Constellation Program Human-System Integration Requirements
19 Nov 2010-
TL;DR: The Human-Systems Integration Requirements (HSIR) as discussed by the authors is a set of human-to-system integration requirements for the Constellation Program (CxP) that must meet NASA's Agency-level human rating requirements, which are intended to ensure crew survival without permanent disability.
Abstract: The Human-Systems Integration Requirements (HSIR) in this document drive the design of space vehicles, their systems, and equipment with which humans interface in the Constellation Program (CxP). These requirements ensure that the design of Constellation (Cx) systems is centered on the needs, capabilities, and limitations of the human. The HSIR provides requirements to ensure proper integration of human-to-system interfaces. These requirements apply to all mission phases, including pre-launch, ascent, Earth orbit, trans-lunar flight, lunar orbit, lunar landing, lunar ascent, Earth return, Earth entry, Earth landing, post-landing, and recovery. The Constellation Program must meet NASA's Agency-level human rating requirements, which are intended to ensure crew survival without permanent disability. The HSIR provides a key mechanism for achieving human rating of Constellation systems.
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TL;DR: It is demonstrated that increasing irradiances of narrowband blue-appearing light can elicit increasing plasma melatonin suppression in healthy subjects, and narrow bandwidth blue LED light may be stronger than 4,000 K white fluorescent light for suppressing melatonin.
Abstract: Light suppresses melatonin in humans, with the strongest response occurring in the short-wavelength portion of the spectrum between 446 and 477 nm that appears blue. Blue monochromatic light has also been shown to be more effective than longer-wavelength light for enhancing alertness. Disturbed circadian rhythms and sleep loss have been described as risk factors for astronauts and NASA ground control workers, as well as civilians. Such disturbances can result in impaired alertness and diminished performance. Prior to exposing subjects to short-wavelength light from light-emitting diodes (LEDs) (peak λ = 469 nm; 1/2 peak bandwidth = 26 nm), the ocular safety exposure to the blue LED light was confirmed by an independent hazard analysis using the American Conference of Governmental Industrial Hygienists exposure limits. Subsequently, a fluence-response curve was developed for plasma melatonin suppression in healthy subjects (n = 8; mean age of 23.9 ± 0.5 years) exposed to a range of irradiances of blue LED light. Subjects with freely reactive pupils were exposed to light between 2:00 and 3:30 AM. Blood samples were collected before and after light exposures and quantified for melatonin. The results demonstrate that increasing irradiances of narrowband blue-appearing light can elicit increasing plasma melatonin suppression in healthy subjects (P < 0.0001). The data were fit to a sigmoidal fluence-response curve (R(2) = 0.99; ED(50) = 14.19 μW/cm(2)). A comparison of mean melatonin suppression with 40 μW/cm(2) from 4,000 K broadband white fluorescent light, currently used in most general lighting fixtures, suggests that narrow bandwidth blue LED light may be stronger than 4,000 K white fluorescent light for suppressing melatonin.
256 citations
TL;DR: The Fully Numerical Predictor-corrector Entry Guidance (FNPEG) is a model-based numerical guidance algorithm capable of performing both direct (orbital or suborbital) entry and skip entry missions as mentioned in this paper.
Abstract: The process, methodology, and results of a two year effort are presented in this paper on verification of an advanced entry guidance algorithm, called Fully Numerical Predictor-corrector Entry Guidance (FNPEG). FNPEG is a model-based numerical guidance algorithm capable of performing both direct (orbital or suborbital) entry and skip entry missions. Few vehicle-dependent adjustments are necessary, and no reference trajectory or mission-dependent planning is required. The algorithm is applicable to a wide range of vehicles with different lift-to-drag ratios and includes state-of-the-art capability to effectively control g load and damp out phugoid oscillations, without adversely affecting the guidance precision. FNPEG has undergone extensive testing and evaluation in the high-fidelity simulation environment for the Orion spacecraft at NASA Johnson Space Center. In this paper, the verification methodology and process are described. The metrics for verification are defined. Extensive testing and simulation r...
74 citations
14 Sep 2009
TL;DR: In this paper, a parametric study of the Mars entry, descent, and landing design space has been conducted, focusing on the entry vehicle shape and the supersonic deceleration technology trades.
Abstract: As the nation sets its sight on returning humans to the Moon and going onward to Mars, landing high mass payloads ( 2 t) on the Mars surface becomes a critical technological need. Viking heritage technologies (e.g., 70 sphere-cone aeroshell, SLA-561V thermal protection system, and supersonic disk-gap-band parachutes) that have been the mainstay of the United States’ robotic Mars exploration program do not provide sucient capability to land such large payload masses. In this investigation, a parametric study of the Mars entry, descent, and landing design space has been conducted. Entry velocity, entry vehicle conguration, entry vehicle mass, and the approach to supersonic deceleration were varied. Particular focus is given to the entry vehicle shape and the supersonic deceleration technology trades. Slender bodied vehicles with a lift-to-drag ratio (L=D) of 0.68 are examined alongside blunt bodies with L=D = 0.30. Results demonstrated that while the increased L=D of a slender entry conguration allows for more favorable terminal descent staging conditions, the greater structural eciencies of blunt body systems along with the reduced acreage required for the thermal protection system aords an inherently lighter vehicle. The supersonic deceleration technology trade focuses on inatable aerodynamic decelerators (IAD) and supersonic retropropulsion, as supersonic parachute systems are shown to be excessively large for further consideration. While entry masses (the total mass at the top of the Mars atmosphere) between 20 and 100 t are considered, a maximum payload capability of 37.3 t results. Of particular note, as entry mass increases, the gain in payload mass diminishes. It is shown that blunt body vehicles provide sucient vertical L=D to decelerate all entry masses considered through the Mars atmosphere with adequate staging conditions for the propulsive terminal descent. A payload mass fraction penalty of approximately 0.3 exists for the use of slender bodied vehicles. Another observation of this investigation is that the increased aerothermal and aerodynamic loads induced from a direct entry trajectory (velocity 6.75 km/s) reduce the payload mass fraction by approximately 15% compared to entry from orbital velocity ( 4 km/s). It should be noted that while both IADs and supersonic retropropulsion were evaluated for each of the entry masses, congurations, and velocities, the IAD proved to be more mass-ecient in all instances. The sensitivity of these results to modeling assumptions was also examined. The payload mass of slender body vehicles was observed to be approximately four times more sensitive to modeling assumptions and uncertainty than blunt bodies.
71 citations
TL;DR: In this paper, the authors present a review of the characterisation of lunar dust or regolith, the toxicity of the dust and associated health effects, the techniques for assessing the health risks from dust exposure and describes the measures used or being developed to mitigate exposure.
Abstract: This paper reviews the characterisation of lunar dust or regolith, the toxicity of the dust and associated health effects, the techniques for assessing the health risks from dust exposure and describes the measures used or being developed to mitigate exposure. Lunar dust is formed from micrometeorite impacts onto the Moon’s surface. The hypervelocity impacts result in communition and the formation of sharp and clingy agglutinates. The dust particles vary in size with the smallest being less than 10 μm. If the chemical reactive particles are deposited in the lungs, they may cause respiratory disease. During lunar exploration, the astronaut’s spacesuits will become contaminated with lunar dust. The dust will be released into the atmosphere when the suits are removed. The exposure risks to health will need to be assessed by relating to a permissible exposure limit. During the Apollo missions, the astronauts were exposed to lunar dust. Acute health effects from dust inhalation exposure included sore throat, sneezing and coughing. Long-term exposure to the dust may cause a more serious respiratory disease similar to silicosis. On future missions the methods used to mitigate exposure will include providing high air recirculation rates in the airlock, the use of a “Double Shell Spacesuit” so that contaminated spacesuits are removed before entering the airlock, the use of dust shields to prevent dust accumulating on surfaces, the use of high gradient magnetic separation to remove surface dust and the use of solar flux to sinter and melt the regolith around the spacecraft.
39 citations
06 Mar 2010
TL;DR: The PredGuid entry guidance algorithm is designed to guide Orion to the desired landing site while accounting for vehicle and environment uncertainties and day of flight dispersions during atmospheric entry as mentioned in this paper.
Abstract: When returning from low Earth orbit, Orion will perform a lifting atmospheric entry with precision landing using the PredGuid entry guidance algorithm.12 The PredGuid algorithm is designed to guide Orion to the desired landing site while accounting for vehicle and environment uncertainties and day of flight dispersions during atmospheric entry. The low Earth orbit mode of the PredGuid entry guidance algorithm consists of three phases: the Initial Roll Phase which maintains proper entry attitude and steers the vehicle to proper transition conditions for the Final Phase; the Final Phase, a terminal point guidance algorithm that uses a stored reference trajectory to steer out range error and achieve precision landing; and the Terminal Phase, which seeks to null the remaining crossrange error through a simple proportional steering law. Simulation results indicate that the PredGuid algorithm provides precision landing capability to Orion as well as significant robustness to day-of-flight uncertainties and dispersions.
22 citations