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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 685 records · Page 38
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NASA NTRS1975

Apollo experience report: Spacecraft relative motion and recontact analyses

Potential collision or accidental recontact problems between the spacecraft and other space vehicles (or components) existed during most of the Apollo missions. These problems were identified before each Apollo flight, and appropriate solutions for eliminating or minimizing the chance of collision were determined through relative motion analyses. A summary of the identification, solution, and analysis process for some of the more significant of these separation problems is presented. In addition, the scope of responsibility, the development of the study effort, and the computer simulation development, which supported the analysis process, are described.

Mcadams, R. E.↗
NASA NTRS1974

A cosmic gamma ray burst measured by Apollo 16

A cosmic gamma ray burst at about 1058:21 UT on April 27, 1972, was detected with an omnidirectional scintillation counter on Apollo 16. The event whose energy was approximately 0.0002 erg/sq cm, was pulse height analyzed in 512 channels over the 0.067 less than or equal to E less than or equal to 5 MeV range, and shows a complex, multipeak structure on a 300 msec time scale. The burst was also measured by a collimated X-ray detector on Apollo 16, giving spectral data in the 2 to 8 keV range which, together with a simultaneous observation by Vela 6A, allows a directional determination.

Matteson, J. L.↗
NASA NTRS1974

Measurements of the 0.1-27 MeV cosmic gamma ray spectrum by Apollos 15 and 16

The spectrum of diffuse cosmic gamma rays over the 0.127 MeV range was measured by a 7 x 7 cm omnidirectional NaI counter on Apollo 15 and 16. Location of the spectrometer on a 7.6 m extensible boom, use of precision pulse-height analysis, and operation in several modes permitted data to be obtained from which spacecraft and other background contributions could be separated. Recent measurements verified the Apollo spectrum.

Peterson, L. E.↗
NASA NTRS1975

Apollo experience report: Guidance and control systems: Automated control system for unmanned mission AS-201

The Apollo command module heat shield and Apollo command and service module/Saturn launch vehicle structural integrity were evaluated in an unmanned test flight. An automated control system was developed to provide the mission event sequencing, the real-time ground control interface, and the backup attitude reference system for the unmanned flight. The required mission events, the design logic, the redundancy concept, and the ground-support-equipment concept are described and some development problem areas are discussed. The mission event time line and the real-time ground command list are included to provide an outline of the control system capabilities and requirements. The mission was accomplished with the automated control system, which functioned without flight anomalies.

Holloway, G. F.↗
NASA NTRS1975

Image processing and data reduction of Apollo low light level photographs

The removal of the lens induced vignetting from a selected sample of the Apollo low light level photographs is discussed. The methods used were developed earlier. A study of the effect of noise on vignetting removal and the comparability of the Apollo 35mm Nikon lens vignetting was also undertaken. The vignetting removal was successful to about 10% photometry, and noise has a severe effect on the useful photometric output data. Separate vignetting functions must be used for different flights since the vignetting function varies from camera to camera in size and shape.

Alvord, G. C.↗
NASA NTRS1975

Doppler measurements of the ionosphere on the occasion of the Apollo-Soyuz test project. Part 1: Computer simulation of ionospheric-induced Doppler shifts

A computer simulation of the ionospheric experiment of the Apollo-Soyuz Test Project (ASTP) was performed. ASTP is the first example of USA/USSR cooperation in space and is scheduled for summer 1975. The experiment consists of performing dual-frequency Doppler measurements (at 162 and 324 MHz) between the Apollo Command Service Module (CSM) and the ASTP Docking Module (DM), both orbiting at 221-km height and at a relative distance of 300 km. The computer simulation showed that, with the Doppler measurement resolution of approximately 3 mHz provided by the instrumentation (in 10-sec integration time), ionospheric-induced Doppler shifts will be measurable accurately at all times, with some rare exceptions occurring when the radio path crosses regions of minimum ionospheric density. The computer simulation evaluated the ability of the experiment to measure changes of columnar electron content between CSM and DM (from which horizontal gradients of electron density at 221-km height can be obtained) and to measure variations in DM-to-ground columnar content (from which an averaged columnar content and the electron density at the DM can be deduced, under some simplifying assumptions).

Grossi, M. D.↗
NASA NTRS1975

Doppler measurements of the ionosphere on the occasion of the Apollo-Soyuz test project. Part 2: Inversion of differential and rotating Doppler shifts

The preparation of the analytical approach and of the related software used in the inversion of the differential and rotating Doppler data obtained from the ionospheric experiment of the Apollo-Soyuz Test Project (ASTP) is discussed. These data were collected in space-to-space paths (between the ASTP Docking Module (DM) and the Apollo Command Service Module and in space-to-ground paths (between the DM and ground). The Doppler links operated at 162 and 324 MHz and have an accuracy better than 3 MHz over 10-sec integration time. The inversion approach was tested with dummy data obtained with a computer simulation. It was found that a measurement accuracy of 1 to 10% in the value of the horizontal electron density gradient at 221-km altitude can be achieved, in space-to-space paths. For space-to-ground paths near the orbital plane, possible effects of the horizontal gradients on the received differential Doppler shifts were identified. It was possible to reduce the gradient-associated errors in the inversion that leads to the columnar electron content by approximately one-half. Accuracies of 5 to 10% in columnar electron content are achievable, with this gradient-compensation technique.

Gay, R. H.↗
NASA NTRS1974

Lunar gravity - Apollo 16

Reduction of Doppler radio tracking of the orbiting spacecraft has shown consistency with Apollo 14 data results and has revealed new gravity anomalies. Large craters are negative anomalies while wrinkle ridge regions are positive. The Central highlands are mostly a positive anomaly except for the Apollo 16 landing site, which is in a negative area. A gravity high northwest of Theophilus is not easily explained.

Sjogren, W. L.↗
NASA NTRS1974

Lunar gravity - Apollo 17

Gravity results are displayed as a band of contours about 60 km wide spanning 140 deg of frontside longitude. The contours traverse Grimaldi, Mare Procellarum, Copernicus, Apennines, Mare Serenitatis, Littrow, and Mare Crisium. Redundant gravity areas previously mapped by Apollos 14, 15, 16, and the Apollo subsatellites are tabulated and show excellent consistency. Modeling of Grimaldi reveals a loading greater than the known mascons and thus makes Grimaldi the smallest known mascon feature. Copernicus' gravity profile is best modeled with a mass defect for the basin and a mass excess for the rim. Mare Serenitatis has an irregular mass distribution with central gravity highs shifted approximately 3 deg in latitude.

Sjogren, W. L.↗
NASA NTRS1974

Observation of a cosmic gamma-ray burst on Apollo 16. II - X-ray time profile and source location

A burst of X-rays was detected during the trans-earth coast phase of Apollo 16 on Apr. 27, 1972 at 10:68 UT, simultaneously with the observation of a transient event by a gamma-ray spectrometer aboard the same spacecraft. The two instruments provide a broad energy range of more than three orders of magnitude for describing the spectral distribution of this event. The conclusion that the incident flux was X-rays and not charged particles is based on the fact that the particle flux detectors in the Apollo gamma ray spectrometer and on the Vela 6A, which also observed the event, did not respond. The time variation of the total count rate in the X-ray range before and after corrections for detector geometry and the analysis for source direction is presented.

Trombka, J. I.↗
NASA NTRS1974

Igneous rocks from Apollo 16 rake samples

Results are reported for a study of seven holocrystalline feldspathic rocks (including a spinel troctolite and six melt rocks) and one mare basalt clast from the Apollo-16 rake samples. The composition and grain structure of each rock is described in detail. Only the spinel troctolite is considered a good candidate for a primary igneous cumulate formed during the original differentiation of the lunar crust. It is shown that the melt rocks probably resulted from shock melting followed by rapid crystallization of heterogeneous highland material and that compositional variations are probably due to mixing of various amounts of heterogeneous cumulates and KREEP components. It is suggested that the mare basalt clast may have been derived from Mare Fecunditatis, although the nearest mare to the Apollo-16 site is Nectaris.

Dowty, E.↗
NASA NTRS1974

Metal silicate relationships in Apollo 17 soils

A petrographic, metallographic, and electron probe study of particles from two Apollo 17 soils is reported. A mixing model for the formation of the Apollo 17 soils is proposed. It is found that equilibration temperatures for two-phase metal aggregates range from 375 to 475 C for metal-phosphide particles and from 480 to 630 C for alpha-gamma particles, and that the anorthositic soil particles contain metal of meteoritic Ni-Co content. The Camelot Crater and the Sculptured Hills soil compositions are discussed.

Goldstein, J. I.↗
NASA NTRS1974

Breccia 66055 and related clastic materials from the Descartes region, Apollo 16

Trace and major element contents obtained by instrumental neutron activation are reported for a number of Apollo 16 soil samples and miscellaneous breccia fragments. In addition, data obtained by instrumental neutron activation and electron microprobe techniques along with petrographic descriptions are presented for selected subsamples of breccia 66055. The compositions of our soil samples can be modeled by mixtures of various amounts of anorthosite, anorthositic gabbro and low-K Fra Mauro basalt components. These mixtures are typical of those found in a number of petrographic surveys of the fines. Breccia 66055 is a complex regolith breccia which consists of at least four distinct types of microbreccias. No systematic relation with respect to stratigraphic age among the various microbreccia types was observed. Compositionally and texturally, the clasts which compose breccia 66055 are similar to a number of previously reported rock types from the Apollo 16 area. The entire breccia appears to have undergone a complex history of thermal metamorphism. We conclude from the study of these samples that the Cayley Formation is probably homogeneous in its gross compositional and petrographic aspects.

Fruchter, J. S.↗
NASA NTRS1974

U-Th-Pb systematics of some Apollo 17 lunar samples and implications for a lunar basin excavation chronology

U, Th, and Pb concentrations and lead isotopic compositions of selected Apollo 17 soil and rock samples are presented. Concordia treatments of U-Pb whole samples of Apollo 17 mare basalts and highland rocks probably reflect several early thermal events about 4.5 b.y. old more consistently than do U-Pb ages of samples collected at other lunar sites. We propose that all lunar U-Th-Pb data reflect a multistate U-Pb evolution history most easily understood as being related to a complex planetesimal bombardment history of the moon which apparently dominated lunar events from about 4.5 to about 3.9 b.y. ago. Semi-distinct events at about 4.0, about 4.2, and 4.4-4.5 b.y. are evident on whole-rock frequency versus Pb-207/Pb-206 age histograms. Each of these events may reflect multiple cratering episodes. For mare basalts, complete resetting of the source rock U-Pb systems owing to Pb loss relative to U was apparently often approached after a major planetesimal impact.

Nunes, P. D.↗
NASA NTRS1974

Volatile-element systematics and green glass in Apollo 15 lunar soils

A number of volatiles in Apollo 15 soils correlate with each other and with decreasing distance from the Apennine Front. These correlations can be understood in terms of a deposition of green glass and cogenetic volatiles on the flanks of the Front followed by addition of secondary magmatic volatiles including excess Ar-40. Mixing of these materials with mare-type regolith resulted in the observed volatile-element patterns. The absence of an increase in siderophilic element content with decreasing distance from the Front probably resulted from the failure of the steeply sloping front to develop a highlands-type mature regolith. Breccia 15015 has a siderophilic element signature typical of a mature Apollo 15 soil, which tends to rule out its transport to the site as part of an Autolycus or Aristillus ray.

Chou, C.-L.↗
NASA NTRS1974

Meteoritic and volatile elements in Apollo 16 rocks and in separated phases from 14306

Recent evidence from two sources provides a basis for a reexamination of the relationship between the stratigraphy at the Apollo 16 site and the trace element distribution. Information concerning the surface exposure ages makes it possible to relate many samples to specific local impact events. At least five ancient meteoritic components have been tentatively assigned to individual basin-forming impacts on the basis of trace element analyses of Apollo 17 rocks. Attention is given to a petrographic examination of separates from two soils from Station 11 (North Ray Crater).

Ganapathy, R.↗
NASA NTRS1974

Labile and nonlabile element relationships among Apollo 17 samples

Volatile and nonvolatile trace element contents in a suite of Apollo 17 soils and rocks are studied. It is found that the halogens exhibit a remarkable degree of coherence because of their apparent diverse geochemistry, that the F-Cl-P2O5 coherence previously noted persists among Apollo 17 samples, that both U and Ru-Os support lateral mixing of regolith on a local scale, and that the meteoritic Ru/Os ratios found in a few samples are attributed to primitive lunar material that has not been extensively recycled.

Jovanovic, S.↗