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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 883 records · Page 49
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Safety in earth orbit study. Volume 3: Analysis of tumbling spacecraft, escape and rescue

Detailed and supporting analyses of the hazards of a disabled spacecraft in a tumbling mode and of crew escape, rescue, and survivability are presented for earth orbital operations of the space shuttle program. Tumbling conditions, arresting tumbling by external means, and escape from a tumbling vehicle are discussed. Details on design concepts for the modular space station, integral tank orbiter, drop tank orbiter, and a small space vehicle are included. Results of the crew safety study indicate that the shuttle orbiter should be the primary vehicle for dealing with emergencies and one vehicle should be available for rapid emergency rescue. An Apollo command module should be carried in the orbiter cargo bay in case an orbiter is not available. Approaches for a quicker escape or rescue capability are also recommended.

Source record↗
NASA NTRS1972

The effects of tracking station coordinate uncertainties on GEOS-2 orbital accuracy

Laser and minitrack observational data from GEOS-2 collected during the period April 23, 1971 to May 1971, have been used for the purpose of assessing the influence of tracking station location on the accuracy of orbit determination. These data were processed using a unified set of coordinates for the tracking station locations. Concurrently, these data were processed using nonunified station locations referred to a variety of geodetic datums. The resultant orbits based on the two different sets of station locations were compared and relative differences in the position of the satellite were determined. Differences between the two groups of orbits fitted over four-day data spans ranged from 250 meters to 500 meters for orbits derived from laser data only. For orbits observed from Minitrack data alone the relative differences in GEOS-2 spacecraft position ranged from 50 meters to 190 meters. Utilizing the laser data alone in each arc, definitive orbits were computed using the unified and nonunified station location coordinates. The differences in the satellite position in the overlap region when using the unified laser station coordinates ranged from 25 meters to 150 meters, whereas when using the nonunified laser station coordinates the differences in position ranges from 180 to 650 meters.

Glazer, J.↗
NASA NTRS1972

Orbital trim by velocity factoring with applications to the Viking mission.

An orbital trim technique has been developed to satisfy terminal rendezvous and intermediate timing constraints for planetary missions involving orbital operations. The technique utilizes a time-open two-impulse transfer from a specified initial orbit to a final orbit which satisfies all geometrical constraints. Each of the two impulses may then be factored, or split, into two or more vectorially equivalent impulses. The periods of the resulting intermediate orbits may be varied along with the number of revolutions in each orbit to satisfy the intermediate and final timing constraints. Factors in the range 0 to 1 result in rendezvous at the same cost as that of the two-impulse transfer. The technique is applied to the Viking mission to Mars although a similar procedure could be utilized for rendezvous operations about any planet.

Kibler, J. F.↗
NASA NTRS1972

The earth orbit shuttle as a space rescue vehicle.

According to present concepts starting with some future date all manned space missions beyond low-earth orbit are to originate in low-earth orbit and to return ultimately to low-earth orbit. The Earth-Orbit-Shuttle (EOS) is visualized as the only vehicle operating between earth and low-earth orbit. The ability of the EOS to provide rescue services in the case of emergency is evaluated. It is found that an employment of the EOS as rescue vehicle is basically feasible, although it has certain limitations. Complementary means of transportation are required for emergencies beyond low-earth orbit. Approaches to enhance the rescue mission utility of the EOS are discussed.

Hinton, M. G., Jr.↗
NASA NTRS1972

The determination of the satellite orbit of Mariner 9.

This paper presents a comprehensive analysis of the Mars orbital phase of the Mariner 9 trajectory as determined from Earth based radio data. Both the method and accuracy of the orbit determination process are reviewed. Analysis is presented to show the effects of Mars gravity model and node in the plane of the sky errors on the accuracy of orbit determination. In addition the long term evolution of the orbit from insertion to date is presented, and is decomposed into effects from the Mars gravity field, n-body perturbations, and solar radiation pressure. Since the orbit period is nearly commensurable with the Mars rotational period, the orbit experiences significant resonance perturbations. The primary perturbation is in-track with a maximum amplitude of 1000 km and a wavelength of 39 revolutions.

Born, G. H.↗
NASA NTRS1973

Study of ballistic mode Mercury Orbiter missions. Volume 1: Summary report

A summary is given of the scope, approach, and major results of the study of ballistic mode Mercury orbit missions (the Mariner Venus-Mercury spacecraft). The performance potential of ballistic flight mode is presented along with a study of alternate flight techniques. Orbit selection considerations are discussed in terms of the thermal environment of Mercury. Orbiter science experiments are summarized. Technology assessments were conducted for major subsystems appropriate to spin-stabilized and three-axis-stabilized spacecraft designs. Conclusions from this study are: ballistic mode Mercury orbiter missions offer adequate performance for effective follow-up of the MVM'73 science findings; the existing and programmed technology base is adequate for implementation of Mercury orbit spacecraft design; and when pending MVM flyby has been accomplished and the results analyzed, the data base will be adequate to support detailed orbiter spacecraft design efforts.

Hollenbeck, G. R.↗
NASA NTRS1973

Effects of resonant tesseral gravity coefficients on Viking-type orbits.

A special perturbation technique has been developed for the long-period and secular motion of a Viking-type orbiter. The technique uses a method of singly averaging the perturbations over the mean anomaly to determine changes in orbital elements due to atmospheric drag, solar radiation pressure, solar gravity, and the asymmetrical Mars gravitational field. The technique has been specialized to treat resonant tesseral gravity effects resulting from the commensurability of the satellite orbit period with the rotational period of the primary. Results are presented which indicate that orbiter lifetimes can be significantly reduced by resonant tesserals for orbits near the critical inclination. Conversely, it is shown that lifetimes can be extended via capture in resonant orbits which are stable against small drag forces.

Compton, H. R.↗
NASA NTRS1973

Satellite orbit determination

A historic account of the activities of the Satellite OD Group during the MM'71 mission is given along with an assessment of the accuracy of the determined orbit of the Mariner 9 spacecraft. Preflight study results are reviewed, and the major error sources described. Tracking and data fitting strategy actually used in the real time operations is itemized, and Deep Space Network data available for orbit fitting during the mission and the auxiliary information used by the navigation team are described. A detailed orbit fitting history of the first four revolutions of the satellite orbit of Mariner 9 is presented, with emphasis on the convergence problems and the delivered solution for the first orbit trim maneuver. Also included are a solution accuracy summary, the history of the spacecraft orbit osculating elements, the results of verifying the radio solutions with TV imaging data, and a summary of the normal points generated for the relativity experiment.

Jordan, J. F.↗
NASA NTRS1974

A feasibility study of unmanned rendezvous and docking in Mars orbit. Volume 1: Summary

The technical feasibility of achieving automatic rendezvous and docking in Mars orbit as a part of a surface sample return mission was investigated based on using as much existing Viking '75 Orbiter and Lander hardware as possible. Both 1981 and 1983/84 mission opportunities were considered. The principle result of the study was the definition of a three stage 289 kg Mars Ascent Vehicle (MAV) capable of accepting a 1 kg sample, injecting itself into a 2200 km circular orbit, and rendezvousing with an orbiting spacecraft carrying an earth return vehicle. Conclusions are that with state of the art systems plus limited application of new developments in areas where feasibility has already been demonstrated, e.g., solid rocket motor sterilization, it is possible to land a small ascent vehicle capable of automatically ascending and rendezvousing with a modified Viking '75 orbiter spacecraft. The mission can be flown in 1981 or 1983/84, but a dual launch or a larger launch vehicle than the Viking Titan 3 Centaur, or the use of space storable propellants for Mars orbit injection, would be required in the 1983/84 opportunity.

Source record↗
NASA NTRS1975

Wind tunnel pressure signatures for a 0.0041-scale model of the space shuttle orbiter

Pressure signatures for a 0.0041-scale model of a space shuttle orbiter were measured in a wind tunnel at Mach numbers from 1.30 to 3.02. The model was tested at 10 deg and 25 deg angle of attack and roll angles were varied from 0 deg to 180 deg in 30 deg increments. Comparisons of sonic boom levels were made for a delta wing configuration and for the space shuttle orbiter which were assumed to have identical lengths and entry trajectories. The sonic boom levels for the orbiter were slightly higher than those for the delta wing orbiter. An example is presented showing that the existing data base for the delta wing orbiter can be used to predict the ground level sonic booms for the orbiter.

Mendoza, J. P.↗
NASA NTRS1975

The resonant orbit of the Lost City meteorite

An integration of the long-period perturbations of Jupiter and Saturn on the orbit of the Lost City meteorite shows that the average nodal rate of the meteorite was nearly the same as the nodal rates of Jupiter and Saturn. This near equality of rates led to a large resonant variation in the inclination of the meteorite's orbit with a period on the order of 1 million years. The resonance makes the orbital evolution too sensitive to the deficiencies of the perturbation calculations and to the values of the elements at impact to allow definitive calculations. It is shown that an orbit similar to the meteorite's orbit can spend approximately 88% of its time with an eccentricity too small to allow for intersections with the earth's orbit. The ordinary cosmic ray exposure age of the Lost City meteorite does not suggest that its collisional lifetime was unusual, but the role of resonances in determining the lifetime of typical meteorites is unknown.

Williams, J. G.↗
NASA NTRS1976

The 1981 Jupiter Orbiter Probe mission

Plans for the 1981 Jupiter Orbiter Probe (JOP) mission are presented in some detail. The need for a Jupiter entry probe, remote sensing of the planet, and an orbiter, in addition to flybys, is made clear. Launch hardware, using the Space Shuttle flight system and Interim Upper Stage, is described, along with scientific tasks laid out for the entry probe and the orbiter. Combined analysis of the Jovian magnetosphere and other orbiter missions calls for a two-part orbiter with one part spun and the other de-spun. Related design problems and solutions are described and diagrammed. Jovian moon flybys and orbiter path adjustments by subsequent earth-launched flybys are discussed. The importance of Jupiter data for solar system evolution and possible analysis of early stages of stellar evolution or of a binary system are also treated.

Moore, J. W.↗
NASA NTRS1978

Orbit Selection for Earth Observation Missions

The orbit selection process is simplified for most earth-oriented satellite missions by a restriction to circular orbits, which reduces the primary orbit characteristics to be determined to only two: altitude and inclination. A number of important mission performance characteristics depend on these choices, however, so a major part of the orbit selection task is concerned with developing the correlating relationships in clear and convenient forms to provide a basis for rational orbit selection procedures. The present approach to that task is organized around two major areas of mission performance, orbit plane precession and coverage pattern development, whose dependence on altitude and inclination is delineated graphically in design chart form. These charts provide a visual grasp of the relationships between the quantities cited above, as well as other important mission performance parameters including viewing time of day (solar), sensor swath width (and fields of view), swath sequencing, and pattern repeat condition and repeat periods.

King, J. C.↗
NASA NTRS1977

The Missions of the Viking Orbiters

A description of the orbiter science instruments is presented and the chronology of the two Viking missions is reviewed. The design of the Viking orbiter spacecraft is discussed, taking into account the propulsion subsystem, the attitude control subsystem, the planetary scan platform, aspects of command processing, problems of instrument operation and data processing, and data quantity limitations. Details concerning the Viking orbits and the visibility of the planet are also considered and the future of the Viking orbiter missions is evaluated. If the orbiters continue to perform well, all the orbiter science investigations will continue to acquire data for another year and perhaps somewhat longer.

Snyder, C. W.↗
NASA NTRS1978

The Space Shuttle Orbiter and aerodynamic testing

The concept of utilizing the Space Shuttle Orbiter as an aerodynamic flight research vehicle is discussed. The orbiter's planned flight frequency and its complex flight control system provide an unprecedented flight research potential. This paper defines the orbiter's flight environment and applicable baseline systems, their capabilities and limitations, as well as those instrument systems required to augment the baseline capability. These required systems, which are being developed under NASA's Orbiter Experiments Program (OEX) are the Aerodynamic Coefficient Identification Package (ACIP), Shuttle Entry Air Data System (SEADS), and the Shuttle Upper Atmosphere Mass Spectrometer (SUMS). Finally, the need for and capability of launching payloads from the orbiter to extend the research potential beyond the orbiter configuration and/or environment is defined.

Siemers, P. M., III↗
NASA NTRS1978

Extended duration Orbiter life support definition

Extending the baseline seven-day Orbiter mission to 30 days or longer and operating with a solar power module as the primary source for electrical power requires changes to the existing environmental control and life support (ECLS) system. The existing ECLS system imposes penalties on longer missions which limit the Orbiter capabilities and changes are required to enhance overall mission objectives. Some of these penalties are: large quantities of expendables, the need to dump or store large quantities of waste material, the need to schedule fuel cell operation, and a high landing weight penalty. This paper presents the study ground rules and examines the limitations of the present ECLS system against Extended Duration Orbiter mission requirements. Alternate methods of accomplishing ECLS functions for the Extended Duration Orbiter are discussed. The overall impact of integrating these options into the Orbiter are evaluated and significant Orbiter weight and volume savings with the recommended approaches are described.

Kleiner, G. N.↗
NASA NTRS1979

How tidal heating in Io drives the Galilean orbital resonance locks

The mechanisms by which orbital resonance locks are maintained among Io, Europa and Ganymede are analyzed, and the effects of the dissipative tides in Jupiter and Io on their establishment and evolution are considered. According to the proposed model, initially all three satellites are in orbits far from the 2:1 commensurabilities or the three body lock. The tide raised on Io damps down the free eccentricity; only modest tidal heating occurs. Subsequently the dissipative tide raised on Jupiter by Io causes Io's orbit to spiral outwards; Io approaches the 2:1 commensurability with Europa. Io's forced eccentricity increases rapidly to a critical value, and thereafter the resonant interaction causes Europa's orbit to expand at half that of Io's orbit. A fluid core is probably formed as the result of tidal heating. Finally Europa approaches the 2:1 commensurability, angular momentum is transferred from Europa's orbit to Ganymede's, and a steady state is attained. On the basis of the observed three-body resonance amplitude (0.066 deg), it is concluded that three-body resonance may have formed less than 500 million years ago; a measurement of the rate of tidal heating in Io may determine the Q value of both Io and Jupiter. Upper and lower limits for the Jovian Q value of 2 million and 20,000 are suggested.

Yoder, C. F.↗
NASA NTRS1980

A study of the lifetimes of geosynchronous transfer orbits

The study concerns the orbit lifetimes of spent upper stages that are used to boost NASA Space Transportation System payloads into geosynchronous transfer orbits. A semi-analytical method of trajectory computation was developed and applied to these particular orbits. It was found that gravitational perturbations of the sun, moon and oblate earth cause large changes in the perigee altitude. The following parameters have a strong influence on orbit lifetimes: Time of year of launch; Inertial orientation of orbital plane; Inclination of orbital plane.

Graf, O. F., Jr.↗