On Earth, tissue weight generates compressive forces that press on body structures and act on the walls of vessels throughout the body. In microgravity, tissues no longer have weight, and tissue compressive forces are lost, suggesting that individuals who weigh more may show greater effects from microgravity exposure. One unique effect of long-duration microgravity exposure is spaceflight-associated neuroocular syndrome (SANS), which can present with globe flattening, choroidal folds, optic disk edema, and a hyperopic visual shift. To determine whether weight or other anthropometric measures are related to ocular changes in space, we analyzed data from 45 individual long-duration astronauts (mean age 47, 36 male, 9 female, mean mission duration 165 days) who had pre- and postflight measures of disk edema, choroidal folds, and manifest ocular refraction. The mean preflight weights of astronauts who developed new choroidal folds [78.6 kg with no new folds vs. 88.6 kg with new folds ( F = 6.2, P = 0.02)] and disk edema [79.1 kg with no edema vs. 95 kg with edema ( F = 9.6, P = 0.003)] were significantly greater than those who did not. Chest and waist circumferences were also significantly greater in those who developed folds or edema. The odds of developing disk edema or new choroidal folds were 55% in the highest- and 9% in the lowest-weight quartile. In this cohort, no women developed disk edema or choroidal folds, although women also weighed significantly less than men [62.9 vs. 85.2 kg ( F = 53.2, P < 0.0001)]. Preflight body weight and anthropometric factors may predict microgravity-induced ocular changes.

In-situ lunar oxygen production has the potential to reduce the cargo mass launched from Earth necessary to sustain a lunar base. As research and development in lunar oxygen production continue, modeling tools are being used to help characterize the many possible system architectures and guide decisions for future plant designs. Using the previously built NASA In-Situ Resource Utilization (ISRU) System Model, an optimization tool was developed to facilitate exploration of the design space of the different system architectures represented in the model. For each architecture, an optimization of the continuous design space is performed using a gradient-based search. In instances when the gradient-based search cannot converge, the tool changes to simulated annealing, a heuristic method. Nine primary lunar oxygen production system architectures were optimized to minimize system mass for oxygen production levels from 500 kg/yr to 6000 kg/yr. Good designs minimized mass and maximized produced oxygen with system masses in the range of 100 kg to 700 kg. Preliminary results show that two particular architectures populate the Pareto-optimal front of best designs for most production levels, making them attractive for further investigation. An economy of scale of .837 was found using a power law regression, indicating that some economy of scale exists (values less than one have economy of scale) and that launching fewer, higher-capacity plants will be less massive overall than many small-capacity plants to achieve the same total production level. A simplified comparison of lunar-produced oxygen for crew breathing supply and ECLSS (environmental control and life support systems) technologies was performed with a space logistics planning tool, SpaceNet. For all but the most advanced ECLSS technologies, use of in-situ oxygen over a 10-year campaign resulted in more than 12,000 kg of consumables cargo launch mass savings. Nomenclature = economy of scale C = investment cost

Blood drains from the brain via two primary pathways: the internal jugular veins (IJV) and the vertebral venous plexus (VP) (Gisolf et al., 2004). On Earth, the IJV drainage pathway predominates supine (66% of blood flow), whereas the VP is the main pathway upright (Doepp et al., 2004). In microgravity, the drainage pathway through the IJV is reduced to varying

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