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NASA NTRS2024

Appendix N. Pc Calculation Approaches – UPDATE 3/20/24

This document represents a technical content update to Appendix N of the NASA Spacecraft Conjunction Assessment and Collision Avoidance Best Practices Handbook (OCE-51, available on NODIS) requested by the Consultative Committee for Space Data Standards (CCSDS) to document the background on why NASA populates certain fields of the Conjunction Data Message (CDM) in certain ways. This update was requested to be used as reference material for the CCSDS CDM documentation update and so is being published as a white paper out of cycle from Handbook updates. When the full Handbook is next updated, these Appendix redlines may be incorporated into the official document. Two versions are attached - the redlines to the published Handbook for use in understanding what has changed and a clean copy.

conjunction assessment↗
NASA NTRS1985

Ultrasonic angle beam standard reflector

A method that provides an impression profile in a reference standard material utilized in inspecting critically stressed components with pulsed ultrasound is described. A die stamp having an I letter is used to impress the surface of a reference material. The die stamp is placed against the surface and struck with an inertia imparting member to impress the I in the reference standard material. Upset may appear on the surface as a result of the impression and is removed to form a smooth surface. The stamping and upset removal is repeated until the entire surface area of a depth control platform on the die stamp uniformly contacts the material surface. The I impression profile in the reference standard material is utilized for reflecting pulsed ultrasonic beams for inspection purposes.

Berry, R. F., Jr.↗
NASA NTRS1981

Creep of oxide dispersion strengthened materials /with special reference to T-D nichrome/

Analyses of oxide dispersion strengthened (ODS) alloys shows that their characteristics are mainly due to the creep behavior of the matrix material. Diffusion-controlled slip creep is established as the rate-controlling process in the alloys investigated, with the glide and climb of edge dislocations associated with the subgrain structure as barriers being the specific rate-controlling step. It is found that the stable subgrain size in ODS alloys is usually associated with the spacing between particles 500-1000 A in size, and that their creep behavior is distinguished from that of the matrix material by the existence of a threshold stress that is not well defined microscopically but appears to be related to particles of less than 500 A size.

Lin, J.↗
NASA NTRS1978

Creep of oxide dispersion strengthened materials (with special reference to TD nichrome)

It was shown that the creep behavior of oxide dispersion strengthened (ODS) alloys is controlled principally by the creep properties of the matrix of the alloy devoid of particles. Thus, diffusion controlled slip process determine the rate controlling step in such materials. The role of the particles is to stabilize a fine substructure which is invariant with the creep stress over a wide range of stress. This characteristic leads to negligible strain hardening during creep and suggests that creep relations developed for pure metals and many solid solution alloys at constant structure should be used to describe the creep of ODS alloys. A second characteristics of the ODS alloys is that a stress may exist below which creep will not occur (threshold stress).

Lin, J.↗
NASA NTRS1986

A thin film degradation study of a fluorinated polyether liquid lubricant using an HPLC method

A High Pressure Liquid Chromatography (HPLC) separation method was developed to study and analyze a fluorinated polyether fluid which is promising liquid lubricant for future applications. This HPLC separation method was used in a preliminary study investigating the catalytic effect of various metal, metal alloy, and ceramic engineering materials on the degradation of this fluid in a dry air atmosphere at 345 C. Using a 440 C stainless steel as a reference catalytic material it was found that a titanium alloy and a chromium plated material degraded the fluorinated polyether fluid substantially more than the reference material.

Morales, W.↗
NASA NTRS1992

Permeability of rayon based polymer composites

Several types of anomalous rayon based phenolic behavior have been observed in post-fired nozzles and exit cones. Many of these events have been shown to be related to the development of internal gas pressure within the material. The development of internal gas pressure is a function of the amount of gas produced within the material and the rate at which that gas is allowed to escape. The latter property of the material is referred to as the material's permeability. The permeability of two dimensional carbonized rayon based phenolic composites is a function of material direction, temperature, and stress/strain state. Recently significant differences in the permeability of these materials has been uncovered which may explain their inconsistent performance. This paper summarizes what is known about the permeability of these materials to date and gives possible implications of these finding to the performance of these materials in an ablative environment.

Stokes, E. H.↗
NASA NTRS1972

Reference data for thermocouple materials below the ice point.

Standard thermoelectric data have been determined for four thermocouple combinations used below the ice point: commercial types E, K, and T and the special combination of KP vs Au-0.07 at.% Fe. Power series coefficients necessary to generate E = f(T) data for these combinations are given. In addition, extensive tests were carried out to ascertain the variability between materials from different manufacturers. Typical wires processed for low-temperature usage often have slightly thermoelectric properties (up to 1%) from those, nominally identical, wires made for high-temperature applications. Generally, type E is the most satisfactory standardized commercial combination. The Au-0.07 at.% Fe material has been examined in particular detail, because it is not yet an ISA standard material. It has excellent sensitivity in the liquid helium/liquid hydrogen temperature range and a nearly linear thermovoltage at higher temperatures.

Sparks, L. L.↗
NASA NTRS1993

Properties of Extruded PS-212 Type Self-Lubricating Materials

Research has been underway at the NASA Lewis Research Center since the 1960's to develop high temperature, self-lubricating materials. The bulk of the research has been done in-house by a team of researchers from the Materials Division. A series of self-lubricating solid material systems has been developed over the years. One of the most promising is the composite material system referred to as PS-212 or PM-212. This material is a powder metallurgy product composed of metal bonded chromium carbide and two solid lubricating materials known to be self-lubricating over a wide temperature range. NASA feels this material has a wide potential in industrial applications. Simplified processing of this material would enhance its commercial potential. Processing changes have the potential to reduce processing costs, but tribological and physical properties must not be adversely affected. Extrusion processing has been employed in this investigation as a consolidation process for PM-212/PS-212. It has been successful in that high density bars of EX-212 (extruded PM-212) can readily be fabricated. Friction and strength data indicate these properties have been maintained or improved over the P.M. version. A range of extrusion temperatures have been investigated and tensile, friction, wear, and microstructural data have been obtained. Results indicate extrusion temperatures are not critical from a densification standpoint, but other properties are temperature dependent.

Waters, W. J.↗
NASA NTRS2019

Stress Corrosion Evaluation of Elgiloy Alloy for the ISS ECLSS — Universal Waste Management System

Elgiloy® alloy (UNS R30003)—a spring material per AMS 5876D (reference 1)—is one among several alloys recently evaluated for stress corrosion cracking resistance in support of the International Space Station (ISS) Environmental Control and Life Support System (ECLSS). Elgiloy was evaluated particularly for its expected use in the Universal Waste Management System (described in references 2 and 3). Data for other alloys previously evaluated were reported in references 4 and 5. Materials included in reference 4 are Inconel 625, Hastelloy® C276, commercially pure titanium, titanium with 6% aluminum and 4% vanadium (Ti6Al4V), extra-low interstitial Ti6Al4V, and Cronidur 30. The results for Nitinol 60 are in reference 5. During the water recovery process, the metallic components fabricated from these materials are exposed to acidic solutions used for waste treatment. The purpose of the current and previous stress corrosion evaluations is to determine if these materials have adequate stress corrosion resistance.

Torres, Pablo D.↗
NASA NTRS1993

Post-impact alteration of the Manson impact structure

Core materials from the Manson impact site (Manson, Iowa) are examined in order to evaluate post-impact alteration processes. Diagenetic interpretation of post-impact events is based on petrologic, mineralogic, and geochemical investigation of core materials including the following: target strata, disturbed and disrupted strata, ejecta, breccias, microbreccias, and impact melt. The diagenetic study utilizes research cores obtained by the continental scientific drilling project (CSDP) at the Manson structure, as well as core and cuttings of related materials. Samples include impactites (breccias, microbreccias, and melt material), crater fill material (sedimentary clast breccias), disturbed and disrupted target rocks, and reference target material (Amoco Eisheid No. 1 materials). The study of multiple cores will permit development of a regional picture of post-impact thermal history. The specific objectives are as follows: (1) provide a detailed description of authigenic and alteration mineralogy from diverse lithologies encountered in research drill cores at the Manson impact structure, and (2) identify and relate significant post-impact mineral alteration to post-impact thermal regime (extent and duration). Results will provide mineralogical and geochemical constraints on models for post-impact processes including the following: infilling of the crater depression; cooling and hydrothermal alteration of melt rocks; and subsequent long-term, low-temperature alteration of target rocks, breccias, and melt rocks. Preliminary petrologic and x-ray diffraction examination of fracture linings and void fillings from research core M1 indicate the presence of quartz, chlorite, mixed-layer clays, gypsum/anhydrite, calcite, and minor pyrite.

Crossey, L. J.↗
NASA NTRS1996

NASA-UVa Light Aerospace Alloy and Structures Technology Program: Aluminum-Based Materials for High Speed Aircraft

This report is concerned with 'Aluminum-Based Materials for High Speed Aircraft' which was initiated to identify the technology needs associated with advanced, low-cost aluminum base materials for use as primary structural materials. Using a reference baseline aircraft, these materials concept will be further developed and evaluated both technically and economically to determine the most attractive combinations of designs, materials, and manufacturing techniques for major structural sections of an HSCT. Once this has been accomplished, the baseline aircraft will be resized, if applicable, and performance objectives and economic evaluations made to determine aircraft operating costs. The two primary objectives of this study are: (1) to identify the most promising aluminum-based materials with respect to major structural use on the HSCT and to further develop those materials, and (2) to assess these materials through detailed trade and evaluation studies with respect to their structural efficiency on the HSCT.

Starke, E. A., Jr.↗
NASA NTRS2011

Methods and instruments for materials testing

Methods and instruments for characterizing a material, such as the properties of bone in a living human subject, using a test probe constructed for insertion into the material and a reference probe aligned with the test probe in a housing. The housing is hand held or placed so that the reference probe contacts the surface of the material under pressure applied either by hand or by the weight of the housing. The test probe is inserted into the material to indent the material while maintaining the reference probe substantially under the hand pressure or weight of the housing allowing evaluation of a property of the material related to indentation of the material by the probe. Force can be generated by a voice coil in a magnet structure to the end of which the test probe is connected and supported in the magnet structure by a flexure, opposing flexures, a linear translation stage, or a linear bearing. Optionally, a measurement unit containing the test probe and reference probe is connected to a base unit with a wireless connection, allowing in the field material testing.

Hansma, Paul↗
NASA NTRS1985

Eddy-Current Reference Standard

Magnetic properties of metallic reference standards duplicated and stabilized for eddy-current coil measurements over long times. Concept uses precisely machined notched samples of known annealed materials as reference standards.

Ambrose, H. H., Jr.↗
NASA NTRS2018

The Importance of Contamination Knowledge - Insights into Mars Sample Return

The Astromaterials Acquisition and Curation Office at NASA Johnson Space Center (JSC), in Houston, TX (henceforth Curation Office) manages the curation of all past, present, and future extraterrestrial samples returned by NASA missions and shared collections from international partners, preserving their integrity for future scientific study while providing the samples to the international community in a fair and unbiased way. The Curation Office also curates all reference and witness materials for each mission (e.g., flight and non-flight hardware coupons; lubricants; non-flight, flight-like, and flown witness plates). These reference and witness materials provide the scientific community with the fundamental ability to reconstruct the contamination/alteration history of the sample collection through the course of the mission, with the overall goal of strengthening the scientific conclusions drawn from the study of returned materials. The information gained from characterizing the physical, biological, inorganic, and organic chemical properties of reference and witness materials is defined as the Contamination Knowledge (CK) of the sample collection. Unlike the data collected for Contamination Control (CC) and Planetary Protection (PP), CK is exclusively concerned with preserving reference and witness materials for study by future scientists upon sample return. Although CC and PP data collected for sample integrity and forward contamination purposes can be complementary to CK, they are two separate data sets with distinct objectives. A robust collection of samples for CK is necessary to allow the extraterrestrial material in a returned sample to be distinguished from terrestrial contamination. Traditionally CK is utilized by sample scientists in order to accomplish the mission’s scientific objectives, however this information can also be utilized by the Office of Planetary Protection to help evaluate the presence of any back contamination. Mars 2020, the first phase of a potential multipart Mars Sample Return (MSR) campaign, is expected to contribute to NASA’s Mars Exploration Program Science Goals by filling in knowledge gaps concerning: 1) the existence of past or present life on Mars, 2) the past and present climate of Mars, 3) the geology of Mars, and 4) hazards associated with human exploration of Mars. Although there is debate concerning which samples will best answer these questions, the necessity for proper sample blanks is well-understood. The CC and PP requirements, driven by the restricted Class V mission designation, are the most stringent of any sample return mission in recent history. The extremely low levels of allowable terrestrial contamination on the spacecraft and rover can complicate these analyses given the detection limits of current analytical instrumentation, especially in the case of biological contamination. By collecting and curating unanalyzed samples specifically for CK, future sample scientists will not be relegated to: 1) relying on data collected using possibly obsolete tools and techniques for return sample blanks, or 2) using remnants of extracted and/or cultured samples from ATLO (Assembly, Test, and Launch Operations), which could be incompatible with the desired experimental endpoints or state-of-the-art techniques available at the time of sample return.The addition of biological experimental endpoints to a sample return campaign’s objectives broadens the requisite range in preservation environments (e.g. inert ultra-pure nitrogen gaseous environment at 18 degrees Centigrade versus less than or equal to minus 80 degrees Centigrade) and types of CK samples. As a result, the Curation Office will also curate the following CK samples at less than or equal to minus 80 degrees Centigrade for the Mars 2020 mission: 1) unanalyzed swabs and wipes in sterile containers, 2) all recirculation filters from the clean rooms used for sample and caching subsystem assembly and all filters from the laminar flow benches used to assemble sample intimate hardware, and 3) witness plates collecting airborne contamination within the assembly clean rooms. It has been Curation Office policy since the Apollo missions to preserve as many pristine samples as possible for future scientific research. Although CK is required to be collected for all stages of the MSR campaign, the CK for the Mars 2020 mission is the most critical for understanding contamination in the returned samples given the intimacy between the Martian samples and the Mars 2020 flight hardware. This presentation highlights the importance of CK for sample return missions as well as the traditional and novel types of CK samples required for a successful MSR campaign.

Harrington, A. D.↗
NASA NTRS1972

Thermal performance of 625-kg/cu m elastomeric ablative materials on spherically blunted 0.44-radian cones

Spherically blunted 0.44-radian (25 deg) half-angle conical models coated with elastomeric ablative materials were tested in supersonic arc-heated wind tunnels to evaluate performance of the ablators over a range of conditions typical of lifting entry. Four test conditions were combinations of stagnation point-heat transfer rates of 2.3 and 4.5 MW/m2 and stagnation pressures of 20 and 2kN/m2. Afterbody values of heat transfer rate and pressure were 0.05 to 0.20 of stagnation point values. Stagnation enthalpy varied from 4.4 to 25 MJ/kg (1900 to 11000 Btu/lbm) and free-stream Mach number was in a range from 3.5 to 4. Ablative materials retained the spherical nose shape throughout tests at the lower heat transfer level, but receded, assuming a flattened nose shape, during tests at the high heat transfer level. The residue layer that formed on the conical after-body was weak, friable, and extensively cracked. The reference ablative material, which contained phenolic microspheres, generally retained the conical shape on the model afterbody. However, a modified ablator, in which phenolic microspheres were replaced with silica microspheres, deformed and separated from the undegraded material, and thereby produced a very uneven surface. Substrate temperatures and ablator recession were in good agreement with values computed by a numerical analysis.

Champman, A. J.↗
NASA NTRS1983

Burden for manufacture of ceramic material

A Soviet invention is discussed. The invention refers to ceramic materials which can be obtained by methods of powder metallurgy and can be used in high temperature technology.

Chechenya, T. V.↗
NASA NTRS2011

Short Range-Ordered Minerals: Insight into Aqueous Alteration Processes on Mars

Short range-ordered (SRO) aluminosilicates (e.g., allophane) and nanophase ferric oxides (npOx) are common SRO minerals derived during aqueous alteration of basaltic materials. NpOx refers to poorly crystalline or amorphous alteration products that can be any combination of superparamagnetic hematite and/or goethite, akaganeite, schwertmannite, ferrihydrite, iddingsite, and nanometer-sized ferric oxide particles that pigment palagonitic tephra. Nearly 30 years ago, SRO phases were suggested as alteration phases on Mars based on similar spectral properties for altered basaltic tephra on the slopes of Mauna Kea in Hawaii and Martian bright regions measured by Earth-based telescopes. Detailed characterization of altered basaltic tephra on Mauna Kea have identified a variety of alteration phases including allophane, npOx, hisingerite, jarosite, alunite, hematite, goethite, ferrihydrite, halloysite, kaolinite, smectite, and zeolites. The presence of npOx and other Fe-bearing minerals (jarosite, hematite, goethite) was confirmed by the M ssbauer Spectrometer onboard the Mars Exploration Rovers. Although the presence of allophane has not been definitely identified on Mars robotic missions, chemical analysis by the Spirit and Opportunity rovers and thermal infrared spectral orbital measurements suggest the presence of allophane or allophane-like phases on Mars. SRO phases form under a variety of environmental conditions on Earth ranging from cold and arid to warm and humid, including hydrothermal conditions. The formation of SRO aluminosilicates such as allophane (and crystalline halloysite) from basaltic material is controlled by several key factors including activity of water, extent of leaching, Si activity in solution, and available Al. Generally, a low leaching index (e.g., wet-dry cycles) and slightly acidic to alkaline conditions are necessary. NpOx generally form under aqueous oxidative weathering conditions, although thermal oxidative alteration may occasional be involved. The style of aqueous alteration (hydrolytic vs. acid sulfate) impacts which phases will form (e.g., oxides, oxysulfates, and oxyhydroxides). Knowledge on the formation processes of SRO phases in basaltic materials on Earth has allowed significant enhancement in our understanding of the aqueous processes at work on Mars. The 2011 Mars Science Laboratory (MSL) will provide an instrument suite that should improve our understanding of the mineralogical and chemical compositions of SRO phases. CheMin is an X-ray diffraction instrument that may provide broad X-ray diffraction peaks for SRO phases; e.g., broad peaks around 0.33 and 0.23 nm for allophane. Sample Analysis at Mars (SAM) heats samples and detects evolved gases of volatile-bearing phases including SRO phases (i.e., carbonates, sulfates, hydrated minerals). The Alpha Particle X-ray Spectrometer (APXS) and ChemCam element analyzers will provide chemical characterization of samples. The identification of SRO phases in surface materials on MSL will be challenging due to their nanocrystalline properties; their detection and identification will require utilizing the MSL instrument suite in concert. Ultimately, sample return missions will be required to definitively identify and fully characterize SRO minerals with state-of-the-art laboratory instrumentation back on Earth.

Ming, Douglas W.↗