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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 505 records · Page 28
All sourcesNASA NTRSDOE OSTI
NASA NTRS1970

Lunar surface magnetometer design review

Design and fabrication parameters of a lunar surface magnetometer are discussed. Drawings and requirements for mechanical design, electronic packaging design, thermal design, quality assurance and systems testing are included.

Source record↗
NASA NTRS1974

High-resolution radar maps of the lunar surface at 3.8-cm wavelength

The entire earth-facing lunar surface has been mapped at a resolution of 2 km using the 3.8-cm radar of Haystack Observatory. The observations yield the distribution of the relative radar backscattering efficiency with an accuracy of about 10% for both the polarized (primarily quasi-specular or coherent) and depolarized (diffuse or incoherent) scattered components. The results show a variety of discrete radar features, many of which are correlated with craters or other features of optical photographs. Particular interest, however, attaches to those features with substantially different ratio and optical contrast. An anomaly near 63 degrees is noted in the mean angular scattering law obtained from a summary of the radar data.

Zisk, S. H.↗
NASA NTRS1978

Lunar surface processes - Report of the 12054 consortium

A variety of lunar surface phenomena were studied using a well-characterized glass-coated ilmenite basalt, 12054, which had a simple surface residence history. Surface processes related to the following effects were studied: microcraters, solar flare and cosmic ray tracks, cosmogenic Al-26, solar wind sputtering, accreta or accretionary material, solar wind implanted noble gases, and loose dust accumulation.

Hartung, J. B.↗
NASA NTRS2008

A Closer Look at Solar Wind Sputtering of Lunar Surface Materials

Solar-wind induced potential sputtering of the lunar surface may be a more efficient erosive mechanism than the "standard" kinetic (or physical) sputtering. This is partly based on new but limited laboratory measurements which show marked enhancements in the sputter yields of slow-moving, highly-charged ions impacting oxides. The enhancements seen in the laboratory can be orders of magnitude for some surfaces and highly charged incident ions, but seem to depend very sensitively on the properties of the impacted surface in addition to the fluence, energy and charge of the impacting ion. For oxides, potential sputtering yields are markedly enhanced and sputtered species, especially hydrogen and light ions, show marked dependence on both charge and dose.

Barghouty, A. F.↗
NASA NTRS1977

Origin and evolution of the lunar surface - The major questions remaining

The major factors in the evolution of the lunar surface have not been determined yet. Huge lava flows and lunar differentiation, though commonly assumed, is in discord with much of the evidence. The alternative is for most of the surface to represent the last stages of accretion of the moon only, with the chemical differentiation having taken place previously in the source material. Radar, seismic, surface exposure, and mascon evidence can then be accounted for. A large-scale surface transport mechanism of soil must then have been present.

Gold, T.↗
NASA NTRSDate not supplied

Modeling Deformable Linear Objects for Autonomous Robotic Outfitting of Lunar Surface Systems

This paper presents structural models of deformable linear objects (DLOs). DLOs are a subclass of deformable objects that encompasses common outfitting elements such as cables and ropes. Models are validated through hardware experiments, and integration in a robotic autonomy architecture for space environments is discussed. A persistent human presence on the lunar surface is one of the next major milestones in space exploration. This requires the development of robust extraplanetary construction technologies including structures and materials modeling and robotic systems. Previous robotic construction technology development has primarily focused on structural assembly, with significantly less focus on robotically performed outfitting tasks to instantiate subsystems providing power, data, life support, etc. These tasks involve manipulation of highly flexible elements, which are difficult to model, such as cable harnesses, ropes, and hoses. Robotic manipulation of DLOs, especially cable harnesses, is an active area of research as cable harnesses are essential for providing power and data to space assets. DLO models that can be used for robot manipulator trajectory generation are necessary for autonomous operation of lunar infrastructure. There are many proposed methods for modeling DLOs, and they primarily fall into three types: 1) discrete model-based, 2) continuum model-based, and 3) Neural Network-based. These types each have pros and cons, and the tradeoff between model accuracy and computational speed informs which type should be used. An understanding of this trade-off is imperative for real-time control of autonomous systems. High computational requirements reduce the speed of the model, making real-time control difficult, while accuracy is critical to preventing collisions. Discrete models, such as a mass-spring multibody representation, require relatively few calculations, and accuracy is directly tied to the step size of the discretization. Continuum models, such as a B-spline representation or a Cosserat rod model (a mix of continuous and discrete), are more informed of the structural properties of the cable and are much more accurate than a rigid body mass-spring model, but at significant computational cost. A Neural Network approach can provide an online solution with very few computational steps, but properly generating training data can be difficult and validation for an in-space application is not trivial. This paper explores the trade-off between different modeling approaches and compares accuracy and computational speed/complexity of the three types mentioned above. Model accuracy is evaluated using a cable in a static configuration. True cable shape is obtained using a depth camera for RGB images and point-cloud segmentation. The purpose of this experiment is to evaluate the trade-offs of different approaches to the DLO modeling problem. Understanding the tradeoffs between different cable modeling techniques paves the way for developing robotic control and planning architectures necessary for real-time manipulation of DLOs for lunar infrastructure outfitting. Real-time control is required for robotic systems to be able to actively manipulate a cable in a harsh environment where model and sensor errors compound, and environmental conditions can cause significant disturbances. Cable routing must be performed in areas with high density of objects/obstacles: through truss structures, near solar panels or mirror arrays, next to bundles of electrical equipment. Understanding the best way to plan and manipulate a cable without disrupting the environment or damaging the cable is imperative to robotic outfitting operations on the lunar surface.

Amy M Quartaro↗
NASA NTRSDate not supplied

Application and Use of Lunar Node-Derived Beacons for Lunar Surface Navigation

To maximize the scientific return and safety of operations on the lunar surface, multiple civil organizations are investing in Position, Navigation, and Timing infrastructure. This approach mimics the deployment of Global Navigation Satellite Systems around the Earth and aims to enable a similar robust capability around the moon. With these satellites, it will be possible to maintain high- fidelity knowledge of positioning and timing both on the surface and in orbit. For initial deployments, this capability is focused on high need areas, such as the Lunar South Pole, the target of the currently in-planning Artemis surface missions to high accuracy. Similar to GNSS systems, this capability will be implemented over time to build up to a level of global access for real-time navigation. For early missions, this means a limited capability in terms of coverage. To provide increased performance, ground augmentation can be leveraged. This not only provides an additional reference signal but helps to supply timing to enable a high accuracy real-time position solutions. This paper discusses the path towards evolving the Lunar Node 1 platform to augment these early constellation deployments. Analysis of notional performance with and without surface aids is provided, as well as discussion and paths towards deployment and operation. Given the analysis results, the benefit of surface navigation aids to both provide additional surface-based signals to fill in coverage gaps helps to provide additional robustness and an early-on capability.

Evan J. Anzalone↗
NASA NTRS1991

Lunar surface structural concepts and construction studies

The topics are presented in viewgraph form and include the following: lunar surface structures construction research areas; lunar crane related disciplines; shortcomings of typical mobile crane in lunar base applications; candidate crane cable suspension systems; NIST six-cable suspension crane; numerical example of natural frequency; the incorporation of two new features for improved performance of the counter-balanced actively-controlled lunar crane; lunar crane pendulum mechanics; simulation results; 1/6 scale lunar crane testbed using GE robot for global manipulation; basic deployable truss approaches; bi-pantograph elevator platform; comparison of elevator platforms; perspective of bi-pantograph beam; bi-pantograph synchronously deployable tower/beam; lunar module off-loading concept; module off-loader concept packaged; starburst deployable precision reflector; 3-ring reflector deployment scheme; cross-section of packaged starburst reflector; and focal point and thickness packaging considerations.

Mikulas, Martin↗