Space Station Orbit Research Articles

Aerospace: Collision avoidance in space: Proliferating payloads and space debris prompt action to prevent accidents

Space is infinite; yet the space in Earth's orbit is finite, and collisions in space between man-launched objects have become a threat. As the number and size of orbiting space stations continue to grow, there is increasing danger that they will hit some fragment of “junk” — spent rockets, dead payloads, fragments from explosions and collisions in space, and the like. This “junk” could threaten smaller spacecraft because of the increasing number of fragments from collisions of pieces of debris.

Cost effectiveness requirements for space power stations

The concept of converting solar energy in orbital space stations and transmitting electrical power to Earth at radio frequency, is receiving increasing attention both in paper studies and experimental and development work. The projects conceived are large in scale and implications and will demand major resources in their development and deployment. In addition to the technological requirements, the problem of reaching international decisions at political levels to fund and operate such systems will be immense. It will therefore be essential to establish as accurately as possible the basic parameters which will lead to a viable project, particularly with regard to economics. This paper, therefore, examines the requirements which together will determine the appropriate levels of cost effectiveness of space power stations and should assist in establishing critical or sensitive areas which will influence the operational validity of the concepts. The r.f. transmission of electric power to and from, or between, spacecraft may itself have wider implications and is another aspect considered in the paper. In summary, the paper does not seek to introduce new design concepts, but appraises the situation and exposes indicators concerning cost effectiveness.

The trajectories of a spaceprobe ejected from a space station in circular orbit

The trajectories of an unpowered spaceprobe ejected into the orbital plane of a space station in circular orbit are investigated using a coordinate reference system attached to the space station. Polar parametric equations for the trajectories are developed by a coordinate transformation of the orbital equations to rotating coordinates, with the true anomaly of the spaceprobe in orbit as parameter. An analysis of these equations leads to descriptions and classifications of the trajectories in which classes of bounded and unbounded trajectories are isolated with subclasses of periodic, aperiodic, central, progressing, reversing, isochronous, isoperiodic, isonumeric, homoperiodic and coterminal trajectories established and identified.

Poland tries the taste of space

During 1978, three cosmonauts from Eastern Europe visited the Soviet Salyut-6 orbiting space station. Vera Rich talks to the Polish cosmonaut, Miroslaw Hermaszewski in Warsaw

Considerations for the application of the lunar occultation technique

view Abstract Citations (22) References (15) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Considerations for the application of the lunar occultation technique. Ridgway, S. T. Abstract The range of applicability of the lunar occultation technique is investigated for existing and forseeable telescopes and photometers. Angular-resolution limits imposed by various factors in the Fresnel and geometric approximations are considered, and constraints are determined which are imposed in both approximations by source-photon-noise-limited, detector-noise-limited, and background-photon-noise-limited detection. The choice of parameter values and the contribution of source scintillation noise are discussed. The potential of the occultation technique is then evaluated for observations performed at wavelengths of 0.55, 2, and 10 microns. Occultation observations from orbiting space stations and satellites are also discussed. Publication: The Astronomical Journal Pub Date: July 1977 DOI: 10.1086/112083 Bibcode: 1977AJ.....82..511R Keywords: Angular Resolution; Infrared Astronomy; Lunar Occultation; Telescopes; Fresnel Diffraction; Photometers; Satellite Observation; Scintillation; Signal To Noise Ratios; Stellar Structure; Visual Photometry; Astronomy full text sources ADS |

An exact and a new first-order solution for the relative trajectories of a probe ejected from a space station

The motion of an unpowered probe, ejected into an elliptic orbit in the orbital plane of a space station in circular orbit, is investigated from a reference system attached to the space station. Existing approximate solutions to this relative trajectory problem, of two bodies in Keplerian orbits about the same primary, are restricted to small relative displacements. A new first-order solution is derived from an exact solution: no restriction is placed on the relative displacement and the solution osculates with the exact solution at points corresponding to perigee and apogee of the probe's orbit. A geometrical description of the trajectories is given in terms of prolate cycloids plotted in a curvilinear coordinate system.

A data base management (DBMP) program for integrated logistics support (ILS) : A. Christensen and R. S. J. Voytek. Proc. 1975 Canadian SRE Reliability Symposium. May 10th, 1975. Ottawa. p. 73

Abstract The Integrated Logistics Support function and its interdependent disciplines such as life cycle costing, reliability and maintainability engineering, spares determination and sparing philosophies is discussed in this paper. This inter-relationship is pursued from a Data Base Management Program (DBMP) viewpoint. The (DBMP) can be applied directly to the optimum design and selection of a system of equipment for a sailing vessel, an aircraft, a computer complex or a large orbiting space station.

A data base management (DBMP) program for integrated logistics support (ILS)

The Integrated Logistics Support function and its interdependent disciplines such as life cycle costing, reliability and maintainability engineering, spares determination and sparing philosophies is discussed in this paper. This inter-relationship is pursued from a Data Base Management Program (DBMP) viewpoint. The (DBMP) can be applied directly to the optimum design and selection of a system of equipment for a sailing vessel, an aircraft, a computer complex or a large orbiting space station.

Progress in regenerative life support systems for a lunar surface base

The authors review some of the Environmental Thermal Control/Life Support System (ETC/LSS) technology for an Earth orbital space station being developed in 1972 by NASA and its possible application for a manned lunar base. The lunar missions considered involve up to 12 crew members and a duration of about three years. The general requirements of a lunar base are discussed and compared with those of an Earth orbital space station. The ETC/LSS is described in particular with regard to reliability and to a means for lunar food production, water recovery, waste processing, atmosphere regeneration and atmosphere trace contaminant control.

Precession rate matching for a space station in orbit about an oblate planet.

Covers advancements in spacecraft and tactical and strategic missile systems, including subsystem design and application, mission design and analysis, materials and structures, developments in space sciences, space processing and manufacturing, space operations, and applications of space technologies to other fields.

Natural Frequencies of an Orbiting Space Station

Covers advancements in spacecraft and tactical and strategic missile systems, including subsystem design and application, mission design and analysis, materials and structures, developments in space sciences, space processing and manufacturing, space operations, and applications of space technologies to other fields.

Motion of a space station. I

In this first part of the work we develop the equations of motion of a triaxial space station in orbit around the oblate Earth. A first order solution of the problem is presented and the method of complete integration of the system is outlined up to second order of approximation. The zero order part of the Hamiltonian includes both the kinetic and potential energy (Earth's Newtonian attraction) of the station, while the motion in the vicinity of a specific configuration is assumed.

Rotational stability of a semielastic body

Semielastic body rotational stability, investigating elastic coupling effects on controllability of rotating space stations in earth orbit

Supply and resupply of stations in synchronous orbit

Logistics system for synchronous orbit space stations supply, discussing parking to synchronous orbit transfer of reusable and disposable logistics vehicles

Orbital stations and studies of the earth from space

The uses and benefits of long lived, or long standing manned orbiting space stations are reviewed along with the history and progress of their development. Finally the special problems associated with the design of the control system structures and equipment are discussed, some of the promising mathematical solutions are presented, and it is concluded that after appropriate experimental verifications are made, the long lived space stations will be developed in the near future.

Problems of Nuclear Rockets

In man's effort to conquer space, he has relied on the same type of propulsion that powers cars, lawn mowers, jet planes, Piper Cubs, battleships and motor boats: chemical propulsion. For a long time to come, burning a fuel and controlling its combustion energy will be the way to boost a rocket into space. This may do for manned missions to the moon. But scientists and engineers at the National Aeronautics and Space Administration and the Atomic Energy Commission regard this method already as antiquated and uneconomical when it comes to missions deep in space. Over the last decade, AEC and NASA have spent $1.2 billion in developing the basic technology of the nuclear rocket; another $1 billion is needed to complete the project. It looks like it's around the corner, says Sen. John D. Pastore (D-R.I.) of the Joint Congressional Committee on Atomic Energy. We've been working on it for years, but where is it? The nuclear rocket, called NERVA (Nuclear Engine for Rocket Vehicle Application), has gone through all its preliminary design and testing stages, and the time from now until 1978-the current project completion date-will be taken up with getting it ready for flight. The rocket is expected to be ready in time to power a shuttle for ferrying men and cargo from low earth orbit to the space stations in high earth (geosynchronous) or lunar orbit, or to send payloads deeper into space on such missions as a trip to Mars for either a manned landing, an unmanned fly-by oI an instrumented sampling mission. Because of the trip time and the heavy payloads involved, NERVA is not only ideally suited for such a job but is considered critical to its success (SN: 9/20, p. 233). In all of these missions, a chemically powered shuttle rocket (SN: 1/3, p. 22) would first place the NERVA and its companion vehicle in low earth orbit. Then the rocket would blast off for its mission. When done it would return to low earth orbit, waiting for another payload tc be launched and docked to it. The nuclear engine, like other future space systems, is being designed with reusability as a guiding principle. Simply stated, the aim of reusability is to make a nuclear rocket engine that can be used a number of times. The idea is motivated by economics. Just as it would be uneconomical to build a car that could only make one round tripwhich is in essence what the present Apollo rockets do-NASA and the AEC want a nuclear engine that can be flown on several round trips. In no case in the foreseeable future is it envisioned for earth liftoff. The main reason is that chemically propelled rockets are adequate for that job, and present nuclear rocket capability would not provide significant advantages. Another reason is radioactivity, which could escape in small amounts to the launch area or in large amounts if an accident occurred. A nuclear rocket can carry heavier payloads on less fuel than a chemical rocket because of the nuclear engine's greater propulsion efficiency, or specific impulse. This is the tiube period in which one pound of thrust is produced by one pound of fuel. For the best chemical rocket using liquid hydrogen and oxygen, the specific impulse is about 450 seconds; NERVA'S specific impulse is nearly double that, 825 seconds, which means that one pound of propellant producing the same thrust as one pound of chemical fuel will last almost twice as long. The saving in fuel can go into carrying extra payload. As it now stands, NERVA iS comKlein: It's still a breadboard engine.

Orbital Stations and Studies of the Earth from Space

The uses and benefits of long lived, or long standing manned orbiting space stations are reviewed along with the history and progress of their development. Finally the special problems associated with the design of the control system structures and equipment are discussed, some of the promising mathematical solutions are presented, and it is concluded that after appropriate experimental verifications are made, the long lived space stations will be developed in the near future.

Getting a Charge Out Of a Solar Power System

A solar power system capable of converting sunlight into all the electricity needed to operate a large manned orbiting space station for a year or more can be built with existing technology and equipment, RCA Astro‐Electronics scientists announced at the Inter‐Society Energy Conversion Engineering Conference in Miami, Fla. Functioning as part of a space station in a 200‐nautical‐mile orbit, the system would generate 5 to 8 kW of usable power.

Gemini 8 Launched

> THE MOST complicated maneuvers in man's first flight to the moon will be the various couplings, uncouplings, dockings and rendezvous performed at the two ends of the journey. Now, after several malfunctions, an aborted launch attempt and some compromises, practice has started. At 11:41 a.m. on March 16. Astronauts Neil Armstrong and David Scott shot spaceward, pursuing their target. an Agena spacecraft launched an hour and 41 minutes earlier. Their attempt to nose Gemini 8 into a mechanical attached to the Agena was successful-another milestone in space flight. However, less than half an hour after docking, while Gemini 8 was still coupled to the Agena, Armstrong reported engine trouble. The two vehicles were rolling and yawing out of control. The astronauts backed their spacecraft away from the Agena target and then stabilized by switching from their maneuvering power system to the one used for reentry into the atmosphere. But it was considered risky to continue the operation on fuel intended for the return trip. Because of this, and because no one was entirely sure what caused the trouble, Gemini Control in Houston cancelled the remainder of the flight. Late in the evening of their launch day the two astronauts landed safely in a recovery area in the Pacific. Had the three-day mission been completed other experiments would have been carried out. Co-pilot Scott was equipped with a long, cable-and-air-hose-filled cord, so that he could leave his cramped position in the spacecraft and spend one-and-a-half orbits of the earth walking in space. Spacewalking. although vitally important to orbiting space stations and any other missions that require outside repairs, will not be a part of the lunar flight. The shirtsleeves environment in the Apollo will prevent any of the threeman crew from stepping out into space, although two of them will step out on reaching the surface of the moon. However, Gemini flights between now and then may do away with the need for umbilical cords. Docking was the most important. While adjusting their orbit to match that of the Agena, the astronauts traveled some 107,000 miles, while keeping track of the roundness of their orbit, and the relative angle between the Gemini and the target, among other things. Rendezvous and docking are not the same thing. The former consists of getting from. say, 100 miles away to within about 100 feet at the proper angle. speed and orbit. Computers do all the heavy mathematics, and the pilot follows their instructions. Docking on the other hand, is done largely by eye. On the nose of the Gemini is a small sighting post, just like a sight on a rifle. At the rear of the Agena. inside the collar, is another sight, in the form of a notch. Neil Armstrong's job as pilot was to center the post in the notch. When two spacecraft are close enough for this. the operation becomes a matter of repeated slow nudges with the thrusters until the two vehicles touch. The collar then automatically locks them together. Similar maneuvers, with somewhat different equipment. will occur several times during the moon journey. At one point, the spacecraft will detach from its booster, turn around 180 degrees, and dock nose-on. . Science News, 89:195 March 26, 1966

Planar motion of a rotating cable-connected space station in orbit.

The planar motion of a rotating space station composed of a manned compartment and a counterweight linked by a long flexible cable is analyzed. It is assumed that initially the system is spinning in the orbital plane. The effects of cable elasticity and vibrational motion are included in the derivation of equations, which reveal that the orbital, rotational, and elastic degrees of freedom are coupled through the gravitational gradient terms. The re- sponses of the coupled nonlinear differential equations to the influence of gravitational gradi- ents are solved by the fourth-order Runge-Kutta numerical integration method. Viscous damping is included in the investigation and found to be effective to the gravitational excita- tion. From the results of the analysis, the feasibility of the configuration is evaluated, and the critical problem areas are discussed. Nomenclature a = sublength of cable d, = position vector from center of mass to a point on cable EA = extensional rigidity Gri, G'>, dGc — gravity forces on mi, m2, and elementary podrjo of cable members, cables, or chains are of considerable interest as structural elements for connecting the compartments or counterweights to form a space station. However, the exact dynamic behavior of a cable-linked configuration is difficult to predict. The deployment, spin-up, artificial gravity, docking capacity, control system, and wobble damping are all formidable problems of a cable-linked configuration. An- other critical question to be answered is whether the cable- connected system, oscillating under the influence of gravity gradient and other perturbing forces, is a stable configuration. Published information concerning dynamic problems of a cable-connected space station is limited. A majority of the authors confined their treatment of the libration of the orbit- ing vehicle to the assumption of small oscillation, and they neglected perturbations from the orbital elements.14 Past experience in the analysis of orbiting satellites indicated that, for a configuration like the cable-connected space sta- tion, the rotational and vibrational motion cannot be treated independently from orbital motion without violating the laws of conservation of energy and conservation of angular momentum.5 In this paper, the planar motion of a rotating space station composed of a manned compartment and a counterweight linked by a long flexible cable is analyzed. This space sta- tion is assumed to be in orbit around a spherical earth with an inverse-squar e-law gravitational field and to be spinning in its orbital plane. (The spin-up phase is not included in the analysis.) The stability and control characteristics may be significantly influenced by the distortions of the cable under transient loading conditions. The effects of cable elasticity and vibrational motion are included in the formu- lation. The time dependence of the elastic motion is based upon the deformation of the cable expressed in terms of its normal modes of free vibration. The equations of planar motion in the earth-fixed coordi- nates are derived from the total kinetic energy of the system, the strain energy of the cable, and the generalized force re- sulting from the work done by the gravitational gradient over the extended body. The resulting equations reveal that the orbital, rotational, and elastic degrees of freedom