ASTM F 3668/F 3668M:2023

1.1 The purpose of this guide is to provide guidance for current and developing space flight operators who intend to fly humans on spacecraft. The occupants include the crew and spaceflight participants in the orbital vehicles. This guide is targeted primarily toward ground launched, Low Earth Orbit (LEO) spacecraft which provide transportation from the surface to orbit followed by subsequent rendezvous with an orbital complex or short-duration free flight orbit operations, and safe return to Earth's surface. As used in the guide, LEO is an approximate circular orbit within ~2000 km of Earth's surface. Longer duration spaceflight (>approximately two weeks) aboard an orbital space station poses unique design and medical constraints which are not specifically addressed in this guide. 1.2 The methods in this guide are best practices. Having prior positive performing systems may be a basis for compliance to this guide. 1.2.1 This is a non-comprehensive subset of best safety practices for crew survivability of catastrophic hazards for which all failure tolerance has been exhausted. This is further elaborated upon in 1.5 and 4.2 . 1.3 Units- The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with the standard. 1.4 Each spacecraft will present its own set of safety hazards that the user of this standard is expected to analyze and implement survivability options where practical. Also, note that safety is an inherent characteristic of a system, not the product of a few key post-hazard mitigation features. History has shown that a safe and successful spaceflight system is built and operated to the highest possible standards of design robustness, manufacturing quality, inspection, test, and operation, including maintenance and sustaining engineering. The addition of the design features and capabilities as recommended in this guide cannot and is not intended to make up for deficiencies in these basics. It is the responsibility of the user of this standard to establish appropriate safety, survivability, health, and environmental practices and determine the applicability of regulatory limitations prior to use. For example, with regard to survivability, certain operators will likely require additional crew survivability capabilities be provided prior to permitting their space vehicle to fly a crew. 1.5 This standard does not purport to address all of the safety or survivability design concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, survivability, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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