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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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All sourcesNASA NTRSDOE OSTI
NASA NTRS2019

Thermal Protection System Technology Maturation and Sustainment in Support of In Situ Science Missions: HEEET and PICA

Challenges faced by the Entry Descent and Landing (EDL) community include the lack of a matured forebody heatshield thermal protection system (TPS) capable of meeting the demanding entry environments for the high priority in-situ science missions identified in the decadal survey at Venus, Saturn and the Ice Giants, and the continued sustainment of thermal protection systems/materials. In response to the identified shortfall in TPS technologies capable of extreme entry environments NASA's Space Technology Mission Directorate (STMD) and Science Mission Directorate (SMD) initiated the Heatshield for Extreme Entry Environment Technology (HEEET) project which has matured a 3D-Woven TPS to Technology Readiness Level 6 and which is ready for infusion into these high priority missions. During the development of HEEET long term sustainability was a key consideration. However existing TPS also continue to face sustainability issues. Phenolic Impregnated Carbon Ablator (PICA) has been/is being utilized by many SMD Missions (Stardust, Mars Science Laboratory, OSIRIS-Rex, Mars 2020, Dragonfly) and is under consideration for others including Mars Sample Return, so maintaining PICA for the long term is a priority for NASA. This presentation will discuss raw material sustainability challenges faced by PICA and the efforts by NASA to work with Fiber Materials Inc (FMI) to resolve these challenges with a more sustainable supply chain. In addition, NASA is working with FMI to increase the manufacturing scale for single piece PICA heatshields and to expand the aerothermal performance envelop maturing PICA for larger sized heatshield and more aggressive entry environments. This presentation will also identify challenges and limitations with these systems, particularly around understanding failure modes in these materials and systems and how understanding these may allow use of these systems in environments that are difficult to achieve in ground based testing

Phenolic Impregnated Carbon Ablator (PICA)↗
NASA NTRSDate not supplied

An Approach to Critical Ablative TPS Capabilities Sustainment for Future NASA Missions

We plan to present an approach for NASA to maintain critical ablative TPS capabilities through small, sus-tained, smart and targeted investment. Historically, we have been pound foolish and penny wise for decades and paid very little attention to sustainability of abla-tive TPS and as a result, spent couple of decades in learning what we lost and inventing newer technology solutions. NASA’s ablative TPS history has been one of in-vesting in new and unique capabilities in anticipation of needs, and once flight proven, letting the capability atrophy due to lack of subsequent near-term mission needs [1]. When the need arises, NASA has resorted to two options: (1) revive the capability at considerable cost impact, or (2) develop an alternate capability with considerable schedule impact. Both these options have had considerable mission impact. The third alternate is to maintain proven capabilities in a cost effective manner. A risk informed decision process in terms of maintaining ablative TPS capabilities is feasible with planning and sustained support. Assured TPS availa-bility will allow the science community to propose competed missions with confidence and at a lower risk for selection. We submitted a white paper to the cur-rent Decadal Survey [2] on the need for and im-portance of sustainability. Since then, we have been formulating an executable cost effective strategy. The intent of this presentation is to outline the develop-ments since the submission of the white paper. NASA and DoD have had a working group related to critical technologies to periodically assess and make recommendations on at-risk items from a national need perspective. This inter-agency working group typically focuses on raw materials availability. While we agree that at-risk raw materials are important, fo-cus solely on them is not sufficient. Instead, we advo-cate for a broader focus that includes not only raw material but also industrial manufacturing and processing, and NASA expertise in design, testing and flight hardware certification. In this proposed presentation, we will give a brief overview of NASA’s ablative TPS history along with recent examples of atrophy to highlight case studies related to the PICA and Carbon-Phenolic TPS. We will present the rationale for sustaining PICA, HEEET and 3MDCP for future NASA missions. We will present an approach for how targeted small investments could lead to maintaining mission critical capabilities over long periods.

E Venkatapathy↗
NASA NTRS2008

Evaluation of the Effect of Silicone Contamination on Various Bond Systems and the Feasibility of Removing the Contamination

Silicone is a contaminant that can cause catastrophic failure of a bond system depending on the materials and processes used to fabricate the bond system. Unfortunately, more and more materials are fabricated using silicone. The purpose of this testing was to evaluate which bond systems are sensitive to silicone contamination and whether or not a cleaning process could be utilized to remove the silicone to bring the bond system performance back to baseline. Due to the extensive nature of the testing, attempts will be made to generalize the understanding within classes of substrates, bond systems, and surface preparation and cleaning methods. This study was done by contaminating various metal (steel, Inconel, and aluminum), phenolic (carbon-cloth phenolic [CCP] and glass-cloth phenolic [GCP]), and rubber (natural rubber, asbestos-silicone dioxide filled natural butyldiene rubber [ASNBR]; silica-filled ethylene propylenediene monomer [SFEPDM], and carbon-filled ethylene propylenediene monomer [CFEPDM]) substrates which were then bonded using various adhesives and coatings (epoxy-based adhesives, paints, ablative compounds, and Chemlok adhesives) to determine the effect silicone contamination has on a given bond system's performance. The test configurations depended on the bond system being evaluated. The study also evaluated the feasibility of removing the silicone contamination by cleaning the contaminated substrate prior to bonding. The cleaning processes also varied depending on bond system.

Stanley, Stephanie D.↗
NASA NTRS1990

Test plan pressure fed thrust chamber technology

Aerojet is developing the technology for the design of a reliable, low cost, efficient, and lightweight LOX/RP-1 pressure fed engine. This technology program is a direct result of Aerojet's liquid rocket booster (LRB) study and previous NASA studies that identified liquid engines using high bulk density hydrocarbon fuels as very attractive for a space transportation system (STS). Previous large thrust LOX/RP-1 engine development programs were characterized by costly development problems due to combustion instability damage. The combustion stability solution was typically obtained through trial and error methods of minimizing instability damage by degrading engine performance. The approach to this program was to utilize existing and newly developed combustion analysis models and design methodology to create a thrust chamber design with features having the potential of producing reliable and efficient operation. This process resulted in an engine design with a unique high thrust-per-element OFO triplet injector utilizing a low cost modular approach. Cost efficient ablative materials are baselined for the injector face and chamber. Technology demonstration will be accomplished through a hot fire test program using appropriately sized subscale hardware. This subscale testing will provide a data base to supplement the current industry data bank and to anchor and validate the applied analysis models and design methodology. Once anchored and validated, these analysis models and design methodology can be applied with greatly increased confidence to design and characterize a large scale pressure fed LOX/RP-1 thrust chamber. The objective of this test program is to generate a data base that can be used to anchor and validate existing analysis models and design methodologies and to provide early concept demonstration of a low cost, efficient LOX/RP-1 thrust chamber. Test conditions and hardware instrumentation were defined to provide data sufficient to characterize combustion stability, performance, and thermal operation over a wide thrust chamber throttling range.

Dunn, Glenn↗
NASA NTRSDate not supplied

STARscan: Spatial Targeting and Alignment Rig for Scanning

The Spatial Targeting and Alignment Rig for Scanning (STARScan) is a 3D photogrammetry system developed at NASA Ames Research Center to address bottlenecks in pre/post-test scanning of arcjet test articles. It reduces scan time from 15 minutes with handheld laser scanners to under 2 minutes, while maintaining high accuracy (±0.2-0.5 mm). STARScan integrates an array of cameras, a 3D-printed rack, turntable, and LED light panels, all controlled via a user-friendly graphical user interface (GUI). The system offers tools for scan visualization, mesh analysis, and data export, automating tasks such as alignment of pre/post-test scans, material recession measurements, surface roughness assessment, and curvature analysis. By integrating scanning, imaging, and post-processing into one application, STARScan significantly improves efficiency in scanning and analyzing arcjet test samples.

Ablation↗
NASA NTRS2012

Testing of Candidate Rigid Heatshield Materials at LHMEL for the Entry, Descent, and Landing Technology Development Project

The material testing results described in this paper were part of a material development program of vendor-supplied, proposed heat shield materials. The goal of this program was to develop low density, rigid material systems with an appreciable weight savings over phenolic-impregnated carbon ablator (PICA) while improving material response performance. New technologies, such as PICA-like materials in honeycomb or materials with variable density through-the-thickness were tested. The material testing took place at the Wright-Patterson Air Force Base Laser Hardened Materials Laboratory (LHMEL) using a 10.6 micron CO2 laser operating with the test articles immersed in a nitrogen-gas environment at 1 atmosphere pressure. Test measurements included thermocouple readings of in-depth temperatures, pyrometer readings of surface temperatures, weight scale readings of mass loss, and sectioned-sample readings of char depth. Two laser exposures were applied. The first exposure was at an irradiance of 450 W/cm2 for 50 or 60 seconds to simulate an aerocapture maneuver. The second laser exposure was at an irradiance of 115 W/cm2 for 100 seconds to simulate a planetary entry. Results from Rounds 1 and 2 of these screening tests are summarized.

Sepka, Steven↗
NASA NTRS2011

Recommendations for Hypersonic Boundary Layer Transition Flight Testing

Much has been learned about the physics underlying the transition process at supersonic and hypersonic speeds through years of analysis, experiment and computation. Generally, the application of this knowledge has been restricted to simple shapes like plates, cones and spherical bodies. However, flight reentry vehicles are in reality never simple. They typically are highly complex geometries flown at angle of attack so three-dimensional effects are very important, as are roughness effects due to surface features and/or ablation. This paper will review our present understanding of the physics of the transition process and look back at some of the recent flight test programs for their successes and failures. The goal of this paper is to develop rationale for new hypersonic boundary layer transition flight experiments. Motivations will be derived from both an inward look at what we believe constitutes a good flight test program as well as an outward review of the goals and objectives of some recent US based unclassified proposals and programs. As part of our recommendations, this paper will address the need for careful experimental work as per the guidelines enunciated years ago by the U.S. Transition Study Group. Following these guidelines is essential to obtaining reliable, usable data for allowing refinement of transition estimation techniques.

Berry, Scott A.↗
NASA NTRS1994

The Influence of SiC on the Ablation Response of Advanced Refractory Composite Materials

In continuing our studies of advanced refractory composite materials we have recently completed an arc-jet test series of a diverse group of ceramics and ceramic matrix composites. The compositions range from continuous fiber reinforced ceramics to monoliths. Many of these materials contain SiC and one objective of this test series was to identify the influence of SiC oxidation mechanisms on material performance. Hence the arc heater was operated at two conditions; one in which the passive oxidation of SiC would be dominant and the other where the active oxidation of SiC would be dominant. It is shown here that the active oxidation mechanism of SiC does not dominate material performance when it is present at levels equal to or below 20 volume percent.

Bull, Jeffrey D.↗
NASA NTRS2000

Search for Extraterrestrial Origin of Atmospheric Trace Molecules Radio Sub-MM Observations During The Leonids

HCN is a minor constituent of the Earth atmosphere, with a typical volume mixing ratio around 10(exp -10) HCN per air molecule. At present, the main source of HCN in the lower atmosphere is expected to be biomass burning. The atmospheric HCN has been observed since 1981, first in the infrared, then at microwave radio frequencies. Globally, above 30 km, HCN measurements are in excess of model predictions based on standard photochemistry and biomass burning as the only HCN source. This excess has been explained by: 1) ion-catalyzed reactions in the entire stratosphere, involving CH.3CN as a precursor and/or 2) a high altitude source as a result of chemical production from the methyl radical CH3, or from injection or production by meteors. HCN is a minor constituent of cometary ices. HCN polymers or copolymers have been suggested as constituents of cometary refractory organic matter, and would thus be present in the incoming meteoroids, if these polymers survived their stay in interplanetary space after ejection. HCN may also be created from the CN radical decomposition product of organic carbon, after reaction with hydrogen-bearing molecules. To test the hypothesis of HCN input by meteoroids or the formation in the upper atmosphere from meteoric ablation products, we decided to monitor the HCN submillimeter lines around a major shower: the Leonids.

Depois, D.↗
NASA NTRS2006

Space Shuttle Thermal Protection System Repair Flight Experiment Induced Contamination Impacts

NASA s activities to prepare for Flight LF1 (STS-114) included development of a method to repair the Thermal Protection System (TPS) of the Orbiter s leading edge should it be damaged during ascent by impacts from foam, ice, etc . Reinforced Carbon-Carbon (RCC) is used for the leading edge TPS. The repair material that was developed is named Non- Oxide Adhesive eXperimental (NOAX). NOAX is an uncured adhesive material that acts as an ablative repair material. NOAX completes curing during the Orbiter s descent. The Thermal Protection System (TPS) Detailed Test Objective 848 (DTO 848) performed on Flight LF1 (STS-114) characterized the working life, porosity void size in a micro-gravity environment, and the on-orbit performance of the repairs to pre-damaged samples. DTO 848 is also scheduled for Flight ULF1.1 (STS-121) for further characterization of NOAX on-orbit performance. Due to the high material outgassing rates of the NOAX material and concerns with contamination impacts to optically sensitive surfaces, ASTM E 1559 outgassing tests were performed to determine NOAX condensable outgassing rates as a function of time and temperature. Sensitive surfaces of concern include the Extravehicular Mobility Unit (EMU) visor, cameras, and other sensors in proximity to the experiment during the initial time after application. This paper discusses NOAX outgassing characteristics, how the amount of deposition on optically sensitive surfaces while the NOAX is being manipulated on the pre-damaged RCC samples was determined by analysis, and how flight rules were developed to protect those optically sensitive surfaces from excessive contamination where necessary.

Smith, Kendall A.↗
NASA NTRS2010

Thermal Protection System (Heat Shield) Development - Advanced Development Project

The Orion Thermal Protection System (TPS) ADP was a 3 1/2 year effort to develop ablative TPS materials for the Orion crew capsule. The ADP was motivated by the lack of available ablative TPS's. The TPS ADP pursued a competitive phased development strategy with succeeding rounds of development, testing and down selections. The Project raised the technology readiness level (TRL) of 8 different TPS materials from 5 different commercial vendors, eventual down selecting to a single material system for the Orion heat shield. In addition to providing a heat shield material and design for Orion on time and on budget, the Project accomplished the following: 1) Re-invigorated TPS industry & re-established a NASA competency to respond to future TPS needs; 2) Identified a potentially catastrophic problem with the planned MSL heat shield, and provided a viable, high TRL alternate heat shield design option; and 3) Transferred mature heat shield material and design options to the commercial space industry, including TPS technology information for the SpaceX Dragon capsule.

Kowal, T. John↗
NASA NTRS2019

Progress in Manufacturing & Characterizing Domestic Lyocell PICA (PICA-D) and Comparison to Heritage PICA

NASA ARC (Ames Research Center) is working with SMD-PSD (NASA Science Mission Directorate- Planetary Science Directorate) to address PICA ( Phenolic Impregnated Carbon Ablator) rayon sustainability concerns. In FY16/17, Lyocell Based PICA (PICA-D (Domestic)) was manufactured and limited testing performed showing it to be a good candidate as a potential replacement for heritage rayon. Establishing PICA-D as a "drop in replacement" will allow missions to depend on and design missions with PICA without any risk typical of a replacement. Establishing the extended capability of PICA-D will allow Sample Return Missions with higher entry speed that were not considered before.

Lyocell↗
NASA NTRS2019

High Velocity Impact Performance of a Dual Layer Thermal Protection System for the Mars Sample Return Earth Entry Vehicle

The Mars Sample Return (MSR) Earth Entry Vehicle (EEV) is currently planned on being released from its Micro-Meteorite/Orbital Debri (MM/OD) shielding housing about two days before the Earth entry phase. This leaves the EEV exposed to incoming MM/OD impacts, potentially damaging the heat shield and compromising its Entry, Decent, and Landing (EDL) integrity. Currently, two materials are proposed to comprise the MSR-EEV heat shield, a dual layer material Heat-shield for Extreme Entry Environment Technology (HEEET) and Phenolic Impregnated Carbon Ablator (PICA). PICA has been well characterized for OD class impacts, ~7km/s high mass impacts, from previous testing done in the Orion program, but hasn't under-gone extensive MM impact testing. HEEET is a rela-tively new material with minimal prior testing in re-gards to High Velocity Impacts (HVI). In order to in-form selectability of a material, it is crucial to under-stand the material performance when faced with an HVI, directly affecting mission success probability.The current measure of a Thermal Protection Sys-tem's (TPS) performance against an HVI is evaluating a thermally sized material against its derived Balistic Limit Equation (BLE). A BLE is generated empirically from multiple shots of HVI testing, and is used as a first order method in evaluating TPS's performance against the expected MM/OD environment. This method has proved useful for previous uniform densi-ty TPS materials, but has never been validated against a dual layer recession material such as HEEET. Testing in the MSR program for FY19 has a re-quirement to assess the effects of a dual layer TPS by testing various thicknesses of HEEET's Recession Layer, seen in Figure 1. From this data, BLE's will be derived for the individual thickness ratio samples, as well as the material as a whole to evaluate if a heritage form of the BLE can capture the complex physics associated with a dual layer system. Crater morpholo-gy will also be assessed with post-test Non-Destructive Evaluation (NDE) methods such as CT scanning to visualize if a BLE can well predict the associated pene-tration depths, since a BLE assumes full disinigration of the impacting particle and is generally only used to size a spherical crater ? disregarding any shrapenel effects from a high density impactor.To inform this analysis, expected MM environ-ments from the Meteoroid Engineering Model (MEM) and analytical equations for mass flux of incoming MM were evaluated against the notional MSR-EEV trajectory [1]. Using those dispersions, a monte-carlo was run to determine the most probable particle pa-rameters, as well as the riskiest in terms of full bondline penetration. From these probabilities, a test matrix was designed to test against bounding cases for the various parameters of the BLE: projectile density, projectile mass, projectile velocity, and the impact angle.This presentation will discuss the performance of the dual layer TPS material HEEET against a wide range of impact kinetic energies and densitites, as well as the comparison of HEEET to PICA in terms of MM/OD performance and selectability criteria.

Libben, B. J.↗
NASA NTRS2015

Laser Surface Preparation of Epoxy Composites for Secondary Bonding: Optimization of Ablation Depth

Surface preparation has been identified as one of the most critical aspects of attaining predictable and reliable adhesive bonds. Energetic processes such as laser ablation or plasma treatment are amenable to automation and are easily monitored and adjusted for controlled surface preparation. A laser ablation process was developed to accurately remove a targeted depth of resin, approximately 0.1 to 20 micrometers, from a carbon fiber reinforced epoxy composite surface while simultaneously changing surface chemistry and creating micro-roughness. This work demonstrates the application of this process to prepare composite surfaces for bonding without exposing or damaging fibers on the surface. Composite panels were prepared in an autoclave and had a resin layer approximately 10 micrometers thick above the fiber reinforcement. These composite panels were laser surface treated using several conditions, fabricated into bonded panels and hygrothermally aged. Bond performance of aged, experimental specimens was compared with grit blast surface treated specimens using a modified double cantilever beam test that enabled accelerated saturation of the specimen with water. Comparison of bonded specimens will be used to determine how ablation depth may affect average fracture energies and failure modes.

Palmieri, Frank L.↗
NASA NTRS1973

Effects of material composition on the ablation performance of low density elastomeric ablators

The ablation performance of materials composed of various concentrations of nylon, hollow silica spheres, hollow phenolic spheres, and four elastomeric resins was determined. Both blunt-body and flat-panel specimens were used, the cold-wall heating-rate ranges being 0.11 to 0.8 MW/sq m, respectively. The corresponding surface pressure ranges for these tests were 0.017 to 0.037 atmosphere and 0.004 to 0.005 atmosphere. Some of the results show that (1) the addition of nylon significantly improved the ablation performance, but the nylon was not compatible with one resin system; (2) panel and blunt-body specimen data do not show the same effect of phenolic sphere content on ablation effectiveness; and (3) there appears to be an optimum concentration of hollow silica spheres for good ablation performance. The composition of an efficient, nonproprietary ablator for lifting body application is identified and the ablation performance of this ablator is compared with the performance of three commercially available materials.

Tompkins, S. S.↗
NASA NTRS2015

Code-to-Code Comparison, and Material Response Modeling of Stardust and MSL using PATO and FIAT

This report provides a code-to-code comparison between PATO, a recently developed high fidelity material response code, and FIAT, NASA's legacy code for ablation response modeling. The goal is to demonstrates that FIAT and PATO generate the same results when using the same models. Test cases of increasing complexity are used, from both arc-jet testing and flight experiment. When using the exact same physical models, material properties and boundary conditions, the two codes give results that are within 2% of errors. The minor discrepancy is attributed to the inclusion of the gas phase heat capacity (cp) in the energy equation in PATO, and not in FIAT.

ablative materials↗
NASA NTRS2014

Thermal Testing of Woven TPS Materials in Extreme Entry Environments

NASAs future robotic missions to Venus and outer planets, namely, Saturn, Uranus, Neptune, result in extremely high entry conditions that exceed the capabilities of current mid density ablators (PICA or Avcoat). Therefore mission planners assume the use of a fully dense carbon phenolic heatshield similar to what was flown on Pioneer Venus and Galileo. Carbon phenolic (CP) is a robust TPS however its high density and thermal conductivity constrain mission planners to steep entries, high heat fluxes, high pressures and short entry durations, in order for CP to be feasible from a mass perspective. In 2012 the Game Changing Development Program in NASAs Space Technology Mission Directorate funded NASA ARC to investigate the feasibility of a Woven Thermal Protection System to meet the needs of NASAs most challenging entry missions. The high entry conditions pose certification challenges in existing ground based test facilities. Recent updates to NASAs IHF and AEDCs H3 high temperature arcjet test facilities enable higher heatflux (2000 Wcm2) and high pressure (5 atm) testing of TPS. Some recent thermal tests of woven TPS will be discussed in this paper. These upgrades have provided a way to test higher entry conditions of potential outer planet and Venus missions and provided a baseline against carbon phenolic material. The results of these tests have given preliminary insight to sample configuration and physical recession profile characteristics.

TPS↗