Space Elevator Research Articles

The Maintenance of Orbital States in a Floating Partial Space Elevator Using the Reinforcement Learning Method

A partial space elevator (PSE) is a multi-body tethered space system in which the main satellite, typically an ultra-large spacecraft or a space station in a higher orbit, is connected to a transport spacecraft in a lower orbit via a tether, maintaining orbital synchronization. One or more climbers can move along the tether driven by electric power, enabling cross-orbital payload transportation between the two spacecraft. The climbers’ motion significantly alters the main satellite’s orbital states, compromising its safe and stable operation. The dynamic coupling and nonlinearity of the PSE further exacerbate this challenge. This study aims to preliminarily address this issue by proposing a new mission planning strategy. This strategy utilizes reinforcement learning (RL) to select the waiting interval between two transfer missions, thereby maintaining the main satellite’s orbital motion in a stable state. Simulation results confirm the feasibility and effectiveness of the proposed mission-based method.

CADefender: Detection of unknown malicious AutoLISP computer-aided design files using designated feature extraction and machine learning methods

Computer-aided design (CAD) files are used to create digital designs for various structures – from the smallest chips in the high-tech industry to large-scale buildings and bridges in the civil engineering space. We found that most exploits and malicious payloads are deployed through Auto List Processing (AutoLISP) source code (LSP) or Fast Load AutoLISP (FAS) files, which are non-executable files (NEFs) containing scripts in the AutoLISP language that are native to AutoCAD; While antivirus software is capable of detecting many malicious CAD files, the potential to improve protection by using a dedicated machine learning (ML) based detection solution remains, especially against unknown and sophisticated CAD malware. In this study, we are the first to propose designated feature extraction methods and a robust framework aimed at the detection of known and unknown AutoLISP malware using ML algorithms. To accomplish this, we examined the structure, functionality, and ecosystems of AutoLISP files and collected the largest known representative collection of LSP files consisting of 6418 malicious and benign files (labeled and verified). We then explored the use of two novel static-analysis-based feature extraction methods (knowledge-based and structural) designated for LSP files to extract a discriminative set of informative features, which can subsequently be used by ML models to detect malicious LSP files. These two feature extraction methods serve as the basis of the proposed detection framework, whose performance we comprehensively compare to both widely used antiviruses and baseline ML models based on existing feature extraction methods, including MinHash, Bidirectional Encoder Representations from Transformers (BERT), and n-gram. Our results highlight our methods' contributions to the detection of unknown AutoLISP malware and demonstrate their ability to outperform existing methods. The best performance in the task of unknown malicious LSP file detection was obtained by the Artificial Neural Networks (ANN) model trained on 100 knowledge-based features, which obtained a true positive rate (TPR) of 99.49% with a false positive rate (FPR) of 0.57%. Our framework's role in explainability is also highlighted, as we also present the prominent features that contribute most to the model's detection capabilities; this information can be used for explainability purposes. We conclude by evaluating the proposed framework's ability to detect a malicious file from an unknown AutoLISP malware family and by evaluating our framework on an additional independent test set that originated from another source, scenarios that are often faced by malware detection solutions.

Statistical reliability estimation of space launch vehicles: 2000–2022

This research examines the reliability of space launch vehicles (SLVs) performing commercial, civil, and military space lift missions through trend analysis and a variety of statistical methods. Data sets obtained from the Seradata database are analyzed for trends by examining data subsets including launch date, sector (commercial, civil or military), launch country, intended mission orbit, SLV family, and failed subsystem. Evolving, time-dependent first-level Bayesian success rate analysis is performed to assess SLV reliability and performance trends on 1873 launches occurring during the period 1 January 2000 to 31 December 2022. It was determined that even with a near-exponential increase in launch events in the 2020s, the number of failures is less than 6% each year, with the average success rate being 95% annually. Overall, 56% of launches were sent into low Earth orbit (LEO) and 32% were sent into geosynchronous Earth orbit (GEO) or geostationary Earth orbit (GSO). Although SLVs servicing missions to these orbital regimes featured success rates above 92%, LEO launches accounted for approximately 73% of total launch failures, while GEO-GSO launches accounted for 18% of failures. Specifically looking at U.S. and Russian SLV families, the main subsystem responsible for failure was propulsion, which accounted for 72.3% of 47 reported launch failures. First-level and second-level (using method of moments) Bayesian techniques were performed on 37 launch vehicle families and it was found that vehicles with a high accrual of launches performed with a higher reliability than vehicles with a low number of launches, resulting in first-level success rates of greater than 90%.

Multi-Objective optimization for stable and efficient cargo transportation of partial space elevator

This paper proposed a new libration decoupling analytical speed function (LD-ASF) in lieu of the classic analytical speed function to control the climber’s speed along a partial space elevator to improve libration stability in cargo transportation. The LD-ASF is further optimized for payload transportation efficiency by a novel coordinate game theory to balance competing control objectives among payload transport speed, stable end body’s libration, and overall control input via model predictive control. The transfer period is divided into several sections to reduce computational burden. The validity and efficacy of the proposed LD-ASF and coordinate game-based model predictive control are demonstrated by computer simulation. Numerical results reveal that the optimized LD-ASF results in higher transportation speed, stable end body’s libration, lower thrust fuel consumption, and more flexible optimization space than the classic analytical speed function.

The role of spacer heteroatomic fragment in spectroscopic and luminescent behaviour of phenyl-substituted phthalocyanine complexes

Peripheral phenyl-substituted metal phthalocyanines with thio and oxa substitution in the spacer bridge fragment were obtained in the work. Spectroscopic properties were studied for the obtained complexes, and the main patterns of behavior and characteristics change depending on the solvent and the nature of the spacer atom. It is shown that the replacement of an oxygen atom in the bridge fragment of a peripheral substituent with a sulfur atom leads to a change in the values of the fluorescence quantum yields. It was revealed that the presence of a spacer fragment is one of the key factors that strongly influence both the solubility of phthalocyanine complexes and their aggregation behavior in various solvents.

SC-CNTs: Thin Film Transistors for High-Performance, Low-Power, Flexible Electronics

Single Walled Carbon Nanotubes (SWNTs) have gained a great deal of media attention over the past almost-two decades. From their theoretical usage as the foundational material for space elevators that would take travelers beyond earth’s atmosphere, to an active material that would allow engineers to create nanobots that internally repair or treat the human body, applications for SWNTs are numerous and have resonated within the imagination of scientists and the media alike. Fast forwarding to the modern era, we find that nanotubes still have a great deal of technological promise, some of which parallel those usages that were theoretically conceived many years ago.For over a decade, NanoIntegris Technologies Inc. has been at the forefront of synthesizing high-purity, electronically enriched SWNT’s and, during that time, has found that our materials have proven to transcend from the theoretical to practical-usage realm. With over 1,900 publications citing the usage of NanoIntegris’ high performance materials, we have not only seen the beneficial properties of our materials studied via techniques such as scanning electron microscopy but have also received many positive use-cases for our materials such as being an additive of highly-conductive, electrode (anode/ cathode) slurries of next-generation lithium-ion batteries, to being used as an active for the highly-sensitive detection of COVID antigens.Within my talk, I will display the usage of our high-purity semiconducting (≥99%) single walled carbon nanotubes to make the next generation of high-performance electronics. I will focus upon the usage of our IsoSol-S100 semiconducting solution that served as the spin-coated semiconducting layer within a short channel (<10 µm) thin film transistor with ON/OFF of 104, a device thickness of 400 nm, and a mobility of 39 cm2V-1s-1. I will further discuss the usage of our IsoNanotubes-S 99% solution to serve as the active material within a low-power, wearable Radio Frequency biosensor that covers the GSM spectra, with an operation frequency up to 2.1GHz, and that can serve as both a frequency multiplier and mixer.

Wet-spinning of carbon nanotube fibers: dispersion, processing and properties

ABSTRACT Owing to the intrinsic excellent mechanical, electrical, and thermal properties of carbon nanotubes (CNTs), carbon nanotube fibers (CNTFs) have been expected to become promising candidates for the next-generation of high-performance fibers. They have received considerable interest for cutting-edge applications, such as ultra-light electric wire, aerospace craft, military equipment, and space elevators. Wet-spinning is a broadly utilized commercial technique for high-performance fiber manufacturing. Thus, compared with array spinning from drawable CNTs vertical array and direct dry spinning from floating catalyst chemical vapor deposition (FCCVD), the wet-spinning technique is considered to be a promising strategy to realize the production of CNTFs on a large scale. In this tutorial review, we begin with a summative description of CNTFs wet-spinning process. Then, we discuss the high-concentration CNTs wet-spinning dope preparation strategies and corresponding non-covalent adsorption/charge transfer mechanisms. The filament solidification during the coagulation process is another critical procedure for determining the configurations and properties for derived CNTFs. Next, we discuss post-treatment, including continuous drafting and thermal annealing, to further optimize the CNTs orientation and compact configuration. Finally, we summarize the physical property-structure relationship to give insights for further performance promotion in order to satisfy the prerequisite for detailed application. Insights into propelling high-performance CNTFs production from lab-scale to industry-scale are proposed, in anticipation of this novel fiber having an impact on our lives in the near future.

Controlled deployment of a long tether to operate as a partial space elevator

Controlled deployment of a long tether to operate as a partial space elevator

A space elevator deployed at the L1 Mars–Phobos libration point

A space elevator deployed at the L1 Mars–Phobos libration point

Ablation of Sam50 is associated with fragmentation and alterations in metabolism in murine and human myotubes.

The sorting and assembly machinery (SAM) Complex is responsible for assembling β-barrel proteins in the mitochondrial membrane. Comprising three subunits, Sam35, Sam37, and Sam50, the SAM complex connects the inner and outer mitochondrial membranes by interacting with the mitochondrial contact site and cristae organizing systemcomplex. Sam50, in particular, stabilizes the mitochondrial intermembrane space bridging (MIB) complex, which is crucial for protein transport, respiratory chain complex assembly, and regulation of cristae integrity. While the role of Sam50 in mitochondrial structure and metabolism in skeletal muscle remains unclear, this study aims to investigate its impact. Serial block-face-scanning electron microscopyand computer-assisted 3D renderings were employed to compare mitochondrial structure and networking in Sam50-deficient myotubes from mice and humans with wild-type (WT) myotubes. Furthermore, autophagosome 3D structure was assessed in human myotubes. Mitochondrial metabolic phenotypes were assessed using Gas Chromatography-Mass Spectrometry-based metabolomics to explore differential changes in WT and Sam50-deficient myotubes. The results revealed increased mitochondrial fragmentation and autophagosome formation in Sam50-deficient myotubes compared to controls. Metabolomic analysis indicated elevated metabolism of propanoate and several amino acids, including ß-Alanine, phenylalanine, and tyrosine, along with increased amino acid and fatty acid metabolism in Sam50-deficient myotubes. Furthermore, impairment of oxidative capacity was observed upon Sam50 ablation in both murine and human myotubes, as measured with the XF24 Seahorse Analyzer. Collectively, these findings support the critical role of Sam50 in establishing and maintaining mitochondrial integrity, cristae structure, and mitochondrial metabolism. By elucidating the impact of Sam50-deficiency, this study enhances our understanding of mitochondrial function in skeletal muscle.

High-fidelity flexible multibody model considering torsional deformation for nonequatorial space elevator

Space elevators are a promising technology for future space transportation. The primary component of a space elevator is a tether deployed from a geostationary orbit towards the Earth and into deep space. Payloads can be transported using a climber moving along the tether. However, obtaining a deeper comprehension of the precise dynamics of a space elevator is challenging. The tether could have various deformations such as elongation, bending, and torsion owing to its flexible nature and the low level of vibration damping in space. Therefore, understanding those effects on the tether is essential for the design concept of a space elevator. Reproducing the behavior of space tether systems on the ground is challenging, which is primarily due to the scale of the system and the difficulty of accurately replicating a space environment. Thus, high-fidelity numerical analysis methods are required to analyze the dynamic response of space elevators precisely. Previously proposed analysis models of space tether systems with climbers have focused on elongation, bending, and rigid body motion of the tether, and the effect of torsional deformation has been neglected. However, a tether can be twisted easily owing to its low torsional stiffness. This study established high-fidelity numerical simulation models for space elevators considering large deformations including the torsion of a tether. This study developed a flexible multibody model with a moving climber using the absolute nodal coordinate formulation with 14 degrees of freedom. Further, the gravitational perturbation caused by the non-sphericity of the Earth was considered. Using the constructed model, the motion and deformation of nonequatorial space elevators caused by the climber motion and the disturbance in the space environment were investigated. The obtained results indicate that gravitational perturbation can induce torsional deformation, particularly at higher anchor latitudes.

Changes to butterfly phenology versus elevation range after four decades of warming in the mountains of central Spain

Shifts over time (phenology) and space (latitude and elevation range) represent common ecological responses to climate change. However, the factors determining how changes in phenology and distribution interact, and the consequences for conservation, remain uncertain. Here, we assess how phenology responded to temperature over four decades of warming across the elevation ranges of 18 univoltine butterfly species in four mountain regions of Spain. Using count data from intermittent surveys in 166 sites between 1985 and 2022, we tested for (1) effects of monthly temperature and elevation on mean annual flight date; (2) changes to flight dates between 1985–2005 and 2017–2022; and (3) whether shifts in flight date were related to shifts in the average elevation occupied. Mean flight dates were later in years with cooler springs, and at higher sites, with a mean delay of nearly twenty days per km elevation increase. As conditions warmed over time, average flight date advanced for two thirds of species, especially those whose average elevation was stable over time. Species with stable flight dates showed greater indication of upward range shifts, although only one species showed a significant shift in average elevation. Implications for insect conservation: We show that spring temperatures influence mountain butterfly phenology, and that shifts in phenology and elevation range could compensate for each other in determining population exposure and responses to climate change. Monitoring these changes over time, including by employing evidence from historical surveys and scientific collections, can help to understand constraints on species adaptive capacity to climate change.

Effect of 3,4‐ethylenedioxythiophene (EDOT) as Bridged Spacer on DSSC and Non Linear Optical (NLO) Properties: A DFT Approach

AbstractDensity functional theory (DFT) and time dependent DFT (TD‐DFT) techniques are used to explore six donor‐pi‐acceptor (D−A) type sensitizers that comprise coumarin as the donor unit and cyanoacrylic acid as the acceptor unit. It is examined how adding a spacer bridge like 3,4‐ethylenedioxythiophene (EDOT) affects the system. The introduction of EDOT leads to destabilization of highest occupied molecular orbital (HOMO) in both bare and TiO2 anchored sensitizers. The frontier molecular orbital (FMO) also depicts an effective intramolecular charge transfer from the EDOT unit to the acceptor unit in bare sensitizers and to the TiO2 core in TiO2 anchored sensitizers respectively. The FMO diagram of TiO2 anchored non‐bridged sensitizers reveals an electron‐deficient sensitizer unit coupled to an electron‐rich TiO2 core resulting in a poor charge transfer. The calculated Voc values are also found to be more for EDOT based sensitizers and hence making the EDOT bridged sensitizers efficient for DSSC application. According to the TD‐DFT investigation, the EDOT bridging sensitizers exhibit red‐shifted vertical excitation when compared to the corresponding non bridged sensitizers, which is consistent with the experimental data reported previously.

Dynamics-Informed hierarchical sliding mode control for libration of partial space elevators in cargo transportation

This study presents an original analysis of out-of-plane libration dynamics and its control in partial space elevator cargo transportation. A comprehensive three-dimensional dynamic model of the partial space elevator has been derived to examine the effects of out-of-plane libration. To ensure a stable in-plane configuration, a coupling-free analytical speed function is developed that cancels out the coupling effects stemming from out-of-plane libration. A novel approach is developed to introduce a thrust control strategy for the elimination of out-of-plane libration using a virtual dynamic-based hierarchical sliding mode control law. By employing a new combined channel implementation mode, it is demonstrated that in and out-of-plane libration can be controlled with a single thruster, resulting in reduced fuel consumption. The stability of the proposed control strategy is proven within the Lyapunov framework. Numerical simulations validate the effectiveness of the control strategy and highlight its significance. Results show that out-of-plane libration increases the magnitude of in-plane libration, while climber movement amplifies out-of-plane libration. The control strategy successfully eliminates out-of-plane libration using limited control input, ensuring stable cargo transportation in the partial space elevator.

New geometric formulation for libration dynamics and suppression of partial space elevator by fuzzy logic and thrust vectoring control

This study proposes a new control strategy for mitigating the libration in a partial space elevator (PSE). First, a libration-free or coupling-free analytical speed function is derived by assuming no in-plane and out-of-plane libration in the cargo transportation phase. Subsequently, a thrust is applied at the PSE's end body to counter any libration during this phase. A new set of geometric measures - bending and departure angles - are introduced to characterize the libration motion in PSE's dynamic equation. Based on these measures, two separate proportional-derivative (PD) stabilizing feedback laws are proposed. These PD laws individually control the bending and departure angles by thrust at the end body to suppress the libration that deviates from the libration-free trajectory. Due to the dynamic coupling between the bending and departure modes, they dominate alternatively. Accordingly, a novel fuzzy logic control law is proposed to switch between two PD controls based on the state of these two angles. Finally, a thrust vectoring control is proposed to combine in-plane and out-of-plane thrusting into a single actuation control. The asymptotic stability of the proposed control scheme is proved by Lyapunov's stability theory. Comprehensive numerical analyses demonstrate the effectiveness of the new geometric representation of the libration and the proposed new control strategy, highlighting their ability to suppress libration with bounded control inputs efficiently.

Unconventional Space Technologies: Engineering Design &amp; Physics Extension to Propellantless Propulsion

The ever-growing desire to explore the cosmos compels us to seek more efficient and sustainable methods for space travel. Conventional rocket propulsion, reliant on the expulsion of propellant, presents limitations in terms of cost and environmental impact. This article extends the paper “Beyond the Rocket: A Minireview of Propellantless Propulsion Technologies and Concepts” and discusses the selection of unconventional space launch and propulsion technologies that have the potential to bring us close to our approach to space exploration. These technologies include the space elevator, a colossal structure tethered to the Earth offering continuous access to space; tethers, versatile tools for electrodynamic power generation and orbital maneuvering; laser-based orbital transfer, a futuristic concept utilizing powerful lasers for propellantless propulsion; and skyhooks, conceptual designs that employ tethered platforms for spacecraft capture. Additionally, we highlight the theoretical concept of Mass Reduction Engines, which propose converting a miniscule amount of a spacecraft's mass into energy for propulsion. While each technology presents unique advantages, they all face significant challenges, ranging from material science limitations to the need for breakthroughs in physics. This letter analyzes the potential, limitations and scientific underpinnings of these unconventional propulsion technologies, providing a glimpse into the exciting possibilities and hurdles that lie ahead in the future of space exploration.

Loss of MTX2 causes mitochondrial dysfunction, podocyte injury, nephrotic proteinuria and glomerulopathy in mice and patients.

Proteinuria is a common and important clinical manifestation of chronic kidney disease (CKD) and an independent risk factor for the progression of kidney disease. As a component of the glomerular filtration barrier (GFB), podocyte plays a key role in the pathogenesis of glomerular diseases and proteinuria. However, the pathophysiology of glomerular diseases associated with mitochondrial function is incompletely understood. Here, we identified three novel mutations in MTX2, encoding a membrane protein in mitochondria, associated with multisystem manifestations including nephrotic proteinuria and kidney injury in two Chinese patients. Conditional podocyte-specific Mtx2 knockout (Pod-Mtx2-KO) mice present a series of podocyte and glomerular abnormalities from 8 weeks to old age, including microalbuminuria, glomerular mesangial hyperplasia, fusion and effacement of foot process. MTX2 deficiency impaired podocyte functions in vitro, manifested by reductions of adhesion, migration and endocytosis, which were further restored by overexpression of MTX2. Moreover, MTX2 defects led to abnormal mitochondrial structure and dysfunction, evidenced with defects of complex I and III, increased production of reactive oxygen species (ROS), and decreased protein levels of Sam50-CHCHD3-Mitofilin axis in the mitochondrial intermembrane space bridging (MIB) complex which is responsible for maintaining mitochondrial cristae morphology. Collectively, these findings reveal that the normal expression of MTX2 in glomerulus plays an important role in the adhesion, migration, endocytosis, proliferation and other physiological functions of podocytes, which may be realized by maintaining the morphological structure and function of mitochondria. Abnormal expression of MTX2 can lead to mitochondrial dysfunction and structural abnormalities by Sam50-CHCHD3-Mitofilin axis in podocyte, which further induces podocyte injury, glomerular lesions and proteinuria.

‘We Taught You How to Teach Us’: An Autoethnography of Decolonising of Social Work Education in a Programme for Bedouin-Arab Social Workers in Israel

Abstract The need to decolonise social work education has become prominent in curricula developed over the past years. The curriculum in social work schools defines and shapes ways of knowing largely in terms of privileged Western knowledge. It is therefore necessary to change it and adopt pedagogical approaches more suitable for populations from different cultures. This article presents a study on a dedicated training programme for Bedouin-Arab social workers in Israel. Its pedagogies are informed by decolonised and culturally adapted social work education. This qualitative study was conducted in a teacher-researcher reflexive autoethnography approach, based on documentation of thirty-six lessons and reflections by the programme lecturers and on a thematic analysis of their experiences as social work educators. The findings present several pedagogies in terms of ‘bridge’: the pedagogic, the cultural sensitivity, the theory–practice and the safe space bridge. These expand the knowledge base in social work education beyond Western knowledge, demonstrating how knowledge practices unique to different cultures and identities may be adopted and adapted within it. Based on these findings, it is suggested to transform and enrich social work education by decolonising it to include new knowledge from diverse populations.

A double pendulum fixed at the L1 libration point: a precursor to a Mars–Phobos space elevator

A double pendulum fixed at the L1 libration point: a precursor to a Mars–Phobos space elevator

Stable cargo transportation for underactuated partial space elevator with model uncertainties and disturbances

An adaptive neural network energy-based control approach is proposed in this paper to address the issue of stabilizing a partial space elevator during cargo transportation. The method handles the challenges presented by external disturbances and model uncertainties. The dynamic model of the partial space elevator, with a typical multi-input and multi-output underactuated system, is presented. A control scheme using energy-based techniques is proposed to guarantee the stable configuration of the system, and auxiliary kinematic vector variables are designed to incorporate the uncontrollable variables to constitute controllable state subsets. Under these frameworks, adaptive control schemes are formulated using multi-layer neural networks to mitigate model uncertainty. Robust compensators are designed to effectively counteract the unknown boundaries of external disturbances and approximation errors. The stability of the closed control system is rigorously demonstrated through the application of the Lyapunov function and LaSalle's invariance principle. Numerical simulations demonstrate that the proposed control method is highly effective in suppressing oscillations during the transfer period of a partial space elevator.