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NASA NTRS2007

Fabrication Infrastructure to Enable Efficient Exploration and Utilization of Space

Unlike past one-at-a-time mission approaches, system-of-systems infrastructures will be needed to enable ambitious scenarios for sustainable future space exploration and utilization. Fabrication infrastructure will be needed to support habitat structure development, tools and mechanical part fabrication, as well as repair and replacement of ground support and space mission hardware such as life support items, vehicle components and crew systems. The fabrication infrastructure will need the In Situ Fabrication and Repair (ISFR) element, which is working in conjunction with the In Situ Resources Utilization (ISRU) element, to live off the land. The ISFR Element supports the entire life cycle of Exploration by: reducing downtime due to failed components; decreasing risk to crew by recovering quickly from degraded operation of equipment; improving system functionality with advanced geometry capabilities; and enhancing mission safety by reducing assembly part counts of original designs where possible. This paper addresses the fabrication infrastructures that support efficient, affordable, reliable infrastructures for both space exploration systems and logistics; these infrastructures allow sustained, affordable and highly effective operations on the Moon, Mars and beyond.

Howell, Joe T.↗

NASA NTRS2008

Imaging and Analysis of Void-defects in Solder Joints Formed in Reduced Gravity using High-Resolution Computed Tomography

As a part of efforts to develop an electronics repair capability for long duration space missions, techniques and materials for soldering components on a circuit board in reduced gravity must be developed. This paper presents results from testing solder joint formation in low gravity on a NASA Reduced Gravity Research Aircraft. The results presented include joints formed using eutectic tin-lead solder and one of the following fluxes: (1) a no-clean flux core, (2) a rosin flux core, and (3) a solid solder wire with external liquid no-clean flux. The solder joints are analyzed with a computed tomography (CT) technique which imaged the interior of the entire solder joint. This replaced an earlier technique that required the solder joint to be destructively ground down revealing a single plane which was subsequently analyzed. The CT analysis technique is described and results presented with implications for future testing as well as implications for the overall electronics repair effort discussed.

Easton, John W.↗

NASA NTRS2007

Replica-based Crack Inspection

A surface replica-based crack inspection method has recently been developed for use in Space Shuttle main engine (SSME) hydrogen feedline flowliners. These flowliners exist to ensure favorable flow of liquid hydrogen over gimble joint bellows, and consist of two rings each containing 38 elongated slots. In the summer of 2002, multiple cracks ranging from 0.1 inches to 0.6 inches long were discovered; each orbiter contained at least one cracked flowliner. These long cracks were repaired and eddy current inspections ensured that no cracks longer than 0.075 inches were present. However, subsequent fracture-mechanics review of flight rationale required detection of smaller cracks, and was the driving force for development of higher-resolution inspection method. Acetate tape surface replicas have been used for decades to detect and monitor small cracks. However, acetate tape replicas have primarily been limited to laboratory specimens because complexities involved in making these replicas - requiring acetate tape to be dissolved with acetone - are not well suited for a crack inspection tool. More recently developed silicon-based replicas are better suited for use as a crack detection tool. A commercially available silicon-based replica product has been determined to be acceptable for use in SSME hydrogen feedlines. A method has been developed using this product and a scanning electron microscope for analysis, which can find cracks as small as 0.005 inches and other features (e.g., pits, scratches, tool marks, etc.) as small as 0.001 inches. The resolution of this method has been validated with dozens of cracks generated in a laboratory setting and this method has been used to locate 55 cracks (ranging in size from 0.040 inches to 0.004 inches) on space flight hardware. These cracks were removed by polishing away the cracked material and a second round of replicas confirmed the repair.

Newman, John A.↗

NASA NTRS2008

From Lunar Regolith to Fabricated Parts: Technology Developments and the Utilization of Moon Dirt

The U.S. Space Exploration Policy has as a cornerstone the establishment of an outpost on the moon. This lunar outpost wil1 eventually provide the necessary planning, technology development, testbed, and training for manned missions in the future beyond the Moon. As part of the overall activity, the National Aeronautics and Space Administration (NASA) is investigating how the in situ resources can be utilized to improve mission success by reducing up-mass, improving safety, reducing risk, and bringing down costs for the overall mission. Marshall Space Flight Center (MSFC), along with other NASA centers, is supporting this endeavor by exploring how lunar regolith can be mined for uses such as construction, life support, propulsion, power, and fabrication. An infrastructure capable of fabrication and nondestructive evaluation will be needed to support habitat structure development and maintenance, tools and mechanical parts fabrication, as well as repair and replacement of space-mission hardware such as life-support items, vehicle components, and crew systems, This infrastructure will utilize the technologies being developed under the In Situ Fabrication and Repair (ISFR) element, which is working in conjunction with the technologies being developed under the In Situ Resources Utilization (ISRU) element, to live off the land. The ISFR Element supports the Space Exploration Initiative by reducing downtime due to failed components; decreasing risk to crew by recovering quickly from degraded operation of equipment; improving system functionality with advanced geometry capabilities; and enhancing mission safety by reducing assembly part counts of original designs where possible. This paper addresses the need and plan for understanding the properties of the lunar regolith to determine the applicability of using this material in a fabrication process. This effort includes the development of high fidelity simulants that will be used in fabrication processes on the ground to drive down risk and increase the Technology Readiness Level (TRL) prior to implementing this capability on the moon. Also discussed in this paper is the on-going research using Electron Beam Melting (EBM) technology as a possible solution to manufacturing parts and spares on the Moon's surface.

McLemore, C. A.↗

NASA NTRS2008

Challenges and Demands on Automated Software Revision

In the past three decades, automated program verification has undoubtedly been one of the most successful contributions of formal methods to software development. However, when verification of a program against a logical specification discovers bugs in the program, manual manipulation of the program is needed in order to repair it. Thus, in the face of existence of numerous unverified and un- certified legacy software in virtually any organization, tools that enable engineers to automatically verify and subsequently fix existing programs are highly desirable. In addition, since requirements of software systems often evolve during the software life cycle, the issue of incomplete specification has become a customary fact in many design and development teams. Thus, automated techniques that revise existing programs according to new specifications are of great assistance to designers, developers, and maintenance engineers. As a result, incorporating program synthesis techniques where an algorithm generates a program, that is correct-by-construction, seems to be a necessity. The notion of manual program repair described above turns out to be even more complex when programs are integrated with large collections of sensors and actuators in hostile physical environments in the so-called cyber-physical systems. When such systems are safety/mission- critical (e.g., in avionics systems), it is essential that the system reacts to physical events such as faults, delays, signals, attacks, etc, so that the system specification is not violated. In fact, since it is impossible to anticipate all possible such physical events at design time, it is highly desirable to have automated techniques that revise programs with respect to newly identified physical events according to the system specification.

Bonakdarpour, Borzoo↗

NASA NTRS2005

Evaluation of Late Effects of Heavy-Ion Radiation on Mesenchymal Stem Cells

The overall objective of this recently funded study is to utilize well-characterized model test systems to assess the impact of pluripotent stem cell differentiation on biological effects associated with high-energy charged particle radiation. These stem cells, specifically mesenchymal stem cells (MSCs), have the potential for differentiation into bone, cartilage, fat, tendons, and other tissue types. The characterization of the regulation mechanisms of MSC differentiation to the osteoblastic lineage by transcription factors, such as Runx2/Cbfa1 and Osterix, and osteoinductive proteins such as members of the bone morphogenic protein family are well established. More importantly, for late biological effects, MSCs have been shown to contribute to tissue restructuring and repair after tissue injury. The complex regulation of and interactions between inflammation and repair determine the eventual outcome of the responses to tissue injury, for which MSCs play a crucial role. Additionally, MSCs have been shown to respond to reactive oxygen species, a secondary effector of radiation, by differentiating. With this, we hypothesized that differentiation of MSCs can alter or exacerbate the damage initiated by radiation, which can ultimately lead to late biological effects of misrepair/fibrosis which may ultimately lead to carcinogenesis. Currently, studies are underway to examine high-energy X-ray radiation at low and high doses, approximately 20 and 200 Rad, respectively, on cytogenetic damage and gene modulation of isolated MSCs. These cells, positive for MSC surface markers, were obtained from three persons. In vitro cell samples were harvested during cellular proliferation and after both cellular recovery and differentiation. Future work will use established in vitro models of increasing complexity to examine the value of traditional 2D tissue-culture techniques, and utilize 3D in vitro tissue culture techniques that can better assess late effects associated with radiation.

Gonda, S.R.↗

NASA NTRS2006

Observations, Ideas, and Opinions: Systems Engineering and Integration for Return to Flight

This presentation addresses project management and systems engineering and integration challenges for return to flight, focusing on the Thermal Protection System Tile Repair Project (TRP). The program documentation philosophy, communication with program requirements flow and philosophy and planned deliverables and documentation are outlined. The development of TRP 'use-as-is' analytical tools is also highlighted and emphasis is placed on the use flight history to assess pre-flight and real-time risk. Additionally, an overview is provided of the repair procedure, including an outline of the logistics deployment chart.

Gafka, George K.↗

NASA NTRS2008

Simulated Reentry Heating by Torching

The two first order reentry heating parameters are peak heating flux (W/cm2) and peak heat load (kJ/cm2). Peak heating flux (and deceleration, gs) is higher for a ballistic reentry and peak heat load is higher for a lifting reentry. Manned vehicle reentries are generally lifting reentries at nominal 1-5 gs so that personnel will not be crushed by high deceleration force. A few off-nominal manned reentries have experienced 8 or more gs with corresponding high heating flux (but below nominal heat load). The Shuttle Orbiter reentries provide about an order of magnitude difference in peak heating flux at mid-bottom (TPS tiles, approximately 6 W/cm2 or 5 BTU/ft2- sec) and leading edge (RCC, approximately 60 W/cm2 or 50 BTU/ft2- sec). Orion lunar return and Mars sample lander are of the same order of magnitude as orbiter leading edge peak heat loads. Flight temperature measurements are available for some orbiter TPS tile and RCC locations. Return-to-Flight on-orbit tile-repair-candidate-material-heating performance was evaluated by matching propane torch heating of candidate-materials temperatures at several depths to orbiter TPS tile flight-temperatures. Char and ash characteristics, heat expansion, and temperature histories at several depths of the cure-in-place ablator were some of the TPS repair material performance characteristics measured. The final char surface was above the initial surface for the primary candidate (silicone based) material, in contrast to a receded surface for the Apollo-type ablative heat shield material. Candidate TPS materials for Orion CEV (LEO and lunar return), and for Mars sample lander are now being evaluated. Torching of a candidate ablator material, PICA, was performed to match the ablation experienced by the STARDUST PICA heat shield. Torching showed that the carbon fiberform skeleton in a sample of PICA was inhomogeneous in that sample, and allowed measurements (of the clumps and voids) of the inhomogeneity. Additional reentry heating-performance characterizations of high temperature insulation materials were performed.

Harvey, Gale A.↗

NASA NTRS2008

Predicting Boundary-Layer Transition on Space-Shuttle Re-Entry

The BLT Prediction Tool ("BLT" signifies "Boundary Layer Transition") is provided as part of the Damage Assessment Team analysis package, which is utilized for analyzing local aerothermodynamics environments of damaged or repaired space-shuttle thermal protection tiles. Such analyses are helpful in deciding whether to repair launch-induced damage before re-entering the terrestrial atmosphere.

Berry, Scott↗

NASA NTRS2008

Simulated Reentry Heating by Torching

The two first order reentry heating parameters are peak heating flux (W/square cm) and peak heat load (kJ/square cm). Peak heating flux (and deceleration, gs) is higher for a ballistic reentry and peak heat load is higher for a lifting reentry. Manned vehicle reentries are generally lifting reentries at nominal 1-5 gs so that personnel will not be crushed by high deceleration force. A few off-nominal manned reentries have experienced 8 or more gs with corresponding high heating flux (but below nominal heat load). The Shuttle Orbiter reentries provide about an order of magnitude difference in peak heating flux at mid-bottom (TPS tiles, approximately 6 W/square cm or 5 BTU/square ft - sec) and leading edge (RCC, approximately 60 W/square cm or 50 BTU/square ft- sec). Orion lunar return and Mars sample lander are of the same order of magnitude as orbiter leading edge peak heat loads. Flight temperature measurements are available for some orbiter TPS tile and RCC locations. Return-to-Flight on-orbit tile-repair-candidate-material-heating performance was evaluated by matching propane torch heating of candidate-materials temperatures at several depths to orbiter TPS tile flight-temperatures. Char and ash characteristics, heat expansion, and temperature histories at several depths of the cure-in-place ablator were some of the TPS repair material performance characteristics measured. The final char surface was above the initial surface for the primary candidate (silicone based) material, in contrast to a receded surface for the Apollo-type ablative heat shield material. Candidate TPS materials for Orion CEV (LEO and lunar return), and for Mars sample lander (MSL) are now being evaluated. Torching of a candidate ablator material, PICA, was performed to match the ablation experienced by the STARDUST PICA heat shield. Torching showed that the carbon fiberform skeleton in a sample of PICA was inhomogeneous in that sample, and allowed measurements (of the clumps and voids) of the inhomogeneity. Additional reentry heating-performance characterizations of high temperature insulation materials were performed.

Harvey, Gale A.↗

NASA NTRS2008

On-Site Fabrication Infrastructure to Enable Efficient Exploration and Utilization of Space

Unlike past one-at-a-time mission approaches, system-of-systems infrastructures will be needed to enable ambitious scenarios for sustainable future space exploration and utilization. So what do we do when we get to the moon for sustainable exploration. On-site fabrication infrastructure will be needed to support habitat structure development, tools and mechanical part fabrication, as well as repair and replacement of ground support and space mission hardware such as life support items, vehicle components and crew systems. The on-site fabrication infrastructure will need the In Situ Fabrication and Repair (ISFR) element, which is working in conjunction with the In Situ Resources Utilization (ISRU) element, to live off the land. The ISFR element has worked closely with the ISRU element in the past year to assess the ability of using lunar regolith as a viable feedstock for fabrication material. Preliminary work has shown promise and the ISFR Element will continue to concentrate on this activity. Fabrication capabilities have been furthered with the process certification effort that, when completed, will allow for space-qualified hardware to be manufactured. Materials being investigated include titanium and aluminum alloys as well as lunar regolith simulants with binders. This paper addresses the latest advancements made in the fabrication of infrastructures that support efficient, affordable, reliable infrastructures for both space exploration systems and logistics; infrastructures that allow sustained, affordable and highly effective operations on the Moon and beyond.

Howell, Joe T.↗

NASA NTRS2009

The Coming Paradigm-Shift in Maintenance: From Metals to Composites

The purpose of this study is to examine the current maintenance practices of airline operators in the detection and repair of damage to composite structures, with the aim of learning lessons that will be applicable to the maintenance of future advanced composite airplanes. A process map was created to capture the events and activities that occur from the moment a damage event occurs, through damage detection, assessment and repair. The study is identifying areas where operational risks may negatively impact the process, where personnel are required to make judgments in the absence of procedural guidance, and areas where future tools or techniques may be of assistance.

Hobbs, Alan↗

NASA NTRS2008

A Flexible Evolvable Architecture for Constellation Mission Systems User Applications

While simulating a complex set of repair tasks to be performed by EVA crewmembers on an upcoming mission, flight controllers and astronauts determine that the repair will take much longer than originally anticipated. All equipment in the vicinity of the worksite must be powered off to maintain a safe environment for the astronauts. Because heater power will be unavailable, several critical components will now be at risk of freezing and permanent damage. If an impending thermal violation is detected, Mission Control will have very limited time to react. Therefore, flight controllers must not only modify their procedures to account for these risks, they must also incorporate into their displays outputs from thermal models, alternate temperature measurements, new alarm limits, and emergency power-on commands to enable the detection and response to freezing conditions. Current software for mission control systems makes scenarios like this difficult to address. Given the time frame for modifying software, operations teams are left with labor-intensive operational workarounds as their only options. NASA Ames Research Center (ARC) and NASA Johnson Space Center (JSC) are collaborating on the development of a flexible software system for mission operations that will enable greater user flexibility than has been available to date. Using composable software, end users in the scenario described above could recompose procedures and command and control displays to allow flight controllers to monitor temperature measurements, identify time-critical conditions, and execute the procedures required to respond to these conditions before flight hardware is permanently damaged.

Trimble, Jay P.↗

NASA NTRS2009

Hubble Space Telescope Crew Rescue Analysis

In the aftermath of the 2003 Columbia accident NASA removed the Hubble Space Telescope (HST) Servicing Mission 4 (SM4) from the Space Shuttle manifest. Reasons cited included concerns that the risk of flying the mission would be too high. There was at the time no viable technique to repair the orbiter s thermal protection system if it were to be damaged by debris during ascent. Furthermore in the event of damage, since the mission was not to the International Space Station, there was no safe haven for the crew to wait for an extended period of time for a rescue. The HST servicing mission was reconsidered because of improvements in the ascent debris environment, the development of techniques for the astronauts to perform on orbit repairs to damage thermal protection, and the development of a strategy to provide a crew rescue capability. However, leading up to the launch of servicing mission, the HST crew rescue capability was a recurring topic. For HST there was a limited amount of time available to perform a crew rescue because of the limited consumables available on the Orbiter. The success of crew rescue depends upon several factors including when a problem is identified, when and to what extent power down procedures are begun, and where the rescue vehicle is in its ground processing cycle. Severe power downs maximize crew rescue success but would eliminate the option for the orbiter servicing the HST to attempt a landing. Therefore, crew rescue success needed to be weighed against preserving the ability of the orbiter to have landing option in case there was a problem with the rescue vehicle. This paper focuses on quantification of the HST mission loss of crew rescue capability using Shuttle historical data and various power down capabilities. That work supported NASA s decision to proceed with the HST service mission, which was successfully completed on May 24th 2009.

Hamlin, Teri L.↗

NASA NTRS2009

ANSI/AIAA S-081A, Pressure Vessel Standards Implementation Guidelines

The stress rupture specification for Composite Overwrapped Pressure Vessels (COPV) is discussed. The composite shell of the COPV shall be designed to meet the design life considering the time it is under sustained load. A Mechcanical Damage Control Plan (MDCP) shall be created and implemented that assures the COPV will not fail due to mechanical damage due to manufacturing, testing, shipping, installation, or flight. Proven processes and procedures for fabrication and repair shall be used to preclude damage or material degradation during material processing, manufacturing operations, and refurbushment.Selected NDI techniques for the liner and/or boss(es) shall be performed before overwrapping with composite. When visual inspection reveals mechanical damage or defects exceeding manufacturing specification levels (and standard repair procedures), the damaged COPV shall be submitted to a material review board (MRB) for disposition. Every COPV shall be subjected to visual and other non-destructive inspection (NDI), per the inspection plan.

Greene, Nathanael J.↗

NASA NTRS2009

A Lunar Surface System Supportability Technology Development Roadmap

This paper discusses the establishment of a Supportability Technology Development Roadmap as a guide for developing capabilities intended to allow NASA's Constellation program to enable a supportable, sustainable and affordable exploration of the Moon and Mars. Presented is a discussion of "supportability", in terms of space facility maintenance, repair and related logistics and a comparison of how lunar outpost supportability differs from the International Space Station. Supportability lessons learned from NASA and Department of Defense experience and their impact on a future lunar outpost is discussed. A supportability concept for future missions to the Moon and Mars that involves a transition from a highly logistics dependent to a logistically independent operation is discussed. Lunar outpost supportability capability needs are summarized and a supportability technology development strategy is established. The resulting Lunar Surface Systems Supportability Strategy defines general criteria that will be used to select technologies that will enable future flight crews to act effectively to respond to problems and exploit opportunities in a environment of extreme resource scarcity and isolation. This strategy also introduces the concept of exploiting flight hardware as a supportability resource. The technology roadmap involves development of three mutually supporting technology categories, Diagnostics Test & Verification, Maintenance & Repair, and Scavenging & Recycling. The technology roadmap establishes two distinct technology types, "Embedded" and "Process" technologies, with different implementation and thus different criteria and development approaches. The supportability technology roadmap addresses the technology readiness level, and estimated development schedule for technology groups that includes down-selection decision gates that correlate with the lunar program milestones. The resulting supportability technology roadmap is intended to develop a set of technologies with widest possible capability and utility with a minimum impact on crew time and training and remain within the time and cost constraints of the Constellation program

Oeftering, Richard C.↗

NASA NTRS2010

Radiation Exposure Alters Expression of Metabolic Enzyme Genes In Mice

Most pharmaceuticals are metabolized by the liver. The health of the liver, especially the rate of its metabolic enzymes, determines the concentration of circulating drugs as well as the duration of their efficacy. Because of the importance of the liver in drug metabolism it is important to understand the effects of spaceflight on the enzymes of the liver. Exposure to cosmic radiation is one aspect of spaceflight that can be modeled in ground experiments. This study is an effort to examine the effects of adaptive mechanisms that may be triggered by early exposure to low radiation doses. Using procedures approved by the JSC Animal Care & Use Committee, C57 male mice were exposed to Cs-137 in groups: controls, low dose (50 mGy), high dose (6Gy) and a fourth group that received both radiation doses separated by 24 hours. Animals were anesthetized and sacrificed 4 hours after their last radiation exposure. Livers were removed immediately and flash-frozen in liquid nitrogen. Tissue was homogenized, RNA extracted and purified (Absolutely RNA, Agilent). Quality of RNA samples was evaluated (Agilent Bioanalyzer 2100). Complementary DNA was prepared from high-quality RNA samples, and used to run RT-qPCR screening arrays for DNA Repair and Drug Metabolism (SuperArray, SABiosciences/Qiagen; BioRad Cfx96 qPCR System). Of 91 drug metabolism genes examined, expression of 7 was altered by at least one treatment condition. Genes that had elevated expression include those that metabolize promethazine and steroids (4-8-fold), many that reduce oxidation products, and one that reduces heavy metal exposure (greater than 200-fold). Of the 91 DNA repair and general metabolism genes examined, expression of 14 was altered by at least one treatment condition. These gene expression changes are likely homeostatic and could lead to development of new radioprotective countermeasures.

Wotring, Virginia E.↗

NASA NTRS1999

Hubble Space Telescope: Servicing Mission 3A. Media Reference Guide

Since its launch in April 1990, the Hubble Space Telescope (HST) has provided scientific data and images of unprecedented resolution from which many new and exciting discoveries have been made. The Telescope's purpose is to spend 20 years probing the farthest and faintest reaches of the cosmos. Crucial to fulfilling this objective is a series of on-orbit manned servicing missions. The First Servicing Mission (SM1) took place in December 1993 and the Second Servicing Mission (SM2) was flown in February 1997. During these missions, astronauts perform planned repairs and maintenance activities to restore and upgrade the observatory s capabilities. To facilitate this process, the Telescope s designers configured science instruments and several vital engineering subsystems as Orbital Replacement Units (ORU) -- modular packages with standardized fittings accessible to astronauts in pressurized suits. Hubble's Third Servicing Mission has been separated into two parts: Servicing Mission 3A (SM3A) will fly in Fall of 1999 and Servicing Mission 3B (SM3B) is planned for 2001. The principal objective of SM3A is to replace all six gyroscopes that compose the three Rate Sensor Units (RSU). In addition, space-walking astronauts will install a new Advanced Computer that will dramatically increase the computing power, speed, and storage capability of HST. They will change out one of the Fine Guidance Sensors (FGS) and replace a tape recorder with a new Solid State Recorder (SSR). The Extravehicular Activity (EVA) crew also will install a new S-band Single-Access Transmitter (SSAT), and Voltage/Temperature Improvement Kits (VIK) for the Telescope s nickel-hydrogen batteries. Finally, they will begin repair of the multilayer insulation on Hubble s outer surface. During SM3B astronauts will install a new science instrument, the Advanced Camera for Surveys (ACS), and an Aft Shroud Cooling System (ASCS) for the other axial science instruments. They will attach a new cryogenic cooler to the Near-Infrared Camera and Multi-Object Spectrometer (NICMOS). They also will replace the HST flexible Solar Arrays with new high-performance rigid arrays.

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