Plant molecular biology in the space station era: utilization of KSC fixation tubes with RNAlater

Spaceflight experiments involving biological specimens face unique challenges with regard to the on orbit harvest and preservation of material for later ground-based analyses. Preserving plant material for gene expression analyses requires that the tissue be prepared and stored in a manner that maintains the integrity of RNA. The liquid preservative RNAlater (Ambion) provides an effective alternative to conventional freezing strategies, which are limited or unavailable in current spaceflight experiment scenarios. The spaceflight use of RNAlater is enabled by the Kennedy space center fixation tube (KFT), hardware designed to provide the necessary containment of fixatives during the harvest and stowage of biological samples in space. Pairing RNAlater with the KFT system provides a safe and effective strategy for preserving plant material for subsequent molecular analyses, a strategy that has proven effective in several spaceflight experiments. Possible spaceflight scenarios for the use of RNAlater and KFTs are explored and discussed.     

The Global Exploration Roadmap and its significance for NASA

The Global Exploration Roadmap reflects the collaborative effort of twelve space agencies to define a long-term human space exploration strategy which provides substantial benefits for improving the quality of life on Earth and is implementable and sustainable. Such a strategy is a necessary precondition to the government investments required to enable the challenging and rewarding missions that extend human presence into the solar system. The article introduces the international strategy and elaborates on NASA's leadership role in shaping that strategy. The publication of the roadmap, a reflection of the space landscape and multilateral agency-level dialog over the last four years, allows NASA to demonstrate its commitment to leading a long-term space exploration endeavor that delivers benefits, maintains strategic human spaceflight capabilities and expands human presence in space, with human missions to the surface of Mars as a driving goal. The road mapping process has clearly demonstrated the complementary interests of the participants and the potential benefits that can be gained through cooperation among nations to achieve a common goal. The present US human spaceflight policy is examined and it is shown that the establishment of a sustainable global space exploration strategy is fully consistent with that policy.     

The O/OREOS mission: first science data from the Space Environment Survivability of Living Organisms (SESLO) payload

We report the first telemetered spaceflight science results from the orbiting Space Environment Survivability of Living Organisms (SESLO) experiment, executed by one of the two 10?cm cube-format payloads aboard the 5.5?kg Organism/Organic Exposure to Orbital Stresses (O/OREOS) free-flying nanosatellite. The O/OREOS spacecraft was launched successfully to a 72° inclination, 650?km Earth orbit on 19 November 2010. This satellite provides access to the radiation environment of space in relatively weak regions of Earth's protective magnetosphere as it passes close to the north and south magnetic poles; the total dose rate is about 15 times that in the orbit of the International Space Station. The SESLO experiment measures the long-term survival, germination, and growth responses, including metabolic activity, of Bacillus subtilis spores exposed to the microgravity, ionizing radiation, and heavy-ion bombardment of its high-inclination orbit. Six microwells containing wild-type (168) and six more containing radiation-sensitive mutant (WN1087) strains of dried B. subtilis spores were rehydrated with nutrient medium after 14 days in space to allow the spores to germinate and grow. Similarly, the same distribution of organisms in a different set of microwells was rehydrated with nutrient medium after 97 days in space. The nutrient medium included the redox dye Alamar blue, which changes color in response to cellular metabolic activity. Three-color transmitted intensity measurements of all microwells were telemetered to Earth within days of each of the 48?h growth experiments. We report here on the evaluation and interpretation of these spaceflight data in comparison to delayed-synchronous laboratory ground control experiments.     

Bacillus subtilis spores on artificial meteorites survive hypervelocity atmospheric entry: implications for Lithopanspermia

An important but untested aspect of the lithopanspermia hypothesis is that microbes situated on or within meteorites could survive hypervelocity entry from space through Earth's atmosphere. The use of high-altitude sounding rockets to test this notion was explored. Granite samples permeated with spores of Bacillus subtilis strain WN511 were attached to the exterior telemetry module of a sounding rocket and launched from White Sands Missile Range, New Mexico into space, reaching maximum atmospheric entry velocity of 1.2 km/s. Maximum recorded temperature during the flight was measured at 145 degrees C. The surfaces of the post-flight granite samples were swabbed and tested for recovery and survival of WN511 spores, using genetic markers and the unique DNA fingerprint of WN511 as recovery criteria. Spore survivors were isolated at high frequency, ranging from 1.2% to 4.4% compared with ground controls, from all surfaces except the forward-facing surface. Sporulation-defective mutants were noted among the spaceflight survivors at high frequency (4%). These experiments constitute the first report of spore survival to hypervelocity atmospheric transit, and indicate that sounding rocket flights can be used to model the high-speed atmospheric entry of bacteria-laden artificial meteorites.     

Medical and surgical applications of space biosensor technology

Researchers in space life sciences are rapidly approaching a technology impasse. Many of the critical questions on the impact of spaceflight on living systems simply cannot be answered with the limited available technologies. Research subjects, particularly small animal models like the rat, must be allowed to function relatively untended and unrestrained for long periods to fully reflect the impact of microgravity and spaceflight on their behavior and physiology. These requirements preclude the use of present hard-wired instrumentation techniques and limited data acquisition systems. Implantable sensors and miniaturized biotelemetry are the only means of capturing the fundamental and critical data. This same biosensor and biotelemetry technology has direct application to Earth-based medicine and surgery. Continuous, on-line data acquisition and improved measurement capabilities combined with the ease and flexibility offered by automated, wireless, and portable instruments and data systems, should provide a boon to the health care industry. Playing a key role in this technology revolution is the Sensors 2000! (S2K!) Program at NASA Ames Research Center. S2K!, in collaboration with space life sciences researchers and managers, provides an integrated capability for sensor technology development and applications, including advanced biosensor technology development, spaceflight hardware development, and technology transfer and commercialization. S2K! is presently collaborating on several spaceflight projects with dual-use medical applications. One prime example is a collaboration with the Fetal Treatment Center (FTC) at the University of California at San Francisco. The goal is to develop and apply implantable chemical sensor and biotelemetry technology to continuously monitor fetal patients during extra-uterine surgery, replacement into the womb, through birth and beyond. Once validated for ground use, the method will be transitioned to spaceflight applications to remotely monitor key biochemical parameters in flight animals. Successful application of NASA implantable biosensor and biotelemetry technologies should accelerate the advancement of this and other modern medical procedures while furthering the exploration of life in space.     

Nemaline rod and degeneration of Z band of muscle cell in weightlessness at spaceflight

There are some studies demonstrating the skeletal muscle degeneration associated with the degeneration of Z band and appearance of nemaline rods in experimental animals of the simulation model for spaceflight but not in human heart tissues. In the present study, therefore, we investigated the pathological changes or degeneration in left auricular heart muscles obtained during operations of mitral valves replacement using both electron and light microscopies. The degeneration of Z band even in the myofibrils of comparatively little damaged cell was found. Furthermore, nemaline rods were detected in most of the heart muscle cells. These results suggest that the existence of nemaline rods is involved in the cell injury in the heart muscle of patients with heart disease without nemaline myopathy. Further study is necessary to know whether the similar pathological findings are observed not only in the skeletal muscle but also in the cardiac muscle in experimental animals of the simulation model for spaceflight or in a prolonged spaceflight.     

The return of the American military to crewed spaceflight: Hypersonic and other visions

Since the 1950s, crewed spaceflight has been the province of NASA, a decision reaffirmed in the 1960s with the cancellation of all military projects which might have competed. That understanding has driven American space policy since that time despite the fact that the military has not given up its dream of crewed spaceflight. Over the past decade, that division of labor has begun to break down in part due to the military's heightened awareness of the usefulness of space as operational location. The Air Force, the service most committed to this vision of military space, has in its planning for the next generation returned to the concept of military space activities across the spectrum. In essence, the implied social contract which drove American crewed spaceflight since the sixties is now undergoing revision and possible reversal. Given the political climate, NASA may be particularly vulnerable to such challenges. The impact of such a change upon the world wide human spaceflight effort is unknown but likely to be extremely disruptive as military considerations move to the fore. The debate is ongoing, the major limitation remains budget so that any agreed upon changes are likely to be slow to occur.     

Skill maintenance in extended spaceflight: a human factors analysis of space and analogue work environments

This paper discusses the implications of increasing mission lengths of manned spaceflight for the design of future space systems from a human factors point of view. It is argued that the increase in mission duration has brought about a number of new problems, which have not been sufficiently addressed in space research. Therefore, a review of analogue work environments is carried out to make up for the paucity of space research found in the area of human performance in long-duration spaceflight. This resulted in an evaluation of seven analogue environments concerning their similarity to space with industrial process control and nuclear submarines coming out as the closest match on the technical dimension. Finally, some recommendations are given from the lessons learned in spaceflight, simulation studies and appropriate analogue environments.     

Surgery in space: Where are we at now?

In the coming decades, as we continue our path of space exploration beyond the Earth's orbit, we will be required to provide sound medical and surgical care for the safety of space travellers and spaceflight 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.     

But what is the true rationale for human spaceflight?

Human interest in spaceflight is ancient. It is therefore ironic that, at a time when humans finally have the capability to travel in space, the notion that we should do so is being questioned. The author analyses the reasons for this — the historical/political and technological contingency of the Space Age and the sudden falling away of the conditions which drove space activity — and in the process provides a critique of the forgoing article and the tendency to search for utilitarian justifications of human spaceflight. He argues rather that space programmes will thrive only when driven by non-material cultural and political forces. US-Russian cooperation, which has principally been undertaken for geopolitical reasons is a model for the future.     

Numerical Simulation of Geomagnetic Trapping of Anomalous Cosmic Ray Ions

A method for simulating the propagation processes for ions of the anomalous component of cosmic rays in the Earth's magnetic field is described with allowance made for a step-by-step stripping of the ions in the residual atmosphere and their trapping by the geomagnetic field. Numerical results are presented for the geomagnetic trapping of high-energy singly charged oxygen ions penetrating into the stripping region from interplanetary space.     

Engaging space: extraterrestrial architecture and the human psyche

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. The objective of this paper is to develop a habitat that expresses the extraterrestrial condition while supporting the mental health of its inhabitants, so as to augment the success of prolonged extraterrestrial residence and interplanetary travel.     

Acetylene as fast food: implications for development of life on anoxic primordial Earth and in the outer solar system

Acetylene occurs, by photolysis of methane, in the atmospheres of jovian planets and Titan. In contrast, acetylene is only a trace component of Earth's current atmosphere. Nonetheless, a methane-rich atmosphere has been hypothesized for early Earth; this atmosphere would also have been rich in acetylene. This poses a paradox, because acetylene is a potent inhibitor of many key anaerobic microbial processes, including methanogenesis, anaerobic methane oxidation, nitrogen fixation, and hydrogen oxidation. Fermentation of acetylene was discovered approximately 25 years ago, and Pelobacter acetylenicus was shown to grow on acetylene by virtue of acetylene hydratase, which results in the formation of acetaldehyde. Acetaldehyde subsequently dismutates to ethanol and acetate (plus some hydrogen). However, acetylene hydratase is specific for acetylene and does not react with any analogous compounds. We hypothesize that microbes with acetylene hydratase played a key role in the evolution of Earth's early biosphere by exploiting an available source of carbon from the atmosphere and in so doing formed protective niches that allowed for other microbial processes to flourish. Furthermore, the presence of acetylene in the atmosphere of a planet or planetoid could possibly represent evidence for an extraterrestrial anaerobic ecosystem.     

Vascular functions in humans following cardiovascular adaptations to spaceflight

Purpose: Diminished vascular function is a primary cardiovascular risk of spaceflight identified in the 2004 NASA Bioastronautics Critical Path Roadmap based on: (1) structural and functional alterations in arterial vessels of animals undergoing hindlimb unloading and; (2) lower peripheral vascular resistance (PVR) in astronauts who became presyncopal after spaceflight.Methods: We conducted a critical review of published data obtained from spaceflight and relevant ground-based microgravity simulations in an effort to interpret the meaning of altered responses in PVR and their relationship to postflight presyncope.Results: Presyncope reported in astronauts on landing day was associated with lower peripheral resistance. However, non-presyncopal astronauts demonstrated significantly elevated vascular resistance in the upright posture after compared with before spaceflight. Results from both space and ground experiments suggest that preflight maximal vasoconstrictor capacity is inherently lower in presyncopal astronauts, but unaltered by spaceflight.Conclusions: Vasoconstrictor reserve is associated with lower blood volume adaptation to microgravity. Rather than reduced vascular function, low inherent maximal vasoconstrictor capacity and reduced vasoconstrictor reserve secondary to decreased circulating vascular volume explain lower peripheral vascular resistance in astronauts who experience presyncopal episodes on landing day.     

Gravitational Interaction of Celestial Bodies and neutron flux bursts from Their Surfaces

The gravitational interaction between the Sun and the planetary solar system gives rise to the well-known tidal waves at the planets. The tidal wave originating in the Earth's crust perpetually transforms the microstructure of the Earth's crust leading to a variation of the concentration of natural radioactive gases in the terrestrial air and to changed conditions of their leakage to the Earth's atmosphere. These variations give rise to bursts of thermal and slow neutrons in the vicinity of the Earth's crust, because the radioactive gases are sources of energetic alpha particles that induce neutron production upon the interaction with the nuclei of elements of the Earth's crust and atmosphere. In this work, the idea of neutron production in the ground coat is extended to the other celestial bodies interacting with one another.     

Multiple-task performance on a computer-simulated life support system during a space mission simulation

This paper presents an experiment which examined the effects of isolation and confinement during a simulation of a short-term space mission. During the 7-day spaceflight simulation, four Canadian astronauts were tested daily on a 30-min performance task. The task, CAMS (Cabin Air Management System), represents a computer-based simulation of a generic life support system. As a multiple-task environment, it allows the measurement of a wide range of task management variables such as primary and secondary task performance, and system control activities. Measures of subjective state variables were also taken. The results did not show any evidence of serious performance decrements for any crew member. The analysis revealed different adjustment patterns with which crew members responded as a function of mission duration and variations in workload. Among the secondary tasks employed, prospective memory was found to be more sensitive than reaction time to increases in workload. The paper concludes with a discussion of the utility of spaceflight simulations and computer-based simulations of space work.     

Effects of prolonged space flight on rat skeletal muscle

The effect of a 20-day space flight on water, Na+, K+, Mg2+, Ca2+ and glycogen contents as well as on activities of glycogen metabolism enzymes--glycogen synthetase and glycogen phosphorylase--of rat skeletal muscles was studied. This data is regarded as an integral test characterizing the state of contractile tissue of the animals at the final stage of flight aboard biosatellites. The measurements indicate that there were no significant changes of cations and glycogen contents nor of the enzymic activities in fast-twitch muscles during the 20-day spaceflight. At the same time dehydration in these muscles was observed, which disappeared on the 25th postflight day. In slow-twitch antigravitational skeletal muscle (m. soleus) there was a decrease of K+ and increase of Na+ in the tissue contents. The changes disappeared at the end of the on-earth readaptation period. From the pattern of these observations, we can conclude that the 20-day space flight leads to some reversible biochemical changes of the rat skeletal muscles. A conclusion can be drawn about necessity of creating, aboard the spaceship, an artificial load on antigravitational skeletal muscles.     

基于断言的形式验证方法应用研究

针对模型检验算法在工程应用中面临的形式语言局限性和状态空间爆炸的危机,提出了基于断言的形式验证解决方案。通过对DW8051_timer模块的实际验证,说明了该方法可以简化模型检验算法在工程实践中的应用,并且与传统仿真方法相比,它能在一定程度上缓解航天领域数字系统设计中的验证困境。     

When will we see a Golden Age of Spaceflight?

The supposed parallels between the development of aviation and of spaceflight are not as great as believed. The most significant differences are the public expectation that spaceflight, unlike aviation, is a matter for governments and the notion that, because it is so technically challenging, it must always be expensive. Early aviation was massively spurred on by the offer of lucrative prizes for the achievement of certain feats and by the activities of private barnstormers. The successfully attained X Prize has been the first attempt to do the same for spaceflight. The creation of further prizes could be the best way of promoting greater public involvement in space and commercially developing the sector.     

Spacelab Life Sciences flight experiments: an integrated approach to the study of cardiovascular deconditioning and orthostatic hypotension

The microgravity environment of spaceflight produces rapid cardiovascular changes which are adaptive and appropriate in that setting, but are associated with significant deconditioning and orthostatic hypotension on return to Earth's gravity. The rapidity with which these space flight induced changes appear and disappear provides an ideal model for studying the underlying pathophysiological mechanisms of deconditioning and orthostatic hypotension, regardless of etiology. Since significant deconditioning is seen after flights of very short duration, muscle atrophy due to inactivity plays, at most, a small role. These changes in circulatory control associated with cephalad fluid shifts, rather than inactivity per se, are probably more important factors. In order to test this hypothesis in a systematic way, a multidisciplinary approach which defines and integrates inputs and responses from a wide variety of circulatory sub-systems is required. The cardiovascular experiments selected for Spacelab Life Sciences flights 1 and 2 provide such an approach. Both human and animal models will be utilized. Pre- and post-flight characterization of the payload crew includes determination of maximal exercise capacity (bicycle ergometry), orthostatic tolerance (lower body negative pressure), alpha and beta adrenergic sensitivity (isoproterenol and phenylephrine infusions), baroreflex sensitivity (ECG-gated, stepwise changes in carotid artery transmural pressure with a pneumatic neck collar), and responses to a 24 h period of 5 deg head-down tilt. Measurements of cardiac output (CO2 and C2H2 rebreathing), cardiac chamber dimensions (phased-array 2-dimensional echocardiography), direct central venous pressure, leg volume (Thornton sock), limb blood flow and venous compliance (occlusion plethysmography), blood and plasma volumes, renal plasma flow and glomerular filtration rates, and various hormonal levels including catecholamines and atrial natriuretic factor will also be obtained. The central venous catheter will be inserted immediately pre-launch and monitored with heart rate and blood pressure in-flight until cardiac output, respiratory gas exchange and quantitative 2D echocardiography measurements can be performed. In-flight hemodynamic measurements will be repeated at rest and during submaximal exercise daily and also during maximal exercise midway through the flight to document the timecourse and extent of cardiovascular changes in the payload crew. Parallel studies are planned for the animals. In addition to measurements of right atrial and aortic pressures and cardiac output, a dorsal micro-circulatory chamber will allow determinations of changes in capillary and venular architecture and function in six of the rats. The techniques and findings from many of the SLS-1 and 2 supporting studies have already yielded significant information about circulatory regulation in patients with both hypo- and hypertension. The flight experiments themselves will provide new data to test the validity of both animal and human models currently used for simulating the fluid shifts of a micro-gravity environment. The development of effective countermeasures, not only for short and long duration space travellers, but also for Earth-bound medical patients can then be physiologically based on experimental data rather than anecdote.