نتایج جستجو برای: space flight
تعداد نتایج: 534568 فیلتر نتایج به سال:
The microgravity experienced during space flight induces physiological changes that affect astronauts' health and performance. Simulations such as prolonged bed rest can mimic some of these changes and provide study conditions that are more accessible than during space flight itself. Previous studies, including several long and short-term bed-rest campaigns supported by ESA, have yielded signif...
A series of studies were conducted to determine the effect of activities preceding spaceflight and during space-flight on calcium utilization during quail embryonic development. In the pre-space trials, fertile quail eggs were subjected to pre-flight dynamics including forces of centrifugation, vibration, or a combination of vibration and centrifugation prior to incubation for 6 or 16 days. Qua...
Mohammad Z. Al-Hamdan 1,*, Dale A. Quattrochi 2, Lahouari Bounoua 3, Asia Lachir 3 and Ping Zhang 3,4,5 1 Universities Space Research Association at NASA Marshall Space Flight Center, National Space Science and Technology Center, Huntsville, AL 35805, USA 2 Earth Science Office at NASA Marshall Space Flight Center, National Space Science and Technology Center, Huntsville, AL 35805, USA; dale.qu...
Seven days' space flight of fertilized chicken eggs pre- incubated for 7 and 10 days on earth caused no differences in the morphology of osteoblasts, osteoclasts, and osteocytes of humerus and tibia from those of control embryos. Bone-resorbing and -forming activities of the femur were not different between control and flight groups. As a consequence, calcium and phosphorus contents of the femo...
The Modelica Space Flight Dynamics Library has been developed as a unified environment to be used throughout the design cycle of the Attitude and Orbit Control System (AOCS) for a generic multibody, possibly flexible, spacecraft. The library architecture has been recently redesigned, exploiting at its best Modelica’s reusability, flexibility and modularity features. In this contribution the mai...
Compared to the well-studied topic of human mobility in real geographic space, very few studies focus on human mobility in virtual space, such as interests, knowledge, ideas, and so forth. However, it relates to the issues of management of public opinions, knowledge diffusion, and innovation. In this paper, we assume that the interests of a group of online users can span a Euclidean space which...
An Adaptive Augmenting Control (AAC) algorithm for the Space Launch System (SLS) has been developed at the Marshall Space Flight Center (MSFC) as part of the launch vehicle’s baseline flight control system. A prototype version of the SLS flight control software was hosted on a piloted aircraft at the Armstrong Flight Research Center to demonstrate the adaptive controller on a full-scale realist...
T H E PROBLEM of supplying man with his oxygen requirement and uncontaminated air during prolonged confinement is receiving considerable research attention. In particular, the recovery of oxygen using biological specimens as the mechanism for converting carbon dioxide into oxygen plus other materials has been the subject of many papers recently. There can be no doubt concerning the need for a r...
The routine use of pseudospectral (PS) optimal control techniques in space applications1 has generated new opportunities for performance enhancement. One of these opportunities is related to the interaction of an outer guidance loop with inner control loops. In current flight applications, knowledge of the initial state vector, padded with high conservatism, is considered necessary to maintain ...
T HE POTENTIAL medical hazards of man's venture into space will span a number of disciplines in regard to the pathology and deranged physiology to which the human body may be subject in travel beyond the earth's atmosphere. Not the least hazard is that having to do with the effects of radiation to be encountered in free space. This problem is one which is receiving considerable attention from a...
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