Strategic, technological and ethical aspects of establishing colonies on Moon and Mars

With the vast experience gained by Aerospace Community in the last five decades, the natural future course of action will be to expand Space Exploration. Our understanding of Moon is relatively better with a number of unmanned satellite missions carried out by the leading Space Agencies and manned missions to Moon by USA. Also a number of unmanned satellite missions and surface rover missions were carried out to Mars by those Space agencies generating many new details about Mars. While the future exploration efforts by global community will also be centered obviously on Moon and Mars, it is noteworthy that already NASA had declared its plans for establishing a Surface Base on Moon and developing the technical infrastructure required. Surface Bases on Moon and Mars give rise to a number of strategic, technical and ethical issues both in the process of development, and in the process of establishing the bases. The strategic issues related to Moon and Mars Surface Bases will be centered around development of enabling technologies, cost of the missions, and international cooperation. The obvious path for tackling both the technological development and cost issues will be through innovative and new means of international cooperation. International cooperation can take many forms like—all capable players joining a leader, or sharing of tasks at system level, or all players having their independent programmes with agreed common interfaces of the items being taken to and left on the surface of Moon/Mars. Each model has its own unique features. Among the technical issues, the first one is that of the Mission Objectives—why Surface Bases have to be developed and what will be the activity of crew on Surface Bases? Surface Bases have to meet mainly the issues on long term survivability of humans on the Mars/Moon with their specific atmosphere, gravity and surface characteristics. Moon offers excellent advantages for astronomy while posing difficulties with respect to solar power utilization and extreme temperature variations. Hence the technical challenges depend on a number of factors starting from mission requirements. Obviously the most important technical challenge to be addressed will be in the areas of crew safety, crew survivability, adequate provision to overcome contingencies, and in-situ resource utilization. Towards this, new innovations will be developed in areas such as specialized space suits, rovers, power and communication systems, and ascent and descent modules. The biggest ethical issue is whether humankind from Earth is targeting ‘habitation’ or ‘colonization’ of Moon/Mars. The next question will be whether the in-situ resource exploitation will be only for carrying out further missions to other planets from Moon/Mars or for utilization on Earth. The third ethical issue will be the long term impact of pollution on Moon/Mars due to technologies employed for power generation and other logistics on Surfaces. The paper elaborates the views of the authors on the strategic, technical and ethical aspects of establishing Surface Bases and colonies on Moon and Mars. The underlying assumptions and gray areas under each aspect will be explained with the resulting long-term implications.     

Optical methods for non-contact measurements of membranes

Structures for space applications very often suffer stringent mass constraints. Lightweight structures are developed for this purpose, through the use of deployable and/or inflatable beams, and thin-film membranes. Their inherent properties (low mass and small thickness) preclude the use of conventional measurement methods (accelerometers and displacement transducers for example) during on-ground testing. In this context, innovative non-contact measurement methods need to be investigated for these stretched membranes.The object of the present project is to review existing measurement systems capable of measuring characteristics of membrane space-structures such as: dot-projection videogrammetry (static measurements), stereo-correlation (dynamic and static measurements), fringe projection (wrinkles) and 3D laser scanning vibrometry (dynamic measurements).Therefore, minimum requirements were given for the study in order to have representative test articles covering a wide range of applications. We present test results obtained with the different methods on our test articles.     

Effect of physical fitness and training on physiological responses to hypogravity.

The studies on the orthostatic tolerance during the hypodynamics exposure seem to be significant in connection with the selection, training and health maintenance of astronauts. Using male human subjects of various physical fitness levels, fluctuations of their physical fitness through 2 weeks of vigorous athletic training were measured in many parameters. For some of the subjects, the effects of 6 hr thermal neutral water immersion exposure in head out supine position on the physical fitness parameters and orthostatic tolerability were compared before training with after training. The results obtained were as follows: (1) Before training, orthostatic tolerability before hypodynamics exposure increased, following the physical fitness levels; the value after the hypodynamics exposure decreased in all the cases, but no differences were observed between the physical fitness levels. (2) As a result of training an increase of the physical fitness capacity was observed. The increase of orthostatic tolerability before hypodynamics exposure was noticed except for athletes. (3) Before hypodynamics exposure the urinary excretion of noradrenaline on non-athlete subjects increased as the physicsl fitness level increased. The values were decreased by physical training, the more so the better the physical fitness. After hypodynamics exposure the same relation was observed. But for athletes the values remain more stable and the decrease by hypodynamics exposure was not so distinctive. Such decreased reaction to hypodynamic conditions seems to reveal the neuro hormonal mechanism for the detrimental adaptation of athletes to hypodynamics. These results suggest that stable athletes do not always have low orthostatic tolerability, but do not respond well to hypodynamic conditions, at least from the orthostatic point of view. The mechanism seems related to sympathetic nerve activity.     

Unloading law for a LEO spacecraft with two-gimbals solar array

The purpose of this paper is to present a modified cross-product unloading law that can be used to provide an open-loop compensation control design to counteract the predominant effects of the gravity gradient torque. The modified cross-product unloading law, is successfully applied to a three-axis stabilized, nadir-pointed LEO spacecraft with two-gimbals solar array. The variation of the two solar array orientations can significantly change the spacecraft's moment of inertia during the nominal operation mode, which can produce significant momentum accumulation in the roll–yaw body plane and cause large yaw pointing error. A rigorous study of momentum management performance capability has been conducted by using a high-fidelity performance simulation software that contains models of four environmental disturbance torque (gravity gradient, aerodynamic, solar, and magnetic). The simulation results show that the proposed momentum unloading control law has enabled a substantial reduction in the maximum accumulated roll momentum, which results in improving the pointing accuracy of the LEO spacecraft enormously.     

Arctic — Antarctic night airglow comparisons

Airglow observations from Eureka, Canada (80° N) and South Pole (90° S) observatories have been made through the winters during the past 1/2 solar cycle. Seasonal and solar activity changes are evident. The intensities also show temporal variations due to wave activity, with periods from 6 hours to 15 days, particularly in the Arctic OI and Na emissions. Comparisons are made of the OH intensities measured at Eureka and South Pole during their respective winters.     

Waste bioregeneration in life support CES: development of soil organic substrate.

An experimental model of matter turnover in the biotic cycle: plants (plant biomass) --> mushrooms (residual substrate + mushroom fruit bodies) --> worms (biohumus) --> microorganisms (soillike substrate) --> plants is presented. The initial mass of soillike substrate was produced from wheat plants grown in a hydroponic system. Three cycles of matter turnover in the biotic cycle were carried out. Grain productivity on soillike substrate was 21.87 g/m2 day. The results obtained were used for designing a CES containing man, plants, soillike substrate, bioregeneration module and aquaculture. It was shown, that the circulating dry mass of the CES is 756 kg. The main part (88%) of the circulating mass accumulates in the soillike substrate and bioregeneration module.     

Automorphosis of higher plants on a 3-D clinostat.

On a three-dimensional (3-D) clinostat, various plant organs developed statocytes capable of responding to the gravity vector. The graviresponse of primary roots of garden cress and maize grown on the clinostat was the same as the control roots, whereas that of maize coleoptiles was reduced. When maize seedlings were grown in the presence of 10(-4) M gibberellic acid and kinetin, the graviresponse of both roots and shoots was suppressed. The corresponding suppression of amyloplast development was observed in the clinostatted and the hormone-treated seedlings. Maize roots and shoots showed spontaneous curvatures in different portions on the 3-D clinostat. The hormone treatment did not significantly influence such an automorphic curvature. When the root cap was removed, maize roots did not curve gravitropically. However, the removal suppressed the automorphic curvatures only slightly. On the other hand, the removal of coleoptile tip did not influence its graviresponse, whereas the spontaneous curvature of decapitated coleoptiles on the clinostat was strongly suppressed. Also, cytochalasin B differently affected the gravitropic and the automorphic curvatures of maize roots and shoots. From these results it is concluded that the graviperception and the early processes of signal transmission are unnecessary for automorphoses under simulated microgravity conditions. Moreover, the results support the view that the amyloplasts act as statoliths probably via an interaction with microfilaments.     

Estimation near "Zero Information" points: angle-of-arrival near the endfire

We examine large-sample properties of the maximum- likelihood estimator (MLE) in the vicinity of points where the Fisher information measure (FIM) equals zero. Under mild regularity conditions the MLE is asymptotically efficient and therefore lower bounded by the Cramer-Rao lower bound (CRLB) [5], which diverges for such points. When a linear sensor array is used for angle-of-arrival (AOA) estimation, the CRLB diverges as the AOA approaches pi/2. We provide new results characterizing the MLE performance in the AOA problem.     

Interference in Frequency-Locked Doppler Tracking Loops

The effects of interference on frequency-locked Doppler tracking loops are investigated. Conditions for jump from locking on the desired signal to locking on the interfering signal are established. Parasitic frequency modulation of the desired signal results when the other signal interferes with it. The index of this parasitic modulation as a function of the interference-to-desired signal amplitude ratio is computed. Both critical amplitude ratio and critical parasitic modulation index at the occurrence of jump are derived. Comparing frequency-locked loops with phase-locked loops with phase-locked loops in the presence of interference shows the former performs better for most cases of practical importance in Doppler tracking systems.     

A New FET-Bipolar Combinational Power Semiconductor Switch

A novel FET-BJT combinational transistor configuration is proposed and demonstrated using discrete devices. This new transistor features fast switching, very simple drive requirement, elimination of reverse bias second breakdown, and good utilization of semiconductor chip area. Initial results indicate that power hybrid construction of the device is essential to enhance the current rating of the device.