, with much of the growth concentrated in the global south. The context for this paper is how urban growth is linked to notions of community values which cross-link to concepts of heritage. Urban places are where the majority of the world’s population lives and will increasingly do so. Inextricably linked to this proposition is that urban places are where community memories, identity and sense of place are inherent, and here is the link with heritage. What do these paces mean to us? Are there regional, national and international differences? Parallel with these ideas of urban heritage is the sense of place and attachment people have for green spaces in cities and the incremental loss of green spaces. This prompts the question of how this phenomenon has stimulated scholarly and professional attention on the concept of greening cities. Underpinning the inquiry is an understanding of how urban green growth has become regarded as critical to the well-being of people in urban areas. Central to such concerns is the role of people and their social and cultural values which shape how they see their cities. Notable also is how there has been growing concern for urban conservation since the 1990s and the need to understand cities as people spaces, not just collections of buildings. Discourse on cities as spaces for people has its roots in, and builds on, a paradigm shift in innovative thinking and concepts in the twentieth century which has continued into the twenty-first century. Mindful of this background, the paper opens with a review of the historical background to these concerns on the premise that the past is not always a foreign country2. It then moves into consideration of heritage values and the role of landscape and what we mean by values. This consideration is central to the paper and moves into an overview of the Historic Urban Landscape (HUL) approach as new approaches and tools for urban conservation came into play.

Next‐Generation Solar‐Powering: Photonic Strategies for Earth and Space Systems

Escalating environmental and energy supply concerns, coupled with an increasing interest in space exploration, are driving the development of advanced energy harvesting systems and the adoption of cutting‐edge photovoltaic (PV) technologies. Photonics allows precise light manipulation in a multitude of ways, empowering PV with the means to tackle the multifaceted challenges inherent to the harsh space environment, with great potential to concomitantly spin off to on‐Earth systems, prioritizing efficiency and reliability. This review thus synthesizes the key insights from the latest experimental and simulation R&D outcomes to inform the design and implementation of advanced photonic strategies for various PV applications. The state‐of‐the‐art performance and foreground of photonic‐managed thick‐ (single‐junction crystalline silicon, c‐Si, and perovskite‐on‐silicon tandem) and thin‐film (hydrogenated amorphous silicon, a‐Si:H, and perovskite) PV devices are assessed by comparison with theoretical ideal light‐trapping scenarios (single‐, double‐pass, and Lambertian absorption models), looking also at the potential of photonic coolers as an emergent platform for effective thermal management. Finally, this work examines novel photonic approaches for spectrum modification, emphasizing the relevance of illumination‐tailoring for outer space systems.

Fault diagnoses of a nonlinear cracked rotor-bearing system based on vibration energy space and incremental learning approach

Fault diagnoses of a nonlinear cracked rotor-bearing system based on vibration energy space and incremental learning approach

An optimization design method for ductwork of air distribution systems in open spaces

An optimization design method for ductwork of air distribution systems in open spaces

Affordable Ranging and Clock Synchronization Device: Development and Field Function Experiment

There have been many studies on navigation systems in cislunar space. Many studies have proposed a special system to be constructed around the moon, similar to the Global Navigation Satellite System (GNSS) around the Earth. In recent years, the authors have presented a new method for providing simultaneous range measurement and clock synchronization. This paper presents recent experimental results performed in two field radio tests using actual hardware. This study aimed to demonstrate a GNSS–based transceiver communication capability built on developed components, along with software functions running a new asynchronous one-way range (AOWR) scheme. Both communication and the new function of simultaneous range and synchronization were successfully verified. The outcome obtained leads to the completion of developing a real device for on-orbit demonstration. This paper presents further applications to space exploration in an evolutionary, step-by-step approach by relaying an absolute clock via a pair of spacecrafts. This shows the high applicability of the method presented here.

Evaluating sensor tasking strategies for object cataloging in GEO

Evaluating sensor tasking strategies for object cataloging in GEO

Computational control framework for tethered space systems using finite element method

Computational control framework for tethered space systems using finite element method

The Influence of Urban Landscape Ecology on Emotional Well-Being: A Case Study of Downtown Beijing

This study focuses on downtown Beijing to explore the spatial distribution characteristics of emotions and their influencing factors from the perspective of landscape ecology. The research reveals significant spatial agglomeration in the distribution of emotions, with hot spots primarily concentrated around parks, commercial centers, and areas surrounding social service facilities, such as schools and hospitals. By contrast, historical sites and museums are mostly cold spots for emotions. An analysis of various landscape pattern indices shows that indices such as the spatially explicit index of evenness (SIEI), the largest patch index (LPI), the number of patches (NP), and the Shannon–Wiener diversity index (SIDI) are positively correlated with residents’ emotions. This suggests that evenly distributed landscape elements, large natural patches, a rich variety of landscape types, and high landscape diversity can effectively enhance residents’ emotional well-being. Conversely, complex landscape shape indices and high aggregation indices may negatively impact emotions. Based on these findings, it is recommended that urban planning optimize the urban green space system, increase the area and number of natural patches, pay attention to the diversity of landscape design, simplify the shape of the landscape, and reasonably control the aggregation of the landscape to create a more emotionally caring urban space.

Improved tangential interpolation-based multi-input multi-output modal analysis of a full aircraft

In the field of Structural Dynamics, modal analysis is the foundation of System Identification and vibration-based inspection. However, despite their widespread use, current state-of-the-art methods for extracting modal parameters from multi-input multi-output (MIMO) frequency domain data are still affected by many technical limitations. Mainly, they can be computationally cumbersome and/or negatively affected by close-in-frequency modes. The Loewner Framework (LF) was recently proposed to alleviate these problems with the limitation of working with single-input data only. This work proposes a computationally improved version of the LF, or iLF, to extract modal parameters more efficiently. Also, the proposed implementation is extended in order to handle MIMO data in the frequency domain. This new implementation is compared to state-of-the-art methods such as the frequency domain implementations of the Least Square Complex Exponential method and the Numerical Algorithm for Subspace State Space System Identification on numerical and experimental datasets. More specifically, a finite element model of a 3D Euler–Bernoulli beam is used for the baseline comparison and the noise robustness verification of the proposed MIMO iLF algorithm. Then, an experimental dataset from MIMO ground vibration tests of a trainer jet aircraft with over 91 accelerometer channels is chosen for the algorithm validation on a real-life application. Its validation is carried out with known results from a single-input multi-output dataset of the starboard wing of the same aircraft. Excellent results are achieved in terms of accuracy, robustness to noise, and computational performance by the proposed improved MIMO method, both on the numerical and the experimental datasets. The MIMO iLF MATLAB implementation is shared in the work supplementary material.

AI-Driven Sociocultural Interactive Digital Module for Papua: Advancing Educational Technology to Sustainable Development Goals

This study presented the development and evaluation of an artificial intelligence driven interactive digital module designed for middle?school science education in Papua and integrating sociocultural content with topics aligned to PISA 2025. The module aimed to enhance educational outcomes while supporting the Sustainable Development Goals. A mixed-methods approach was used, combining qualitative ethnographic research to embed relevant cultural elements with quantitative assessments of the module's impact on science literacy. The study involved 200 middle school students and 40 science teachers, who were divided into two groups: an experimental group using the artificial intelligence based module and a control group following the standard curriculum. Data analysis was conducted using a paired-sample t-test to determine the statistical significance of learning improvements. Instruments included pre- and post-tests, surveys, and focus group discussions with students and teachers. The data analysis showed a 49.19% improvement in understanding complex scientific concepts. This improvement was observed particularly in the structure and properties of matter, earth and space systems, global?warming climate change, chemical changes of matter, energy, motion and forces, light waves, radio, sound, seismic activity, and absorption of radiation by CO2. The findings highlighted the effectiveness of culturally responsive digital education tools in improving science literacy in underrepresented regions. Recommendations included expanding the module's use to other regions with similar educational challenges and developing AI features to enhance personalized learning experiences in science education.

A unified criterion for semiglobal and global finite/fixed-time stability of stochastic systems

In this paper, semiglobal and global finite/fixed-time stability of a class of semilinear stochastic systems in Hilbert spaces are studied. By employing the stopping time technique and applying the infinite-dimensional Itô formula, a unified Lyapunov criterion is established under which global finite-time, global fixed-time, semiglobal finite-time and semiglobal fixed-time stability can all be obtained. This fills the research gaps in the finite/fixed-time stability of stochastic distributed parameter systems and the semiglobal finite/fixed-time stability of stochastic systems. Moreover, compared to existing results on finite/fixed-time stability for stochastic systems, our Lyapunov criterion can still work well under more stringent conditions. This is done by adding a term which can reflect the stabilising effect of the diffusion term and replacing original fractional power functions with a class of piecewise continuous fractional power functions that are no longer required to be increasing. Finally, illustrative examples are given and the obtained theoretical results are verified by numerical simulations.

InSitu Imaging of a Single-Atom Wave Packet in Continuous Space.

We report on the imaging of the insitu spatial distribution of deterministically prepared single-atom wave packets as they expand in a plane, finding excellent agreement with the scaling dynamics predicted by the Schrödinger equation. Our measurement provides a direct and quantitative observation of the textbook free expansion of a one-particle Gaussian wave packet, which we believe has no equivalent in the existing literature. Second, we utilize these expanding wave packets as a benchmark to develop a protocol for the controlled projection of a spatially extended wave function from continuous space onto the sites of a deep optical lattice and subsequent single-atom imaging using quantum gas microscopy techniques. By probing the square modulus of the wave function for various lattice ramp-up times, we show how to obtain a near-perfect projection onto lattice sites. Establishing this protocol represents a crucial prerequisite to the realization of a quantum gas microscope for continuum physics. The method demonstrated here for imaging a wave packet whose initial extent greatly exceeds the pinning lattice spacing, is designed to be applicable to the many-body wave function of interacting systems in continuous space, promising a direct access to their microscopic properties, including spatial correlation functions up to high order and large distances.

Modelling cross-diffusion with Beverton-Holt-like additional food dynamics

Abstract The dynamics of a ratio-dependent interacting species system in space and time, concerning Beverton-Holt-like additional food for predators, are explored within the present framework. Initially, the non-spatial scenario is examined, revealing a variety of dynamical phenomena, including co-dimension 1 and 2 bifurcations in both local and global contexts, through the application of dynamical systems in biology and normal form theory. Additionally, bi-stability phenomena are observed in distinct regions under appropriate parameter values. In the two-phase mathematical analysis, the second phase focuses on the corresponding reaction-diffusion system, uncovering various rich spatiotemporal patterns. Comprehensive numerical simulations are subsequently performed to support the analytical results. The relationship between Beverton-Holt-like additional food and cross-diffusion structures gives rise to spatiotemporal complexity, as demonstrated by the simulation results that validate the behaviour of both temporal and spatiotemporal models.

Design optimization of a lightweight secondary mirror assembly for a 1-m class ground telescope for satellite laser ranging

Large-sized ground telescopes have been developed to meet the high demands for opto-mechanical imaging systems in space and military applications. In line with these advancements, we developed a 1-m class ground telescope for astronomical imaging and satellite laser ranging (SLR). In a ground telescope, mirror deflection is mainly induced by gravity and temperature change. In particular, the gravity vector varies depending on the pointing direction of a telescope, so the surface deformations of the mirrors due to self-gravity need to be managed in different observation directions. This study introduces a mechanical design for an optical tube assembly (OTA) and suggests an optimized design for the secondary mirror (M2) assembly. For a kinematic positioning of the M2, its lightweight was achieved based on the partially open-back structure with hexagonal pocket cells. Then, we optimized the flexure mount design with a bipod structure to minimize the surface errors (SFEs) of the M2 in both the horizontal and vertical pointing directions. Additionally, we simulated the deflections of the primary mirror (M1) and M2 assemblies when installed on the telescope. Based on our design, the M2 was fabricated and processed, and we demonstrated its assembly process and surface quality test.

Sunlight Photons Made of Electrons from Stars

From the 1900s to 2020s, humans believed photons were massless particles. However, solar wind is made of ionized particles such as hydrogen and helium stripped of electrons. This study is one of the first to identify photons as electrons based on analysis with photosynthesis, oxidation reduction reactions, ionization energy, vertical electric fields, and negative air ions (NAIs), when O<sub>2</sub> combines with electron to form O<sub>2</sub><sup>-</sup>. Earth's electrical field is around 100-300 V/metre which further suggests charge is due to light photons or electrons. Electron kinetic and ionization energies of both electrons (e-) and photons are analyzed. A photon electron radiation flux analysis across each planetary body also quantifies photons/m<sup>2</sup>, which helps to advance systems and models in orbit and at surface of planets. After first discovery of photons as electrons from Kole Lutz in 2024, research helps to quantify electron interactions, absorption/emission to improve weather climate models, photosynthesis, power systems (PV Cells, detectors, etc.), corrosion redox reactions, and materials across a variety of fields from energy, communication to biology and space systems. Research holds potential to increase instrument sensitivity for Earth and planetary science, physics, lasers, communication, and to characterize absorption spectra, and light flux from stars.

Open space system and science parks

This article presents a possible connection between the so-called Technology or Science Parks and the disciplinary field of Landscape Architecture. These knowledge areas have been committed to planning and designing sustainable and resilient places in contemporary times. Because science parks can also be instruments for creating urban space, they are intended to relate these concepts to the strategic key of landscape architecture, the open space system. Landscape involves not only formalizing ecosystems but also its capacity to deal with the complexity of the territory. In this context, the role of open spaces as a system is used as parameters for analysis, potential categorization, and valuation. The methodological strategy for building analysis parameters took as the first example the Science Park Sophia Antipolis, located on the French Riviera and considered the first Science Park in Europe. The second example was the HIDS, the International Hub for Sustainable Development, located in Campinas on the rural-urban fringe between two universities, UNICAMP and PUC-Campinas. Although this proposal of relationship is in the initial phase, the observation of these case studies is strategic once they reveal the intention of producing a design innovative and engaged with aspects of Landscape, providing references for new forms of Brazilian urban planning that can overcome environmental problems created by traditional methods and their consequences.