To address the hitherto unknown mechanism of boundary-layer transition on blunt reentry capsules, the role of roughness-induced disturbance growth on a spherical-section forebody is assessed via optimal transient growth theory and direct numerical simulations (DNS). Optimal transient-growth studies have been performed for the blunt capsule experiments at Mach 5.9 in the Hypersonic Ludwieg tube Braunschweig (HLB) of the Technische Universität Braunschweig, which included measurements behind a patch of controlled, distributed micron-sized surface roughness. Transient-growth results for the HLB capsule indicate similar trends as the corresponding numerical data for a Mach 6 experiment in the Actively Controlled Expansion (ACE) facility of the Texas A&M University (TAMU) at a lower Reynolds number. Both configurations indicate a similar dependence on surface temperature ratio, and more important, rather low values of maximum energy gain. DNS are performed for the conditions of the HLB experiment to understand the generation of stationary disturbances by the roughness patch and the accompanying evolution of unsteady perturbations. However, no evidence of either modal or nonmodal disturbance growth in the wake of the roughness patch is found in the DNS data; thus, the physical mechanism underlying the observed onset of transition still remains unknown.

While low disturbance ("quiet") hypersonic wind tunnels are believed to provide more reliable extrapolation of boundary layer transition behavior from ground to flight, the presently available quiet facilities are limited to Mach 6, moderate Reynolds numbers, low freestream enthalpy, and subscale models. As a result, only conventional ("noisy") wind tunnels can reproduce both Reynolds numbers and enthalpies of hypersonic flight configurations, and must therefore be used for flight vehicle test and evaluation involving high Mach number, high enthalpy, and larger models. This article outlines the recent progress and achievements in the characterization of tunnel noise that have resulted from the coordinated effort within the AVT-240 specialists group on hypersonic boundary layer transition prediction. New Direct Numerical Simulation datasets elucidate the physics of noise generation inside the turbulent nozzle wall boundary layer, characterize the spatiotemporal structure of the freestream noise, and account for the propagation and transfer of the freestream disturbances to a pitot-mounted sensor. The new experimental measurements cover a range of conventional wind tunnels with different sizes and Mach numbers from 6 to 14 and extend the database of freestream fluctuations within the spectral range of boundary layer instability waves over commonly tested models. Prospects for applying the computational and measurement datasets for developing mechanism-based transition prediction models are discussed.

This paper develops an atmospheric state estimator based on inertial acceleration and angular rate measurements combined with a vehicle aerodynamic model. The approach utilizes the navigation state of the vehicle to recast the vehicle aerodynamic model to be a function solely of the atmospheric state. Force and moment measurements are based on vehicle sensed accelerations and angular rates. These measurements are combined with an aerodynamic model and a Kalman-Schmidt filter to estimate the atmospheric conditions. The method is applied to data from the Mars Science Laboratory mission, which landed the Curiosity rover on the surface of Mars in August 2012. The results of the estimation algorithm are compared with results from a Flush Air Data Sensing algorithm based on onboard pressure measurements on the vehicle forebody. The comparison indicates that the proposed method provides estimates consistent with the air data measurements, without the use of pressure transducers. Implications for future missions such as the Mars 2020 entry capsule are described.

The scheduling of crew rotations for up to 180 days on Space Station Freedom presents a special challenge for behavioral scientists who are tasked with providing psychological support for the crews, their families, and mission flight controllers. Preflight psychological support planning may minimize the negative impact of psychological and social issues on mission success, as well as assist NASA management in making real-time mission planning decisions in the event of a significant social event (for example, the death of a family member). During flight, the combined psychological, emotional, and social stressors on the astronauts must be monitored, along with other aspects of their health. The Health Maintenance Facility (HMF) will have the capability of providing preventive, diagnostic, and therapeutic assistance for significant psychiatric and interpersonal problems which may develop. Psychological support will not end with the termination of the mission. Mental health professionals must be part of the team of medical personnel whose job will be to facilitate the transition--physical and mental--from the space environment back to planet Earth. This paper reviews each phase of mission planning for Space Station Freedom and specifies those factors that may be critical for psychological health maintenance on extended-duration space missions.

In current Mars scenario descriptions, an entire mission is estimated to take 500-1000 days round trip with a 100-600 day stay time on the surface. To maintain radiation dose levels below permissible limits, dose estimates must be determined for the entire mission length. With extended crew durations anticipated on Mars, the characterization of the radiation environment on the surface becomes a critical aspect of mission planning. The most harmful free-space radiation is due to high energy galactic cosmic rays (GCR) and solar flare protons. The carbon dioxide atmosphere of Mars has been estimated to provide a sufficient amount of shielding from these radiative fluxes to help maintain incurred doses below permissible limits. However, Mars exploration crews are likely to incur a substantial dose while in transit to Mars that will reduce the allowable dose that can be received while on the surface. Therefore, additional shielding may be necessary to maintain short-term dose levels below limits or to help maintain career dose levels as low as possible. By utilizing local resources, such as Martian regolith, shielding materials can be provided without excessive launch weight requirements from Earth. The scope of this synopsis and of Ref. 3 focuses on presenting our estimates of surface radiation doses received due to the transport and attenuation of galactic cosmic rays and February 1956 solar flare protons through the Martian atmosphere and through additional shielding provided by Martian regolith.

The human radiation environment for several short-duration stay manned Mars missions is predicted using the Mission Radiation Calculation (MIRACAL) program, which was developed at NASA Langley Research Center. This program provides dose estimates for galactic cosmic rays (GCR) and large and ordinary solar proton flare events for various amounts of effective spacecraft shielding (both operational and storm shelter thicknesses) and a given time history of the spacecraft's heliocentric position. The results of this study show that most of the missions can survive the most recent large flares (if they were to occur at the missions' perihelion) if a 25 g/cm2 storm shelter is assumed. The dose predictions show that missions during solar minima (when solar flare activity is the lowest) are not necessarily the minimum dose cases, due to increased GCR contribution during this time period. The direct transfer mission studied has slightly lower doses than the outbound Venus swingby mission [on the order of 10-20 centi-Sieverts (cSv) lower], with the greatest dose differences for the assumed worst case scenario (when the large flares occur at perihelion). The GCR dose for a mission can be reduced by having the crew spend some fraction of its day nominally in the storm shelter (other than during flare events).

This paper evaluates the factors that control the flexibility of fabric space-suit elements, in particular gloves, by examining a bending model of a pressurized fabric tube. Results from the model are used to evaluate the design strategies used in space-suit components, to evaluate the current direction in research on highly mobile space-suit gloves and to suggest changes necessary for optimum glove fabric selection. Finally it is shown that the modulus of the fabric used in space-suit joint construction is as important to the flexibility of the joint as the glove size and design.

Ample research evidence from space analogs points to the crucial role that teamwork plays in the performance of small groups in isolation and confinement. This paper surveys findings about the impacts of group behavior and social interaction on crew morale, coordination, and productivity. Implications for the organization, selection, and training of crews for extended spaceflight are discussed.

This paper discusses intergroup dynamics in human spaceflight operations. A definition of intergroup behavior is presented and prerequisite conditions for intergroup conflict are explored. Research and anecdotal evidence of intergroup conflict between groups and subgroups in exotic environments and space operations is presented. Concepts from the literature on intergroup conflicts are discussed in the context of possible conflict resolution interventions. Factors that may affect intergroup dynamics in human spaceflight operations and the need for intergroup research are highlighted.

We report on the development of an air-quality monitoring and early detection system for an enclosed environment with specific emphasis on manned spacecraft. The proposed monitoring approach is based on a distributed parameter model of contaminant dispersion and real-time contaminant concentration measurements. Kalman filtering is identified as a suitable method for generating on-line estimation of the spatial contamination profile, and an implicit Kalman filtering algorithm is shown to be preferable for rear-time implementation. The identification of the contaminant concentration profile allows for a straightforward solution of the early detection of an air contamination event and provides information that enables potential automatic diagnosis of an unknown contamination source.

A description is given of the design and implementation of a method to track the presence of air contaminants aboard a spacecraft using an accurate physical model and of a procedure that would raise alarms when certain tolerance levels are exceeded. Because our objective is to monitor the contaminants in real time, we make use of a state estimation procedure that filters measurements from a sensor system and arrives at an optimal estimate of the state of the system. The model essentially consists of a convection-diffusion equation in three dimensions, solved implicitly using the principle of operator splitting, and uses a flowfield obtained by the solution of the Navier-Stokes equations for the cabin geometry, assuming steady-state conditions. A novel implicit Kalman filter has been used for fault detection, a procedure that is an efficient way to track the state of the system and that uses the sparse nature of the state transition matrices.

In preparation for the International Space Station, the Enhanced Dynamic Load Sensors Space Flight Experiment measured the forces and moments astronauts exerted on the Mir Space Station during their daily on-orbit activities to quantify the astronaut-induced disturbances to the microgravity environment during a long-duration space mission. An examination of video recordings of the astronauts moving in the modules and using the instrumented crew restraint and mobility load sensors led to the identification of several typical astronaut motions and the quantification of the associated forces and moments exerted on the spacecraft. For 2806 disturbances recorded by the foot restraints and hand-hold sensor, the highest force magnitude was 137 N. For about 96% of the time, the maximum force magnitude was below 60 N, and for about 99% of the time the maximum force magnitude was below 90 N. For 95% of the astronaut motions, the rms force level was below 9.0 N. It can be concluded that expected astronaut-induced loads from usual intravehicular activity are considerably less than previously thought and will not significantly disturb the microgravity environment.

This paper describes some of the salient implications of evolving mission parameters for spacecraft design. Among the requirements for future spacecraft are new, higher standards of living, increased support of human productivity, and greater accommodation of physical and cultural variability. Design issues include volumetric allowances, architecture and layouts, closed life support systems, health maintenance systems, recreational facilities, automation, privacy, and decor. An understanding of behavioral responses to design elements is a precondition for critical design decisions. Human factors research results must be taken into account early in the course of the design process.

This paper examines the utility of remote, isolated Antarctic research stations as analogs for long-duration spaceflights from the perspective of psychosocial processes of adaptation and adjustment. Certain features of the physical and man-made environments found in Antarctica are similar to those that will be encountered in outer space. In both settings, men and women are likely to experience a number of physiological and psychological changes in response to the extreme environmental conditions and the prolonged isolation and confinement. Biomedical research in Antarctica provides an opportunity to study the causes of these changes and to develop strategies for reducing the risks to health and well-being before they pose a serious threat to crew safety and mission success. A number of lessons for long-duration spaceflight are examined, including screening and selection of personnel; training programs designed to facilitate individual adjustment and group adaptation and minimize group conflict; identification of optimal leadership characteristics for small, isolated groups; an understanding of social dynamics and group "microcultures" necessary for the organization and management of small but heterogeneous groups; organization of work activities; facility design; and support infrastructure.

This Note describes the dynamic load sensors (DLS) spaceflight experiment that measured middeck astronaut-induced disturbances during the 14-day STS-62 Space Shuttle mission in March 1994. The DLS experiment was flown in conjunction with the reflight of the Middeck 0-Gravity Dynamics Experiment (MODE). The objective of MODE was to investigate effects of the microgravity environment on large space structures. Where Skylab experiments focused on measuring the forces exerted during vigorous soaring activities, the DLS experiment quantified the reaction forces and moments exerted by the crew going about their normal on-orbit activities. The objective of this Note is to present DLS force data and frequency analysis that characterize astronaut-induced loads during spaceflight.

America's future in space calls for manned missions that are of long duration and increasing complexity. Under these conditions, psychological and interpersonal stressors will take on added importance in affecting the safely of the crew and the outcome of the mission. Through an analysis of reports from manned American and Soviet space missions and Earth-bound simulations, several psychological, psychiatric, and interpersonal issues can be identified that could affect the success of the space station and other long-duration space ventures. Psychological issues include sleep problems, alteration in time sense, demographic effects, career motivation, transcendent experiences, homesickness, and alteration in perceptual sensitivities. Psychiatric issues include anxiety, depression, and psychosis, psychosomatic symptoms, emotional problems related to the stage of the mission, and postflight personality changes. Interpersonal issues include interpersonal tension, decreased cohesiveness over time, need for privacy, and task vs emotional leadership. Steps can be taken to minimize the impact of these issues, both before and during the mission.

Microgravity life-science research requires hardware that can be easily adapted to a variety of experimental designs and working environments. The Biomodule is a patented, computer-controlled fluid-mixing device that can accommodate these diverse requirements. A typical shuttle payload contains eight Biomodules with a total of 64 samples, a sealed containment vessel, and a NASA refrigeration-incubation module. Each Biomodule contains eight gas-permeable Silastic T tubes that are partitioned into three fluid-filled compartments. The fluids can be mixed at any user-specified time. Multiple investigators and complex experimental designs can be easily accommodated with the hardware. During flight, the Biomodules are sealed in a vessel that provides two levels of containment (liquids and gas) and a stable, investigator-controlled experimental environment that includes regulated temperature, internal pressure, humidity, and gas composition. A cell microencapsulation methodology has also been developed to streamline launch-site sample manipulation and accelerate postflight analysis through the use of fluorescent-activated cell sorting. The Biomodule flight hardware and analytical cell encapsulation methodology are ideally suited for temporal, qualitative, or quantitative life-science investigations.

The charged-particle telescope (CPT) onboard the Clementine spacecraft measured the fluxes of energetic protons emitted in solar energetic particle events. Protons in the energy range from 10 to 80 MeV were of greatest interest for radiation effects such as total dose and single event upsets. Energetic electrons were also of interest for spacecraft charging and their contribution to total dose. The lower-energy CPT electron channels (25-500 keV) were mainly of geophysical interest. While orbiting the moon, the CPT observed the wake created by the moon when it blocked the flow of energetic particles in the magnetotail region. The CPT provided opportunities to observe energetic electron bursts during magnetic storms and magnetospheric substorms. CPT data are particularly useful in multispacecraft studies of interplanetary disturbances and their interaction with the magnetosphere. The proton channels on the CPT provided data on solar energetic protons and storm-time protons associated with the passage of an interplanetary shock at 0903 UT on Feb. 21, 1994. Results are compared with those from GOES-7, SAMPEX, and GEOTAIL.