RESUMO
Measurements of the radiation environment inside the Mir space station were performed with a tissue equivalent proportional counter (TEPC) during the Antares mission in 1992, and over a long period following it. Interesting results concerning radiation measurements show (a) the South Atlantic Anomaly crossing, (b) the increase of radiation near the poles, and (c) the effects of solar particle events (the most important one occurring in early November 1992). This data also provides information about the dose and the quality factor of the radiation to which the cosmonauts were exposed during different missions. These data are compared with measurements obtained using a solid state detector.
Assuntos
Radiação Cósmica , Monitoramento de Radiação/instrumentação , Atividade Solar , Voo Espacial/instrumentação , Astronave/instrumentação , Regiões Árticas , Astronautas , Oceano Atlântico , Humanos , Transferência Linear de Energia , Prótons , Doses de Radiação , América do Sul , Ausência de PesoRESUMO
Measurements on board the MIR space station by the Bulgarian-Russian dosimeter LIULIN have been used to study the solar cycle variations of the radiation environment. The fixed locations of the instrument in the MIR manned compartment behind 6-15 g/cm2 of shielding have given homogeneous series of particle fluxes and doses measurements to be collected during the declining phase of 22nd solar cycle between September 1989 and April 1994. During the declining phase of 22nd solar cycle the GCR (Galactic Cosmic Rays) flux observed at L>4 (where L is the McIlwain parameter) has enhanced from 0.6-0.7 cm-2 s-1 up to 1.4-1.6 cm-2 s-1. The long-term observations of the trapped radiation can be summarized as follows: the main maximum of the flux and dose rate is located at the southeast side of the geomagnetic field minimum of South Atlantic Anomaly (SAA) at L=1.3-1.4. Protons depositing few (nGy cm2)/particle in the detector predominantly populate this region. At practically the same spatial location and for similar conditions the dose rate rises up from 480 to 1470 microGy/h dose in silicon in the 1990-1994 time interval, during the declining phase of the solar cycle. On the other hand the flux rises from 35 up to 115 cm-2 s-1 for the same period of time. A power law dependence was extracted which predicts that when the total neutral density at the altitude of the station decreases from 8x10(-15) to 6x10(-16) g/cm3 the dose increase from about 200 microGy/h up to 1200 microGy/h. At the same time the flux increase from about 30 cm-2 s-1 up to 120 cm-2 s-1. The AP8 model predictions give only 5.8% increase of the flux for the same conditions.
Assuntos
Radiação Cósmica , Monitoramento de Radiação/instrumentação , Atividade Solar , Voo Espacial/instrumentação , Astronave/instrumentação , Oceano Atlântico , Atmosfera/química , Modelos Teóricos , Doses de Radiação , Radiometria , América do Sul , Ausência de PesoRESUMO
The Mir station has been in a 51.65 degrees inclination orbit since March 1986. In March 1995, the first US astronaut flew on the Mir-18 mission and returned on the Space Shuttle in July 1995. Since then three additional US astronauts have stayed on orbit for up to 6 months. Since the return of the first US astronaut, both the Spektr and Priroda modules have docked with Mir station, altering the mass shielding distribution. Radiation measurements, including the direct comparison of US and Russian absorbed dose rates in the Base Block of the Mir station, were made during the Mir-18 and -19 missions. There is a significant variation of dose rates across the core module; the six locations sampled showed a variation of a factor of nearly two. A tissue equivalent proportional counter (TEPC) measured a total absorbed dose rate of 300 microGy/day, roughly equally divided between the rate due to trapped protons from the South Atlantic Anomaly (SAA) and galactic cosmic radiation (GCR). This dose rate is about a factor of two lower than the rate measured by the thinly shielded (0.5 g cm-2 of Al) operational ion chamber (R-16), and about 3/2 of the rate of the more heavily shielded (3.5 g cm-2 of Al) ion chamber. This is due to the differences in the mass shielding properties at the location of these detectors. A comparison of integral linear energy transfer (LET) spectra measured by TEPC and plastic nuclear track detectors (PNTDs) deployed side by side are in remarkable agreement in the LET region of 15-1000 keV/micrometer, where the PNTDs are fully efficient. The average quality factor, using the ICRP-26 definition, was 2.6, which is higher than normally used. There is excellent agreement between the measured GCR dose rate and model calculations, but this is not true for trapped protons. The measured Mir-18 crew skin dose equivalent rate was 1133 microSv/day. Using the skin dose rate and anatomical models, we have estimated the blood-forming organ (BFO) dose rate and the maximum stay time in orbit for International Space Station crew members.
Assuntos
Radiação Cósmica , Prótons , Monitoramento de Radiação/instrumentação , Atividade Solar , Voo Espacial/instrumentação , Oceano Atlântico , Sistema Hematopoético/efeitos da radiação , Humanos , Transferência Linear de Energia , Doses de Radiação , Proteção Radiológica , Radiometria/instrumentação , Federação Russa , Pele/efeitos da radiação , América do Sul , Astronave/instrumentação , Estados Unidos , United States National Aeronautics and Space Administration , Ausência de PesoRESUMO
In March 1991 the CRRES spacecraft measured a new transient radiation belt resulting from a solar proton event and subsequent geomagnetic disturbance. The presence of this belt was also noted by dosimeter-radiometers aboard the Mir space station (approx. 400 km, 51 degrees orbit) and by particle telescopes on the NOAA-10 spacecraft (850 km, 98 degrees). This event provides a unique opportunity to compare particle flux and dose measurements made by different instruments in different orbits under changing conditions. We present here a comparison of the measurements made by the different detectors. We discuss the topology and dynamics of the transient radiation belt over a period of more than one year.
Assuntos
Prótons , Atividade Solar , Voo Espacial/instrumentação , Astronave/instrumentação , Oceano Atlântico , Planeta Terra , Elétrons , Meio Ambiente Extraterreno , Magnetismo , Doses de Radiação , Monitoramento de Radiação/instrumentação , Monitoramento de Radiação/métodos , Radiometria , América do SulRESUMO
A joint NASA Russia study of the radiation environment inside the Space Shuttle was performed on STS-63. This was the second flight under the Shuttle-Mir Science Program (Phase 1). The Shuttle was launched on 2 February 1995, in a 51.65 degrees inclination orbit and landed at Kennedy Space Center on 11 February 1995, for a total flight duration of 8.27 days. The Shuttle carried a complement of both passive and active detectors distributed throughout the Shuttle volume. The crew exposure varied from 1962 to 2790 microGy with an average of 2265.8 microGy or 273.98 microGy/day. Crew exposures varied by a factor of 1.4, which is higher than usual for STS mission. The flight altitude varied from 314 to 395 km and provided a unique opportunity to obtain dose variation with altitude. Measurements of the average east-west dose variation were made using two active solid state detectors. The dose rate in the Spacehab locker, measured using a tissue equivalent proportional counter (TEPC), was 413.3 microGy/day, consistent with measurements made using thermoluminescent detectors (TLDs) in the same locker. The average quality factor was 2.33, and although it was higher than model calculations, it was consistent with values derived from high temperature peaks in TLDs. The dose rate due to galactic cosmic radiation was 110.6 microGy/day and agreed with model calculations. The dose rate from trapped particles was 302.7 microGy/day, nearly a factor of 2 lower than the prediction of the AP8 model. The neutrons in the intermediate energy range of 1-20 MeV contributed 13 microGy/day and 156 microSv/day, respectively. Analysis of data from the charged particle spectrometer has not yet been completed.
Assuntos
Radiação Cósmica , Prótons , Monitoramento de Radiação/instrumentação , Voo Espacial , Oceano Atlântico , Transferência Linear de Energia , Modelos Teóricos , Doses de Radiação , Proteção Radiológica , Radiometria , Federação Russa , América do Sul , Astronave , Dosimetria Termoluminescente , Estados Unidos , United States National Aeronautics and Space AdministrationRESUMO
A tissue equivalent proportional counter designed to measure the linear energy transfer spectra (LET) in the range 0.2-1250 keV/micrometer was flown in the Kvant module on the Mir orbital station during September 1994. The spacecraft was in a 51.65 degrees inclination, elliptical (390 x 402 km) orbit. This is nearly the lower limit of its flight altitude. The total absorbed dose rate measured was 411.3 +/- 4.41 microGy/day with an average quality factor of 2.44. The galactic cosmic radiation (GCR) dose rate was 133.6 microGy/day with a quality factor of 3.35. The trapped radiation belt dose rate was 277.7 microGy/day with an average quality factor of 1.94. The peak rate through the South Atlantic Anomaly was approximately 12 microGy/min and nearly constant from one pass to another. A detailed comparison of the measured LET spectra has been made with radiation transport models. The GCR results are in good agreement with model calculations; however, this is not the case for radiation belt particles and again points to the need for improving the AP8 omni-directional trapped proton models.
Assuntos
Radiação Cósmica , Transferência Linear de Energia , Modelos Teóricos , Prótons , Atividade Solar , Voo Espacial/instrumentação , Brasil , Nêutrons , Doses de Radiação , Monitoramento de Radiação/instrumentação , Radiometria/instrumentaçãoRESUMO
Since 1988 high sensitivity semiconductor dosimeter-radiometer "Liulin" worked on board of MIR space station. Device measured the absorbed dose rate and the flux of penetrating particles. The analysis of the data shows the following new results: In October 1989 and after March 24, 1991, two additional stable maximums in flux channel were observed in the southern-eastern part of South Atlantic Anomaly (SAA). These two maximums existed at least several months and seem to be due to trapped high energy electron and proton fluxes. In April 1991 additional maximums were localized in the following geographical coordinates regions: latitude = (-35 degrees)-(-50 degrees) longitude = 332 degrees-l6 degrees and lat.(-46 degrees)-(-52 degrees) long. 360 degrees-60 degrees. Additional maximums diffusion occurs inside radiation belt. Appearance of these maximums seems to be closely connected with preceding powerful solar proton events and associated geomagnetic dynamics of new belt disturbances. Alter the series of solar proton events in June 1991 we observed significant enhancement of this new radiation belt formation. To achieve sufficient accuracy of dose rate predictions in low Earth orbits the structure and dynamics of new belt should be carefully analyzed to be included in a new environment model. From the inter comparison of the data from "Liulin" and French developed tissue equivalent LET spectrometer NAUSICAA in the time period August-November 1992 we come to the following conclusions: Mainly there is good agreement between both data sets for absorbed dose in the region of SAA; Different situation of the instruments on the station can explain the cases when differences up to 2 times are observed; At high latitudes usually the tissue equivalent absorbed dose observations are 2 times larger than "Liulin" doses.
Assuntos
Prótons , Monitoramento de Radiação/instrumentação , Atividade Solar , Astronave/instrumentação , Oceano Atlântico , Transferência Linear de Energia , Doses de Radiação , América do SulRESUMO
Since the end of July 1992, the NAUSICAA system, a low gas pressured tissue equivalent proportional counter, recorded in real time the dose equivalent rate, the absorbed dose rate, the quality factor and the Linear Energy Transfer spectra, aboard the Russian orbital station MIR. The results since the ANTARES mission are presented. Some parameters like the proton flux, the previous solar cycles, the location of the NAUSICAA system inside the station and the South Atlantic Anomaly crossing seem to have an influence on these results. The total dose equivalent (H) during the ANTARES mission (between 1992 July the 30th and August the 10th) was 12 mSv and the total absorbed dose (D) 6.4 mGy with a quality factor (Q) equal to 1.9. The NAUSICAA system gives a good knowledge of LET spectra for the first time in space dosimetry.
Assuntos
Radiação Cósmica , Transferência Linear de Energia , Atividade Solar , Voo Espacial/instrumentação , Oceano Atlântico , Prótons , Doses de Radiação , Monitoramento de Radiação/instrumentação , América do Sul , Astronave/instrumentaçãoRESUMO
Since Dec 1988, date of the French-Soviet joint space mission "ARAGATZ", the CIRCE device (Compteur Intégrateur de Rayonnement Complexe dans l'Espace) had recorded dose equivalent and quality factor inside the MIR station (380-410 km, 51.5 degrees). After the initial gas filling two years ago, the low pressure tissue equivalent proportional counter is still in good working conditions. Some results of three periods, viz Dec 1988, Mar-Apr 1989 and Jan-Feb 1990 are presented. The average dose equivalent rates measured are respectively 0.6, 0.8 and 0.6 mSv/day with a quality factor equal to 1.9. Some detailed measurements show the increasing of the dose equivalent rates through the SAA and near polar horns. The real time determination of the quality factors allows to point out high LET (Linear Energy Transfer) events with quality factors in the range 10-20.
Assuntos
Radiação Cósmica , Transferência Linear de Energia , Monitoramento de Radiação/instrumentação , Proteção Radiológica/normas , Voo Espacial , Astronave/instrumentação , Oceano Atlântico , Planeta Terra , França , Doses de Radiação , América do Sul , Fatores de Tempo , U.R.S.S.RESUMO
A dosimetry-radiometry system has been developed at the Space Research Institute of the Bulgarian Academy of Science to measure the fluxes and dose rates on the flight of the second Bulgarian cosmonaut. The dosimetry system is designed for monitoring the different space radiations, such as solar cosmic rays, galactic cosmic rays and trapped particles in the earth radiation belts. The system consists of a battery operated small size detector unit and a "read-write" and telemetry microcomputer unit. The sensitivity of the instrument (3.67 x 10(-8) rad/pulse) permits high resolution measurements of the flux and dose rate along the track of the Mir space station. We report our initial results for the period of the flight between the 7th and 17th June 1988.
Assuntos
Radiação Cósmica , Monitoramento de Radiação/instrumentação , Atividade Solar , Voo Espacial/instrumentação , Oceano Atlântico , Calibragem , Desenho de Equipamento , Meio Ambiente Extraterreno , Microcomputadores , Prótons , Radiometria , América do Sul , Astronave/instrumentação , Ausência de PesoRESUMO
An experiment involving active detection of space radiation was carried out in the Space Research Institute (SRI) of Bulgarian Academy of Sciences, in preparation of the flight of the second Bulgarian cosmonaut. The radiations that would be encountered on the flight were modelled including solar and galactic cosmic rays and the particle radiation in the Earth's radiation belts. The dose rate was calculated for these different radiations behind the shielding of the space station. The variations in dose rates over the period of the flight were calculated and compared with measurements made during the orbit of the Mir Space Station. The calculated and measured dose rates agreed within 15-35%.