Descent guidance and mission planning for space shuttle

The Space Shuttle descent mission planning, mission design, deorbit targeting, and entry guidance have necessarily become interrelated because of the nature of the Orbiter's design and mission requirements. The desired descent trajectory has been formulated in a drag acceleration/relative velocity state space since nearly all of the vehicle's highly constraining flight limitations can be uniquely represented in this plane. Constraints and flight requirements that affect the descent are described. The guidance logic which allows the Orbiter to follow the designed trajectory, the impacts of contingency aborts and flightcrew interaction are discussed. The mission planning and guidance techniques remain essentially unchanged through the Shuttle flight test program and subsequent operational flights

Accessing the Lunar Poles for Human Exploration Missions

The National Vision for Space Exploration calls for an American return to the Moon in preparation for the human exploration of Mars and other destinations. The surface environment of the Moon is a challenge for human operations, but recent findings from robotic and Earth-based studies have indicated that the polar regions of the Moon may offer advantages in terms of thermal conditions, availability of solar energy, and access to local resources. While accessing these regions represents a challenge due to orbital dynamics and propulsive performance, methods for accessing the regions with humans are being actively pursued, and environmental data gathering is planned through future robotic missions

Assessing motor skills to inform a fetal alcohol spectrum disorder diagnosis focusing on persons older than 12 years: A systematic review of the literature

Background Motor impairments are one of the difficulties present in people prenatally exposed to alcohol, and are included in the diagnostic criteria for Fetal Alcohol Spectrum Disorder. Objectives The aim of this review was to examine the extent and common types of motor impairment present in persons aged over 12 years prenatally exposed to alcohol as evidence for determining the skills that should be assessed and addressed in intervention. Methods A systematic review of curren t evidence using various electronic databases was conducted. Studies were appraised using a recognized clinical appraisal tool. Results Seven studies published between 1998 and 2014 met the inclusion criteria. There is some evidence that difficulties with fine motor skills, visual motor integration, and balance skills persist in people who have been prenatally exposed to alcohol. Most studies did not focus on adolescent or adult participants in isolation, making it difficult to generalize results. Varied methodological designs made it difficult to compare studies as few used common standardized assessments. Conclusion A review of functional difficulties in each individual would be required to determine if a motor assessment is warranted. Further research is required using assessments recommended in diagnostic guidelines to determine the common motor difficulties seen in adolescents and adults

Preparing for Human Exploration

NASA's Human Exploration and Development of Space (HEDS) Enterprise is defining architectures and requirements for human exploration that radically reduce the costs of such missions through the use of advanced technologies, commercial partnerships and innovative systems strategies. In addition, the HEDS Enterprise is collaborating with the Space Science Enterprise to acquire needed early knowledge about Mars and to demonstrate critical technologies via robotic missions. This paper provides an overview of the technological challenges facing NASA as it prepares for human exploration. Emphasis is placed on identifying the key technologies including those which will provide the most return in terms of reducing total mission cost and/or reducing potential risk to the mission crew. Top-level requirements are provided for those critical enabling technology options currently under consideration

Human Outer Solar System Exploration via Q-Thruster Technology

Propulsion technology development efforts at the NASA Johnson Space Center continue to advance the understanding of the quantum vacuum plasma thruster (QThruster), a form of electric propulsion. Through the use of electric and magnetic fields, a Q-thruster pushes quantum particles (electrons/positrons) in one direction, while the Qthruster recoils to conserve momentum. This principle is similar to how a submarine uses its propeller to push water in one direction, while the submarine recoils to conserve momentum. Based on laboratory results, it appears that continuous specific thrust levels of 0.4 - 4.0 N/kWe are achievable with essentially no onboard propellant consumption. To evaluate the potential of this technology, a mission analysis tool was developed utilizing the Generalized Reduced Gradient non-linear parameter optimization engine contained in the Microsoft Excel platform. This tool allowed very rapid assessments of "Q-Ship" minimum time transfers from earth to the outer planets and back utilizing parametric variations in thrust acceleration while enforcing constraints on planetary phase angles and minimum heliocentric distances. A conservative Q-Thruster specific thrust assumption (0.4 N/kWe) combined with "moderate" levels of space nuclear power (1 - 2 MWe) and vehicle specific mass (45 - 55 kg/kWe) results in continuous milli-g thrust acceleration, opening up realms of human spaceflight performance completely unattainable by any current systems or near-term proposed technologies. Minimum flight times to Mars are predicted to be as low as 75 days, but perhaps more importantly new "retro-phase" and "gravity-augmented" trajectory shaping techniques were revealed which overcome adverse planetary phasing and allow virtually unrestricted departure and return opportunities. Even more impressively, the Jovian and Saturnian systems would be opened up to human exploration with round-trip times of 21 and 32 months respectively including 6 to 12 months of exploration at the destinations. Finally, interstellar trip times are assessed at milli-g acceleration levels

Functional consequences of sphingomyelinase-induced changes in erythrocyte membrane structure.

Inflammation enhances the secretion of sphingomyelinases (SMases). SMases catalyze the hydrolysis of sphingomyelin into phosphocholine and ceramide. In erythrocytes, ceramide formation leads to exposure of the removal signal phosphatidylserine (PS), creating a potential link between SMase activity and anemia of inflammation. Therefore, we studied the effects of SMase on various pathophysiologically relevant parameters of erythrocyte homeostasis. Time-lapse confocal microscopy revealed a SMase-induced transition from the discoid to a spherical shape, followed by PS exposure, and finally loss of cytoplasmic content. Also, SMase treatment resulted in ceramide-associated alterations in membrane-cytoskeleton interactions and membrane organization, including microdomain formation. Furthermore, we observed increases in membrane fragility, vesiculation and invagination, and large protein clusters. These changes were associated with enhanced erythrocyte retention in a spleen-mimicking model. Erythrocyte storage under blood bank conditions and during physiological aging increased the sensitivity to SMase. A low SMase activity already induced morphological and structural changes, demonstrating the potential of SMase to disturb erythrocyte homeostasis. Our analyses provide a comprehensive picture in which ceramide-induced changes in membrane microdomain organization disrupt the membrane-cytoskeleton interaction and membrane integrity, leading to vesiculation, reduced deformability, and finally loss of erythrocyte content. Understanding these processes is highly relevant for understanding anemia during chronic inflammation, especially in critically ill patients receiving blood transfusions

Indications and clinical outcome in pediatric tracheostomy:Lessons learned

Objective: Indications for tracheostomy have changed over the last decades and clinical outcome varies depending on the indication for tracheostomy. By gaining more insight in the characteristics and outcome of the tracheostomized pediatric population, clinical care can be improved and a better individual prognosis can be given. Therefore, we studied the outcome of our pediatric tracheostomy population in relation to the primary indication over the last 16 years. Methods: We retrospectively included children younger than 18 years of age with a tracheostomy tube in the Erasmus Medical Center, Sophia children's hospital. The primary indication for tracheostomy, gender, age at tracheostomy, age at decannulation, comorbidity, mortality, closure of a persisting tracheocutaneous fistula after decannulation, surgery prior to decannulation and the use of polysomnography were recorded and analyzed. Results: Our research group consisted of 225 children. Reasons for a tracheostomy were first divided in two major diagnostic groups: 1) airway obstruction group (subgroups: laryngotracheal obstruction and craniofacial anomalies) and 2) pulmonary support group (subgroups: cardio-pulmonary diseases and neurological diseases). Children in the airway obstruction group were younger when receiving a tracheostomy (3.0 months vs. 31.0 months, p &lt; 0.05), they were tracheostomy dependent for a longer time (median 21.5 months vs. 2.0 months, p &lt; 0.05) and they required surgery more often (74.5% vs. 8.3%, p &lt; 0.05) than the children in the pulmonary support group. The decannulation rate of children with a laryngotracheal obstruction is high (74.8%), but low in all other subgroups (craniofacial anomalies; 38.5%, cardio-pulmonary diseases; 34.6% and neurological diseases; 52.9%). Significantly more children (36.7%) died in the pulmonary support group due to underlying comorbidity, mainly in the cardio-pulmonary diseases subgroup. Surgery for a persisting tracheocutaneous fistula was performed in 34 (37.8%) children, with a significant relationship between the duration of the tracheostomy and the persistence of a tracheocutaneous fistula. No cannula related death occurred during this study period. Conclusion: Main indications for a tracheostomy were airway obstruction and pulmonary support. Children in the airway obstruction group were younger when receiving a tracheostomy and they were tracheostomy dependent for a longer period. Within the airway obstruction group, the decannulation rate for children with laryngotracheal stenosis was high, but low for children with craniofacial anomalies. In the pulmonary support group, the decannulation rate was low and the mortality rate was high. Surgery for a persisting tracheocutaneous fistula was frequently needed.</p

Factors associated with laryngeal injury after intubation in children:a systematic review

Purpose: The purpose of this study is to evaluate all potential factors associated with laryngeal injury after endotracheal intubation in the pediatric population. Methods: A systematic literature search was conducted in Medline, Embase, Cochrane, web of science and Google scholar up to 20th of March 2023. We included all unique articles focusing on factors possibly associated with intubation-injury in pediatric patients. Two independent reviewers determined which articles were relevant by coming to a consensus, quality of evidence was rated using GRADE criteria. All articles were critically appraised according to the PRISMA guidelines. The articles were categorized in four outcome measures: post-extubation stridor, post-extubation upper airway obstruction (UAO) necessitating treatment, laryngeal injury found at laryngoscopy and a diagnosed laryngotracheal stenosis (LTS). Results: A total of 24 articles with a total of 15.520 patients were included. The incidence of post-extubation stridor varied between 1.0 and 30.3%, of post-extubation UAO necessitating treatment between 1.2 and 39.6%, of laryngeal injury found at laryngoscopy between 34.9 to 97.0% and of a diagnosed LTS between 0 and 11.1%. Although the literature is limited and quality of evidence very low, the level of sedation and gastro-esophageal reflux are the only confirmed associated factors with post-extubation laryngeal injury. The relation with age, weight, gender, duration of intubation, multiple intubations, traumatic intubation, tube size, absence of air leak and infection remain unresolved. The remaining factors are not associated with intubation injury. Conclusion: We clarify the role of the potential factors associated with laryngeal injury after endotracheal intubation in the pediatric population.</p

Preliminary Assessment of Artificial Gravity Impacts to Deep-Space Vehicle Design

Even after more than thirty years of scientific investigation, serious concerns regarding human physiological effects of long-duration microgravity exposure remain. These include loss of bone mineral density, skeletal muscle atrophy, and orthostatic hypertension, among others. In particular, "Safe Passage: Astronaut Care for Exploration Missions," states "loss of bone density, which apparently occurs at a rate of 1% per month in microgravity, is relatively manageable on the short-duration missions of the space shuttle, but it becomes problematic on the ISS [International Space Station]. ...If this loss is not mitigated, interplanetary missions will be impossible." While extensive investigations into potential countermeasures are planned on the ISS, the delay in attaining full crew complement and onboard facilities, and the potential for extending crews tours of duty threaten the timely (< 20 years!) accumulation of sufficient data for countermeasures formulation. Indeed, there is no guarantee that even with the data, a practical or sufficiently robust set of countermeasures will be forthcoming. Providing an artificial gravity (AG) environment by crew centrifugation aboard deep-space human exploration vehicles, long a staple technique of science fiction, has received surprisingly limited engineering assessment. This is most likely due to a number of factors: the lack of definitive design requirements, especially acceptable artificial gravity levels and rotation rates, the perception of high vehicle mass and performance penalties, the incompatibility of resulting vehicle configurations with space propulsion options (i.e., aerocapture), the perception of complications associated with de-spun components such as antennae and photovoltaic arrays, and the expectation of effective crew micro-gravity countermeasures. These perception and concerns may have been overstated, or may be acceptable alternatives to countermeasures of limited efficacy. This study was undertaken as an initial step to try to understand the implications of and potential solutions to incorporating artificial gravity in the design of human deep-space exploration vehicles. Of prime interest will be the mass penalties incurred by incorporating AG, along with any mission performance degradation

The launch of the ESPEN Special Interest Group in Paediatric Clinical Nutrition

Background &amp; aims: At the 37th annual ESPEN congress in Lisbon, a new Special Interest Group (SIG) in Paediatric Clinical Nutrition was formed. As a first activity of this group, a survey was sent out to all ESPEN members to collect opinions about the objectives of this SIG, explore the interest of ESPEN members in paediatric related nutrition research and clinical practice and to offer to the opportunity for a wider future participation. Methods: A web-based questionnaire survey was distributed to all members of ESPEN via the regular society's newsletter. Results: In total, 123/2828 (4.3%) ESPEN members from 50 countries completed the survey. Fifty-nine of the responders were working in paediatric clinical practice and/or research, 42 in adult medicine, and 20 in both. Fifty-seven (51%) respondents agreed that there is inadequate representation of paediatric nutrition in the current ESPEN activities and 90% of all would like to see more paediatric topics at the ESPEN annual congresses. The development of paediatric clinical practice guidelines should be the scope of this SIG, as indicated by 85 (69%) respondents. Seventy-six (69%) believed that the creation of a Paediatric Clinical Nutrition SIG is likely to impact positively on the society's membership. Conclusions: There is an unmet need for more paediatric related topics and representation with the activities of the ESPEN group. The SIG in Paediatrics aspires to foster multicentre research, development of guidelines and provide a hub for interaction and knowledge exchange