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Facilities and organization at the Wallops station are reviewed and some current research work is described that pertains to noise abatement studies as well as some testing phases on V/STOL aircraft. Radiation biology results of various space flights are reviewed and some efforts for the Regulatory Biology Program, involving depressed metabolism aspects of space travel are detailed.
The principal features of this document are the analysis of a large dual-reflector antenna system by vector Kirchhoff theory, the evaluation of subreflector aperture-blocking, determination of the diffraction and blockage effects of a subreflector mounting structure, and an estimate of strut-blockage effects. Most of the computations are for a frequency of 15.3 GHz, and were carried out using the IBM 360/91 and 360/95 systems at Goddard Space Flight Center. The FORTRAN 4 computer program used to perform the computations is of a general and modular type so that various system parameters such as frequency, eccentricity, diameter, focal-length, etc. can be varied at will. The parameters of the 60-foot NRL Ku-band installation at Waldorf, Maryland, were entered into the program for purposes of this report. Similar calculations could be performed for the NELC installation at La Posta, California, the NASA Wallops Station facility in Virginia, and other antenna systems, by a simple change in IBM control cards. A comparison is made between secondary radiation patterns of the NRL antenna measured by DOD Satellite and those obtained by analytical/numerical methods at a frequency of 7.3 GHz.
NASA?s Space Communications and Navigation (SCaN) Program Office maintains a year-round educational program for undergraduate and graduate students. Within NASA?s Goddard Space Flight Center, the Exploration and Space Communications Projects Division implements the SCaN intern program with a focus on space operations, including operations of orbiting spacecraft, space communications, ground activities and networking. The intern program enables students to work with various NASA projects in solving real-world problems inside the Exploration and Space Communications division. Goddard interns have been assigned to the NASA?s Near Earth Network facilities in Greenbelt, Maryland, and Wallops, Virginia. They have also been assigned to NASA?s Space Network facilities in Greenbelt, Maryland, and Las Cruces, New Mexico.
Tensys have a long-established background in the shape generation and load analysis of architectural stressed membrane structures. Founded upon their inTENS finite element analysis suite, these activities have broadened to encompass 'lighter than air' structures such as aerostats, airships, hybrid air vehicles and stratospheric balloons. Tensys have acted as consultants to the NASA Super Pressure Balloon (SPB) Program since 2004. Previous papers have focussed upon the application of inTENS to the overall structural and stability analysis of pumpkin type balloons as used in the SPB Program. Particular emphasis has been placed upon the ability to study both stress and stability at all stages of a flight. As the program has developed, increasing modelling fidelity has been introduced as design refinement has moved emphasis from the overall shape to the performance of individual details. Examples include the introduction of a contact capability into inTENS to better represent the separate cap layer of film. Localised investigations have considered the consequence of local geometric anomalies introduced during fabrication and the effects of debonding of the PBO tendon within its sleeve. Analysis to date has used a material model for the polyethylene shell film developed by Dr Rand of Winzen Engineering, supported by a program of fine resolution material tests at the Balloon Research and Development Laboratory (BRDL) at the GSFC Wallops Island Facility. Based upon work first reported by Schapery, this model has been incorporated into so-called 'snapshot' analyses within inTENS. For a given elapsed time point and temperature distribution, non-linear material properties are iteratively updated for the current stress state in each individual element until changes in those material properties are insignificant. This process has to be iterative as the film stresses and material properties are interdependent. Attempts to derive a time-stepping incremental viscoelastic capability using the Schapery Rand model encountered problems when dealing with the varying temperatures associated with balloon deployment, pressurisation and diurnal behaviour. An alternative approach has been developed by Pellegrino et al at Caltech, again with support from the NASA Balloon Program Office. This is a large strain non-linear viscoelastic model that includes film out-of-plane mechanical and thermal effects. Working from a unified base, this model can be utilised for time-stepping analyses in both a modulus or compliance mode, or a combination of both. This new capability is intended to enhance the current NASA balloon design process. This paper presents the implementation of the Caltech model into a specialist finite element suite, inTENS and its application to whole flight simulations.
It has been long realized that radiosonde temperature measurements are subject to errors, not the least of which is the effect of long- and short-wave radiation. Methods of adjusting the daytime temperatures to a nighttime equivalent temperature were developed a number of years ago, and are used by some analysis centers. Other than providing consistent observations for analysis this procedure does not provide a true correction. The literature discusses the problem of radiosonde temperature errors but it is not apparent what effort, if any, has been taken to quantify these errors. In order to quantify this radiation error, radiosondes containing multiple thermistors with different coatings were flown at Goddard Space Flight Center/Wallops Flight Facility. The coatings employed had different spectral characteristics and, therefore, different absorption and emissivity properties. Discrimination of the recorded temperatures enabled day and night correction values to be determined for the US standard white-coated rod thermistor. The correction magnitudes are given and a comparison of US measured temperatures before and after correction are compared with temperatures measured with the Vaisala radiosonde. The US and Vaisala radiosonde data are from the recently completed WMO International Radiosonde Intercomparison held at Wallops. The corrections are in the proper direction, day and night, and reduce day-night temperature differences to less than 0,5°C between surface and 30 hPa. The present uncorrected temperatures used with the Viz radiosonde have day-night differences that exceed 1°C at levels below 90 hPa. Additional measurements are planned to confirm these preliminary results and determine the solar elevation angle effect on the corrections. The technique used to obtain the corrections may also be used to recover a true 'absolute' value and might be considered a valuable contribution to the meteorological community for use as a reference instrument.
Established by the National Advisory Committee for Aeronautics (NACA) to function under the supervision of the Pilotless Aircraft Research Division (PARD) of the Langley Research Center, the Wallops Island flight test range began operations in 1945. Before the end of the decade, researchers at Wallops Island had developed two techniques for studying transonic problems - the free-falling body technique and the wing-flow technique - accomplishments which won NACA the needed funds to develop a guided missile for the Army Armed Forces. PARD kept abreast of developments in solid rocket motor technology and added new rockets to its inventory as they became available, and by 1955 Wallops Island programs encompassed sounding-rocket and spaceflight research. By 1959, after the Wallops range had become a NASA facility, it had played essential roles in the development of such satellite programs as Echo and Project Mercury.
The Gondola for High-Altitude Planetary Science (GHAPS) project is a balloon-borne astronomical observatory designed operate in the UV, Visible, and near-mid IR spectral region. The GHAPS Optical Telescope Assembly (OTA) is designed around a one meter aperture narrow field-of-view telescope with near diffraction limited performance. GHAPS will utilize Wallops Arc-Second Pointing System (WASP) for pointing the OTA with an accuracy of 1 arc second or better. WASP relies heavily on a self-contained star tracker assembly to determine the OTA line of sight. Preliminary structural analysis indicated that potential misalignments could be present between the OTA line of sight and the star tracker FOV center during the expected flight conditions that could compromise GHAPS pointing accuracy. An analysis is presented that estimates the worst case long-term (or bias) pointing misalignments for the GHAPS opto-mechanical configuration, examines the need for additional hardware to correct pointing errors, and determines the best hardware and software implementation to do so. The analysis includes the development of a photometric model to predict the limiting magnitude of a GHAPS Facility Guide System (FGS) for a variety of image sensor technologies from visible to mid IR. FGS system performance is estimated using star magnitude and spectral data from actual star catalogs for more realistic predictions. Based on expected performance and other factors, such as size, weight, power, and cost, a final recommendation is made for the GHAPS configuration.
ti March 26, 1964, Centro Ricerche Aerospaziali (CRA) successfully launched a two-stage Nike sounding rocket from the Santa Rita launch platform off the Kenya coast, concluding Phase I. It carried basic elements of the San Marco science instrumentation and served further to flight qualify these canponents as well as provide a means of check-out of range instrumentation and equipment. The second phase culminated in the launch of the San Marco-I Spacecraft fran Wallops Island on a Scout vehicle on December 15, 1964. This launch derronstrated the readiness of the CRA launch crews for Phase III operations and qualified the basic spacecraft design. In addition it confirmed the usefulness and reliability of the drag balance device for accurate determinations of air density values and satellite attitude. phase III was completed with the launching of San Marco-11 frcm the San Marco platform off the coast of Kenya on April 26, 1967. ?he San Marco-II carried the same instrunentation as the San Marco-I, but the equatorial orbit permitted a more detailed study to be made of density variations versus altitude in the equatorial region. Ihe successful launch also served to qualify the San Marco Range as a reliable facility for future satellite launches. The successful culmination of the first San Marco endeavor paved the way for still closer collaboration in future space explorations.
On or about 24 April 1971, the San Marco-C spacecraft will be launched from the San Marco Range located off the coast of Kenya, Africa, by a Scout launch vehicle. The launch will be conducted by an Italian crew. The San Marco-C is the third cooperative satellite project between Italy and the United States. The first such cooperative project resulted in the San Marco-1 satellite which was launched into orbit from the Wallops Island Range with a Scout vehicle on 15 December 1964. The successful launch demonstrated the readiness of the Italian Centro Ricerche Aerospaziuli (CRA) launch crews to launch the Scout vehicle and qualified the basic spacecraft design. The second in the series of cooperative satellite launches was the San Marco-II which was successfully launched into orbit from the San Marco Range on 26 April 1967. This was the first Scout launch from the San Marco Range. The San Marco-II carried the same accelerometer as San Marco-1, but the orbit permitted the air drag to be studied in detail in the equatorial region. The successful launch also served to qualify the San Marco Range as a reliable facility for future satellite launches, and has since been used for the successful launch of SAS-A (Explorer 42). This cooperative project has been implemented jointly by the Italian Space Commission and NASA. The CRA provided the spacecraft, its subsystems, and an air drag balance; Goddard Space Flight Center (GSFC) provided an omegatron and a neutral mass spectrometer, technical consultation and support. In addition, NASA provided the Scout launch vehicle. The primary scientific objective of the San Marco-C is to obtain, by measurement, a description of the equatorial neutral-particle atmosphere in terms of its density, com- position, and temperature at altitudes of 200 km and above, and to obtain a description of variations that result from solar and geomagnetic activities. The secondary scientific objective is to investigate the interdependence of three neutral-density-measurement techniques from one spacecraft: direct particle detection, direct drag, and integrated drag.