SCIENTIFIC AND TECHNICAL AEROSPACE REPORTS

A Biweekly Publication of the National Aeronautics and Space Administration
VOLUME 44, ISSUE 8 - April 21, 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.

20060010432 Wyle Labs., Inc., Houston, TX, USA

GO/NO-GO - When is medical hazard mitigation acceptable for launch?

Hamilton, Douglas R.; Polk, James D.; January 2005; 1 pp.; In English; Aerospace Medicine Association Annual Conference, 8-12 May 2005, Kansas City, MO, USA; No Copyright; Avail.: Other Sources; Abstract Only

Medical support of spaceflight missions is composed of complex tasks and decisions that dedicated to maintaining the health and performance of the crew and the completion of mission objectives. Spacecraft represent one of the most complex vehicles built by humans, and are built to very rigorous design specifications.

In the course of a Flight Readiness Review (FRR) or a mission itself, the flight surgeon must be able to understand the impact of hazards and risks that may not be completely mitigated by design alone. Some hazards are not mitigated because they are never actually identified. When a hazard is identified, it must be reduced or waivered. Hazards that cannot be designed out of the vehicle or mission, are usually mitigated through other means to bring the residual risk to an acceptable level. This is possible in most engineered systems because failure modes are usually predictable and analysis can include taking these systems to failure.

Medical support of space missions is complicated by the inability of flight surgeons to provide 'exact' hazard and risk numbers to the NASA engineering community. Taking humans to failure is not an option. Furthermore, medical dogma is mostly comprised of 'medical prevention' strategies that mitigate risk by examining the behaviour of a cohort of humans similar to astronauts. Unfortunately, this approach does not lend itself well for predicting the effect of a hazard in the unique environment of space.

This presentation will discuss how Medical Operations uses an evidence-based approach to decide if hazard mitigation strategies are adequate to reduce mission risk to acceptable levels. Case studies to be discussed will include:

1. Risk of electrocution risk during EVA

2. Risk of cardiac event risk during long and short duration missions

3. Degraded cabin environmental monitoring on the ISS.

Learning Objectives 1.) The audience will understand the challenges of mitigating medical risk caused by nominal and off-nominal mission events. 2.) The audience will understand the process by which medical hazards are identified and mitigated before launch. 3.) The audience will understand the roles and responsibilities of all the other flight control positions in participating in the process of reducing hazards and reducing medical risk to an acceptable level. Author

Launching; Health; Hazards; Flight Surgeons; Extravehicular Activity; Environmental Monitoring; Astronauts; Risk

20060010433 NASA Johnson Space Center, Houston, TX, USA

Space Shuttle Hot Cabin Emergency Responses

Stepaniak, P.; Effenhauser, R. K.; McCluskey, R.; Gillis, D. B.; Hamilton, D.; Kuznetz, L. H.; [2005]; 1 pp.; In English; Aerospace Medicine Association Annual Conference, 8-12 May 2005, Kansas City, MO, USA; No Copyright; Avail.: Other Sources; Abstract Only

Methods: Human thermal tolerance, countermeasures, and thermal model data were reviewed and compared to existing shuttle ECS failure temperature and humidity profiles for each failure mode. Increases in core temperature associated with cognitive impairment was identified, as was metabolic heat generation of crewmembers, temperature monitoring, and communication capabilities after partial power-down and other limiting factors. Orbiter landing strategies and a hydration and salt replacement protocol were developed to put wheels on deck in each failure mode prior to development of significant cognitive impairment or collapse of crewmembers. Thermal tradeoffs for use of the Advanced Crew Escape Suit (ACES), Liquid Cooling Garment, integrated G-suit and Quick Don Mask were examined. candidate solutions involved trade-offs or conflicts with cabin oxygen partial pressure limits, system power-downs to limit heat generation, risks of alternate and emergency landing sites or compromise of Mode V-VIII scenarios. Results: Rehydration and minimized cabin workloads are required in all failure modes. Temperature/humidity profiles increase rapidly in two failure modes, and deorbit is recommended without the ACES, ICU and g-suit. This latter configuration limits several shuttle approach and landing escape modes and requires communication modifications. Additional data requirements were identified and engineering simulations were recommended to develop more current shuttle temperature and humidity profiles. Discussion: After failure of the shuttle ECS, there is insufficient cooling capacity of the ACES to protect crewmembers from rising cabin temperature and humidity. The LCG is inadequate for cabin temperatures above 76 F. Current shuttle future life policy makes it unlikely that major engineering upgrades necessary to address this problem will occur. Derived from text

Emergencies; Human Tolerances; Mental Performance; Workloads (Psychophysiology); Temperature Profiles; Hydration; Heat Generation; Countermeasures

20060010435 NASA Johnson Space Center, Houston, TX, USA

Space Suit Electrocardiographic Electrode Selection: Are commercial electrodes better than the old Apollo technology?

Redmond, M.; Polk, J. D.; Hamilton, D.; Schuette, M.; Guttromson, J.; Guess, T.; Smith, B.; [2005]; 1 pp.; In English; Aerospace Medicine Association Annual Meeting, 8-12 May 2005, Kansas City, MO, USA; No Copyright; Avail.: Other Sources; Abstract Only

The NASA Manned Space Program uses an electrocardiograph (ECG) system to monitor astronauts during extravehicular activity (EVA). This ECG system, called the Operational Bioinstrumentation System (OBS), was developed during the Apollo era. Throughout the Shuttle program these electrodes experienced failures during several EVAs performed from the Space Shuttle and International Space Station (ISS) airlocks. An attempt during Shuttle Flight STS-109 to replace the old electrodes with new commercial off-the-shelf (COTS) disposable electrodes proved unsuccessful. One assumption for failure of the STS-109 COTS electrodes was the expansion of trapped gases under the foam electrode pad, causing the electrode to be displaced from the skin. Given that our current electrodes provide insufficient reliability, a number of COTS ECG electrodes were tested at the NASAAltitude Manned Chamber Test Facility. Methods: OBS disposable electrodes were tested on human test subjects in an altitude chamber simulating an Extravehicular Mobility Unit (EMU) operating pressure of 4.3 psia with the following goals: (1) to confirm the root cause of the flight certified, disposable electrode failure during flight STS-109. (2) to identify an adequate COTS replacement electrode and determine if further modifications to the electrodes are required. (3) to evaluate the adhesion of each disposable electrode without preparation of the skin with isopropyl alcohol. Results: There were several electrodes that failed the pressure testing at 4.3psia, including the electrodes used during flight STS-109. Two electrodes functioned well throughout all testing and were selected for further testing in an EMU at altitude.Avent hole placed in all electrodes was also tested as a possible solution to prevent gas expansion from causing electrode failures. Conclusions: Two failure modes were identified: (1) foam-based porous electrodes entrapped air bubbles under the pad (2) poor adhesion caused some electrodes to fail Author

Space Suits; Electrocardiography; Electrodes; Space Transportation System Flights; Space Shuttles; Extravehicular Activity; Failure Modes; Astronauts; Bioinstrumentation

20060010452 NASA Johnson Space Center, Houston, TX, USA

International Space Station Integration of Automated Safing Responses

Curry, Kim; Prokhorov, Kimberlee; January 2006; 2 pp.; In English; 34th International Conference on Environmental Systems (ICES), 19-22 Jul. 2004, Colorado Springs, CO, USA; Original contains black and white illustrations Report No.(s): SAE-2004-01-0054; Copyright; Avail.: Other Sources

Environmental Control and Life Support (ECLS) functionality aboard the International Space Station (ISS) includes responding to various emergency conditions. The ISS requirements define three types of emergencies: fire, rapid depressurization, and hazardous or toxic atmosphere. The ISS has automatic integrated vehicle responses to each of these emergencies. These responses are designed to aid the crew in their response actions to the emergencies. This paper focuses on the integration of ISS responses to these three emergencies. It includes the ISS automatic integrated vehicle response and the initial crew response. Philosophies regarding the generic response to an on-orbit emergency are described. Software responses are defined for modules on orbit up to the addition of the Docking Compartment (DC1) in the assembly sequence. Possible future improvements are also described. Author

International Space Station; Emergencies; Spacecrews; Life Support Systems; Pressure Reduction; Fires; Toxicity

Source: NASA