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An analysis of X ray bursts form globular clusters gathered by the Astronomical Netherlands Satellite is presented. Publications were prepared on the cosmic ray induced environment, and maps of these radiations as functions of latitude and longitude were generated.
The Spacelab-2 Small Helium-Cooled Infrared Telescope will be used to map extended astronomical sources of low surface brightness emission, to measure the Shuttle induced environment and to develop techniques for managing large volumes of superfluid helium in space. The instrument is an f/4 15.2-cm Herschelian telescope with ten photoconductor detectors in the focal plane. This paper describes the hardware and software aspects of the instrument with emphasis on mission operations. In particular, a description is given of the observing plan formulated to meet the scientific and engineering objectives, the scan drive system, the precautions in design and operation necessary to prevent the sun, moon, and earth from adversely affecting the observations, the implications of thruster firings, and the on-board experiment computer application software to control the scanning of the telescope and support on-board displays.
A Passive Optical Sample Assembly (POSA) unit was mounted and flown in the cargo bay of the space shuttle Columbia during the first Orbital Flight Test (OFT-1). A similar unit was mounted in a different location in the cargo bay during the postflight operations. The samples in both POSA arrays were subjected to a series of optical and analytical measurements prior to delivery for installation in the cargo bay and after retrieval of the flight hardware. The final results of a comparison of the two series of measurements are presented. These STS-1 results are based on data obtained from only a portion of one of the ten Induced Environment Contamination Monitor instruments to be flown on several shuttle flights beginning with STS-2. These limited results do not indicate shuttle contamination levels in excess of those anticipated.
Emphasis was placed on data from payloads flown on the subject flights including results from the Induced Environment Contamination monitor (IECM). Brief summaries of the vibroacoustics, loads, electromagnetic and thermal aspects of the environment, as derived from Shuttle system measurements, were presented primarily to indicate where the environment was different than observed and, therefore, where specification changes may be forthcoming. In addition, brief summaries of two somewhat unexpected effects, the vehicle glow and interaction between the low Earth environment and Shuttle payload by materials were presented as an aid in interpreting other environmental data. Papers for each payload/experiment involved in Shuttle flights were presented essentially in flight related chronological order. A significant portion of time was allocated for presentation of IECM data since this payload was flown on STS-2, STS-3, and STS-4 and, therefore, represents the largest data base relative to the contamination environment. Summaries of papers are presented.
The neutral gas mass spectrometer on the Induced Environment Contamination Monitor is described. The results of the measurements are presented.
Results of contamination measurements performed on the initial four flights of the Space Shuttle Orbiter are summarized and compared with requirements contained in the Space Shuttle Flight and Ground System Specifications and those formulated by the Contamination Requirements Definition Group. In general, the results of measurements carried out with the induced environment contamination monitor indicate that molecular fluxes, deposition rates, and average counts of particulates are within the requirements and close to predicted values. Among the exceptions, were such special circumstances as water dumps, payload bay door closures, and RCS engine, APU, and flash evaporator operations which led to molecular and particulate contamination levels exceeding the limits. In cases where these circumstances would interfere with sensitive payload operations, careful mission planning to preclude a contamination source by operational limitation should be done to avoid losses.
On the basis of early estimates of the Shuttle induced environment, Scialdone (1979) concluded that in the vicinity of the cargo, the cargo would have the largest influence on the environment. As a contamination control device, realtime monitors can indicate safe operational periods for sensitive attached payloads. It was, therefore, decided to develop the OSS-1/Contamination Monitor Package (CMP) experiment which was seen as a forerunner of an operational monitor. A description of the CMP is provided, taking into account four actively temperature controlled quartz crystal microbalances (TQCM). The TQCM temperatures could be varied from -60 C to +80 C. The sensor consisted of a matched pair of quartz crystals. The crystals were designated as a sensor and reference crystal. Results obtained during the STS-3 mission are discussed. These results show the feasibility and advantages of a small real-time contamination monitor.
The quadrupole Mass Spectrometer of the Induced Environment Contamination Monitor (IECM) operates in the range from 2 to 150 amu. It is pointed out that the Mass Spectrometer on STS-2 performed very well. It was found that the column density of H2O effluent from the Shuttle reached a maximum of 1 x 10 to the 13th per sq cm at 7 hr, 30 min and decreased by a factor of 7.5 during the subsequent 40 hrs. The count rate response of H2O could be correlated with mission-related events, taking into account the dumping of supply water, the operation of the Flash Evaporator System, and the firing of a primary reaction control system engine.
Ensuring the compatibility of the space shuttle system with payloads and payload measurements is discussed. An extensive set of quantitative requirements and goals was developed and implemented by the space shuttle program management. The performance of the Shuttle system as measured by these requirements and goals was assessed partly through the use of the induced environment contamination monitor on Shuttle flights 2, 3, and 4. Contamination levels are low and generally within the requirements and goals established. Additional data from near-term payloads and already planned contamination measurements will complete the environment definition and allow for the development of contamination avoidance procedures as necessary for any payload.
Transient vibration test criteria, developed for spacecraft hardware, provide a test rationale to verify the capability of the hardware to withstand the low and mid frequency transient vibration environments induced by launch vehicle events. A test method, consisting of a series of discrete frequency, limited cycle, modulated sine wave pulses, was developed to avoid the slow swept sine drawbacks, yet provide a repeatable test that would excite all frequencies. The shape of the waveform is that of the classic response of the mass of a one degree of freedom system when it is base-excited by an exponentially decayed sine wave transient. Criteria were developed to define pulse amplitudes, shapes, and center frequencies from spacecraft loads analyses. Test tolerance criteria were also developed and specified. The transient vibration test criteria were implemented on spacecraft flight hardware and provided a more realistic test simulation (i.e., less conservative) for qualification of spacecraft hardware without risk of undertest.
The Temperature-Controlled Quartz Crystal Microbalance (TQCM) system was flown on the Spacelab I Mission as part of the Induced Environment Contamination Monitor to monitor surface contamination (SC) in the payload bay. SC on the five sensors of the TQCM was analyzed by means of IR spectroscopy, scanning electron spectroscopy, and energy dispersive X-ray fluorescence. The amount of SC ranged from 1.4 micrograms/sq cm for the -Z sensor to 39.9 micrograms/sq cm for the +X sensor. The IR analysis showed strong CH2, CH3, and carbonyl absorption bands, indicative of ester and polyester compounds found in adhesives, plasticizers, and tape. The particulates (mostly ranging from 1 micron to 20 microns in size) were mainly composed of Mg, Al, Al2O3, and Si, and probably originated in the solid rocket firings.
On the night of Mar. 9, 1983 (UT) at Punta Lobos Launch Site, Peru (12.5 deg S, 76.8 deg W, magnetic dip -0.7 deg), a sequence of sounding rockets was flown to study the electrical structure of the equatorial middle atmosphere and to evaluate perturbations on this environment induced by the X-ray star Sco X-1. The rocket series was anchored by two Nike Orion payloads (31.032 and 31.033) which were launched at 0327 and 0857 UT, near Sco X-1 star-rise and after it had attained an elevation angle of 70 deg E. An enhanced flux of X-rays was observed on the second Nike Orion flight (31.033). This increase is directly attributed to Sco X-1, both from the spectral properties of the measured X-ray distribution and by spatial information acquired from a spinning X-ray detector during the upleg portion of the 31.033 flight. Simultaneously, a growth in ion conductivity and density was seen to occur in the lower mesosphere between 60 and 80 km on the second flight, specifically in the region of maximum energy deposition by the Sco X-1 X-rays. The results imply the presence of a significant number of ionized heavy constituents within the lower mesosphere, with masses possibly in the submacroscopoic range.
The external induced environment generated by space station activity, or more specifically by gases, particles, and light background is discussed. These contaminant species must be controlled if sensitive systems, such as solar energy collectors or science experiments exposed to the external environment are to function properly. The requirements generally set limits on the level of gas species, matter deposited on surfaces and light background levels over various spectral regions. They also address environment monitoring and contamination controls during manufacturing. Limits on effluent release and system leakages are in turn derived from these requirements.
The Camera/Photometer was one of the ten instruments comprising the Induced Environment Contamination Monitor (IECM) developed to monitor the contamination about the Space Shuttle Orbiter during early missions. This experiment consisted of two motion picture cameras, integrating photometers, and associated electronics enclosed in pressurized canisters and separated by 40 cm in order to make stereoscopic observation of particulates. The objectives of the experiment were to record the occurrence of particulates and to determine their velocities, sizes and origins, as well as to measure the background brightness due to unresolved particles. Particle tracks were detected on over 1800 data frames recorded during continuous operations throughout STS-2, -3, -4, and -9. This report discusses the analysis techniques employed in reducing subsequent results, with an emphasis placed on particle size and velocity data. It also describes the operation of the overall experiment and some of the results obtained.
A small helium cooled IR telescope flown on Spacelab-2 in July/August 1985 was used to make infrared measurements between 2 microns and 120 microns. New data were obtained on the structure of the Galaxy at 2 microns and 7 microns showing it to be much broader at these wavelengths than at longer wavelengths. The IR emission due to contamination from the Shuttle was found to be greater than anticipated, indicating the induced environment to be much higher than the planned limits. Aspects of superfluid helium management in zero-G and of a cryogenically cooled telescope design were also tested.
The results presented show that spectral emissions which arise as a result of vehicle-ambient atmospheric interactions are significant and can become competitive with the natural zodiacal background up to altitudes as high as 400 km for the Vacuun Ultraviolet (VUV) and Visible Infrared Spectra (VIS) for the worst case conditions used. The empirical database on the induced environment of space vehicles is very sparse, and these results are based on a number of assumptions and cannot be regarded as definitive at the present time. Since the technique for doing calculations of this kind was developed in its preliminary form for the purpose of this study, a list of greatly improved estimates are provided of the contamination irradiances. Tasks which are considered most important in order to achieve a higher confidence level for the preliminary conclusions drawn are provided.
It is pointed out that the current Space Station Freedom (SSF) design is the minimum station capable of satisfying the top-level user requirements, effectively incorporating the international partners, and providing the 'hooks' and 'scars' required to cost-effectively evolve the capabilites of the SSF. Research requirements have resulted in very important design drivers on the SS: three labs, three crewmembers per shift, low microgravity in the labs, minimum disturbances, high power for users, high data rates, multiple external attach points, and clean induced environment. Also addressed are the design capabilities that allow the SSF to support the development of technologies and the operations to expand the human presence in the solar system.
Structural dynamic characteristics and responses of the Space Station due to the natural and induced environment are discussed. Problems that are peculiar to the Space Station are also discussed. These factors lead to an overall acceleration environment that users may expect. This acceleration environment can be considered as a loading, as well as a disturbance environment.