Search Our Scientific Publications & Authors

Acta Astronaut 2018 Jul 23;148:294-300. Epub 2018 Apr 23.

BioServe Space Technologies, Aerospace Engineering Sciences Department, University of Colorado, Boulder, 80309, USA.

Biofilm growth has been observed in Soviet/Russian (Salyuts and Mir), American (Skylab), and International (ISS) Space Stations, sometimes jeopardizing key equipment like spacesuits, water recycling units, radiators, and navigation windows. Biofilm formation also increases the risk of human illnesses and therefore needs to be well understood to enable safe, long-duration, human space missions. Here, the design of a NASA-supported biofilm in space project is reported. Read More

Acta Astronaut 2017 Mar 18;132:268-281. Epub 2016 Dec 18.

Dept. of Earth Sciences, Brock University, St. Catharines, ON, Canada L2S 3A1.

We tested science operations strategies developed for use in remote mobile spacecraft missions, to determine whether reconnoitering a site of potential habitability prior to in-depth study (a walkabout-first strategy) can be a more efficient use of time and resources than the linear approach commonly used by planetary rover missions. Two field teams studied a sedimentary sequence in Utah to assess habitability potential. At each site one team commanded a human "rover" to execute observations and conducted data analysis and made follow-on decisions based solely on those observations. Read More

Acta Astronaut 2016 Jun;123:16-25

NASA, Ames Research Center, Moffett Field, CA 94035, Bldg. N-245, MS-245-3.

Mars Sample Return is the highest priority science mission for the next decade as recommended by the 2011 Decadal Survey of Planetary Science [1]. This article presents the results of a feasibility study for a Mars Sample Return mission that efficiently uses emerging commercial capabilities expected to be available in the near future. The motivation of our study was the recognition that emerging commercial capabilities might be used to perform Mars Sample Return with an Earth-direct architecture, and that this may offer a desirable simpler and lower cost approach. Read More

Acta Astronaut 2016 09 10;126:411-423. Epub 2016 May 10.

SGT/NASA Ames Research Center, United States.

This work provides an efficiency analysis of the LightForce space debris collision avoidance scheme in the current debris environment and describes a simulation approach to assess its impact on the long-term evolution of the space debris environment. LightForce aims to provide just-in-time collision avoidance by utilizing photon pressure from ground-based industrial lasers. These ground stations impart minimal accelerations to increase the miss distance for a predicted conjunction between two objects. Read More

Acta Astronaut 2014 Feb;94(2):807-812

Department of Radiation Oncology, 3620 Hamilton Walk, 183 John Morgan Building, University of Pennsylvania, Philadelphia, PA, 19104, USA.

Changes in intracranial pressure (ICP) during space flight have stimulated an area of research in space medicine. It is widely speculated that elevations in ICP contribute to structural and functional ocular changes, including deterioration in vision, which is also observed during space flight. The aim of this study was to investigate changes in OP occurring as a result of ionizing radiation exposure (at doses and dose-rates relevant to solar particle event radiation). Read More

Acta Astronaut 2013 Nov;92(1):89-96

Integrative Skeletal Adaptation & Genetics Laboratory, Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA.

A single exposure to hindlimb unloading leads to changes in body mass, body composition and bone, but the consequences of multiple exposures are not yet understood. Within a 18wk period, adult C57BL/6 male mice were exposed to one (1x-HLU), two (2x-HLU) or three (3x-HLU) cycles of 2 wk of hindlimb unloading (HLU) followed by 4 wk of reambulation (RA), or served as ambulatory age-matched controls. µCT longitudinally tracked changes in abdominal adipose and lean tissues, lumbar vertebral apparent volumetric bone mineral density (vBMD) and upper hindlimb muscle cross-sectional area before and after the final HLU and RA cycle. Read More

Acta Astronaut 2013 Nov;92(1):79-88

Stony Brook University, Department of Biomedical Engineering, Bioengineering Building, Rm 215, Stony Brook, NY 11794-5281, United States.

Microgravity induced bone loss represents a critical health problem in astronauts, particularly occurred in weight-supporting skeleton, which leads to osteopenia and increase of fracture risk. Lack of suitable evaluation modality makes it difficult for monitoring skeletal status in long term space mission and increases potential risk of complication. Such disuse osteopenia and osteoporosis compromise trabecular bone density, and architectural and mechanical properties. Read More

Acta Astronaut 2013 Nov;92(1):73-78

Department of Medicine, University of California San Francisco and Endocrine Research Unit, San Francisco Veterans Affairs Medical Center, 4150 Clement St, 111N, San Francisco, CA 94121, USA.

Skeletal loading and unloading has a pronounced impact on bone remodeling, a process also regulated by insulin-like growth factor 1 (IGF-1) signaling. Skeletal unloading leads to resistance to the anabolic effect of IGF-1, while reloading after unloading restores responsiveness to IGF-1. However, a direct study of the importance of IGF-1 signaling in the skeletal response to mechanical loading remains to be tested. Read More

Acta Astronaut 2013 Nov;92(1):15-20

Dept. of Medicine, UCSD, La Jolla, CA, USA ; Dept. of Radiology, UCSD, La Jolla, CA, USA.

Rationale: Exposure to extraterrestrial dusts is an almost inevitable consequence of any proposed planetary exploration. Previous studies in humans showed reduced deposition in low-gravity compared with normal gravity (1G). However, the reduced sedimentation means that fewer particles deposit in the airways, increasing the number of particles transported to the lung periphery where they eventually deposit albeit at a smaller rate than in 1G. Read More

Acta Astronaut 2012 Aug;77:207-213

Division of Sleep and Chronobiology, Department of Psychiatry, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, 19104, USA.

Several laboratories have found large, highly reliable individual differences in the magnitude of cognitive performance, fatigue and sleepiness, and sleep homeostatic vulnerability to acute total sleep deprivation and to chronic sleep restriction in healthy adults. Such individual differences in neurobehavioral performance are also observed in space flight as a result of sleep loss. The reasons for these stable phenotypic differential vulnerabilities are unknown: such differences are not yet accounted for by demographic factors, IQ or sleep need, and moreover, psychometric scales do not predict those individuals cognitively vulnerable to sleep loss. Read More

Acta Astronaut 2012 ;79:61-66

Medical Student, McGill University. Montreal, Quebec.

In the coming decades, as we continue our path of space exploration beyond Earth's orbit, we will be required to provide sound medical and surgical care for the safety of space travellers and space flight participants. A few investigations have taken place in the field of surgery in space. In this paper, the authors review the present literature in order to identify possible limitations that currently exist and that could impair our ability to provide surgical care during spaceflight, from the pre-operative to the post-operative period. Read More

Acta Astronaut 2011 Dec;69(11-12):949-959

Unit of Experimental Psychiatry, Division of Sleep and Chronobiology, Department of Psychiatry, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania.

The Psychomotor Vigilance Test (PVT) objectively assesses fatigue-related changes in alertness associated with sleep loss, extended wakefulness, circadian misalignment, and time on task. The standard 10-min PVT is often considered impractical in applied contexts. To address this limitation, we developed a modified brief 3-min version of the PVT (PVT-B). Read More

Acta Astronaut 2008 Sep;63(5-6):594-602

Department Of Biomedical Engineering, The Johns Hopkins University School Of Medicine, Baltimore, MD.

Flying a parabolic trajectory in an aircraft is one of the few ways to create freefall on Earth, which is important for astronaut training and scientific research. Here we review the physics underlying parabolic flight, explain the resulting flight dynamics, and describe several counterintuitive findings, which we corroborate using experimental data. Typically, the aircraft flies parabolic arcs that produce approximately 25 seconds of freefall (0 g) followed by 40 seconds of enhanced force (1. Read More

Acta Astronaut 2008 ;63(7-10):833-840

Division of Sleep and Chronobiology, Department of Psychiatry, and Center for Sleep and Respiratory Neurobiology, University of Pennsylvania School of Medicine, Philadelphia, PA, USA.

The demands of sustaining high levels of neurobehavioral performance during space operations necessitate precise scheduling of sleep opportunities in order to best preserve optimal performance. We report here the results of the first split-sleep, dose-response experiment involving a range of sleep/wake scenarios with chronically reduced nocturnal sleep, augmented with a diurnal nap. To characterize performance over all combinations of split sleep in the range studied, we used response surface mapping methodology. Read More

Acta Astronaut 2005 Nov;57(9):713-21

Department of Kinesiology, University of Minnesota, Minneapolis, MN 55455, USA.

The designation of a simple, non-invasive, and highly precise method to monitor the thermal status of astronauts is important to enhance safety during extravehicular activities (EVA) and onboard emergencies. Finger temperature (Tfing), finger heat flux, and indices of core temperature (Tc) [rectal (Tre), ear canal (Tec)] were assessed in 3 studies involving different patterns of heat removal/insertion from/to the body by a multi-compartment liquid cooling/warming garment (LCWG). Under both uniform and nonuniform temperature conditions on the body surface, Tfing and finger heat flux were highly correlated with garment heat flux, and also highly correlated with each other. Read More

Acta Astronaut 2005 Jul-Oct;57(2-8):676-83

NASA Johnson Space Center, Houston, TX, 77058, USA.

The Vision for Space Exploration invokes activities on the Moon in preparation for exploration of Mars and also directs International Space Station (ISS) research toward the same goal. Lunar missions will emphasize development of capability and concomitant reduction of risk for future exploration of Mars. Earlier papers identified three critical issues related to the so-called NASA Mars Design Reference Mission (MDRM) to be addressed in the lunar context: (a) safety, health, and performance of the human crew; (b) various modalities of mission operations ranging surface activities to logistics, planning, and navigation; and (c) reliability and maintainability of systems in the planetary environment. Read More

Acta Astronaut 2005 Jul-Oct;57(2-8):661-75

International Space University, France.

The paper addresses the evolution of the Canadian Space Station Program between 1981 and 2003. Discussions with potential international partners, aimed at jointly developing the current International Space Station program, were initiated by NASA in 1982. Canada chose, through the further development of the technologies of Canadarm on the space shuttle, to provide and operate an advanced and comprehensive external robotics system for space station, and to use the space station for scientific and commercial purposes. Read More

Acta Astronaut 2005 Jul-Oct;57(2-8):649-60

NASA Ames Research Center, Moffett Field, CA 94035-1000, USA.

As we move boldly forward into the 21st century, there has rarely been a more exciting time in which to contemplate the future of space exploration. The President of the United States has made a new and ambitious commitment to exploration of the solar system and beyond. Robotic partners will play a vital role in ensuring that the Vision is truly "sustainable and affordable". Read More

Acta Astronaut 2005 Jul-Oct;57(2-8):634-41

Department of Psychosocial Science, University of Bergen, Norway.

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. Read More

Acta Astronaut 2005 Jul-Oct;57(2-8):630-3

University of California, San Francisco, USA.

Being in space is a powerful experience that can have an enduring, positive impact on the psychological well-being of astronauts and cosmonauts. We sought to examine the frequency, intensity and distribution of such salutogenic experiences among persons who have flown in space, using a questionnaire we developed based on the scientific literature and first person accounts. All participants reported positive effects of being in space, but the degree of change varied widely, and some experiences were particularly common. Read More

Acta Astronaut 2005 Jul-Oct;57(2-8):594-603

NASA Johnson Space Center, Houston, TX, USA.

Nearly six years after the launch of the first International Space Station element, and four years after its initial occupation, the United States and our 6 international partners have made great strides in operating this impressive Earth orbiting research facility. This past year we have done so in the face of the adversity of operating without the benefit of the Space Shuttle. In his January 14, 2004, speech announcing a new vision for America's space program, President Bush affirmed the United States' commitment to completing construction of the International Space Station by 2010. Read More

Acta Astronaut 2005 Jul-Oct;57(2-8):277-87

Technical University of Munich, Germany.

The Space Elevator (SE) concept has begun to receive an increasing amount of attention within the space community over the past couple of years and is no longer widely dismissed as pure science fiction. In light of the renewed interest in a, possibly sustained, human presence on the Moon and the fact that transportation and logistics form the bottleneck of many conceivable lunar missions, it is interesting to investigate what role the SE could eventually play in implementing an efficient Earth to Moon transportation system. The elevator allows vehicles to ascend from Earth and be injected into a trans-lunar trajectory without the use of chemical thrusters, thus eliminating gravity loss, aerodynamic loss and the need of high thrust multistage launch systems. Read More

Acta Astronaut 2005 Jul-Oct;57(2-8):205-14

NASA Glenn Research Center, Cleveland Ohio 44135, USA.

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). Read More

Acta Astronaut 2005 Jul-Oct;57(2-8):161-6

Space Technology Consultant, The Glebe House, Kirkby Thore, Cumbria UK.

A long-term goal of space exploration is the development of a lunar settlement that will not only be largely self-sufficient but also contribute to the economy of the Earth-Moon system. Proposals for lunar mining and materials processing developments, as well as tourism-based applications, have appeared in the literature for many years. However, so great are the technical and financial difficulties associated with sustained lunar development that, more than 30 years after the end of the Apollo programme, there have been no practical advances towards this goal. Read More

Acta Astronaut 2005 Jul-Oct;57(2-8):156-60

European Space Agency, Headquarters, France.

After a large consultation with the scientific and industrial communities in Europe, the Aurora Space Exploration Programme was unanimously approved at the European Space Agency (ESA) Council at ministerial level in Edinburgh in 2001. This marked the start of the programme's preparation phase that was due to finish by the end of 2004. Aurora features technology development robotic and crewed rehearsal missions aimed at preparing a human mission to Mars by 2033. Read More

Acta Astronaut 2005 Jul-Oct;57(2-8):121-34

Jet Propulsion Laboratory, California Institute of Technology, USA.

NASA has initiated the first of a new series of missions to augment the current Mars Program. In addition to the systematic series of planned, directed missions currently comprising the Mars Program plan, NASA has started a series of Mars Scout missions that are low cost, price fixed, Principal [correction of Principle] Investigator-led projects. These missions are intended to provide an avenue for rapid response to discoveries made as a result of the primary Mars missions, as well as allow more risky technologies and approaches to be applied in the investigation of Mars. Read More

Acta Astronaut 2005 Jul-Oct;57(2-8):81-8

Department of Environmental Biology, University of Guelph, Guelph, Canada.

Investigations of Mir, Space Shuttle, Skylab and Apollo missions report extensive colonisation of the spacecraft by bacteria and fungi, which can lead to degradative effects on spacecraft equipment and devastating effects on space-grown crops. More than 80% of terrestrial greenhouse epidemics are due to the fungal genera Phytophthora, Pythium and Fusarium, which have been found in life support system test-beds. The advent of recombinant antibody technologies, including ribosome display and phage display, has made it possible to develop antibodies against virtually any toxin or organism and allows for maturation of antibodies by in vitro molecular evolution. Read More

Acta Astronaut 2005 Jul-Oct;57(2-8):75-80

Aichi Medical University, Nagakute, Aichi, Japan.

To test the effectiveness of centrifuge-induced artificial gravity with ergometric exercise, 12 healthy young men (20.7 +/- 1.9 yr) were exposed to simulated microgravity for 14 days of -6 degrees head-down bedrest. Read More

Acta Astronaut 2005 Jul-Oct;57(2-8):67-74

SSC Institute of Biomedical Problems RAS, Moscow, Russian Federation.

Cell-to-cell interactions play an important role in all physiological processes and are mediated by humoral and mechanical factors. Mechanosensitive cells (e.g. Read More

Acta Astronaut 2005 Jul;57(1):48-58

University of Houston, Houston, TX 77204-4000, USA.

The Sasakawa International Center for Space Architecture (SICSA) is undertaking a multi-year research, planning and design study that is exploring near- and long-term commercial space development opportunities. The central goal of this activity is to conceptualize a scenario of sequential, integrated private enterprise initiatives that can carry humankind forward to Mars. Each development stage is planned as a building block to provide the economic foundation, technology advancements and operational infrastructure to support others that follow. Read More

Acta Astronaut 2005 Jul;57(1):31-6

Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germany.

We studied in a randomized, strictly controlled cross-over design, the effects of 6 days 6 degrees head-down tilt bed rest (HDT) in eight male healthy subjects in our metabolic ward. The study consisted of two periods (phases) of 11 days each in order to allow for the test subjects being their own controls. Both study phases were identical with respect to environmental conditions, study protocol and diet. Read More

Acta Astronaut 2005 Jul;57(1):22-30

Department of Space Science and Engineering, Luigi G. Napolitano, University of Naples, Napoli, Italy.

The different acceleration components on the ISS that are responsible for the generation of convective motions in a fluid cell either in the presence of density gradients or in quasi-isodense processes, are analyzed. The NASA measurements of the quasi-steady and periodic acceleration on the ISS are considered and their effects on fluid-dynamic experiments are computed and discussed under different assumptions. In particular, numerical simulations are carried out to identify the relative importance of linear and pendular accelerations, due to possible rotations of the P/L around its center of mass. Read More

Acta Astronaut 2005 May-Jun;56(9-12):1025-32

Centre for Vision Research, York University, Toronto, Ontario, Canada.

In order to measure the perceived direction of "up", subjects judged the three-dimensional shape of disks shaded to be compatible with illumination from particular directions. By finding which shaded disk appeared most convex, we were able to infer the perceived direction of illumination. This provides an indirect measure of the subject's perception of the direction of "up". Read More

Acta Astronaut 2005 May-Jun;56(9-12):1017-24

Thomas Jefferson University, Philadelphia, Pennsylvania, USA.

Light is being used as a pre-launch countermeasure to circadian and sleep disruption in astronauts. The effect of light on the circadian system is readily monitored by measurement of plasma melatonin. Our group has established an action spectrum for human melatonin regulation and determined the region of 446-477 nm to be the most potent for suppressing plasma melatonin. Read More

Acta Astronaut 2005 May-Jun;56(9-12):801-8

Institute of Cardiology and Sports Medicine, German Sports University, Cologne, Germany.

Astronauts are often on a voluntarily reduced energy intake during space missions, possibly caused by a metabolic or emotional stress response with involvement of the central serotonergic system (SES). We investigated 24 h urinary excretion (24 h-E) of serotonin (5-HT) and 5-hydroxyindol acidic acid as indicators of the SES in healthy males under two different normocaloric conditions: normal physical activity (NPA) and -6 degree head-down-tilt (HDT). HDT or NPA were randomly arranged with a recovery period of 6 months in between. Read More

Acta Astronaut 2005 May-Jun;56(9-12):1041-7

Department of Medicine, Dartmouth Medical School, Dartmouth-Hitchcock Medical Center, Lebanon, NH 03756, USA.

ISS construction and Mars exploration require extensive extravehicular activity (EVA), exposing crewmembers to increased decompression sickness risk. Improved bubble detection technologies could help increase EVA efficiency and safety. Creare Inc. Read More

Acta Astronaut 2005 May-Jun;56(9-12):1033-40

Centre for Vision Research, York University, Toronto, Ont., Canada.

We measured the amount of visual movement judged consistent with translational head movement under normal and microgravity conditions. Subjects wore a virtual reality helmet in which the ratio of the movement of the world to the movement of the head (visual gain) was variable. Using the method of adjustment under normal gravity 10 subjects adjusted the visual gain until the visual world appeared stable during head movements that were either parallel or orthogonal to gravity. Read More

Acta Astronaut 2005 May-Jun;56(9-12):1005-16

Research Center for Carbon Recycling and Energy, Tokyo Institute of Technology, Japan.

In a virtual weightless environment, subjects' orientation skills were studied to examine what kind of cognitive errors people make when they moved through the interior space of virtual space stations and what kind of visual information effectively decreases those errors. Subjects wearing a head-mounted display moved from one end to the other end in space station-like routes constructed of rectangular and cubical modules, and did Pointing and Modeling tasks. In Experiment 1, configurations of the routes were changed with such variables as the number of bends, the number of embedding planes, and the number of planes with respect to the body posture. Read More

Acta Astronaut 2005 May-Jun;56(9-12):996-1004

School of Industrial Engineering, Purdue University, West Lafayette, IN 47907-2023, USA.

Evolving space operations requirements and mission planning for long-duration expeditions require detailed examinations and evaluations of information flow dynamics, knowledge-sharing processes, and information technology use in distributed expert networks. This paper describes the work conducted with flight controllers in the Mission Control Center (MCC) of NASA's Johnson Space Center. This MCC work describes the behavior of experts in a distributed supervisory coordination framework, which extends supervisory control/command and control models of human task performance. Read More

Acta Astronaut 2005 May-Jun;56(9-12):980-95

MAIBC, M. Arch., B.E.D., Intern Architect, Canada.

The human fascination with exploring and inhabiting the space that lies beyond Earth's atmosphere continues to grow. Nevertheless, 40 years of experience to date have clearly established that humans in outer space routinely suffer significant psychological impairment arising from their stressful extraterrestrial living conditions. This paper explores those extraterrestrial conditions through the interactions between the extraordinarily harsh environment of outer space, the sensations that humans encounter in space, and the qualities of a habitat that physically interposes itself between the two. Read More

Acta Astronaut 2005 May-Jun;56(9-12):975-9

Bubble Technology Industries Inc., Chalk River, ON, Canada.

Bubble Technology Industries Inc. (BTI), with the support of the Canadian Space Agency, has finished the construction of the Canadian High-Energy Neutron Spectrometry System (CHENSS). This spectrometer is intended to measure the high energy neutron spectrum (approximately 1-100 MeV) encountered in spacecraft in low earth orbit. Read More

Acta Astronaut 2005 May-Jun;56(9-12):969-74

Department of Nuclear Engineering, The University of Tennessee, Knoxville, TN 37996-2300, USA.

Over the past two decades, hypothetical models of "worst-case" solar particle event (SPE) spectra have been proposed in order to place an upper bound on radiation doses to critical body organs of interplanetary crews on deep space missions. These event spectra are usually formulated using hypothetical extrapolations of space measurements for previous large events. Here we take a different approach. Read More

Acta Astronaut 2005 May-Jun;56(9-12):961-8

Department of Nuclear Engineering, The University of Tennessee, Knoxville, TN 37996-2300, USA.

A methodology for predicting solar particle event doses using Bayesian inference is being developed. As part of this development, we have tested criteria for categorization of new solar particle events (SPE) using calculated asymptotic doses and dose rates for the 22 SPEs that occurred in 2001. In 9 out of 22 events, our criteria for categorization would have over-predicted the range of asymptotic doses in which the tested events would have fallen. Read More

Acta Astronaut 2005 May-Jun;56(9-12):949-60

Royal Military College of Canada, Kingston, ON, Canada.

In light of the importance of the neutron contribution to the dose equivalent received by space workers in the near-Earth radiation environment, there is an increasing need for a personal dosimeter that is passive in nature and able to respond to this neutron field in real time. Recent Canadian technology has led to the development of a bubble detector, which is sensitive to neutrons, but insensitive to low linear energy transfer (LET) radiation. By changing the composition of the bubble detector fluid (or "superheat"), the detectors can be fabricated to respond to different types of radiation. Read More

Acta Astronaut 2005 May-Jun;56(9-12):937-48

Johns Hopkins Bayview Medical Center, Johns Hopkins University School of Medicine, Division of Behavioral Biology, Baltimore, MD 21224, USA.

The present report describes the development and application of a distributed interactive multi-person simulation in a computer-generated planetary environment as an experimental test bed for modeling the human performance effects of variations in the types of communication modes available, and in the types of stress and incentive conditions underlying the completion of mission goals. The results demonstrated a high degree of interchangeability between communication modes(audio, text) when one mode was not available. Additionally, the addition of time pressure stress to complete tasks resulted in a reduction in performance effectiveness, and these performance reductions were ameliorated via the introduction of positive incentives contingent upon improved performances. Read More

Acta Astronaut 2005 May-Jun;56(9-12):932-6

Veterans Affairs Medical Center 116A, University of California/San Francisco, San Francisco, CA 94121, USA.

In isolated and confined environments, two important leadership roles have been identified: the task/instrumental role (which focuses on work goals and operational needs), and the supportive/expressive role (which focuses on morale goals and emotional needs). On the International Space Station, the mission commander should be familiar with both of these aspects of leadership. In previous research involving a 135-day Mir space station simulation in Moscow and a series of on-orbit Mir space station missions during the Shuttle/Mir program, both these leadership roles were studied. Read More

Acta Astronaut 2005 May-Jun;56(9-12):923-31

Wyle Laboratories, Houston, USA.

The purpose of this study was to methodologically explore the links among social support, gender, age, prior experience, leader/follower status, and leadership effectiveness noted in previous accounts from Antarctic stations. Data for this study were collected from volunteers involved in Australian National Antarctic Research Expeditions conducted from 1996 to 2001. Multilevel analysis revealed that most of the variance in perceptions of social support was at the individual level (71%). Read More

Acta Astronaut 2005 May-Jun;56(9-12):918-22

Department of Laboratory Medicine and Pathology, University of Alberta Hospitals, Edmonton, Alberta, Canada.

Recent studies have demonstrated that stem cells derived from adult hematopoietic tissues are capable of trans-differentiation into non-hematopoietic cells, and that the culture in microgravity (microg) may modulate the proliferation and differentiation. We investigated the application of microg to human umbilical cord blood stem cells (CBSC) in the induction of vascular endothelial phenotype expression and cellular proliferation. CD34+ mononuclear cells were isolated from waste human umbilical cord blood samples and cultured in simulated microg for 14 days. Read More

Acta Astronaut 2005 May-Jun;56(9-12):911-7

Centre National de la Recherche Scientifique, Centre de Recherche Cerveau et Cognition, Toulouse Cedex, France.

The occurrence of geometric orientation illusions and the perception of ambiguous figures were analyzed in 24 subjects during static body tilt relative to gravity on Earth. Results showed that illusions such as the Rock's diamond/square, the Ponzo illusion, and orientation contrast illusions occurred less frequently, and that depth reversal of ambiguous figures took more time when subjects were lying on their side or supine compared to upright, thus suggesting that the gravitational reference plays a significant role in these "visual" illusions. The structure of images, our representation of the environment, and orientation relative to gravity are all integral parts in interpreting visual images. Read More

Acta Astronaut 2005 May-Jun;56(9-12):900-10

NITLab, TBM Bioengineering Department, Politecnico di Milano Technical University, Milan, Italy.

Due to high redundancy of degrees of freedom in the human body, we can perform any movement, from the simplest to the most complex, in many different ways. Several studies are still trying to identify the motor strategies that master this redundancy and generate the movements whose characteristics are highly stereotyped. The aim of this work is to build a simulator that is able to evaluate different motor planning hypotheses. Read More