Recovery of lower limb function following 6 weeks of non-weight bearing

Skeletal muscle weakness and atrophy occur following an extended period of decreased use, including space flight and limb unloading. It is also likely that affected muscles will be susceptible to a re-loading injury when they begin return to earth or weight bearing. However, there is a paucity of literature evaluating the response of human unloaded muscle to exercise and return to activity.

The purpose of this pilot study was to evaluate the soreness, function and strength response of muscle to re-loading in seven patients who were non-weight bearing for 6 weeks, compared to five healthy subjects.

Function improved significantly over time for the patients but was still less than the healthy subjects over 12 weeks of physiotherapy. Concentric quadriceps muscle strength increased significantly over time for the patients. There was considerable variability in the patients’ reports of muscle soreness but there were no significant changes over time or between groups.     

Neutral buoyancy and sleep-deprived serum factors alter expression of cytokines regulating osteogenesis

We examined expression of genes associated with cytokine production, and genes implicated in regulating bone metabolism, in bone stromal and osteoblast cells incubated under standard ground conditions and under conditions of neutral buoyancy, and in the presence/absence of serum from normal or sleep-deprived mice. We observed a clear interaction between these two conditions (exposure to neutral buoyancy and serum stimulation) in promoting enhanced osteoclastogenesis. Both conditions independently altered expression of a number of cytokines implicated in the regulation of bone metabolism. However, using stromal cells from IL-1 and TNFx cytokine(r) KO mice, we concluded that the increased bone loss under microgravity conditions was not primarily cytokine mediated.     

Ground based ISS payload microgravity disturbance assessments

In order to verify that the International Space Station (ISS) payload facility racks do not disturb the microgravity environment of neighboring facility racks and that the facility science operations are not compromised, a testing and analytical verification process must be followed. Currently no facility racks have taken this process from start to finish. The authors are participants in implementing this process for the NASA Glenn Research Center (GRC) Fluids and Combustion Facility (FCF). To address the testing part of the verification process, the Microgravity Emissions Laboratory (MEL) was developed at GRC. The MEL is a 6 degree of freedom inertial measurement system capable of characterizing inertial response forces (emissions) of components, sub-rack payloads, or rack-level payloads down to 10(-7) g's. The inertial force output data, generated from the steady state or transient operations of the test articles, are utilized in analytical simulations to predict the on-orbit vibratory environment at specific science or rack interface locations. Once the facility payload rack and disturbers are properly modeled an assessment can be made as to whether required microgravity levels are achieved. The modeling is utilized to develop microgravity predictions which lead to the development of microgravity sensitive ISS experiment operations once on-orbit. The on-orbit measurements will be verified by use of the NASA GRC Space Acceleration Measurement System (SAMS). The major topics to be addressed in this paper are: (1) Microgravity Requirements, (2) Microgravity Disturbers, (3) MEL Testing, (4) Disturbance Control, (5) Microgravity Control Process, and (6) On-Orbit Predictions and Verification.     

Social desirability bias in personality testing: implications for astronaut selection

The assessment of personality is recognized by space agencies as an approach to identify candidates likely to perform optimally during spaceflights. In the use of personality scales for selection, the impact of social desirability (SD) has been cited as a concern. Study 1 addressed the impact of SD on responses to the Personality Characteristic Inventory(PCI) and NEO-FFI. This was achieved by contrasting scores from active astronauts (N=65) with scores of successful astronaut applicants (N=63), and between pilots applicants (N=1271) and pilot research subjects (N=120). Secondly, personality scores were correlated with scores on the Marlow Crown Social Desirability Scale among applicants to managerial positions (N=120). The results indicated that SD inflated scores on PCI scales assessing negative interpersonal characteristics, and impacted on four of five scales in NEO-FFI. Still, the effect sizes were small or moderate. Study 2 addressed performance implications of SD during an assessment of males applying to work as rescue personnel operations in the North Sea (N=22). The results showed that SD correlated negatively with cognitive test performance, and positively with discrepancy in performance ratings between self and two observers. In conclusion, caution is needed in interpreting personality scores in applicant populations. SD maybe a negative predictor for performance under stress.     

Multibeam array designed for use in a maritime system using an OTS platform

The study, based on actual hardware specifically developed for a multibeam array, has been concerned with the definition of a payload compatible with the requirements of a second generation maritime system. The proposed payload designed to operate in an OTS spacecraft has the following performance. 19 beam global coverage, give 70 Maritime channels having 52.4 dB Hz quality in deep fades. Mass of payload incl. antenna, 112 kg; d.c. power consumption, 334 W; Operational life time, 7 yr.     

Empirical models of the thermosphere and requirements for improvements

The different types of variation in the thermosphere are briefly examined and the solar-activity effect is singled out for special attention. To this day, empirical models have made use of the decimetric solar flux F_10.7 as an index of the variable XUV radiation from the sun. To account for the change in the relative intensity of the different types of emissions in the course of the solar cycle, F_10.7 is made to perform double duty: The daily values are used to represent the day-to-day and “27-day” variations, while its averages over several solar rotations are used to represent the variations with the 11-year cycle. The availability of direct solar XUV data should eventually eliminate the need for such a make-shift procedure. Accuracy and continuity requirements of XUV intensity measurements are discussed and a strategy is outlined for sorting out the relevant features from the observational material and putting them to practical use in thermospheric modeling. It is suggested that future models of the diurnal and the geomagnetic variation use as a guide theoretical models which have achieved considerable success in qualitatively representing the observed phenomena.     

Electric Field Detection and Ranging of Aircraft

The electric field transported by charged aircraft during free flight can be observed quantitatively in distances of up to some 100 m. A system of three plane sensors arranged in the corners of a triangle or the Earth surface is described, by which the flight path of aircraft is detected in the range of 40 to 500 m with velocities of approximately 50 m/s. The theory and typical experimental results are discussed.     

On ionospheric investigations by coherent radiowaves emitted from artificial Earth satellites

Results of radio-investigations of the ionosphere with the help of coherent radiowaves emitted by beacons placed on artificial Earth satellites are given. The data discussed cover the period from 1958, after the launch of Sputniks 1 and 3, until the last years, when the geostationary satellites ATS were launched. It is shown that up to the present justice has not be done in these experiments to investigations of the local properties of the near Earth plasma. This is a great deficiency in this field of investigation. Data are given which illustrate results of investigations of local ionospheric characteristics. Such data may help to solve some problems in the present stage of the near Earth plasma study. A new possibility of radio-investigation of the near Earth plasma with the help of a chain of satellites connected together is pointed out.     

The X-ray background 2–50 kev: A superposition of known sources,or evidence of a new component?

The contribution of the canonical Quasars to the XRB 2–50 keV is not likely to exceed 50%. Nay, consideration of X-ray selection effects results in a further reduction of the value of sensible estimators for the intensity ratio L_X/L_O; in addition, recent counts of radioloud and radio-quiet Quasars definitely limit the number of faint sources. A missing component with definite spectral properties should comprise a sizeable fraction of the XRB.     

Enhanced Power Generation of GSS4PS by Optical Solar Reflectors

A novel arrangement is proposed to enhance the power generation capabilities of a gravitationally stabilized solid-state-satellite solar-power station (GSS4PS) spherical solar collector. The unilluminated portion of a GSS4PS is illuminated by employing optical solar reflectors. The different mechanisms required for implementation of this arrangement are already space proven. The detailed study of this arrangement made by the authors reveals that practical realization of this concept will enhance the power generation capability of the GSS4PS and simultaneously reduce the weight per unit power and cost per unit power in GSS4PS spherical solar collectors.