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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 1,729 records · Page 96
All sourcesNASA NTRSDOE OSTI
NASA NTRS2017

Very Large Array Ammonia Observations of the HH 111/HH 121 Protostellar System: A Detection of a New Source with a Peculiar Chemistry

We present the results of Very Large Array NH3 (J, K) = (1, 1) and (2, 2) observations of the HH 111/HH 121 protostellar system. HH 111, with a spectacular collimated optical jet, is one of the most well-known Herbig-Haro objects. We report the detection of a new source, NH3-S, in the vicinity of HH 111/HH 121 (approximately 0.03 parsecs from the HH 111 jet source) in two epochs of the ammonia observations. This constitutes the first detection of this source, in a region that has been thoroughly covered previously by both continuum and spectral line interferometric observations. We study the kinematic and physical properties of HH 111 and the newly discovered NH3-S. We also use HCO plus and HCN (J=4-3) data obtained with the James Clerk Maxwell Telescope and archival Atacama Large Millimeter/submillimeter Array (sup 13) CO, (sup 12) CO, and C (sup 18) O (J=2-1), N2D plus (J=3-2), and (sup 13) CS (J=5-4) data to gain insight into the nature of NH3-S. The chemical structure of NH3-S shows evidence for "selective freeze-out," an inherent characteristic of dense cold cores. The inner part of NH3-S shows subsonic nonthermal velocity dispersions indicating a "coherent core," while they increase in the direction of the jets. Archival near- to far-infrared data show no indication of any embedded source in NH3-S. The properties of NH3-S and its location in the infrared dark cloud suggest that it is a starless core located in a turbulent medium, with the turbulence induced by Herbig-Haro jets and associated outflows. More data are needed to fully understand the physical and chemical properties of NH3-S and if/how its evolution is affected by nearby jets.

James Clerk Maxwell Telescop↗
NASA NTRS2018

Design and Development of CubeSat Solar Array Deployment Mechanisms Using Shape Memory Alloys

The Advanced eLectrical Bus (ALBus) project is a technology demonstration mission of a 3U CubeSat with an advanced, digitally controlled electrical power system capability and the novel use of Shape Memory Alloy (SMA) technology for reliable solar array (SA) deployable mechanisms. The ALBus CubeSat deploys four SAs in addition to the body-mounted arrays on each side of the CubeSat. A goal of the mission is to utilize the SMAs being developed at the NASA Glenn Research Center to deploy these SAs. The use of SMAs allows for the ability to test and reset the flight deployment mechanism prior to flight, which reduces the risk of in orbit deployment failures common to CubeSats. As a result, an SMA-driven Retention and Release (R&R) mechanism and an SMA-driven hinge were designed, developed, and integrated for flight. This paper summarizes the development of these mechanisms, types and functionalities of the SMAs used, as well as the lessons learned throughout the process.

cubesat↗
NASA NTRS2018

Integration of Multilevel Superconducting Buried Wiring Layers with Transition-Edge Sensor Detectors for Large Scale Arrays

Lynx, one of the four mission concepts under consideration for the next Astrophysics DecadalReview, will include a microcalorimeter array consisting of more than 100,000 pixels in a compact arrangement with absorber pitch as small as 25 microns. In order to realize the desired array scale, fine-pitch multi-level superconducting wiring with high yield, compatible with rapid expansion of our hydra absorber designs, is essential. We have demonstrated a method of integrating transition edge sensor (TES) microcalorimeters with suitable multilevel buried wiring, fabricated at MIT Lincoln Laboratory using advanced tools dedicated to superconducting circuit fabrication. The TES Mo/Au bilayer is deposited on a high-quality oxide surface created by chemical-mechanical polishing, allowing tight specifications on the TES superconducting transition and link conductivity to be achieved even though the process order has been inverted. The TESs contact the top-level niobium wiring through vias etched through silicon dioxide down to the topmost wiring layer. The article discusses the overall fabrication process, as wellas the behavior of sensors with different via designs, proximity structures, and lateral sizes. An initial iteration of the integrated fabrication process indicates that microcalorimeters fabricated in this way should meet mission specifications using a Mo/Au bilayer with a reasonable critical temperature below 100 mK.

Detector↗
NASA NTRS2019

Rotary-motion-extended Array Synthesis (R-MXAS)

R-MXAS is a revolutionary aerospace architecture for realizing a synthetic aperture imaging radiometer (SAIR) with dramatically lower SWaP than existing state-of-the-art (SOTA) methods. The space-based component of the RMXAS system (Figure 1) is a single platform comprising a 1-D sparse / decimated antenna array on a rigid tether (deployed parallel to the horizon) and one or more additional tethered antennas that rotate in a plane orthogonal to the 1-D array.The processing that correlates the data from these two antenna systems and performs image reconstruction has both space-based and ground-based components. The processing exploits the interferometric baselines formed between the rotating tethered antenna at radius R and each of the antennas of the 1-D array on the rigid tether.

Radiometer↗
NASA NTRS2017

Preliminary Aeroacoustic Measurements of In-Flow Reference Arrays and Sources at ARC

This presentation will review progress in recent testing of in-flow reference arrays and sources for aeroacoustic research testing at NASA aerodynamic centers. The sources were speakers and a multiple air jet source in an aerodynamic fairing, placed in the test section of the Army 7x10 untreated wind tunnel at ARC. The array used was an 8D, 24 element pattern in a similar aerodynamic fairing.

phased microphone arrays↗
NASA NTRS2020

Effects of Resistive Windscreens and Foam Inserts on The Acoustic Response of an In-Flow Phased Microphone Array

The effects of varying windscreen resistance and cavity foam treatments on the acoustic response of an in-flow phased microphone array have been characterized by recent experiments at ARC, GRC, and LaRC using common array and calibration source designs. New correction models have been developed and validated with results from recent impedance tube, anechoic chamber, and wind tunnel tests.

Wind tunnel aeroacoustics research↗
NASA NTRS2000

The Development of Inflatable Array Antennas

Three inflatable array antennas recently developed for spacecraft applications are a 3.3m x 1.0m L-band synthetic aperture radar (SAR) array, a 1.0m-diameter X-band telecom reflectarray, and a 3m-diameter Ka-band telecom reflectarray.

inflatable↗
NASA NTRS2001

Novel multiplexing technique for detector and mixer arrays

Future space submillimeter telescopes will require large-format imaging detector arrays to perform state-of-the-art astronomical observations. A crucial issue related to a focal plane array is a readout scheme which is combatible with large numbers of cryogenic detectors elements.

submillimeter↗
NASA NTRS1998

Continuum Modeling of the Dynamics of Externally Injection Locked Coupled Oscillator Arrays

Mutually injection locked arrays of electronic oscillators provide a novel means of controlling the aperture phase of a phased array antenna thus achieving the advantages of spatial power combining while retaining the ability to steer the radiated beam. In this work we develop a continuum model which results in a single partial differential equation for the aperture phase as a function of time.

Coupled↗
NASA NTRSDate not supplied

Cognitive Tapered Slot Circular Array Antenna for Lunar Surface Communications

In this paper, we present the design of a cognitive tapered slot circular array (TSCA) antenna with multiple electronically switched sector beams for lunar surface communication. The circular array is capable of sensing the frequency, power, and direction of arrival of the RF signals. The design of the TSCA builds on our prior work on the development of a single TSA element with a balanced microstrip/coax feed. The measured return loss of the single TSA element shows wide bandwidth with good impedance match across the 5 to 35 GHz frequency range. Additionally, the single TSA has good radiation patterns. The single TSA serves as the building block for a four-element TSCA with multiple electronically switched sector beams for sensing and communications.

Cognitive communications↗
NASA NTRSDate not supplied

Cognitive Tapered Slot Circular Array Antenna for Lunar Surface Communications

In this paper, we present the design of a cognitive tapered slot circular array (TSCA) antenna with multiple electronically switched sector beams for lunar surface communication. The circular array is capable of sensing the frequency, power, and direction of arrival of the RF signals. The design of the TSCA builds on our prior work on the development of a single TSA element with a balanced microstrip/coax feed. The measured return loss of the single TSA element shows wide bandwidth with good impedance match across the 5 to 35 GHz frequency range. Additionally, the single TSA has good radiation patterns. The single TSA serves as the building block for a four-element TSCA with multiple electronically switched sector beams for sensing and communications.

Antenna↗
NASA NTRSDate not supplied

Characterizations of Optimized Microshutter Arrays for Space Borne Observatory Applications

We report the latest design, fabrication, and characterization result of the Next-Generation Microshutter Arrays (NGMSA) for space borne observatory applications. Our improved blade design aims to reduce the counter torque induced by the potential on the opposing wall to eliminate the torque bump, and thus enables pure electrostatic actuation for more reliable and stable microshutter operations. This paper presents the experimental performances of micro-fabricated microshutter arrays with varying design parameters and compares the results with simulation predictions.

Electrostatic↗
NASA NTRSDate not supplied

SPACE-Gateway: Modeling the Electrical Performance of the Gateway Power & Propulsion Element (PPE) Solar Arrays

The System Power Analysis for Capability Evaluation (SPACE) computer model was originally developed in 1988 at NASA Glenn Research Center to model the International Space Station (ISS) electrical power system (EPS). Since then, SPACE development has continued with the rise of new NASA human spaceflight missions. Today, SPACE’s uniquely complex and robust solar array model is being leveraged to model the solar arrays on the Gateway Power & Propulsion Element (PPE) for NASA's Artemis Program. This presentation will discuss the model’s integrated features, including its solar cell current-voltage (IV) curve, degradation, temperature, and on-orbit shadowing components. The presentation will also discuss recent SPACE advancements to meet the needs of NASA's latest spaceflight missions.

SPACE↗
NASA NTRSDate not supplied

Sidelobe Reduction and Mode-Purity Enhancement of Vortex Beams from a Programmable, Rectangular Phased Array Antenna

Tapering the magnitude of the electric field excitation of a programmable, rectangular phased array has been employed to achieve sidelobe reduction and enhancement of mode purity in vortex beams, which carry non-zero orbital angular momentum. Far-field radiation patterns pertaining to a commercial-off-the-shelf, 256-element antenna were generated via electromagnetic simulation. The patterns were decomposed into weighted sums of Laguerre-Gaussian modes. The extracted coupling coefficients were used to gauge mode purity. In comparison to a uniform excitation of the phased array elements, our studies indicate that employing a tapering technique can result in a 10.7 dB reduction of sidelobe power and a 7.22 dB improvement in worst-case, mode-to-mode cross-talk.

orbital angular momentum, phased array, beamformin↗
NASA NTRS2014

Identification of Noise Sources in a Rocket Engine Test Stand using Microphone Phased Array

A new, phased array of microphones, suitable for the harsh environment of a rocket launch, was built and tested during a static firing of a RS-25 engine. It uses 70 piezo-resistive, dynamic pressure sensors, optimally distributed on a 10.5ft diameter open frame dome structure, and has a 200-ft long cable bundle to carry the signals to a weather-protected cabinet containing the data systems. The test stand was imaged using an infra-red camera and a visible wavelength camera, and the beamformed noise maps were superimposed on the photographs. The first-time data from a full-scale engine test stand showed that the plume deflector at the bottom of the engine to be the primary noise source. The openings of the test stand around the nozzle exit were also found to be noise sources particularly at higher frequencies. The final goal is to use the array during NASA’s Artemis-II launch at Kennedy Space Center.

Identification of Noise Source↗