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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Analysis of Bioburden Associated with Nonmetallic Spacecraft Materials

Planetary Protection (PP) requirements help to ensure the integrity of life-detection science conducted on solar system bodies, particularly those with liquid water. Such requirements are often met by a combination of cleaning and verification steps to reduce microbial contamination (i.e. bioburden) to an acceptable limit. There are only two cleaning methods approved by the National and Space Administration (NASA), vapor hydrogen peroxide (VHP) and heat microbial reduction (HMR), the latter of which is the most commonly employed. However, HMR can be harsh and produce its own concerns about material integrity, like aging or increasing hardness. When bioburden reduction methods cannot be employed, the project must rely on assumed NASA specification values of bioburden which can cause compliance issues with strict PP bioburden limitations. This work aimed to more accurately define the risk of contamination of a target body by providing empirical data associated with raw materials commonly used in solid rocket motors for lander missions. In this study, we pulverized nonmetallic materials using a cryogenic grinder, then analyzed the resulting substrate for microbial colony forming units (CFU). We found that many nonmetallic materials do not harbor large bioburden when compared with the NASA specification values, though a range existed depending on the material, treatment, and handling. The results from this work provide quantitative data to help reduce concerns of contamination, while also providing a foundation for follow up studies into additional sterilization methods and molecular identification of contaminating microbes.

Planetary Protection↗
NASA NTRS1976

Scintillations during occultations by planets. I - An approximate theory

Fluctuations are observed during occultations of both stars and spacecraft by planetary atmospheres. Existing treatments of spacecraft scintillations ignore a major effect unique to occultations: the severe flattening of the Fresnel zone or source image by defocusing. Other large effects, due to 'saturation' of the scintillation, have also been ignored. The deeper portions of atmospheric temperature and density profiles inferred from occultation data are seriously in error if other planets' atmospheres are as turbulent as our own. Thus, profiles obtained from entry probes (e.g., the Soviet Venera series) are probably more accurate than those from radio occultation (Mariner 5 and 10) data. Scintillation greatly reduces the information obtainable from occultation observations; much of the detail attributed to layering in published profiles is probably due to aliasing of turbulence. This paper gives an approximately correct theoretical treatment that is a substantial improvement over published theories, and shows how a more accurate theory could be constructed. Some methods for a more accurate determination of atmospheric structure are proposed.

Young, A. T.↗
NASA NTRSDate not supplied

Mechanisms of Ejecta Streak Formation During Spacecraft Landings on the Moon

When landing on another planetary body, spacecraft most often employ retropropulsion to decelerate for a soft landing. This process generates a crater and ejects high-speed particles, which can destabilize the lander and pose risks to nearby infrastructure. From the Apollo missions in the 1960s to the recent Chang'E-5 mission, particles leave the impingement region as streak filaments, regardless of landing site, lander mass, or thrust. This study aims to uncover the mechanism behind the formation of these ejecta streaks.

PSI↗
NASA NTRS1972

Application of planetary quarantine methodology and spacecraft sterilization technology to improved health care delivery.

In 1969 the Jet Propulsion Laboratory undertook an investigation to determine which of its space-derived capabilities could make significant contributions to the improvement of health care delivery in the U.S. The area of planetary quarantine was identified as one of high relevance. Two studies were conducted in this connection. The first study, which could contribute to infection reduction and control, was concerned with conversion of infection implicated complex, nonheat sterilizable equipment to dry heat, sterilizable equipment by changes in design and materials of construction. The second study area related to hospital acquired infection is clean room technology. A definite investigation has been performed to demonstrate and statistically evaluate performance under controlled conditions.

Green, R. H.↗