Toroidal magnetic fields for protecting astronauts from ionizing radiation in long duration deep space missions

Among the configurations of superconducting magnet structures proposed for protecting manned spaceships or manned deep space bases from ionizing radiation, toroidal ones are the most appealing for the efficient use of the magnetic field, being most of the incoming particle directions perpendicular to the induction lines of the field. The parameters of the toroid configuration essentially depend from the shape and volume of the habitat to be protected and the level of protection to be guaranteed. Two options are considered: (1) the magnetic system forming with the habitat a unique complex (compact toroid) to be launched as one piece; (2) the magnetic system to be launched separately from the habitat and assembled around it in space (large toroid).     

模拟载人探月中航天员空间辐射风险评估

空间辐射是长期载人航天飞行任务中影响航天员健康的重要风险因素。为了探求载人探月过程中对空间辐射的合理防护方式,文章借助空间辐射场模型对"嫦娥三号"飞行任务在不同质量厚度材料屏蔽下的舱内空间辐射环境进行了仿真计算,并确定了航天员各器官接受的空间辐射剂量、剂量当量以及有效剂量等辐射防护量以进行辐射风险评估。结果表明,随着屏蔽厚度的增加,航天员的各组织或器官的吸收剂量和剂量当量以及有效剂量均明显降低;采用质量屏蔽的方法对低于100 Me V的质子具有很好的防护效果,但对高能质子或重离子的防护效果不明显。计算和分析显示,载人探月过程中,只要采取适当的防护措施,航天员的空间辐射风险是可控的。     

Using radiation risk for assessment of space radiation hazard

Radiation hazard caused by exposure during a spaceflight is characterized by radiobiological consequences at all levels of organism. These consequences have a stochastic nature. Even deterministic effects are basically random quantity having all attributes of such mathematical values. The radiation risk is defined in this case as an additional probability of health damage or as a death probability in extreme case. For the manned spaceflight additional peculiarity of a human’s exposure is added. A natural space radiation environment has a stochastic character because solar particle events and crew of a spacecraft can be exposed to dose from background level up to lethal one.The report presents a procedure of radiation risk assessment for quantitative expression of radiation hazard level during a flight and using this value for developing protection recommendations. It is emphasized that the risk value is connected specifically with the time interval of possible hazard’s existent. The form of risk representation must be chosen depending on a time scale of radiobiological processes induced by the exposure (expressing in fact the radiation hazard model). Surviving function specified for the crewmember mortality rate changed by the professional exposure must be used for risk calculation. Solar particle events determine a stochastic character of radiation environment in space that must be taken into account for a risk assessment. The reliability of radiation risk assessment can be used for this goal.     

Estimation of radiation risk for astronauts on the Moon

The problem of estimating the risk of radiation for humans on the Moon is discussed, taking into account the probabilistic nature of occurrence of solar particle events. Calculations of the expected values of tissue-averaged equivalent dose rates, which are created by galactic and solar cosmic-ray particle fluxes on the lunar surface behind shielding, are made for different durations of lunar missions.     

Risks of radiation cataracts from interplanetary space missions

Recognition of the human risks from radiation exposure during manned missions in deep space has been fostered by international co-operation; interagency collaboration is facilitating their evaluation. Further co-operation can lead, perhaps by the end of this decade, to an evaluation of one of the three major risks, namely radiation cataractogenesis, sufficient for use in the planning of the manned mission to Mars.     

Improved space safety for astronauts

The 2003 Columbia accident demonstrated that spaceflight remains a risky and dangerous human endeavor, yet there have been few ‘unofficial’ investigations into astronaut safety. This report summarizes the findings of one such study by George Washington University's Space & Advanced Communications Research Institute—e.g. that simplicity of design may be better than complexity, that cargo missions would be better carried out robotically and that all new space transportation systems should be developed to common international standards—before examining ways that international cooperation can advance the cause of space safety. In establishing future space safety standards input from a wider range of participants (industry, universities and private research institutes, as well as space agencies, etc.) will need to be sought.     

空间辐射对空间站航天员的剂量影响分析

为有效实施对航天员的空间辐射防护,采用计算机断层扫描数据（CT）建立了精细化男性体素模型;基于Geant4建立蒙特卡罗程序计算空间站轨道辐射经过舱壁（5 g·cm^-2等效铝屏蔽）后在体模中的辐射剂量;分析了不同辐射粒子在体素模型组织或器官中的吸收剂量、当量剂量和有效剂量。计算结果表明：航天员体内吸收剂量大约80%来源于地球辐射带（ERB）质子;大约14%来源于银河宇宙线（GCR）质子;α粒子的剂量贡献占比约为5%;其余重离子的剂量贡献占比在1%左右。另外,航天员吸收的当量剂量和有效剂量50%左右来自于ERB质子,另50%左右来自于GCR粒子。计算结果将有助于评估航天员在空间站舱内的潜在辐射风险并提供辐射防护参考。     

Biofeedback monitoring-devices for astronauts in space environment

After a reconsideration of the state-of-the-art in biofeedback research the implementation of biofeedback systems is envisioned as a countermeasure of stress for the psychoprophylaxis of the astronaut. A one-session experiment performed on two groups of subjects to assess the interference from EMG-feedback on the performance in a simultaneous psychomotor trial with a view to expanding biofeedback application is described. The results show that the experimental group performed in the same way as the control without feedback, but with less CNS activation. Some general conclusions are drawn from the advances in technology.     

Rapid assessment of radiobiological doses for terrestrial and interplanetary space missions

This paper presents the doses levels expected in orbits in chart form, covering the range 300-800 km of altitude and 0-90 degrees of inclination behind shieldings similar to the Hermes spacecraft and the EVA spacesuit matter distributions. These charts allow users to rapidly find the radiobiological dose received in the most critical organs of the human body either in normal situations or during a large solar event. Outside the magnetosphere, during interplanetary or lunar missions, when the dose received during crossing of the radiation belts become negligible, the dose is due to galactic cosmic rays (GCR) and solar flares. The correct radiobiological assessment of the components of this radiation field becomes a major problem. On the Moon a permanent ground-based station can be shielded by lunar materials against meteoroids and radiations. The radiobiological hazard, essentially linked to the solar flare risk during the transfer phase and the extra-station activities, may be solved by mission planning. For interplanetary flights the problem comes from both increased risk of solar events and from the continuous exposure to GCR. These energetic particles cannot be easily stopped by shieldings; cost considerations imply that more effective materials must be used. Impact on the vehicle design and the mission planning is important.     

Effects of simulated space radiation on immunoassay components for life-detection experiments in planetary exploration missions

Abstract The Life Marker Chip (LMC) instrument is part of the proposed payload on the ESA ExoMars rover that is scheduled for launch in 2018. The LMC will use antibody-based assays to detect molecular signatures of life in samples obtained from the shallow subsurface of Mars. For the LMC antibodies, the ability to resist inactivation due to space particle radiation (both in transit and on the surface of Mars) will therefore be a prerequisite. The proton and neutron components of the mission radiation environment are those that are expected to have the dominant effect on the operation of the LMC. Modeling of the radiation environment for a mission to Mars led to the calculation of nominal mission fluences for proton and neutron radiation. Various combinations and multiples of these values were used to demonstrate the effects of radiation on antibody activity, primarily at the radiation levels envisaged for the ExoMars mission as well as at much higher levels. Five antibodies were freeze-dried in a variety of protective molecular matrices and were exposed to various radiation conditions generated at a cyclotron facility. After exposure, the antibodies' ability to bind to their respective antigens was assessed and found to be unaffected by ExoMars mission level radiation doses. These experiments indicated that the expected radiation environment of a Mars mission does not pose a significant risk to antibodies packaged in the form anticipated for the LMC instrument. Key Words: Life-detection instruments-Planetary habitability and biosignatures-Radiation-Mars-Life in extreme environments. Astrobiology 12, 718-729.     

The case for small space missions

Three orders of arguments are outlined to illustrate the importance of small missions. First, the classical reasons (one has to begin small, educational aspects, introduction to the space field) are summarized; then some thoughts are introduced on the efficacy and the efficiency of the effort invested (how expensive is a national project, and how advantageous the inevitable multinational cooperation); finally, a synopsis of the considerations about the need for cultural changes in the space program (the challenge of the coming era, the resulting needs, the philosophy of “small missions” and its contributions) is given.     

Funding for space - private finance for public space missions?

Private users of space capability are used to buying a service, not a spacecraft. The supplier builds, launches and operates the spacecraft and the users only pay for the service that they receive. Publicly funded users could benefit from the same approach. Transferring responsibility for the success of the mission to a true prime contractor who is best able to manage technical and programme risks can lead to significant reductions in costs and timescales, but demands changes in attitudes by governments, users, industry and space agencies.     

OLTARIS: On-line tool for the assessment of radiation in space

OLTARIS (On-Line Tool for the Assessment of Radiation In Space) is a space radiation analysis tool available on the World Wide Web. It can be used to study the effects of space radiation for various spacecraft and mission scenarios involving humans and electronics. The transport is based on the HZETRN transport code and the input nuclear physics model is NUCFRG. This paper describes the tools behind the web interface and the types of inputs required to obtain results. Typical inputs are mission parameters and slab definitions or vehicle thickness distributions. Radiation environments can be chosen by the user. This paper describes these inputs as well as the output response functions including dose, dose equivalent, whole body effective dose equivalent, LET spectra and detector response models.     

Optimization of space orbits design for Earth orbiting missions

In Earth orbiting space missions, the orbit selection dictates the mission parameters like the ground resolution, the area coverage, and the frequency of coverage parameters. To achieve desired mission parameters, usually Earth regions of interest are identified and the spacecraft is maneuvered continuously to visit only these regions. This method is expensive, it requires a propulsion system onboard the spacecraft, working throughout the mission lifetime. It also requires a longer time to cover all the regions of interest, due to the very weak thrust forces compared to that of the Earth's gravitational field. This paper presents a methodology to design natural orbits, in which the regions of interest are visited without the use of propulsion systems, depending only on the gravitational forces. The problem is formulated as an optimization problem. A genetic algorithm along with a second order gradient method is implemented for optimization. The design process takes into consideration the gravitational second zonal harmonic, and hence allows for the design of repeated Sun-synchronous orbits. The field of view of the payload is also taken into consideration in the optimization process. Numerical results are presented that demonstrates the efficiency of the proposed method.     

Positive psychological effects of space missions

Being in space is a powerful experience that can have an enduring, positive impact on the psychological well-being of astronauts and cosmonauts. We sought to examine the frequency, intensity and distribution of such salutogenic experiences among persons who have flown in space, using a questionnaire we developed based on the scientific literature and first person accounts. All participants reported positive effects of being in space, but the degree of change varied widely, and some experiences were particularly common. Three of our five predicted attitude-behavior relationships were supported by the data. Response patterns did not vary according to demographics or time in space. Cluster analysis yielded two groups of participants. One group was generally more reactive and also placed a higher priority on perceptions of space than did the other group. We conclude that positive experiences are common among space travelers and seem to cluster into meaningful patterns that may be consequential for Mars missions. We consider the possible selection, training, and monitoring issues raised by our findings.     

Emergency and rescue considerations for manned space missions.

Man in space is totally dependent upon spacecraft systems. particularly those providing Environmental Control and Life Support (ECLS). It is therefore required that the design of manned spacecraft systems include provision for backup emergency and rescue modes of operation to insure adequate crew safety margin. This paper discusses safety, emergency and rescue provisions included in the Space Transportation System (STS), with emphasis on ECLS subsystems. Similar discussion is included for systems projected for use in future, extended duration manned space missions.     

Radiation engineering analysis of shielding materials to assess their ability to protect astronauts in deep space from energetic particle radiation

An analysis is performed on four typical materials (aluminum, liquid hydrogen, polyethylene, and water) to assess their impact on the length of time an astronaut can stay in deep space and not exceed a design basis radiation exposure of 150 mSv. A large number of heavy lift launches of pure shielding mass are needed to enable long duration, deep space missions to keep astronauts at or below the exposure value with shielding provided by the vehicle. Therefore, vehicle mass using the assumptions in the paper cannot be the sole shielding mechanism for long duration, deep space missions. As an example, to enable the Mars Design Reference Mission 5.0 with a 400 day transit to and from Mars, not including the 500 day stay on the surface, a minimum of 24 heavy lift launches of polyethylene at 89,375 lbm (40.54 tonnes) each are needed for the 1977 galactic cosmic ray environment. With the assumptions used in this paper, a single heavy lift launch of water or polyethylene can protect astronauts for a 130 day mission before exceeding the exposure value. Liquid hydrogen can only protect the astronauts for 160 days. Even a single launch of pure shielding material cannot protect an astronaut in deep space for more than 180 days using the assumptions adopted in the analysis. It is shown that liquid hydrogen is not the best shielding material for the same mass as polyethylene for missions that last longer than 225 days.     

中国航天固体火箭技术的发展

叙述了20世纪50年代以来中国航天固体火箭推进技术的发展历程，介绍了9种最具代表性的固体火箭发动机的技术特征、研制过程、地面试验和飞行情况，这些发动机分别应用于中国的探空火箭、运载火箭上面级和应用卫星变轨系统。文中还简要地评述了中国固体推进各单项技术的发展水平。     

Leisure time activities in space: a survey of astronauts and cosmonauts

Questionnaires were returned from 54 astronauts and cosmonauts which addressed preferences for media and media-generated subjects that could be used to occupy leisure time in space. Ninety-three percent of the respondents had access to records or audio cassettes, and cosmonauts had greater access than astronauts to multiple media. Cosmonauts and long-duration space travelers reported that they missed various media more than their astronaut and short-duration counterparts. Media subjects that related to international events, national events and historical topics were rated as most preferable by all respondents and by several of the respondent groups. The findings are discussed in terms of their relevance for occupying free time during future long-duration manned space missions.