| 1. |
- Mortazavi, S. A.R., et al.
(författare)
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Can Reactivation of SARS-CoV-2 Decrease the Chance of Success of Future Deep Space Missions?
- 2021
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Ingår i: IEEE Aerospace Conference Proceedings. - 1095-323X. ; 2021-March
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Konferensbidrag (refereegranskat)abstract
- Korean CDC experts first reported the likelihood of reactivation in COVIOD-19 patients. They hypothesized that like childhood chicken pox infections which lie dormant for tens of years only to cause shingles in seniors, SARS-CoV-2 can reactivate. However, as testing for the virus had been flawed at that time, U.S. infectious disease experts were skeptical about the reports of second COVID-19 infections. New reports have addressed the urgent need to conduct large-scale studies to better understand the potential recurrence of SARS-CoV-2 in COVID-19 patients. Moreover, some case studies show possible reactivation of SARS-CoV-2 in a family cluster. Given this consideration, major space stressors such as microgravity and space radiation and their interactions which are not fully known, so far can increase the risk of reactivation of SARS-CoV-2 in future space missions, an event that can easily impact the success of any space mission. Since about 80% of infected people are either asymptomatic or show only mild symptoms, in a near future, it would be likely that astronauts who start their mission even after complex medical examinations, experience reactivation of the virus during their mission. Moreover, we have previously addressed the potential higher fatality of COVID-19 infections in space due to 1) uselessness of social distancing due to microgravity 2) immune system dysregulation 3) possibly higher mutation rates of the novel coronavirus (SARS-CoV-2) as a RNA virus 4) higher risk of reactivation of the virus 5) existence of strong selective pressure and 6) decreased maximum oxygen uptake.
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| 2. |
- Mortazavi, S. M. J., et al.
(författare)
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Can Adaptive Response and Evolution Make Survival of Extremophile Bacteria Possible on Mars?
- 2020
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Ingår i: 2020 IEEE AEROSPACE CONFERENCE (AEROCONF 2020). - 1095-323X. - 9781728127347
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Konferensbidrag (refereegranskat)abstract
- The humidity on the surface of the red planet, Mars, drops steeply during the daytime as the temperature rises. In this situation, Martian microorganisms should have the capability to cope with desiccation. Extremophiles are microorganisms that are capable of surviving in extreme environmental conditions. It has previously been shown that a pre-exposure to low levels of either ionizing or non-ionizing radiation can induce resistance against subsequent exposure to high levels of different stressors (e.g. high doses of ionizing radiation) in a wide variety of living systems. Moreover, it has been shown that E. coli bacteria repeatedly exposed to a dose needed for 1% survival, and increasing the dose each time due to increased radioresistance for the same survival (1%), generates extremely radioresistant bacteria through directed evolution. Mortazavi et al. have warned that in a similar manner with extremophiles such as Deinococcus radiodurans, it would be very likely that this type of human-directed radioresistance makes E. coli bacteria resistant to all physical and chemical agents (generation of serious life-threatening micro-organisms). There are reports about the possibility of the existence of microbes in the salty puddles of Mars. On Mars, with its thin atmosphere and lack of the protective magnetic field, higher levels of space radiation cause more genetic mutations. Interestingly, these mutations in bacteria, which can make them resistant against radiation, can also make them resistant against desiccation. Moreover, the adaptive response to radiation in bacteria might play an important role in this process. As stated in a NASA report, the cells in the astronauts will be traversed by multiple protons before exposure to HZE particles. This sequential exposure might significantly increase the resistance against radiation. The same exposure in bacteria might not only induce resistance against the high levels of damage caused by HZEs, but also to other life-threatening factors for bacteria such as desiccation. In this paper, the current understanding of extremophiles and their capability of surviving in extreme environmental conditions as well as current findings about radioadaptive responses in bacteria will be discussed.
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| 3. |
- Mortazavi, S. M. J., et al.
(författare)
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Does Exposure of Astronauts' Brains to High-LET Radiation in Deep Space Threaten the Success of the Mission?
- 2020
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Ingår i: 2020 IEEE AEROSPACE CONFERENCE (AEROCONF 2020). - 1095-323X. - 9781728127347
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Konferensbidrag (refereegranskat)abstract
- Astronauts' exposure to radiation is different from exposure to radiation on Earth. Besides cancer, cardiovascular disease and acute radiation syndrome, there are concerns over the potential behavioral and cognitive impairments caused by exposure of the astronauts' central nervous system to high levels of space radiation. Therefore, potential behavioral and cognitive i mpairments caused by astronauts' brains exposure to high levels of space radiation and the possibility of developing dementia and other motor neuron diseases are getting more attention. As NASA is interested in studies on radium deposition in human brain, and exposure of the brain to high linear energy transfer (LET) alpha particles, we have assessed the cognitive effects of long-term exposure of human brain to alpha particles which partly mimics astronauts' exposure to high charge and energy (HZE) particles during upcoming mars missions. Dr. John Boice, President of NCRP, and his colleagues' have stated that human brain exposed for years to alpha particles on Earth may be more relevant to a Mars mission in contrast with the mouse brain exposed to heavy ions for a few minutes. Interestingly, both Boice and NASA did not pay enough attention to this fact that radium as well as many other alpha emitters tend to accumulate in the bone, and the alpha particles whose energies are typically -5 MeV have a very short range (maximum lOs of um), so the radiation dose due to the alpha emitters would be localized to volumes near the cranium rather than being uniformly distributed throughout the cerebral and cerebellar parenchyma. Extraordinary high levels of Ra-226 have previously been reported in high background radiation areas of Ramsar, where people are consuming locally grown foods. In this paper, we will present data which provide a human brain radiation exposure analogue for upcoming Mars missions. Normally the dose to the functional parts of the brain are not likely to be significant, even with higher uptakes of the radium or other alpha-emitting isotopes in the cranium. Therefore, only residents with calcium-rich diet were selected for the study. Measurements of background gamma radiation was performed in their bedrooms, dining rooms, vegetable yards and gardens with citrus fruit trees of the dwellings in areas with high levels of Ra-226 in the soil and at a nearby control area with the same socio-economic factors. Moreover, the food frequency, reaction time, working memory and computational abilities as well as the Radium Ingestion Index (RII) of 47 participants (22 males and 24 females) from the hot areas, where the annual radiation absorbed dose from background radiation is up to 260 mSv/y, were studied, and the same things were studied for 17 participants (4 males and 13 females) from a nearby normal background radiation area with the same socioeconomic factors as at the hot areas. Our study showed that exposure of human brain to high LET particles did not affect the working memory. However, individuals with higher levels of radium ingestion had significantly increased reaction times. The increased reaction time in individuals with higher exposure levels to alpha particles emitted from ingested Ra-226 is an important finding, since similar conditions might occur in deep space, when astronauts' brain cells are exposed to HZE particles. As the astronauts face numerous challenges in isolated and confined space environment, they should be able to respond quickly to different hazards. However, further studies are needed to verify if the fmdings in high radiation dose areas in Ramsar are relevant for deep space mission.
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| 4. |
- Mortazavi, S. M. J., et al.
(författare)
-
Radioadaptation of Astronauts' Microbiome and Bodies in a Deep Space Mission to Mars and Beyond
- 2020
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Ingår i: 2020 IEEE AEROSPACE CONFERENCE (AEROCONF 2020). - 1095-323X. - 9781728127347
-
Konferensbidrag (refereegranskat)abstract
- During manned space missions, humans will be accompanied by microorganisms. This prompts us to study the characteristics of bacteria grown in space [1]. It has been shown that a pre-exposure to low levels of either ionizing or non-ionizing radiation can make microorganisms more resistant not only to high doses of ionizing radiation but to any factor that threatens their survival (e.g. antibiotics) [2,3]. This phenomenon that is called "adaptive response" (i.e. increased resistance in living organisms pre-exposed to a low level stressor such as a low dose of ionizing radiation) [4] significantly increases the risk of serious infections in deep space missions. It's worth noting that both animal and human data confirm the disruption of the immune system during spaceflight [5]. In addition, the virulence of bacteria can also be increased significantly in space [4], hence this kind of adaptive response which increases the resistance of bacteria can endanger the astronauts' lives in space. On the other hand, A NASA report notes that as astronauts' cells will be exposed to multiple protons before being traversed by HZE particles, they can show adaptive responses. Given this consideration, it would be realistic to expect co-radioadaptation of astronauts' microbiome and their body in a deep space journey to Mars and beyond. The complexity of these phenomena and current uncertainties, which highlight the need for further studies before any long-term manned mission, will be discussed in this paper.
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| 5. |
- Sihver, Lembit, 1962, et al.
(författare)
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Space Dosimetry and Space Phantom Experiments
- 2021
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Ingår i: IEEE Aerospace Conference Proceedings. - 1095-323X. ; 2021-March
-
Konferensbidrag (refereegranskat)abstract
- To estimate the space radiation risks for the future planned Mars missions, the radiation fields in the spacecraft and in the habitats on Mars must be fully known. For radiation risk estimations, benchmarking and improving particle and ion transport codes which are currently used for space radiation and shielding calculations, radiation detection and monitoring of the space radiation field as a function of the solar activity, the orbital parameters and the different shielding configurations of the International Space Station (ISS) have been performed and are still ongoing. There are also many ongoing measurements of the spatial and temporal distribution of the radiation field at the ISS. In addition to the measurements at the ISS, important information about radiation environment in deep space was achieved with the Mars Science Laboratory (MSL) spacecraft, containing the Curiosity rover, which was launched to Mars on 26 November 2011, and traveled for 253 days, 560 million kilometers to Mars. The Radiation Assessment Detector (RAD) on the spacecraft showed that the dose equivalent for even the shortest round-trip Earth-Mars journeys, with current propulsion systems and current available shielding, is 0.7 +/- 0.1 Sv, depending on the solar cycle and duration of the mission. Although the dose rate on the surface of Mars is lower than in deep space, measurements with RAD showed that an astronaut would still get around 40% of the dose rate in deep space. If the astronauts are exposed to large Solar Particle Events (SPEs), the dose can reach lethal doses. Effective countermeasures should therefore be developed before performing a manned mission to Mars. The use of human phantoms in space that simulate an astronaut's body, has provided detailed information of the depth-dose distributions, and radiation quality, inside the human body in space. This information is essential for developing more accurate space radiation transport and risk models to be used for evaluating short and long-term radiation risks in deep space and on Mars. Although reports state that background radiation in some high background radiation areas approaches that of the Martian surface, new estimates show that the maximum annual radiation dose in these areas can be much higher than that of the Martian surface. Given this consideration, study of the health effects of exposure to high levels of natural radiation can help scientist better evaluate the risk of radiation in deep space manned missions. This paper presents a short review of some important published space dosimetry and phantom experiments, and discusses some recently proposed counter measures to reduce the health risks of the astronauts on deep space missions.
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| 6. |
- Sihver, Lembit, 1962, et al.
(författare)
-
Space Radiation Risk Reduction through Prediction, Detection and Protection
- 2021
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Ingår i: 2021 IEEE AEROSPACE CONFERENCE (AEROCONF 2021). - 1095-323X. - 9781728174365
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Konferensbidrag (refereegranskat)abstract
- To enable the planned rapid growth of both government and private operators in space, including satellites, space tourism and manned missions to the Moon and to Mars, a realistic and holistic approach to radiation risk reduction is needed. In deep space, ionizing radiation from Galactic Cosmic Rays (GCRs), which originate outside the solar system and Solar Energetic Particles (SEPs) from the sun pose a critical threat to human life and equipment. The composition and energy spectra of the radiation from these two sources are different and must be considered separately. GCRs provide a chronic, slowly varying, highly energetic background source of High-Z high-Energy (HZE) particles, while the Sun's activity varies with an 11-year cycle during which the Sun produces Solar Wind (SW) at varying intensities. The SW influences GCRs, since the GCRs are at maximum intensity during solar minimum when the decreased intensity of the solar wind causes less attenuation. In addition to the SW, there are solar events such as solar flares and coronal mass ejections (CMEs), which increase during solar max. These events give rise to SEPs, which pose a danger both to humans and electronics in space. It is therefore very important to be able to predict, forecast and measure the SEPs to apply the best possible protection for humans and electronics. Currently, the only proven and practical countermeasure to reduce the exposure to GCRs and SEPs is passive shielding. However, the presence of passive shielding does not always reduce the radiation risks for HZE particle exposure, e.g. metal shielding can increase the effective dose behind the shielding. The basic physics to estimate the shielding efficiency is straightforward as the energy loss of heavy ions in the shield is caused by electron and nuclear interactions, which can be approximated by simple stopping power and total reaction cross section formulas. It is therefore easy to show that a hydrogen rich material is best for charge particle protection. To increase shielding against secondary neutrons, the shielding material should also contain additives with high neutron capture cross section, e.g. Boron-10. Cosmic Shielding Corporation (CSC) provides the first holistic commercial solution to radiation risk reduction for both humans and electronics. CSC can predict SEPs using a modified version of MAG4 program, developed for the NASA Space Radiation Analysis Group (SRAG), which gives the likelihood of major solar flares, CMEs, and SEPs occurring up to 48 hours in advance. Furthermore, simulations of radiation transport through the spacecraft material, electronics and crew can be performed to estimate what possible damage an event can cause. Finally, we offer an improved version of a state-of-the-art, ultra-high molecular weight (UHMW) polyethylene composite material RFX-1, developed by NASA and assigned to CSC, which can either act as the main structural element of a spacecraft or habitat, or as a shielding layer on top of other structural materials. The improved version of RFX-1 is a lightweight Polyethylene composite with multifunctional strength, thermal management, ballistic impact resistance, low flammability, a high melting point and almost three times higher Ultimate Tensile Strength (UTS) then traditional Al alloys used in spacecraft. We also offer sophisticated embedded radiation detectors systems and Fiber-Optic Bragg Grating sensors for real time Prognostics and Health Management (PHM) of the shielding efficiency and mechanical strength.
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