International coordination of space solar power related activities

Because the need for energy is global, and many energy networks are already interdependent, because no one country has sufficient technological capability or sufficient funds to provide a space solar powered solution on its own, and because any such solution will require international regulation, international coordination will be vital to any attempt to produce energy for Earth from space. This will be made easier by the fact that work on the subject has already been widely publicized and distributed and cooperative efforts have already been made. Various coordinating approaches are described and the need to forge partnerships between government, industry and academia — with greater involvement of all non-space groups concerned with energy — is emphasized. A “terracing approach” to the actual implementation of SPS is suggested and outlined.     

Microwave policy issues for solar space power

This article reviews the three major policy issues likely to arise from an SSP system: environmental safety, frequency allocation and prevention of interference with other frequency-using activities. Supporters of SSP must make sure that their case is heard clearly at the ITU, but they must also do more to promote public awareness of the technology's potential benefits in order to counter inappropriate use of the Precautionary Principle by anti-technology groups. The strengthening of standard-setting groups world-wide will also assist this process.     

An alternative strategy process for government space activities

This article is a revised and updated version of a paper presented at the 49th International Astronautical Congress, held in Melbourne, Australia from September 28 to October 2, 1998. It presents a methodical approach to the future planning of government space activities. Rather than generating detailed programme plans that are hard to implement in a dynamic environment, the method described herein is rather modelling the priorities of different project alternatives. This is less detailed as the plans that usually result from the classic space planning approach, yet is highly usable as a roadmap for implementation. This approach enables a dynamic planning with inherent learning cycles that can easily be adapted to the dynamic changes which are plaguing today’s space policies.     

Net electric power of concentrating solar mirror systems for application in space as a function of the distance to the sun

The use of solar radiation by means of concentrating solar mirror systems, such as parabolic and spheric configurations, mainly is an engineering problem. A decisive characteristic for the optimisation of a complete system with turboelectric power conversion is the thermal cycle applied. Besides the Carnot process, here taken up into the study as an ideal comparative process, suitable processes for the technological realisation are the Brayton process and the Rankine process. The Brayton process is a typical gas turbine process using only the gaseous phase. The Rankine process is a steam engine process using liquid and gaseous phase.The work in hand shows how such solar systems with turboelectric conversion are optimised with respect to their specific weight (kg/kW_e) and how the distance to the sun as well as technological data enter into the analysis.As expected, the Carnot cycle as an ideal comparative process for both types of systems shows the best results for the optimum specific mass of the system. Regarding the real processes, the Rankine cycle shows more favourable characteristics than the Brayton cycle. The difference of the specific masses of the real processes mainly results from the different thermal conditions at the radiator.The influence of the distance to the sun is as expected. The nearer to the sun the solar power system operates, the better is the optimum specific mass of the system. For distances to the sun between 0.3 and 1.0 AU the spheric system shows a better behaviour than the parabolic system. For distances to the sun greater than 2.0 AU the parabolic system shows better behaviour of the specific weight. In the region between 1 and 2 AU the better optimum specific mass of the system belongs to the technological data used in the analysis.     

An exploration of the effectiveness of artificial mini-magnetospheres as a potential solar storm shelter for long term human space missions

If mankind is to explore the solar system beyond the confines of our Earth and Moon the problem of radiation protection must be addressed. Galactic cosmic rays and highly variable energetic solar particles are an ever-present hazard in interplanetary space.     

The European Union draft Code of Conduct for outer space activities: An appraisal

The European Union draft Code of Conduct for outer space activities is one of the primary international initiatives, that are currently active, to enhance the safety, security and sustainability of outer space activities. Although the spirit underlying the instrument is commonly shared by space-faring countries, substantial disagreement exists among States as to some of its core provisions. This article proposes that the Code of Conduct should make a clear distinction between commercial activities and military activities, and adopt more balanced measures on the restriction of military activities in outer space.     

Force and power characteristics of a resistive exercise device for use in space

We have developed a non-gravity dependent mechanical device, which provides resistance during coupled concentric and eccentric muscle actions, through the inertia of a spinning fly-wheel (Fly-Wheel Ergometry; FWE). Our research shows that lower-limb FWE exercise can produce forces and thus muscular stress comparable to what is typical of advanced resistance training using free weights. FWE also offers greater training stimuli during eccentric relative to concentric muscle actions, as evidenced by force and electromyographic (EMG) measurements. Muscle use of specific muscle groups, as assessed by the exercise-induced contrast shift of magnetic resonance images, is similar during lower-limb FWE and the barbell squat. Unlike free-weight exercise, FWE allows for maximal voluntary effort in each repetition of an exercise bout. Likewise, FWE exercise, not unassisted free-weight exercise, produces eccentric "overload". Collectively, the inherent features of this resistive exercise device and the results of the physiological evaluations we have performed, suggest that resistance exercise using FWE could be used as an effective exercise counter-measure in space. The flywheel principle can be employed to any exercise configuration and designed into a compact device allowing for exercises stressing those muscles and bone structures, which are thought to be most affected by long-duration spaceflight.     

Advantages and disadvantages of prizes in a portfolio of financial incentives for space activities

The National Aeronautics and Space Administration (NASA) has proposed to use financial prizes to encourage innovation in space technology. Public debate about the use of prizes questions their effectiveness, the role of government compared with the private sector in administering prizes—for example, the Ansari X-Prize for human suborbital flight was privately funded and administered—and other issues that are likely to influence the success of this approach.     

A new role for a new millennium? The changing nature of space activities

Space activity has lost the momentum it had in the past. During the Cold War the use of space was constrained by specific political and military conditions which gave it a strong but narrow identity. The aerospace industry, in particular, was in a position to develop protected and exclusive ties with the public sector. These times have passed and diminishing competition between the two main space powers has had consequences for the planning of major space undertakings. Space activity is in the process of being thoroughly transformed as it is forced to become more connected to general economic and industrial activity, especially in the field of information. An opportunity for a sector that has been struggling could also prove to be risky as space activity is losing some of its previously strong identity. Space currently seems to lack the high level of public support from governments it once enjoyed, while not finding an alternative in the industry itself to this declining investment. This situation should lead both the space community and the political authorities to consider new general space applications that will be more in line with the preoccupations of our modern societies and thus contribute to solving the principal global issues of tomorrow.     

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.     

空间推进系统可靠性评估方法的改进

空间推进系统可靠性评估时,采用Lindstrom-Maddens(L-M)法评估比传统方法得到的结果更高。对比分析评估数据后发现L-M法更合理,因此建议采用L-M法进行可靠性评估,可以在满足可靠性指标前提下防止对产品提出过分苛刻的要求,从而降低设计难度和减少试验费用。     

Bright light as a chronobiological countermeasure for shiftwork in space

Work-rest schedules during long duration space missions involve several factors which could disrupt sleep and circadian temporal organisation: (1) displacement of sleep due to two-shift operations; (2) planned or unplanned schedule changes due to operational requirements; (3) social and light Zeitgebers different from those on earth; (4) changes in the gravitational exposure. Timed bright light treatment has the potential to accelerating adaptation to schedule changes. Four male subjects were exposed to two sessions of 11 d of simulated microgravity (6 ° head down tilt bedrest) with 6-h extensions of the wake period on 2 days (12-h phase delay). In a blind crossover design, subjects were exposed to bright light (> 3500 lux) for 5 h on each of the 2 shift days and the following day, at times either expected to accelerate the adjustment to the phase delay (experimental condition) or to have no phase shifting effect (control condition). Sleep was recorded polygraphically, the circadian system was monitored by recordings of heart rate and body temperature, and by collection of urine (electrolyte and hormone excretion). Only the rhythms of 6-hydroxymelatoninsulphate and potassium excretions showed significantly enhanced adjustment under the experimental condition. Different rhythms Actapted to the 12-h delay at different rates, comparable to those observed after time zone shifts. Sleep was shorter in simulated weightlessness than in normal ambulatory age-matched subjects, consistent with the shorter sleep durations characteristic of space flight. These results confirm the disruptive effects of wake-rest schedule shifts on sleep and circadian rhythms. Contrary to our initial hypothesis, 5-h exposures to bright light finishing at the time of the circadian temperature minimum were not more effective at accelerating adjustment to a 12-h schedule delay than exposures coinciding with the temperature maximum. We conclude that, while bright light may accelerate adjustment to work-rest schedule delays, any such effect seems to be largely independent from the timing of the light exposure.     

Public funding of space activities: a case of semantics and misdirection

The semantic ambiguity of the word ‘space’ causes problems for both the funding of space activities and the determining of space policies. The historical practice of lumping all space activities together, to be funded by a single budgetary line, is inappropriate to the range of such activities and for the economic and strategic interests at stake: it has direct consequences for the priorities governments want to make, and can pervert the directions industry is trying to go in. While continued government support for space is imperative, given the strategic, national-development nature of many of its applications, new ways must be found of allocating it a budget that take account of the diversity of the areas in which it plays a role.     

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.     

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.     

An international symbol for the sustained exploration of space

As humanity prepares to extend its reach beyond low-Earth-orbit for the first time since the 1970s, a new symbol of international cooperation is needed to further promote the message of peace and collaboration such exploration entails. The space race that occurred between the USSR and the USA is an ill-suited model for long-term sustained space exploration because it is too costly and too resource-intensive for a single nation to bear. While competition is healthy for technology development, the success of a sustained space exploration strategy lies beyond technological capabilities. It lies in international cooperation, space policy, and public support. Without these, no program can realistically achieve a sustained presence in space beyond low-Earth orbit. To this effect, this paper proposes a cost-effective first step in the form of a universal symbol which, when placed alongside national flags displayed on hardware and astronaut/cosmonaut/taikonaut flight-suits, would send a strong message to the world that space exploration is done for the benefit of humanity as a whole, not just for spacefaring nations. The “Blue Marble”, the first complete picture of Earth taken from space by humans in 1972, fits this universally appealing symbol. This symbol requires no political collaboration between countries, yet is an image that anyone, anywhere in the world, can relate to regardless of nationality, ethnic origin or religious beliefs. Placed on the shoulder pads of human ’nauts – ambassadors of planet Earth – or prominently displayed on spacebound hardware, this symbol would send a universal message to present and future generations that, in space, our planet is working together for the benefit of everyone.     

Dominance in space — a new means of exercising global power?

Sustained criticism of the strategy of nuclear deterrence and technological developments in the military uses of space suggest that nuclear weapons may soon be replaced by control of outer space as the USA and USSR's primary instrument of global power. This article traces the change in perceptions of nuclear weapons policy and assesses the potential of outer space as a means of control, and the plans of the two superpowers for its exploitation, especially in the military sphere. The consequences for Western Europe of a shift from nuclear to space-based weapons as the primary guarantor of national security are also discussed.     

Strategy for capturing of a tumbling space debris

In general space debris objects do not possess much convenient features and are non-cooperative. In such cases, since the conditions for capture are not favorable, tracking errors will lead to loading, and momentum transfer will occur during the capture process.In most cases, detailed mass and inertial characteristics of the target are unknown, either because design details are unavailable or due to changes as a result of damage sustained when failure occurred or gradual degradation over the years, and this makes impedance matching of the capture arm force control system difficult.This led to us to devise a “joint virtual depth control” algorithm for robot arm control, which brakes the rotation of a target with unknown inertia. This paper deals with a removal work strategy and control method for capturing and braking a tumbling, non-cooperative target space debris.We propose a new brush type contactor as end-effecter of a robot arm for reducing the rotational rate of the target debris. As a means for relieving the loads generated during target tapping, in addition to joint compliance control we propose a new control method that controls the arm tip force according to a contact force profile.     

As assessment of habitat pressure, oxygen fraction, and EVA suit design for space operations

At high cabin pressure [e.g. 1013 hPa (14.7 psi) 21% O2] there are serious issues relative to specification of suit pressure and the need for prebreathing. A high pressure suit will be costly but use of the existing, flexible suit requires up to 6 h of prebreathing. Or one could use a cabin pressure of 700 hPa (10.2 psi) prior to extravehicular activity (EVA) in order to use the existing suit with only 1 h of prebreathing. If these normal cabin pressures and O2 levels are utilized, existing physiological and medical databases apply, providing a known basis for evaluating effects of long duration space missions. If a 345 hPa (5 psi), 70-100% O2 atmosphere is adopted the existing suit can be used with no prebreathing required. However, there is no reference database on physiological effects under the conditions of lower pressure and higher O2 concentration. This paper considers the major issues involved in defining habitat pressure, O2 fraction, and EVA suit design for operations in space. A preliminary model for evaluating habitat/suit pressure and O2% strategies is presented.