Space Station Orbit Research Articles

Waiting for Instantaneity

Waiting for Instantaneity

Observations of small-sized noctilucent clouds from the Mir orbital space station in 1996-1997

Get PDF Email Share Share with Facebook Tweet This Post on reddit Share with LinkedIn Add to CiteULike Add to Mendeley Add to BibSonomy Get Citation Copy Citation Text A. Yu. Kaleri, "Observations of small-sized noctilucent clouds from the Mir orbital space station in 1996-1997," J. Opt. Technol. 67, 426- (2000) Export Citation BibTex Endnote (RIS) HTML Plain Text Citation alert Save article

Virtuelle Realität in der Neurochirurgie

Virtual reality enables users to immerse themselves in a virtual three-dimensional world and to interact in this world. The simulation is different from the kind in computer games, in which the viewer is active but acts in a nonrealistic world, or on the TV screen, where we are passively driven in an active world. In virtual reality elements look realistic, they change their characteristics and have almost real-world unpredictability. Virtual reality is not only implemented in gambling dens and the entertainment industry but also in manufacturing processes (cars, furniture etc.), military applications and medicine. Especially the last two areas are strongly correlated, because telemedicine or telesurgery was originated for military reasons to operate on war victims from a secure distance or to perform surgery on astronauts in an orbiting space station. In medicine and especially neurosurgery virtual-reality methods are used for education, surgical planning and simulation on a virtual patient.

Optical Characteristics of C60 Single Crystals Grown in Microgravity Conditions

This work is devoted to the growing and characterization of perfect C{sub 60} single crystals with the aim of further understanding of the physical properties of this material related to the low energy excited states which determine in a considerable degree its electronic properties, which, in turn, are important for its possible application. Here the authors present several characterization techniques based on optical properties of C{sub 60} crystals and the first results of the investigation of the C{sub 60} samples grown at the orbital space station MIR.

Application of real-time radiation dosimetry using a new silicon LET sensor

A new type of real-time radiation monitoring device, RRMD-III, consisting of three double-sided silicon strip detectors (DSSDs), has been developed and tested on-board the Space Shuttle mission STS-84. The test succeeded in measuring the linear energy transfer (LET) distribution over the range of 0.2 keV/μm to 600 keV/μm for 178 h. The Shuttle cruised at an altitude of 300 to 400 km and an inclination angle of 51.6° for 221.3 h, which is equivalent to the International Space Station orbit. The LET distribution obtained for particles was investigated by separating it into galactic cosmic ray (GCR) particles and trapped particles in the South Atlantic Anomaly (SAA) region. The result shows that the contribution in dose-equivalent due to GCR particles is almost equal to that from trapped particles. The total absorbed dose rate during the mission was 0.611 mGy/day; the effective quality factor, 1.64; and the dose equivalent rate, 0.998 mSv/day. The average absorbed dose rates are 0.158 mGy/min for GCR particles and 3.67 mGy/min for trapped particles. The effective quality factors are 2.48 for GCR particles and 1.19 for trapped particles. The absorbed doses obtained by the RRMD-III and a conventional method using TLD (Mg 2SiO 4), which was placed around the RRMD-III were compared. It was found that the TLDs showed a lower efficiency, just 58% of absorbed dose registered by the RRMD-III.

Spending without results: lessons from the space station program

The US spent all of the funds originally estimated for the initial development of its orbital space station without producing any significant amount of flight hardware. This article shows how a project with large design costs and significant “non-prime” outlays can quickly deplete program funds. The authors recount the way in which budgetary politics, congressional micro-management, and technological risk conspired to produce this result.

Dusty plasma induced by solar radiation under microgravitational conditions: An experiment on board the Mir orbiting space station

The dynamics of the formation of ordered structures of macroparticles charged by photoemission under the action of solar radiation under microgravitational conditions without the use of electrostatic traps to confine the particles is studied experimentally and theoretically. The working conditions needed for the formation of structures of charged macroparticles are chosen as a result of a numerical solution of the problem posed, the particle charges and the interparticle interaction parameter are determined, and the characteristic times specifying the dynamics of the formation of an ordered system of macroparticles are calculated. The behavior of an ensemble of macroparticles under the effect of solar radiation is observed experimentally on board the Mir space station. An analysis and comparison of the results of the experimental and theoretical investigations permit drawing a conclusion regarding the possibility of the existences of extended ordered formations of macroparticles charged by photoemission under microgravitational conditions.

Geno-fuzzy control in autonomous servicing of a space station

The provision of spacecraft servicing to a space station comprises the tasks of assembly, resupply, repair and maintenance of manufactured space parts in-orbit. Servicing tasks use rendezvous and docking operations to accomplish their objectives. Autonomous servicing relies on intelligent fly control systems to perform fast, soft, and precise docking operations. This paper proposes the use of a fuzzy logic control system, mounted on an active chaser vehicle which wants to dock with a big passive space station in orbit around the Earth. The geno-fuzzy controller is a knowledge-based controller that performs the closed-loop operations autonomously. It produces smooth control actions in the proximity of the target and during the docking, to avoid disturbance torques in the final assembly orbit. The use of a genetic algorithm tool to optimise the controller so as to reduce docking time and fuel consumption is analyzed. It performs the optimization by finding the best fuzzy sets of the controller membership functions, and the most suitable rule data base.

Metabolic assessments during extra-vehicular activity

Extra-vehicular activity (EVA) has a significant role during extended space flights. It demonstrates that humans can survive and perform useful work outside the Orbital Space Stations (OSS) while wearing protective space suits (SS). When the International Space Station ‘Alpha’(ISSA) is fully operational, EVA assembly, installation, maintenance and repair operations will become an everyday repetitive work activity in space. It needs new ergonomic evaluation of the work/rest schedule for an increasing of the labor amount per EVA hour. The metabolism assessment is a helpful method to control the productivity of the EVA astronaut and to optimize the work/rest regime. Three following methods were used in Russia to estimate real-time metabolic rates during EVA: 1. 1. Oxygen consumption, computed from the pressure drop in a high pressure bottle per unit time (with actual thermodynamic oxygen properties under high pressure and oxygen leakage taken into account). 2. 2. Carbon dioxide production, computed from CO 2 concentration at the contaminant control cartridge and gas flow rate in the life support subsystem closed loop (nominal mode) or gas leakage in the SS open loop (emergency mode). 3. 3. Heat removal, computed from the difference between the temperatures of coolant water or gas and its flow rate in a unit of time (with assumed humidity and wet oxygen state taken into account). Comparison of heat removal values with metabolic rates enables us to determine the thermal balance during an operative medical control of EVA at “Salyut-6”, “Salyut-7” and “Mir” OSS. Complex analysis of metabolism, body temperature and heat rate supports a differential diagnosis between emotional and thermal components of stress during EVA. It gives a prognosis of human homeostasis during EVA. Available information has been acquired into an EVA data base which is an effective tool for ergonomical optimization.

Heavy particle fluxes in Salyut space station orbit

Results of a detailed analysis of heavy ion fluences measured on the Salyut and MIR orbital stations from 1978 to 1990 are presented. The analysis has made use of new models that describe the cosmic ray fluxes and their transition through the magnetosphere. The penetration of solar cosmic ray particles to the orbit, the increase of the (Sc Cr)/Fe flux ratio in the orbit, and the occurrences of 200–500 MeV/nucl heavy nuclei in <30° latitudes have been analyzed.

Radiation environment induced by cosmic ray particle fluxes in the international space station orbit according to recent galactic and solar cosmic ray models

Radiation characteristics (particle fluxes, doses, and LET spectra) are calculated for spacecraft in the International Space Station orbit. The calculations are made in terms of the dynamic model for galactic cosmic rays and the probabilistic model for solar cosmic rays developed at the Institute of Nuclear Physics of Moscow State University.

Development of potato minitubers in microgravity.

Stem segments of aseptically grown potato (Solanum tuberosum L. cv. Zarevo) were cultivated for 4 weeks under laboratory conditions and were then grown for 8 d on board the "Mir" orbital space station. Timing was such that minitubers initiated and developed during the 8 d on the "Mir". Under space flight and stationary conditions, spherical minitubers were formed with no statistically significant differences in either the frequency of tuber formation or tuber size. These observations are the first to document the formation of vegetative reproductive organs and of well developed amylogenic storage tissue during the microgravity conditions of orbital space flight. In these minitubers, a majority of the starch was stored in parenchyma, with numerous amyloplasts per cell. In space flight tissue, however, grain size of starch was decreased and lamellae within the amyloplasts was locally enlarged. Furthermore, mitochondria of these tissues were characterized by increased matrix density and well developed cristae.

Economics of small fully reusable launch systems (SSTO vs. TSTO)

The paper presents a design and cost comparison of an SSTO vehicle concept with two TSTO vehicle options. It is shown that the ballistic SSTO concept feasibility is NOT a subject of technology but of proper vehicle SIZING. This also allows to design for sufficient performance margin. The cost analysis has been performed with the TRANSCOST- Model, also using the “Standardized Cost per Flight” definition for the CpF comparison. The results show that a present-technology SSTO for LEO missions is about 30 % less expensive than any TSTO vehicle, based on Life-Cycle-Cost analysis, in addition to the inherent operational/ reliability advantages of a single-stage vehicle. In case of a commercial development and operation it is estimated that an SSTO vehicle with 400 Mg propellant mass can be flown for some 9 Million $ per mission (94/95) with 14 Mg payload to LEO, 7 Mg to the Space Station Orbit, or 2 Mg to a 200 800 km polar orbit. This means specific transportation cost of 650 $/kg (300 $/lb), resp.3.2 MYr/Mg, to LEO which is 6 −10% of present expendable launch vehicles.

Market architectures and institutional testbedding: An experiment with space station pricing policies

By the year 2000 the National Aeronautics and Space Administration (NASA) plans to launch and operate an earth orbiting space station. For decades into the future the station is expected to play a dominant role in U.S. space research and in the commercialization of space. If the expectations are correct, then the station will be a complex of potentially valuable resources and services. Much sentiment exists within the government that the allocation of those resources should be based on some sort of market-oriented policy (a more “business-like” approach). This paper is part of a larger project that is intended to ascertain what that policy might be.

Approximate initial Lagrange costates for continuous-thrust spacecraft

A method is presented to obtain approximate initial costate values and flight time for the optimal control of a continuous-thrust spacecraft on a coplanar, circle-to-circle transfer. The approximate initial costates are then used as starting values for the associated boundary-value problem to match the desired final states. The exact, nonlinear differential equations are integrated to solve the boundary-value problem with a shooting method. The approximate expressions for the initial costates and flight time are useful when the thrust acceleration is greater than or equal to the change in orbital radius, in canonical units. Numerical examples are provided for a geocentric and an Earth-Mars orbital transfer. EW propulsion technologies have raised interest in the space community for continuous-thrust orbital missions. In military applications, this could mean more responsive deployment of space assets and longer on-orbit lifetimes. Tactical repositioning of a satel- lite using chemical propulsion can consume large amounts of the available fuel mass per maneuver. This is certainly unacceptable for many reasons including lifetime, reliability, and cost. A space- craft propelled by high-efficiency thrusters could accomplish many more maneuvers for the same amount of fuel mass as a chemical propulsion system. Another interesting application of continuous-th rust propulsion is interplanetary space travel. A permanently orbiting space station could serve as a launch point for solar system exploration. Maintain- ing cryogenic fuels for this purpose, however, would be technically difficult and extremely costly. These problems would be less signif- icant if the orbiting space station were used as an assembly point for an exploration vehicle propelled by high-efficien cy continuous thrusters. Such a vehicle could be made reusable much more easily in terms of reliability and cost than a chemically propelled space- craft. Also, a vehicle using continuous thrust with existing technol- ogy could shorten travel times compared to fuel-optimal impulsive maneuvers, then could return to Earth orbit for reconditioning. Although the optimization of impulsive transfers has a direct solution,1 none has been found for the continuous-thrust case. This problem may be solved numerically, and many examples of this are to be found in the literature.2 Optimization of a continuous- thrust trajectory involves the simultaneous solution of an optimal control problem and a boundary-value problem. The initial and final states are normally known, but there is usually no infor- mation available for the initial values of the Lagrange costates. This presents quite a problem, since the optimal control law is often a function of the Lagrange costates that must be initialized for numerical integration. The usual approach is to make an edu- cated guess for the initial values, then update them by solving the boundary-value problem. Trussing,3 Broucke,4 and others2 have re- cast the boundary-value problem in terms of other variables, but the initial values of these must be guessed and refined as well. Prussing3 incorporated the second derivative of the primer vec- tor into a fourth-order dynamics equation, thus eliminating the control variables. Once this is accomplished, four constants of

Geomagnetic transmission disturbances and heavy-ion fluences observed in low Earth orbit during the solar energetic particle events of October 1989

The large solar energetic particle (SEP) events and simultaneous large geomagnetic disturbances observed during October 1989 posed a significant, rapidly evolving space radiation hazard. Using data from the GOES-7, NOAA-10, IMP-8 and LDEF satellites, we determined the geomagnetic transmission, heavy ion fluences, mean Fe ionic charge state, and effective radiation hazard observed in low Earth orbit (LEO) for these SEPs. We modeled the geomagnetic transmission by tracing particles through the combination of the internal International Geomagnetic Reference Field (IGRF) and the Tsyganenko (1989) magnetospheric field models, extending the modeling to large geomagnetic disturbances. We used our results to assess the radiation hazard such very large SEP events would pose in the anticipated 52° inclination space station orbit.

The use of dynamics in an intelligent controller for a space faring rescue robot

The NASA Extra Vehicular Activity Retriever (EVAR) robot is being designed to retrieve astronauts or objects that become detached from the orbiting Space Station. This task requires that the robot's intelligent controller must rely heavily on orbital dynamics predictions, without becoming blind to the wide variety of anomalies that may occur. This article describes the controller's Universal Plan (U.P.) and some technical lessons learned from it. The U.P. reacts not to actual current states but to estimated states, which are obtained using goal-directed active perception. A modal logic formalization of discrete-event dynamics allows us to finely analyze and specify the interactions of knowledge, belief, sensing, acting, and time within the U.P. The U.P. now acts like a hands-off manager: it makes regular observations, grants some leeway for unobservable or ill-modelled processes, has faith in subsystem dynamics, and takes action only to manipulate subsystems into delivering desired progress. Most of the time, the appropriate action is to do nothing. Finally we examine properties of the application that allowed the U.P. to deliver robust goal achievement despite misleading state estimates, weak models of relevant processes, and unpredictable disturbances.

Two-decade experience of application of plastic nuclear track detectors to cosmic ray research on satellites and orbital space stations

The work generalizes the results obtained during the last two decades in our spaceborne experiments aimed at studying galactic cosmic rays and cosmic ray anomalous component and carried out using solid-state nuclear track detectors (SSNTD) mounted mostly outside spacecraft. The experimental equipment and the techniques for identifying cosmic ray ions and for calculating particle flux values are described. The experimental data are used to construct a modified model for the fluxes and spectra of cosmic ray protons and heavy nuclei to be calculated to within a higher accuracy compared with the earlier models.

Fluxes of galactic iron nuclei and associated HZE secondaries, and resulting radiation doses, in the brain of an astronaut

Although galactic iron nuclei constitute only a small percentage of the total flux of radiation in space, they are extremely significant from a biological standpoint, and represent a concern for long-term manned space missions of the future. Dosages resulting from iron nuclei, and the high-charge secondary nuclei subsequently produced in nuclear fragmentation reactions, have been calculated at the centre of a simple model of the human brain, shielded by various thicknesses of aluminium. Three mission scenarios are considered representing different geomagnetic shielding conditions at solar minimum. Without artificial shielding absorbed dose rates outside the magnetosphere, in polar orbit and in the proposed Space Station orbit, are approximately 0.3, 0.1 and 0.03 cGy/year respectively, corresponding to dose equivalent rates of 8.0, 2.5 and 0.8 cSv/year, and decreasing by roughly a factor of two behind 10 g/cm 2 of aluminium. In line with new approaches to risk estimation based on particle fluence and track structure, calculations of the number of cell nuclei likely to be struck by these HZE particles are also presented. Behind 10 g/cm 2 of aluminium, 3.4%, 1.3% and 0.5% of cell nuclei at the centre of the brain will be traversed at least once by such a particle within three years, for the three mission scenarios respectively.

Optimal Multi-Criteria Aeroassisted Orbital Transfer Trajectories

Single and multiple atmospheric pass aeroassisted orbital transfers for three representative AOTV configurations on a geostationary to space station orbit transfer mission are investigated using multi-criteria trajectory optimization. The fuel optimal results indicate that independent of the vehicle type, the maximum heat flux is reduced by 20% and 35%, respectively, using two and three atmospheric passes in comparison to a single-pass. The multi-criteria results show that the ability to trade-off fuel consumption for a lower peak heating rate improves for all transfer modes (single- and multiple-pass) with increasing lift-to-drag ratio.