The space station assembly phase: Flight telerobotic servicer feasibility, volume 1

The question is addressed which was raised by the Critical Evaluation Task Force (CETF) analysis of the space station: if a Flight Telerobotic Servicer (FTS) of a given technical risk could be built for use during space station assembly, could it save significant extravehicular (EVA) resources. Key issues and trade-offs associated with using an FTS to aid in space station assembly phase tasks such as construction and servicing are identified. A methodology is presented that incorporates assessment of candidate assembly phase tasks, telerobotics performance capabilities, development costs, operational constraints (STS and proximity operations), maintenance, attached payloads, and polar platforms. A discussion of the issues is presented with focus on potential FTS roles: (1) as a research-oriented test bed to learn more about space usage of telerobotics; (2) as a research-based test bed with an experimental demonstration orientation and limited assembly and servicing applications; or (3) as an operational system to augment EVA, to aid the construction of the space station, and to reduce the programmatic (schedule) risk by increasing the flexibility of mission operations. During the course of the study, the baseline configuration was modified into Phase 1 (a station assembled in 12 flights), and Phase 2 (a station assembled over a 30 flight period) configuration

The modeling of human functional arm reach

Includes bibliographical references (pages 38-42)The determination of human functional arm reach for purposes of designing work stations to accommodate specific user populations is a continuing problem. Functional reach is influenced by anthropometric factors, workspace geometry, and task requirements to the extent that costly programs are required to accurately determine reach capabilities for each new configuration of these factors. Development of a mathematical prediction model to provide the necessary estimates of reach requirements initially necessitates a demonstration of the feasibility of predicting reach from associated anthropometric variables.\ud Measures of arm reach at twenty-six points in space, as well as height, weight, age, arm length, shoulder height and shoulder breadth for a sample of 110 U.S. truck drivers were treated by stepwise multiple regression analysis to develop linear equations which predict reach from values of the other six anthropometric variables.\ud Of the six variables, height was uniformly the best predictor, with age and weight contributing significantly to the variance in reach accounted for. Arm length, shoulder height, and shoulder breadth were negligible contributors to prediction and were eliminated from the final form of the prediction equations. At best, however, the variables chosen as predictors of reach failed to account for more than twenty-seven percent of the variance in arm reach. This model of reach was consequently considered an inadequate demonstration of the feasibility of arm reach prediction from anthropometric variables.\ud Several amendments to the procedures employed in this study were proposed, including means to obtain more objective measures of reach, refinement of the variables used as predictors, and identification of additional variables causally related to reach

Reduced Serum and Hypoxic Culture Conditions Enhance the Osteogenic Potential of Human Mesenchymal Stem Cells

Current protocols for inducing osteogenic differentiation in mesenchymal stem/stromal cells (MSCs) in culture for tissue engineering applications depend on the use of biochemical supplements. However, standard in vitro culture conditions expose cells to ambient oxygen concentrations and high levels of serum (21% O(2), 10% FBS) that do not accurately recapitulate the physiological milieu. While we and others have examined MSC behavior under hypoxia, the synergistic effect of low serum levels, such as those present in ischemic injury sites, on osteogenic differentiation has not been clearly examined. We hypothesized that a concomitant reduction of serum and O(2) would enhance in vitro osteogenic differentiation of MSCs by more accurately mimicking the fracture microenvironment. We show that serum deprivation, in conjunction with hypoxia, potentiates osteogenic differentiation in MSCs. These data demonstrate the role of serum levels in regulating osteogenesis and its importance in optimizing MSC differentiation strategies