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

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

Global Rescue Response to a Multivehicle Deorbit from the International Space Station

The U.S. Department of Defense (DoD) has been tasked to support rescue efforts in the event of an off-nominal landing of a Commercial Crew Program vehicle transporting NASA crewmembers to or from the International Space Station. The DoD is further tasked to support returning U.S. and International Partner crewmembers on Russian Soyuz spacecraft missions, specifically to ensure aeromedical evacuation capability in the event of a crewmember injury at the time of launch or landing. This DoD mission is primarily considered during planned launch and landing operations, with forces placed in an alert posture to support if needed. However, overall mission concept of operations encompasses a no-notice rescue capability in the event of an on-orbit emergency. Such contingency scenarios are pre-coordinated and simulated to ensure a ready posture of associated DoD assets and to promote coordination of government, commercial, and military stakeholders. To date, planning and simulations have focused on execution of a single rescue mission; the possibility of a multi-vehicle evacuation and rescue scenario has not been adequately explored. This presentation will examine the process of responding to an emergency onboard the International Space Station that results in the early departure and deorbit of multiple docked vehicles to preserve the health and safety of the crew. We will highlight the complexity of this recovery scenario and discuss potential complications that could arise, as well as identify areas in which deliberate planning and simulation can better ensure successful preparation for such a multifaceted recovery operation.

Travis Levon Houser↗
NASA NTRS1984

Manned maneuvering unit simulations on the Space Operations Simulator

Details of the Manned Maneuvering Unit (MMU) and its use is discussed. MMU simulations in the Space Operations Simulator (SOS) use two major devices. The first is a six-degree-of-freedom moving base carriage that allows the trainee freedom to fly the MMU in a large room and to match rates and dock with full scale targets. The second device is a large screen television display that provides the trainee with accurate views of tumbling targets from any point in a surrounding sphere up to 300 meters (1000 feet) in diameter. Astronauts used the SOS to train for the Solar Max repair mission and are now using it to train for a mission to recover the Palapa-B communications satellite. Subjective comparisons by astronauts of an orbit MMU performance to simulated MMU performance in the SOS indicate that the simulations are very realistic. Data from the Solar Max mission have resulted in two software upgrades that increase SOS fidelity for the next MMU mission: a model of contact dynamics between the MMU and a target spacecraft, and a model of MMU plume impingement forces during docking.

Hartley, C.↗
DOE OSTI2024

Structure-Based Identification of Novel Histone Deacetylase 4 (HDAC4) Inhibitors

Histone deacetylases (HDACs) are important cancer drug targets. Existing FDA-approved drugs target the catalytic pocket of HDACs, which is conserved across subfamilies (classes) of HDAC. However, engineering specificity is an important goal. Herein, we use molecular modeling approaches to identify and target potential novel pockets specific to Class IIA HDAC-HDAC4 at the interface between HDAC4 and the transcriptional corepressor component protein NCoR. These pockets were screened using an ensemble docking approach combined with consensus scoring to identify compounds with a different binding mechanism than the currently known HDAC modulators. Binding was compared in experimental assays between HDAC4 and HDAC3, which belong to a different family of HDACs. HDAC4 was significantly inhibited by compound 88402 but not HDAC3. Two other compounds (67436 and 134199) had IC50 values in the low micromolar range for both HDACs, which is comparable to the known inhibitor of HDAC4, SAHA (Vorinostat). However, both of these compounds were significantly weaker inhibitors of HDAC3 than SAHA and thus more selective, albeit to a limited extent. Five compounds exhibited activity on human breast carcinoma and/or urothelial carcinoma cell lines. The present result suggests potential mechanistic and chemical approaches for developing selective HDAC4 modulators.

60 APPLIED LIFE SCIENCES↗
NASA NTRS1980

Computer control of a robotic satellite servicer

The advantages that will accrue from the in-orbit servicing of satellites are listed. It is noted that in a concept in satellite servicing which holds promise as a compromise between the high flexibility and adaptability of manned vehicles and the lower cost of an unmanned vehicle involves an unmanned servicer carrying a remotely supervised robotic manipulator arm. Because of deficiencies in sensor technology, robot servicing would require that satellites be designed according to a modular concept. A description is given of the servicer simulation hardware, the computer and interface hardware, and the software. It is noted that several areas require further development; these include automated docking, modularization of satellite design, reliable connector and latching mechanisms, development of manipulators for space environments, and development of automated diagnostic techniques.

Fernandez, K. R.↗
NASA NTRS1992

Solar dynamic modules for Space Station Freedom: The relationship between fine-pointing control and thermal loading of the aperture plate

Dynamic simulations of Space Station Freedom (SSF) configured with solar dynamic (SD) power modules were performed. The structure was subjected to Space Shuttle docking disturbances, while being controlled with a 'natural' vibration and tracking control approach. Three control cases were investigated for the purpose of investigating the relationship between actuator effort, SD pointing, and thermal loading on the receiver aperture plate. Transient, one-dimensional heat transfer analyses were performed to conservatively predict temperatures of the multi-layered receiver aperture plate assembly and thermal stresses in its shield layer. Results indicate that the proposed aperture plate is tolerant of concentrated flux impingement during short-lived structural disturbances. Pointing requirements may be loosened and the requirement control torques lessened from that previously specified. Downsizing and simplifying the joint drive system should result in a considerable savings mass.

Quinn, Roger D.↗
NASA NTRS1992

MSFC Three Point Docking Mechanism design review

In the next few decades, we will be launching expensive satellites and space platforms that will require recovery for economic reasons, because of initial malfunction, servicing, repairs, or out of a concern for post lifetime debris removal. The planned availability of a Three Point Docking Mechanism (TPDM) is a positive step towards an operational satellite retrieval infrastructure. This study effort supports NASA/MSFC engineering work in developing an automated docking capability. The work was performed by the Grumman Space & Electronics Group as a concept evaluation/test for the Tumbling Satellite Retrieval Kit. Simulation of a TPDM capture was performed in Grumman's Large Amplitude Space Simulator (LASS) using mockups of both parts (the mechanism and payload). Similar TPDM simulation activities and more extensive hardware testing was performed at NASA/MSFC in the Flight Robotics Laboratory and Space Station/Space Operations Mechanism Test Bed (6-DOF Facility).

Schaefer, Otto↗
NASA NTRS2010

Low-Friction, Low-Profile, High-Moment Two-Axis Joint

The two-axis joint is a mechanical device that provides two-degrees-of-freedom motion between connected components. A compact, moment-resistant, two-axis joint is used to connect an electromechanical actuator to its driven structural members. Due to the requirements of the overall mechanism, the joint has a low profile to fit within the allowable space, low friction, and high moment-reacting capability. The mechanical arrangement of this joint can withstand high moments when loads are applied. These features allow the joint to be used in tight spaces where a high load capability is required, as well as in applications where penetrating the mounting surface is not an option or where surface mounting is required. The joint consists of one base, one clevis, one cap, two needle bearings, and a circular shim. The base of the joint is the housing (the base and the cap together), and is connected to the grounding structure via fasteners and a bolt pattern. Captive within the housing, between the base and the cap, are the rotating clevis and the needle bearings. The clevis is attached to the mechanical system (linear actuator) via a pin. This pin, and the rotational movement of the clevis with respect to the housing, provides two rotational degrees of freedom. The larger diameter flange of the clevis is sandwiched between a pair of needle bearings, one on each side of the flange. During the assembly of the two-axis joint, the circular shims are used to adjust the amount of preload that is applied to the needle bearings. The above arrangement enables the joint to handle high moments with minimal friction. To achieve the high-moment capability within a low-profile joint, the use of depth of engagement (like that of a conventional rotating shaft) to react moment is replaced with planar engagement parallel to the mounting surface. The needle bearings with the clevis flange provide the surface area to react the clevis loads/moments into the joint housing while providing minimal friction during rotation. The diameter of the flange and the bearings can be increased to react higher loads and still maintain a compact surface mounting capability. This type of joint can be used in a wide variety of mechanisms and mechanical systems. It is especially effective where precise, smooth, continuous motion is required. For example, the joint can be used at the end of a linear actuator that is required to extend and rotate simultaneously. The current design application is for use in a spacecraft docking-system capture mechanism. Other applications might include industrial robotic or assembly line apparatuses, positioning systems, or in the motion-based simulator industry that employs complex, multi-axis manipulators for various types of motions.

Lewis, James L.↗
NASA NTRSDate not supplied

Towards Plume Impingement Modeling in Space Environments

After 30 years human presence in low-earth orbit, NASA is returning to the moon and eventually will go to Mars. To this end, NASA is constructing the Lunar Gateway, an ISS-like space station to act as a home base for Lunar exploration. A large space station must be assembled while in orbit, using a “piecemeal” approach. In this context, it means that the different modules will arrive at different times and attach to what is already in service. The ISS provides an excellent example of this approach, and the proposed Lunar Gateway will undergo a similar assembly process. This assembly is achieved via “docking” maneuvers between modules, which are made possible by sequential firings of the onboard reaction control system (RCS) thrusters. They work by firing hot gases to produce adverse thrust and the needed change in velocity to safely finish the docking approach. The issue is that the gas from these thrusters' forms flow structures described as “plumes” and can impinge onto the outer surfaces of the space station, causing unwanted forces and moments, heat loads, sediment deposition, and in extreme cases, even surface erosion. All mechanisms that can damage the space station and must be avoided. Both permanent and visiting modules will have these RCS thruster exhaust impingement problems. Accurately and efficiently modeling these plume is an involved multi-physics calculation but also an important tool when designing the control algorithms of approaching modules. This poster presents progress towards this simulation on two fronts. First is the verification of OpenFOAM for rarefied plume impingement calculations by direct comparison to published DAC cases. Second is the estimation of plume impingement strikes over the time scale of an entire docking event. This is done by using a simple plume source flow model and a prescribed motion visualizer—coded in Python. Together these tools help push NASA's capabilities for simulating these plume impingement effects.

Rarefied Flows↗
NASA NTRS1990

Space Systems Integrated Simulation (SPASIS)

Complex program models everything on user-defined space station, from control gyros to mass effect of astronaut moving along strut. Other features include plume impingement, attitude control, propellant slosh, docking, and gravity.

Stecklein, J. M.↗
NASA NTRS1973

Apollo/Soyuz test project operational data book. Volume 2: ASTP mass properties data book

Spacecraft mass properties data are provided for use in mission planning, trajectory documentation, mission simulations, and consumable loading. Spacecraft for use in determining locations of spacecraft components and the relationship to coordinate systems in the launch and docked configuration. Mass properties and consumable loading data for the ASTP mission are included along with consumables mass property data and mission independent consumable loading information for the CSM and DM.

Source record↗
NASA NTRS1991

Dynamic and control assessment of the Space Station Freedom payload pointing system

An analysis of the proposed Space Station Freedom Payload Pointing System (PPS) was performed to assess its dynamic payload pointing capability in the dynamic environment of the Space Station Freedom (SSF). In addition, the stability and control the the SSF was examined to verify the capability of its control devices to accommodate the impact of PPS operations. An analysis of the PPS ability to provide continuous, accurate pointing was performed and compared to the program requirements specified in the 1988 Program Definition and Requirement Document (PDRD). Results indicated that the PPS was not able to perform within the program requirements during the worst case scenario of a shuttle hard docking maneuver to the port side SSF docking adapter. The PPS maintained marginal pointing accuracy during crew treadmill activity. The Space Station attitude control system easily accommodated all PPS operations simulated. The PPS caused a negligible impact on the SSF's control environment.

Shannon, David T., Jr.↗
NASA NTRS2008

Overview of LIDS Docking Seals Development

NASA is developing a new docking system to support future space exploration missions to low-Earth orbit, the Moon, and Mars. This mechanism, called the Low Impact Docking System (LIDS), is designed to connect pressurized space vehicles and structures including the Crew Exploration Vehicle, International Space Station, and lunar lander. NASA Glenn Research Center (GRC) is playing a key role in developing the main interface seal for this new docking system. These seals will be approximately 147 cm (58 in.) in diameter. GRC is evaluating the performance of candidate seal designs under simulated operating conditions at both sub-scale and full-scale levels. GRC is ultimately responsible for delivering flight hardware seals to NASA Johnson Space Center around 2013 for integration into LIDS flight units.

Dunlap, Pat↗
NASA NTRS1994

Simulation of the coupled multi-spacecraft control testbed at the Marshall Space Flight Center

The capture and berthing of a controlled spacecraft using a robotic manipulator is an important technology for future space missions and is presently being considered as a backup option for direct docking of the Space Shuttle to the Space Station during assembly missions. The dynamics and control of spacecraft configurations that are manipulator-coupled with each spacecraft having independent attitude control systems is not well understood and NASA is actively involved in both analytic research on this three dimensional control problem for manipulator coupled active spacecraft and experimental research using a two dimensional ground based facility at the Marshall Space Flight Center (MSFC). This paper first describes the MSFC testbed and then describes a two link arm simulator that has been developed to facilitate control theory development and test planning. The motion of the arms and the payload is controlled by motors located at the shoulder, elbow, and wrist.

Ghosh, Dave↗
DOE OSTI2021

Enhancing Paraoxon Binding to Organophosphorus Hydrolase Active Site

Organophosphorus hydrolase (OPH) is a metalloenzyme that can hydrolyze organophosphorus agents resulting in products that are generally of reduced toxicity. The best OPH substrate found to date is diethyl p-nitrophenyl phosphate (paraoxon). Most structural and kinetic studies assume that the binding orientation of paraoxon is identical to that of diethyl 4-methylbenzylphosphonate, which is the only substrate analog co-crystallized with OPH. In the current work, we used a combined docking and molecular dynamics (MD) approach to predict the likely binding mode of paraoxon. Then, we used the predicted binding mode to run MD simulations on the wild type (WT) OPH complexed with paraoxon, and OPH mutants complexed with paraoxon. Additionally, we identified three hot-spot residues (D253, H254, and I255) involved in the stability of the OPH active site. We then experimentally assayed single and double mutants involving these residues for paraoxon binding affinity. The binding free energy calculations and the experimental kinetics of the reactions between each OPH mutant and paraoxon show that mutated forms D253E, D253E-H254R, and D253E-I255G exhibit enhanced substrate binding affinity over WT OPH. Interestingly, our experimental results show that the substrate binding affinity of the double mutant D253E-H254R increased by 19-fold compared to WT OPH.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1988

Dual keel Space Station payload pointing system design and analysis feasibility study

A Space Station attached Payload Pointing System (PPS) has been designed and analyzed. The PPS is responsible for maintaining fixed payload pointing in the presence of disturbance applied to the Space Station. The payload considered in this analysis is the Solar Optical Telescope. System performance is evaluated via digital time simulations by applying various disturbance forces to the Space Station. The PPS meets the Space Station articulated pointing requirement for all disturbances except Shuttle docking and some centrifuge cases.

Smagala, Tom↗
NASA NTRS2012

Ground Simulation of an Autonomous Satellite Rendezvous and Tracking System Using Dual Robotic Systems

A hardware-in-the-loop ground system was developed for simulating a robotic servicer spacecraft tracking a target satellite at short range. A relative navigation sensor package "Argon" is mounted on the end-effector of a Fanuc 430 manipulator, which functions as the base platform of the robotic spacecraft servicer. Machine vision algorithms estimate the pose of the target spacecraft, mounted on a Rotopod R-2000 platform, relay the solution to a simulation of the servicer spacecraft running in "Freespace", which performs guidance, navigation and control functions, integrates dynamics, and issues motion commands to a Fanuc platform controller so that it tracks the simulated servicer spacecraft. Results will be reviewed for several satellite motion scenarios at different ranges. Key words: robotics, satellite, servicing, guidance, navigation, tracking, control, docking.

Trube, Matthew J.↗
NASA NTRS2015

Innovative Electrostatic Adhesion Technologies

Developing specialized Electro-Static grippers (commercially used in Semiconductor Manufacturing and in package handling) will allow gentle and secure Capture, Soft Docking, and Handling of a wide variety of materials and shapes (such as upper-stages, satellites, arrays, and possibly asteroids) without requiring physical features or cavities for a pincher or probe or using harpoons or nets. Combined with new rigid boom mechanisms or small agile chaser vehicles, flexible, high speed Electro-Static Grippers can enable compliant capture of spinning objects starting from a safe stand-off distance. Electroadhesion (EA) can enable lightweight, ultra-low-power, compliant attachment in space by using an electrostatic force to adhere similar and dissimilar surfaces. A typical EA enabled device is composed of compliant space-rated materials, such as copper-clad polyimide encapsulated by polymers. Attachment is induced by strong electrostatic forces between any substrate material, such as an exterior satellite panel and a compliant EA gripper pad surface. When alternate positive and negative charges are induced in adjacent planar electrodes in an EA surface, the electric fields set up opposite charges on the substrate and cause an electrostatic adhesion between the electrodes and the induced charges on the substrate. Since the electrodes and the polymer are compliant and can conform to uneven or rough surfaces, the electrodes can remain intimately close to the entire surface, enabling high clamping pressures. Clamping pressures of more than 3 N/cm2 in shear can be achieved on a variety of substrates with ultra-low holding power consumption (measured values are less than 20 microW/Newton weight held). A single EA surface geometry can be used to clamp both dielectric and conductive substrates, with slightly different physical mechanisms. Furthermore EA clamping requires no normal force be placed on the substrate, as conventional docking requires. Internally funded research and development has demonstrated that EA can function effectively in space, even in the presence of strong ultraviolet radiation, atomic oxygen, and free electrons. We created a test setup in an existing vacuum chamber to simulate low-Earth-orbit conditions. An EA mechanism was fabricated and installed in the chamber, instrumented, operated in a vacuum, and subjected to ultraviolet photons and free electrons generated by an in-chamber multipactor electron emitter. Extensions to EA that can add value include proximity and contact sensing and transverse motion or rotation, both of which could enhance docking or assembly applications. Possible next steps include development of targeted applications for ground investigation or on-orbit subsystem performance demonstrations using low cost access to space such as CubeSats.

Bryan, Tom↗
NASA NTRS1974

Unmanned docking

An algorithm is developed which effects unmanned docking of two space vehicles. The docking is controlled by an onboard computer and sensor. Control laws are expressed in two phase-plane trajectories such that modest computer load results. Simulation reveals time-fuel trades and effects of orbit, noise, etc.

Pace, M.↗