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At least 1,117 records · Page 62

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NASA NTRS2020

An Initial Concept for a JUMP Mating Mechanism

Lunar landers currently under development for crew and cargo missions to the Moon are limited by the available boosters to launch them from Earth. Most landers are being developed for commercial launch vehicles (CLVs) in the Falcon Heavy / Vulcan / New Glenn / Atlas V class, limiting their performance with many lunar surface studies consequently restricted to 5-10 metric ton payloads. The JUMP Lander (Joinable Undercarriage to Maximize Payload) attempts to overcome this limitation by performing an in-space mating, linking multiple landers together. This research provides an initial proof of concept demonstration that two or more CLV-launched lunar landers can be mated in-space to produce a larger lander with greater payload capacity. Multiple rockets have been connected hundreds if not thousands of times in spaceflight history. An example is the space shuttle. The External Tank-Orbiter interface is an example where the 100-ton Orbiter is bolted to the side of the External Tank. This example serves as a concept metaphor for JUMP where a system of bolts is used as the mating system. This paper performs a high-level sizing analysis of the bolt, including the structural connection to each lander and the physical dimensions of the bolt, given the projected lander and payload masses. It sizes the necessary motors to perform the in-space mating and describes the motor to bolt integration. It describes the mounting and translation for the bolt-motor assembly, including structural supports, physical stops, and range of travel. It discusses active-active and active-passive implementations for the mating system and post-mating options to jettison no-longer-needed components of the assembly, including a discussion of benefits of jettisoning or not jettisoning. Finally, forward work for the mating mechanism and overall JUMP Lander concept is described.

Lunar Lander↗

NASA NTRS2020

On the Maximum Stellar Rotation to Form a Black Hole without an Accompanying Luminous Transient

The collapse of a massive star with low angular momentum content is commonly argued to result in the formation of a black hole without an accompanying bright transient. Our goal in this Letter is to understand the flow in and around a newly-formed black hole, involving accretion and rotation, via general relativistic hydrodynamics simulations aimed at studying the conditions under which infalling material can accrete without forming a centrifugally supported structure and, as a result, generate no effective feedback. If the feedback from the black hole is, on the other hand, significant, the collapse would be halted and we suggest that the event is likely to be followed by a bright transient. We find that feedback is only efficient if the specific angular momentum of the infalling material at the innermost stable circular orbit exceeds that of geodesic circular flow at that radius by at least≈20%. We use the results of our simulations to constrain the maximal stellar rotation rates of the disappearing massive progenitors PHL293B-LBV and N6946-BH1, and to provide an estimate of the overall rate of disappearing massive stars. We find that about a few percent of single O-type stars with measured rotational velocities are expected to spin below the critical value before collapse and are thus predicted to vanish without a trace.

Scott C Noble↗

NASA NTRS2004

Inflatable space structures technology development for large radar antennas.

There has been recent interest in inflatable space-structures technology for possible applications on US. Department of Defense (DOD) missions because of the technology's potential for high mechanical-packaging efficiency, variable stowed geometry, and deployment reliability. In recent years, the DOD-sponsored Large Radar Antenna Program (LRA) applied this new technology to a baseline concept: an inflatablehigidizable (lU) perimeter-truss structure supporting a meshhet parabolic-reflector antenna. The program addressed (a) truss concept development, (b) rigidizable materials concepts assessment, (c) meshhet concept selection and integration, and (d) developed potential mechanical-system p erformance estimates. Critical and enabling technologies were validated, especially orbital radiation durable rigidized materials, and high modulus, inflatable-deployablet russ numbers.

Willis, Paul↗

NASA NTRS1998

In-Flight Measurements of Dynamic Force and Comparison With Methods Used to Derive Force Limits for Ground Vibration Tests

In-flight measurements of the dynamic forces acting between an aerospace component and its supporting structure have recently been obtained on the Advanced Composition Explorer (ACE) spacecraft.

The↗

NASA NTRS1994

Economical 10-Meter-Class Ground-Based Receiver for Deep-Space Optical Communications

Modifications to an existing radiofrequency telescope are described which would enable it to operate as an R&D optical receiver terminal for deep-space communications. The low overall cost of the telescope is due to the unique process of fabricating the 10.4 meter primary mirror and its support structure, the lightweight of the primary (10-11 kg/m 2 ), and the requirement that the telescope act only as a photon bucket, which lowers the cost of optically figuring and polishing the mirror. The entrie optical ground terminal facility is estimated to cost approximately $10M to construct.

deep-space↗

NASA NTRS2017

Development of a Turn Key Cryogenic Cooling Module for Space Flight Based on a Commercial Cryocooler

Commercial cryocoolers have significant price and lead time advantages over coolers built exclusively for the space market, but there are many challenges that must be overcome before using a COTS cooler for flight. The initial cost advantage is significantly narrowed by the cost of adapting the COTS cooler for flight. JPL is developing a “turnkey” cryogenic cooling solution based on a commercial cryocooler with the intention that it can become a standard product. The goal is to develop a complete, fully redundant cryogenic cooling solution based on the Thales 9310. The system includes the cooler, brackets to provide mounting and cooling, supporting structures, vibration isolation, thermal straps, thermal switches, and drive electronics. This paper discusses qualification of the various components for flight, including launch vibration and thermal performance testing, as well as a full up testing of the completed assembly.

Ramsey, Perry G.↗

NASA NTRS2017

Development of a Turn Key Cryogenic Cooling Module for Space Flight Based on a Commercial Cryocooler

Commercial cryocoolers have significant price and lead time advantages over coolers built exclusively for the space market, but there are many challenges that must be overcome before using a COTS cooler for flight. The initial cost advantage is significantly narrowed by the cost of adapting the COTS cooler for flight. JPL is developing a “turn key” cryogenic cooling solution based on a commercial cryocooler with the intention that it can become a standard product. The goal is to develop a complete, fully redundant cryogenic cooling solution based on the Thales 9310. The system includes the cooler, brackets to provide mounting and cooling, supporting structures, vibration isolation, thermal straps, thermal switches, and drive electronics. This paper discusses qualification of the various components for flight, including launch vibration and thermal performance testing, as well as a full up testing of the completed assembly.

Ramsey, Perry G.↗

NASA NTRSDate not supplied

Ceramic Heat Pipe for Thermal Management of a High Frequency Inductor

As the power density of electric machines and power electronics continues to increase to meet the demands of more electric aircraft, the thermal management of these devices becomes increasingly important. Ideally, the thermal management solution of the device should have high thermal conductivity and be electrically insulating so that it can be directly integrated with the device in question. Technical ceramics are a class of materials that meet these two requirements. Direct liquid cooling by submerging electric components in a dielectric fluid is an alternate option, but adds system complexity and may incur pumping loss. In this work, the thermal management solution for a high frequency inductor is presented. A conventional wicked heat pipe is designed that is made from a solid ceramic case with a sintered ceramic wick. This heat pipe can provide structural support for the core and windings and is electrically insulating, so it does not incur any additional eddy current losses from the high frequency magnetic fields. It does not require additional pumping power, because conventional wicked heat pipes are passive devices. In this paper, the manufacturing process of the ceramic heat pipe is also presented. It is shown that the sintering of large diameter spherical ceramic particles is difficult due to their high specific surface area and low surface free energy. To overcome this difficulty, a flux material was used to initiate liquid phase sintering. The results of the sintering trials show that for the 120 μm diameter α-Al2O3powder selected for the wick, the combination of 1650°C sintering temperature and the addition of 5 wt% talc sintered the porous matrix together sufficiently for use as a heat pipe wic

High-frequency Inductor↗

NASA NTRSDate not supplied

Ceramic Heat Pipe for Thermal Management of a High Frequency Inductor

As the power density of electric machines and power electronics continues to increase to meet the demands of more electric aircraft, the thermal management of these devices becomes increasingly important. Ideally, the thermal management solution of the device should have high thermal conductivity and be electrically insulating so that it can be directly integrated with the device in question. Technical ceramics are a class of materials that meet these two requirements. Direct liquid cooling by submerging electric components in a dielectric fluid is an alternate option, but adds system complexity and may incur pumping loss. In this work, the thermal management solution for a high frequency inductor is presented. A conventional wicked heat pipe is designed that is made from a solid ceramic case with a sintered ceramic wick. This heat pipe can provide structural support for the core and windings and is electrically insulating, so it does not incur any additional eddy current losses from the high frequency magnetic fields. It does not require additional pumping power, because conventional wicked heat pipes are passive devices. In this paper, the manufacturing process of the ceramic heat pipe is also presented. It is shown that the sintering of large diameter spherical ceramic particles is difficult due to their high specific surface area and low surface free energy. To overcome this difficulty, a flux material was used to initiate liquid phase sintering. The results of the sintering trials show that for the 120 μm diameter α-Al2O3 powder selected for the wick, the combination of 1650°C sintering temperature and the addition of 5 wt% talc sintered the porous matrix together sufficiently for use as a heat pipe wick.

High frequency inductor↗

NASA NTRSDate not supplied

Computational Aerodynamic Analysis in Support of the CRM Tail Cone Thruster Configuration Wind Tunnel Test

NASA’s Advanced Air Transport Technology (AATT) project is breaching the boundaries of aircraft design in pursuit of eco-friendly solutions that are compatible with urban noise comfort levels. Boundary layer ingesting (BLI) propulsion systems promise to reduce fuel burn with additional potential benefits in noise reduction. Type-II BLI systems of the STARC-ABL type are the subject of a test campaign planned for fiscal year 2022 in the National Transonic Facility (NTF), for which a CRM-based model with a retrofitted tail cone thruster (TCT) has been designed. The present work is a precursor to the NTF test, where the 240 cases planned for the experiment were simulated using the Launch, Ascent and Vehicle Aerodynamics (LAVA)computational framework. Solution sensitivity to angle of attack, engine operating conditions, and the presence of the supporting structure (sting) in the wind tunnel test are analyzed in the extensive dataset. The main flow features contributing to the inlet distortion are identified as the vertical tail wake, wing downwash and fuselage upsweep vortices, with the latter two experiencing the greatest sensitivity to angle of attack. Finally, results from an inlet-guide-vane(IGV) design/integration study are presented. The LAVA team and the turbomachinery design team at NASA’s Ames and Glenn Research Centers are collaborating in an effort to reduce flow distortion upstream of the fan by means of integrating an IGV system into the CRM-TCT model. A significant improvement in flow distortion metrics has been achieved since the initial design iteration. Results employing an actuator zone model with realistic radially-varying thrust profiles to simulate first-order fan effects within LAVA are presented.

AATT↗

NASA NTRS2020

InSight Robotic Arm Testing Activities for HP3 Mole Anomaly Recovery on Mars

The InSight lander’s Heat Flow and Physical Properties Package (HP3) was deployed on Mars in February 2019and began attempting to penetrate to its target depth range of3-5 meters shortly thereafter. However, the mole’s downwardprogress stopped after only 35 cm of penetration. In response,the project convened an Anomaly Response Team (ART) andsince then has been attempting to diagnose the problem andassist the mole using the tools available on Mars. The key assetused in this effort has been the Instrument Deployment System(IDS), which includes two cameras and a robotic InstrumentDeployment Arm (IDA). Since the IDS was originally intendedonly to deploy InSight’s primary instruments to the Martiansurface, new testbed setups, experiments, and operational protocols (e.g., command sequences) were required and had to bedeveloped on a short timeline. The HP3 Mole ART first focusedon gathering all observable data on Mars about the state ofthe mole and Support Structure Assembly (SSA), as well asthe physical properties of the Martian regolith. This includedusing the robotic arm to point the IDC at the SSA duringdiagnostic hammering attempts to observe motion of the SSAand science tether. Images taken during these attempts revealedsome motion of the SSA, but no apparent change in mole depth.At JPL, the IDS and Testbed teams re-created the hardwareconfiguration on Mars based on limited knowledge of the mole’sstate. They devised and tested techniques to use the roboticarm and cameras to accomplish previously untested activitieson Mars, including imaging the HP3, using the IDA to interactwith the terrain, and using the IDA to move the SSA awayfrom the partially-embedded mole. The team executed the morepromising techniques on Mars. After diagnostic hammering onMars, the team decided to move the SSA to gain visibility ofthe mole’s configuration and access to the soil around the mole.After developing the technique and practicing the maneuver inthe InSight testbed, the team lifted the SSA on Mars and placedit behind the mole. This revealed a pit surrounding the nowexposed mole, observations of which provided essential cluesfor determining the root cause of the mole’s lack of progress.The IDS and Testbed teams altered the testbed to match thesituation on Mars. They devised IDA techniques to determinethe Martian soil properties and assist the mole’s descent. Theytested these techniques in the testbed and executed the more978-1-7281-2734-7/20/$31.00 c 2021 IEEE. Copyright 2020 CaliforniaInstitute of Technology. U.S. Government sponsorship acknowledged.promising ones on Mars. These include using the robotic arm toalter the regolith near the mole and to push on the mole while ithammers. This paper discusses the anomaly resolution testing inthe testbed at JPL, describes how the IDS team prepared for theanomaly recovery activities on Mars, and provides preliminaryresults of the efforts to assist the HP3 mole on Mars.

Kim, Junggon↗

NASA NTRS2021

InSight Robotic Arm Testing Activities for HP3 Mole Anomaly Recovery on Mars

The InSight lander’s Heat Flow and Physical Properties Package (HP3 ) was deployed on Mars in February 2019 and began attempting to penetrate to its target depth range of 3-5 meters shortly thereafter. However, the mole’s downward progress stopped after only 35 cm of penetration. In response, the project convened an Anomaly Response Team (ART) and since then has been attempting to diagnose the problem and assist the mole using the tools available on Mars. The key asset used in this effort has been the Instrument Deployment System (IDS), which includes two cameras and a robotic Instrument Deployment Arm (IDA). Since the IDS was originally intended only to deploy InSight’s primary instruments to the Martian surface, new testbed setups, experiments, and operational protocols (e.g., command sequences) were required and had to be developed on a short timeline. The HP3 Mole ART first focused on gathering all observable data on Mars about the state of the mole and Support Structure Assembly (SSA), as well as the physical properties of the Martian regolith. This included using the robotic arm to point the IDC (Instrument Deployment Camera) at the SSA during diagnostic hammering attempts to observe motion of the SSA and science tether. Images taken during these attempts revealed some motion of the SSA, but no apparent change in mole depth. At JPL, the IDS and Testbed teams re-created the hardware configuration on Mars based on limited knowledge of the mole’s state. They devised and tested techniques to use the robotic arm and cameras to accomplish previously untested activities on Mars, including imaging the HP3 , using the IDA to interact with the terrain, and using the IDA to move the SSA away from the partially-embedded mole. The team executed the more promising techniques on Mars. After diagnostic hammering on Mars, the team decided to move the SSA to gain visibility of the mole’s configuration and access to the soil around the mole. After developing the technique and practicing the maneuver in the InSight testbed, the team lifted the SSA on Mars and placed it behind the mole. This revealed a pit surrounding the now exposed mole, observations of which provided essential clues for determining the root cause of the mole’s lack of progress. The IDS and Testbed teams altered the testbed to match the situation on Mars. They devised IDA techniques to determine the Martian soil properties and assist the mole’s descent. They tested these techniques in the testbed and executed the more promising ones on Mars. These include using the robotic arm to alter the regolith near the mole and to push on the mole while it hammers. This paper discusses the anomaly resolution testing in the testbed at JPL, describes how the IDS team prepared for the anomaly recovery activities on Mars, and provides preliminary results of the efforts to assist the HP3 mole on Mars.

Kim, Junggon↗

NASA NTRSDate not supplied

Obtaining cryogenic molecular transport data for analysis

The James Webb Space Telescope (JWST) has a primary mirror, made of 18 segments, and a secondary mirror (SM) that are used to direct the light of desired targets. While on orbit, the secondary mirror assembly (SMA) was stowed for approximately 10 days and was subject to molecular contamination outgassing from the cavity of the secondary mirror support structure (SMSS) in-board hinge (IBH) which contains cables, motors, resolvers, and coatings. The main concern during this period before SMA deployment is the accumulation of ice due to the lack of a heater on the SMA. The temperature differentials between the IBH surfaces and SMA could cause redistribution of contaminants. To address this concern, single layer insulation (SLI) was used to create adequate venting and path redirection of outgassing from the IBH. Two separate thermal vacuum tests were performed to quantify this contamination: one Z307 ASTM E 1559 materials test of the radiator paint used on the motor of the IBH and a separate test on a primary mirror backplane assembly (PMBA) qualification engineering test unit (ETU) of the IBH. These tests approximately followed the predicted SMA pre-deployment thermal environment. To quantify source rates in case of a leak, the motor and resolver sides were separated and quartz crystal microbalances (QCM) were used to measure the deposition of water. The SLI redesign and implementation and outgassing measurements to understand leak effects from the IBH were essential to mitigate the deposition of contamination on the SMA.

James Webb Space Telescope, contamination, cleanro↗

NASA NTRSDate not supplied

Obtaining Cryogenic Molecular Transport Data for Analysis

James Webb Space Telescope↗

NASA NTRSDate not supplied

Sample Polishing Without Epoxy

In recent years, we have received requests for meteorite sample sections to be prepared without using epoxy impregnation or mounting. The reasoning for these requests ranges from potential contamination of analyses from epoxy chemical components to degradation of instrumental vacuum from epoxy outgassing (e.g., SEM, SIMS, EPMA, etc.). An alternative approach that we employ involves sawing off a 1-5 mm thick wafer of the sample. The wafer is ground using silica carbide lapping media wetted with 190 proof ethyl alcohol to make both sides flat and parallel. The sample is then polished on one or both sides using diamond paste or dry diamond powder on a rotating lap wheel until the desired finish is obtained. The sample is cleaned in between steps using 200 proof ethyl alcohol in an ultrasonic cleaner. Friable and altered samples need to have higher thickness in order for polishing to be attempted. Without epoxy to hold the sample together or a glass slide for backing, the sample needs additional material to provide the necessary support structure. The machining steps of this process need to be undertaken at a much slower speed than in traditional thin or thick section preparation.

Meteorite↗

NASA NTRSDate not supplied

Commissioning the James Webb Space Telescope Optical Telescope Element

The James Webb Space Telescope (JWST) launched on December 25th, 2021. The observatory was deployed and commissioned during its first six months. The Optical Telescope Element includes both large deployments of the Deployable Tower Assembly, Secondary Mirror Support Structure and the Primary Mirror Wings and it includes the deployment and alignment of the 18 primary mirror segments and the secondary mirror. The initial phase included cooldown and ice mitigation efforts followed by telescope deployments, mirror deployment and wavefront sensing and control. This paper will discuss the entire OTE commissioning from deployment through alignment including a discussion of results and lessons learned.

Lee D Feinberg↗

NASA NTRSDate not supplied

Coupled Reactor Multiphysics and Mass Scalability Assessment for Crewed Megawatt-Class NEP System Architectures

Nuclear Electric Propulsion (NEP) is an in-space propulsion technology capable of enabling opposition and conjunction class crewed Mars missions. NEP subsystems include the reactor for heat generation, a power conversion system (PCS), power management and distribution (PMAD), electric propulsion subsystem (EPS), and a primary heat rejection system. Specific mass, or αe (kg / kWe), is a key performance parameter (KPP) of the propulsion system which is directly scalable with the performance and mass estimates for individual components. To inform technology maturation planning, full system and component level parametric modeling is ongoing to explore the design trade space and illustrate the effect of subsystem design choices on the system KPPs. In this study, scaling of high-assay, low-enriched uranium (HALEU) reactor designs is assessed through coupled reactor physics and thermal hydraulics analyses. Scaling analyses evaluate the impact of system performance parameters (power level, interface temperatures) on mass for direct gas cooled, pumped liquid metal, and passively cooled heat pipe reactor concepts. Each concept requires specific geometries and working fluids to reach the performance goals of PCS interface conditions (temperature, pressure, flow rate) and system mass. The reactor assembly includes the active core (fuel, moderator, cladding, working fluid), axial and radial neutron reflectors, control drums, structural support / pressure vessel, and external radiation shielding. Each of these components are parametrically sized based on performance parameters for a megawatt-class power cycle. Results of this scaling analysis increase NEP propulsion system modeling fidelity and ultimately aim to support technology down-selection along with related technology development planning. The reactor and shield αe are a function of several PCS design choices, and reactor scaling with these parameters must be considered to enable an informed decision on reactor geometry and working fluid combination.

Nuclear Electric Propulsion↗

NASA NTRSDate not supplied

Coupled Reactor Multiphysics and Mass Scalability Assessment for Crewed Megawatt-Class NEP System Architectures

Nuclear Electric Propulsion (NEP) is an in-space propulsion technology capable of enabling opposition and conjunction class crewed Mars missions. NEP subsystems include the reactor for heat generation, a power conversion system (PCS), power management and distribution, electric propulsion system, and heat rejection system. Specific mass, or α (kg/kWe), is a key performance parameter (KPP) of the propulsion system which is directly scalable with the performance and mass predictions for each individual component. To inform technology maturation planning activities, full system and component level parametric modeling is ongoing to explore the design trade space and illustrate the effect of subsystem design choices on the system KPPs. In this study, scaling of high-assay, low-enriched uranium reactor designs is assessed through coupled reactor physics and thermal hydraulics analyses. Scaling analyses evaluate the impact of system performance parameters (power level, interface temperatures) on mass for direct gas cooled, pumped liquid metal, and passively-cooled heat pipe reactor concepts. Each concept requires specific geometries, fluids, and power conversion interface conditions (temperature, pressure, flow rate) to meet desired performance and mass. The reactor assembly includes the active core (fuel, moderator, cladding, working fluid), axial and radial neutron reflectors, control drums, structural support / pressure vessel, and external radiation shielding. Each of these components are parametrically sized based on performance parameters for a megawatt-class power cycle. Results of this scaling analysis increase NEP propulsion system modeling fidelity and ultimately aim to support concept down-selection along with related technology development planning. The reactor and shield α are a function of several PCS and heat rejection system design choices, and reactor scaling with these parameters must be considered to enable an informed decision on an optimal reactor geometry and working fluid combination.

Nuclear Electric Propulsion↗