Space Elevator Research Articles

A novel looped space tether transportation system with multiple climbers for high efficiency

This paper proposes a novel concept of looped tether transportation system with multiple climbers for highly efficient transportation of payloads. It is formed by connecting two parallel tether transportation systems or partial space elevators with multiple climbers per tether at upper and lower ends. A high-fidelity and accurate model for the system is built up to capture the high order flexural modes of tethers based on the nodal position finite element method in the arbitrary Lagrangian-Eulerian description. Numerical analysis is conducted to understand the dynamic characteristics of the looped tether transportation system compared to the tether transportation system with a single tether. The results show that the high-order flexural modes of tethers must be considered in the system's engineering analysis. The analysis also shows the interaction between two tethers caused by climbers on different tethers moving in different directions could be beneficial. It will reduce the overall libration of the system while keeping the magnitude of tether tension comparable to the tether transportation system with a single tether. In addition, the analysis of high order flexural modes of tether indicates that there exists a risk of tether collision in the payload transportation, which indicates again the necessity to include the high order flexural modes of tether in the analysis. Finally, the study shows the risk of tether collision could be avoided by optimizing the number of climbers per tether, the climber's moving profiles, and the distance between climbers using the optimal control methodology.

The orbital mechanics of space elevator launch systems

The construction of a space elevator would be an inspiring feat of planetary engineering of immense cost and risk. But would the benefit outweigh the costs and risks? What, precisely, is the purpose for building such a structure? For example, what if the space elevator could provide propellant-free (free release) orbital transfer to every planet in the solar system and beyond on a daily basis? In our view, this benefit might outweigh the costs and risks. But can a space elevator provide such a service? In this manuscript, we examine 3 tiers of space elevator launch system design and provide a detailed mathematical analysis of the orbital mechanics of spacecraft utilizing such designs. We find the limiting factor in all designs is the problem of transition to the ecliptic plane. For Tiers 1 and 2, we find that free release transfers to all the outer planets is possible, achieving velocities far beyond the ability of current Earth-based rocket technology, but with significant gaps in coverage due to planetary alignment. For Tier 3 elevators, however, we find that fast free release transfers to all planets in the solar system are possible on a daily basis. Finally, we show that Tier 2 and 3 space elevators can potentially use counterweights to perform staged slingshot maneuvers, providing a velocity multiplier which could dramatically reduce transit times to outer planets and interstellar destinations.

Libration and end body swing stabilization of a parallel partial space elevator system

This paper studies the libration and stabilization of a parallel partial space elevator system in circular orbits. The system is made up of two paralleled partial space elevators, each of which consists of one main satellite, one end body and a climber moving along the tether between them. The libration characteristics of the elevator are studied through numerical analysis by a new dynamic model, and a novel control strategy is proposed to stabilize the swing of the end body by projecting the climber speeds only. Optimal control method is used to implement the new control strategy in the case where the climbers move in opposite direction. The simulation results validate the effectiveness of the proposed control strategy whose application will neither sacrifice the transport efficiency nor exacerbate libration significantly.

A study on contactless airborne transfer of textile fibres between different garments in small compact semi-enclosed spaces

Interpretation of fibre evidence at activity level requires extensive knowledge of all the possible transfer mechanisms that may explain the presence of fibres on a recipient surface of interest. Herein, we investigate a transfer method that has been largely understudied in previous literature: contactless transfer between garments through airborne travel. Volunteers were asked to wear UV-luminescent garments composed of different textile materials and situate themselves in a semi-enclosed space (elevator) for a pre-determined period of time with other participants, who wore non-luminescent recipient garments. The latter were then inspected for fibres using UV-luminescent photographic techniques. Results showed that contactless transfer between garments is possible. Indeed, a number of fibres were observed after most of the experiments. As many as 66 and 38 fibres were observed in the experiments involving cotton and polyester donor garments, compared to 2 and 1 fibres in those involving acrylic and wool donor garments, respectively. In this regard, the type of donor garment was found to be a significant factor. Multifactorial ANOVA supported these observations (p<0.001) and further indicated a statistically significant influence of elevator door opening/closing (p<0.001), people entering/exiting (p=0.078) and the recipient garment (p=0.030). Therefore, contactless transfer of fibres between garments can occur and can do so in (ostensibly) high numbers. This should be taken into consideration when interpreting fibre evidence at activity level and may have a major implication for the assignment of evidential values in some specific cases.

Space elevator cable's oscillation caused in space thermal environment

On the assumption that the tether's Young's modulus depends on the tether temperature, we analyzed the behavior of the space elevator tether with taking the tether's temperature change into account. The results show the tether has no vibration in the north-south direction, but a vibration in the east-west direction. This vibration's amplitude is about 40 km with a half-day cycle. Since the temperature change in most of the part of the tether has a half-day cycle, it is concluded that this vibration is caused by the temperature change through the expansion and contraction of the tether. Coriolis force generated by the expansion and contraction of the tether makes the tether vibrate by acting as an excitation force. The natural frequency was calculated assuming the space elevator to be a string. The first-order natural frequency is 1.59 [day−1] and the period is 0.628 [day], meaning there is a risk of resonance with the vibration (frequency; 2[day−1]). By changing the values of the two parameters (the length of the space elevator and the internal stress generated in the tether), the natural frequency of the space elevator can be changed. By increasing the tether length or decreasing the internal stress, the natural frequency can be shifted to the lower side. Contrarily, by shortening the tether length or increasing the internal stress, the natural frequency can be shifted to the higher side. For the actual operation of the space elevator, it is suggested that shifting to the higher frequency side is better. Then, the amplitude of the vibration was calculated when the natural frequency is changed by varying the internal stress or the tether length. When the internal stress is changed, the vibration amplitude peaks out when the natural frequency is around 1 [day−1], and when the tether length is changed, the shorter the tether length (the higher the natural frequency), the smaller the amplitude. From this result, it is concluded that the internal stress should be higher and/or the tether length should be shortened to shift the natural frequency to the higher side to suppress the vibration.

Libration suppression of moon-based partial space elevator in cargo transportation

This paper studies the libration suppression of a moon-based partial space elevator in the Earth-Moon three-body system. The elevator is connected to the Moon surface by a tether and a space station is connected to the free end of tether as the end body. One or multiple climber(s) can move along the tether to transfer cargos between the Moon and the end body. A high-fidelity dynamic model is derived to describe the motion of the climber(s), the end body and the flexible tether by the combination of rigid body dynamics and nodal position finite element method. The validity of the proposed model and the effect of element discretization along the tether on the dynamic behaviour of the elevator are investigated through numerical simulations. To ensure the stability and satisfy the mission constraints in the cargo transfer period, an optimal control based on the high-fidelity model is employed to regulate the control input with limited magnitude. Case studies show that by adjusting the thrusts on the end body reasonably, the libration of the Moon-based partial space elevator can be suppressed with limited control input effectively.

Mimicking Functions of Native Enzymes or Photosynthetic Reaction Centers by Nucleoapzymes and Photonucleoapzymes.

The covalent linkage of catalytic units to aptamer sequence-specific nucleic acids exhibiting selective binding affinities for substrates leads to functional scaffolds mimicking native enzymes, nucleoapzymes. The binding of the substrates to the aptamer and their structural orientation with respect to the catalytic units duplicate the functions of the active center of enzymes. The possibility of linking the catalytic sites directly, or through spacer units, to the 5′-end, 3′-end, and middle positions of the aptamers allows the design of nucleoapzyme libraries, revealing structure–functions diversities, and these can be modeled by molecular dynamics simulations. Catalytic sites integrated into nucleoapzymes include DNAzymes, transition metal complexes, and organic ligands. Catalytic transformations driven by nucleoapzymes are exemplified by the oxidation of dopamine or l-arginine, hydroxylation of tyrosine to l-DOPA, hydrolysis of ATP, and cholic acid-modified esters. The covalent linkage of photosensitizers to the tyrosinamide aptamer leads to a photonucleoapzyme scaffold that binds the N-methyl-N′-(3-aminopropane)-4,4′-bipyridinium-functionalized tyrosinamide to the aptamer. By linking the photosensitizer directly, or through a spacer bridge to the 5′-end or 3′-end of the aptamer, we demonstrate a library of supramolecular photosensitizer/electron acceptor photonucleoapzymes mimicking the functions of photosystem I in the photosynthetic apparatus. The photonucleoapzymes catalyze the photoinduced generation of NADPH, in the presence of ferredoxin-NADP+-reductase (FNR), or the photoinduced H2 evolution catalyzed by Pt nanoparticles. The future prospects of nucleoapzymes and photonucleoapzymes are discussed.

Brain to blood efflux as a mechanism underlying the neuroprotection mediated by rapid remote preconditioning in brain ischemia.

Glutamate represents the main excitatory neurotransmitter in the mammalian brain; however, its excessive elevation in the extracellular space is cytotoxic and can result in neuronal death. The ischemia initiated brain damage reflects changes in glutamate concentration in peripheral blood. This paper investigated the role of the brain in blood efflux of the glutamate in an improved tolerance of the brain tissue to ischemic conditions. In the rat model of focal brain ischemia, the neuroprotection was initiated by rapid remote ischemic preconditioning (rRIPC). Our results confirmed a strong neuroprotective effect of rRIPC. We observed reduced infarction by about 78% related to improved neuronal survival by about 70% in the ischemic core. The level of tissue glutamate in core and penumbra dropped significantly and decreased to control value also in the core region of the contralateral hemisphere. Despite significant improvement of blood-brain barrier integrity (by about 76%), the additional gain of glutamate content in the peripheral blood was caused by rRIPC. Based on our results, we can assume that neuroprotection mediated by rapid remote ischemic preconditioning could lie in the regulated, whole-brain release of glutamate from nerve tissue to the blood, which preserves neurons from the exposure to glutamate toxicity and results in reduced infarction.

Evaluative and enabling infrastructures: supporting the ability of urban co-production processes to contribute to societal change

As widely attested in the literature, the evaluation of co-production is complex and unsuited to the use of conventional quality, monitoring and evaluation indicators. This reflects the uncertainties, co-contributory factors and time lags involved, particularly when seeking to assess institutional and wider societal effects of multi-stakeholder participatory processes and deliberative fora. The most widely assessed effects include the immediate outputs and outcomes of a project or activity (so-called first order effects) while wider societal or third order effects continue to be the most difficult to capture and, consequently, are the least well studied. Because of this difficulty, the intermediate, second order effects of organisational transformation and policy implementation constitute a growing challenge for evaluation. This is our focus here. After 10 years of transdisciplinary co-productive research practice, Mistra Urban Futures, as an interstitial research space bridging academia and practice working through city-based institutional partnerships called platforms, has reached a phase where some of these effects are becoming distinguishable. Accordingly, we discuss the prerequisites for co-production practitioners, including policy makers, to engage their respective organisations in transitional and incremental experimentation in order to achieve relevant institutional changes. This requires enabling infrastructures that support training, facilitation and the creation of ‘safe’ spaces to promote trust and legitimacy. These are needed to underpin the long-lasting personal and organisational commitments which are crucial to achieve transformative organisational effects.

Difficult airway management of a patient with limited range of motion in the temporomandibular joint and cervical extension caused by psoriatic arthritis: a case report

BackgroundPsoriasis vulgaris, a chronic inflammatory skin disease, rarely causes temporomandibular arthritis. We report a case of difficult airway management of a patient with limited range of motion in the temporomandibular joint and cervical extension caused by psoriatic arthritis.Case presentationA 33-year-old man was scheduled to undergo laparoscopic colectomy. On admission, he was diagnosed with psoriatic arthritis. After induction of general anesthesia, we attempted intubation using Pentax Airway Scope® with a thin intlock blade and using a bronchoscope, but it was impossible because of the limited oral space and mandibular elevation. Because of concerns about cannot intubate, cannot ventilate, we antagonized the neuromuscular block and he emerged from general anesthesia. Finally, we succeeded in awake intubation via the nasal cavity using a bronchoscope under spontaneous respiration.ConclusionsAlthough psoriasis vulgaris is very rarely associated with temporomandibular arthritis, anesthesiologists should consider that it can cause perioperative difficult airways.

Low-loss and flat dispersion umbrella-shaped and porous-core photonic crystal fiber for terahertz applications

A novel design of a single-mode photonic crystal fiber for applications in the terahertz region is proposed and numerically analyzed. The geometrical and optical parameters of the structure are estimated by using algebraic expressions while the guidance properties are calculated by using the full-vector finite element method. The porous-core of the fiber is suspended by eight equally spaced bridges connected to an outer cladding. The obtained results show that by adjusting the structural parameters appropriately, low-loss and flat dispersion properties could be easily achieved. The numerical results show that our best configuration, with a 60% filling fraction, exhibits a low effective material loss, below 0.2 dB/cm, and a flattened dispersion behavior in the frequency range from 0.79 THz to 1.5 THz.

POSTERIOR SHOULDER TIGHTNESS AND SUBACROMIAL IMPINGEMENT CHARACTERISTICS IN BASEBALL PITCHERS: A BLINDED, MATCHED CONTROL STUDY

Baseball pitchers frequently develop varying levels of posterior shoulder tightness (PST) and often present with characteristics associated with subacromial impingement. To determine if a group of baseball pitchers with excessive PST (bilateral internal rotation ROM difference >18 ° and bilateral total arc of motion difference >5 °) have differences in subacromial joint space, forward scapular posture, or glenohumeral elevation range of motion (ROM) when compared to a control group. Descriptive, cross-sectional study. Thirty-five asymptomatic professional baseball pitchers with excessive PST were matched with 35 pitchers with acceptable levels of PST. The investigators measured subacromial space using diagnostic ultrasound, glenohumeral elevation ROM using a digital goniometer, and scapular posture using a double square, and were blinded to the group of each participant. Separate t-tests were used to determine significant differences between groups (p < 0.05). The excessive PST group presented with significantly less subacromial space (p = .0007) and glenohumeral elevation ROM (p = .03) compared to the acceptable level PST group. The excessive PST group also had significantly more forward scapular posture than the control group (p = .03). The baseball pitchers with excessive PST had less subacromial space and glenohumeral elevation ROM, as well as more forward scapular posture in their throwing arms compared to pitchers with acceptable levels of PST. 3.

Energy and orbital stability in a partially-deployed earth space elevator

The Earth Space Elevator is an ingenious concept aimed at providing easy access to space, eliminating the need for rockets and potentially reducing drastically the launch costs. Technical advancements that could make the Space Elevator possible, among others, would be the availability of long carbon nanotubes or other super-strong and light material. This paper aims at addressing issues related with the stability of the system when the elevator is partially deployed starting from a nucleus in geostationary orbit (GEO). As noted by various authors, the energy increase needed to keep the orbital centre (where the gravity and centrifugal forces balance out) at GEO altitude during deployment while the tether is lengthened leads to an orbit with a positive orbital energy, i.e., the circular orbit has an energy level pertaining to a hyperbolic orbit. This situation leads to the instability of the unanchored system that would tend to escape from the geostationary orbit. The paper illustrates the change in orbital energy during assembly for a system made of a cylindrical tether and then investigate the stability of the coupled orbital and attitude motion in the orbital plane before anchoring. The analysis leads to the conclusion that the orbital motion instability ensues well before the orbital energy of the unperturbed system becomes positive.

3D bioprinting applications in neural tissue engineering for spinal cord injury repair.

Spinal cord injury (SCI) is a disease of the central nervous system (CNS) that has not yet been treated successfully. In the United States, almost 450,000 people suffer from SCI. Despite the development of many clinical treatments, therapeutics are still at an early stage for a successful bridging of damaged nerve spaces and complete recovery of nerve functions. Biomimetic 3D scaffolds have been an effective option in repairing the damaged nervous system. 3D scaffolds allow improved host tissue engraftment and new tissue development by supplying physical support to ease cell function. Recently, 3D bioprinting techniques that may easily regulate the dimension and shape of the 3D tissue scaffold and are capable of producing scaffolds with cells have attracted attention. Production of biologically more complex microstructures can be achieved by using 3D bioprinting technology. Particularly in vitro modeling of CNS tissues for in vivo transplantation is critical in the treatment of SCI. Considering the potential impact of 3D bioprinting technology on neural studies, this review focus on 3D bioprinting methods, bio-inks, and cells widely used in neural tissue engineering and the latest technological applications of bioprinting of nerve tissues for the repair of SCI are discussed.

Stairway to Heaven

From sub-surface freight delivery tubes, to space elevators for ferrying workers to off-planet manufacturing facilities, resident science fiction writer Gareth L. Powell ponders some of the ingenious transit technologies of the future.

Space experimental results of STARS-C CubeSat to verify tether deployment in orbit

STARS-C was the first trial of a tether deployment in orbit using a CubeSat to certify and acquire data for the important technology of space elevators. STARS-C is 2U in size and consists of a mother satellite (MS) and a daughter satellite (DS). It is designed to deploy a 100-m aramid fiber tether between the MS and DS. STARS-C was launched on December 9, 2016, released from J-SSOD on December 19, 2016, and operated until its re-entry on March 2, 2018. Unfortunately, the transmission conditions were so poor that detailed data on tether deployment could not be obtained. However, we found that STARS-C rotated from its JAPOS-supported optical data detected from the ground, and this rotation largely influenced the tether dynamics during and after deployment. We also estimated the tether deployment state from the STARS-C altitude history data, the satellite condition from the optical data, and additional ground tests.

Rapunzel! Rapunzel! How Strong Is Your Hair?

In this issue, the strength of a well-known biological material, hair, is assessed across a number of mammalian species, from humans to elephants. The multiscale keratin-based structure of hair is of interest, representing a possible archetype for biomimetic high-strength threads.

Design and Analysis of Driving Roller for Climber in Space Elevator

Design and Analysis of Driving Roller for Climber in Space Elevator

Quantum bridges in phase space: interference and nonclassicality in strong-field enhanced ionisation

We perform a phase-space analysis of strong-field enhanced ionisation in molecules, with emphasis on quantum-interference effects. Using Wigner quasi-probability distributions and the quantum Liouville equation, we show that the momentum gates reported in a previous publication (Takemoto and Becker 2011 Phys. Rev. A 84 023401) may occur for static driving fields, and even for no external field at all. Their primary cause is an interference-induced bridging mechanism that occurs if both wells in the molecule are populated. In the phase-space regions for which quantum bridges occur, the Wigner functions perform a clockwise rotation whose period is intrinsic to the molecule. This evolution is essentially non-classical and non-adiabatic, as it does not follow equienergy curves or field gradients. Quasi-probability transfer via quantum bridges is favoured if the electron’s initial state is either spatially delocalised, or situated at the upfield molecular well. Enhanced ionisation results from the interplay of this cyclic motion, adiabatic tunnel ionisation and population trapping. Optimal conditions require minimising population trapping and using the bridging mechanism to feed into ionisation pathways along the field gradient.

Global Interactome Mapping of Mitochondrial Intermembrane Space Proteases Identifies a Novel Function for HTRA2.

A number of unique proteases localize to specific sub-compartments of the mitochondria, but the functions of these enzymes are poorly defined. Here, in vivo proximity-dependent biotinylation (BioID) is used to map the interactomes of seven proteases localized to the mitochondrial intermembrane space (IMS). In total, 802 high confidence proximity interactions with 342 unique proteins are identified. While all seven proteases co-localized with the IMS markers OPA1 and CLPB, 230 of the interacting partners are unique to just one or two protease bait proteins, highlighting the ability of BioID to differentiate unique interactomes within the confined space of the IMS. Notably, high-temperature requirement peptidase 2 (HTRA2) interacts with eight of 13 components of the mitochondrial intermembrane space bridging (MIB) complex, a multiprotein assembly essential for the maintenance of mitochondrial cristae structure. Knockdown of HTRA2 disrupts cristae in HEK 293 and OCI-AML2 cells, and leads to increased intracellular levels of the MIB subunit IMMT. Using a cell-free assay it is demonstrated that HTRA2 can degrade recombinant IMMT but not two other core MIB complex subunits, SAMM50 and CHCHD3. The IMS protease interactome thus represents a rich dataset that can be mined to uncover novel IMS protease biology.