SCIENTIFIC AND TECHNICAL AEROSPACE REPORTS

A Biweekly Publication of the National Aeronautics and Space Administration
VOLUME 44, ISSUE 7 - April 07, 2006

16 SPACE TRANSPORTATION AND SAFETY
Includes passenger and cargo space transportation, e.g., shuttle operations; and space rescue techniques.

For related information see also 03 Air Transportation and Safety; 15 Launch Vehicles and Launch Operations; and 18 Spacecraft Design, Testing and Performance.

For space suits see 54 Man/System Technology and Life Support.

20060009022 NASA Johnson Space Center, Houston, TX, USA

Crew Restraint Design for the International Space Station

Norris, Lena; Holden, Kritina; Whitmore, Mihriban; [2006]; 2 pp.; In English; Space 2004 Conference and Exposition, 28-30 Sep. 2004, San Diego, CA, USA Contract(s)/Grant(s): NAS9-02078; No Copyright; Avail.: Other Sources; Abstract Only

With permanent human presence onboard the International Space Station (ISS), crews will be living and working in microgravity, dealing with the challenges of a weightless environment. In addition, the confined nature of the spacecraft environment results in ergonomic challenges such as limited visibility and access to the activity areas, as well as prolonged periods of unnatural postures. Without optimum restraints, crewmembers may be handicapped for performing some of the on-orbit tasks. Currently, many of the tasks on ISS are performed with the crew restrained merely by hooking their arms or toes around handrails to steady themselves. This is adequate for some tasks, but not all. There have been some reports of discomfort/calluses on the top of the toes. In addition, this type of restraint is simply insufficient for tasks that require a large degree of stability.

Glovebox design is a good example of a confined workstation concept requiring stability for successful use. They are widely used in industry, university, and government laboratories, as well as in the space environment, and are known to cause postural limitations and visual restrictions. Although there are numerous guidelines pertaining to ventilation, seals, and glove attachment, most of the data have been gathered in a 1-g environment, or are from studies that were conducted prior to the early 1980 s. Little is known about how best to restrain a crewmember using a glovebox in microgravity.

Another ISS task that requires special consideration with respect to restraints is robotic teleoperation. The Robot Systems Technology Branch at the NASA Johnson Space Center is developing a humanoid robot astronaut, or Robonaut. It is being designed to perform extravehicular activities (EVAs) in the hazardous environment of space. An astronaut located inside the ISS will remotely operate Robonaut through a telepresence control system. Essentially, the robot mimics every move the operator makes. This requires the operator to be stable enough to prevent inadvertent movements, while allowing the flexibility to accomplish the controlled movements of the robot. Some type of special purpose restraint will be required to operate Robonaut and similar devices. Derived from text

International Space Station; Crews; Teleoperators; Robotics; Constraints; Aerospace Environments; Man Machine Systems; Stability; Weightlessness

20060009194 NASA Johnson Space Center, Houston, TX, USA

The Vision of Human Spaceflight

Mendell, Wendell; [2005]; 7 pp.; In English Contract(s)/Grant(s): 090-28-AP; No Copyright; Avail.: CASI: A02, Hardcopy

First, we live in a world where change is the norm, not the exception. The scientific revolution springing from quantum mechanics yielded new understanding of solid state physics leading to stunning advances in computation, communication, and transportation. Two World Wars and one Cold War introduced massive governmental investment in research and development.

The unusual pragmatic and classless entrepreneurship of U.S. society promoted commercialization and innovative marketing of new technology. As a result, the 20th Century experienced a constantly accelerating culture of change. Those societies that accepted and embraced the new capabilities dominated commercially and militarily; those that did not fell behind.

I remember when there was no color television, when there were no personal computers, when there was no email, when there was no World Wide Web, when there were no cell phones. Now many of us cannot live without these things. Change has become the measure of success. Our children anticipate the future and do not expect it to look like the past.

Secondly, our elementary school students are fascinated by dinosaurs, ghosts, and space. Astronauts create excitement. None question that humans will be in space in their future. They see it every week, even every day, in stories on television. To be an astronaut is considered a legitimate ambition. They see space travel to be an adventure just as our grandparents saw exploring Africa or the polar regions to be an adventure into the unknown.

Third, we live in a time when our understanding of the space environment makes us realize that the existence of our species is one large impact away from extinction. We understand that our population explosion is changing our home planet in fundamental ways and that wars over terrestrial resources may be less than two generations away. We feel more connected to our space neighborhood than ever before. Many nations of the world are looking outward toward our Moon in an unprecedented way. A lunar space mission will be launched from somewhere every year for the next decade, at least. Derived from text

Space Flight; Aerospace Environments; Technology Utilization; Space Missions; Quantum Mechanics

20060009469 NASA Langley Research Center, Hampton, VA, USA

Evaluation Of Risk And Possible Mitigation Schemes For Previously Unidentified Hazards

Linzey, William; McCutchan, Micah; Traskos, Michael; Gilbrech, Richard; Cherney, Robert; Slenski, George; Thomas, Walter, III; January 2006; 28 pp.; In English; 9th Joint FAA/DoD/NASA Conference on Aging Aircraft, 6-9 Mar. 2006, Atlanta, GA, USA; Original contains color and black and white illustrations Contract(s)/Grant(s): 23-104-08-46; Copyright; Avail.: CASI: A03, Hardcopy

This report presents the results of arc track testing conducted to determine if such a transfer of power to un-energized wires is possible and/or likely during an arcing event, and to evaluate an array of protection schemes that may significantly reduce the possibility of such a transfer. The results of these experiments may be useful for determining the level of protection necessary to guard against spurious voltage and current being applied to safety critical circuits.

It was not the purpose of these experiments to determine the probability of the initiation of an arc track event only if an initiation did occur could it cause the undesired event: an inadvertent thruster firing. The primary wire insulation used in the Orbiter is aromatic polyimide, or Kapton , a construction known to arc track under certain conditions [3]. Previous Boeing testing has shown that arc tracks can initiate in aromatic polyimide insulated 28 volts direct current (VDC) power circuits using more realistic techniques such as chafing with an aluminum blade (simulating the corner of an avionics box or lip of a wire tray), or vibration of an aluminum plate against a wire bundle [4]. Therefore, an arc initiation technique was chosen that provided a reliable and consistent technique of starting the arc and not a realistic simulation of a scenario on the vehicle. Once an arc is initiated, the current, power and propagation characteristics of the arc depend on the power source, wire gauge and insulation type, circuit protection and series resistance rather than type of initiation.

The initiation method employed for these tests was applying an oil and graphite mixture to the ends of a powered twisted pair wire. The flight configuration of the heater circuits, the fuel/oxider (or ox) wire, and the RCS jet solenoid were modeled in the test configuration so that the behavior of these components during an arcing event could be studied. To determine if coil activation would occur with various protection wire schemes, 145 tests were conducted using various fuel/ox wire alternatives (shielded and unshielded) and/or different combinations of polytetrafuloroethylene (PTFE), Mystik tape and convoluted wraps to prevent unwanted coil activation. Test results were evaluated along with other pertinent data and information to develop a mitigation strategy for an inadvertent RCS firing. The SSP evaluated civilian aircraft wiring failures to search for aging trends in assessing the wire-short hazard. Appendix 2 applies Weibull statistical methods to the same data with a similar purpose. Derived from text

Wiring; Arcs; Circuit Protection; Insulation; Risk; Probability Theory

Source: NASA