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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 721 records · Page 40
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NASA NTRSDate not supplied

Network Jets as the Driver of Counter-streaming Flows in a Solar Filament

We investigate the driving mechanism of counter-streaming flows in a solar filament, using EUV images from SDO/AIA, line of sight magnetograms from SDO/HMI, IRIS SJ images, and H-alpha data from GONG. We find that: (i) persistent counter-streaming flows along adjacent threads of a small (100” long) solar filament is present; (ii) both ends of the solar filament are rooted at the edges of magnetic network flux lanes; (iii) recurrent small-scale jets (also known as network jets) occur at both ends of the filament; (iv) some of the network jets occur at the sites of flux cancelation between the majority-polarity flux and merging minority-polarity flux patches; (v) these multiple network jets clearly drive the counter-streaming flows along the adjacent threads of the solar filament for ~2 hours with an average speed of 70 km/s; (vi) some the network jets show base brightenings, analogous to the base brightenings of coronal jets; and (vii) the filament appears wider (4”) in EUV images than in H-alpha images (2.5”), consistent with previous studies. Thus, our observations show that counter-streaming flows in the filament are driven by network jets and possibly these driving network jet eruptions are triggered by flux cancelation.

Navdeep K Panesar↗
NASA NTRS2017

Characterization Testing of Lockheed Martin High-Power Micro Pulse Tube Cryocooler

This paper describes the thermal vacuum, microphonics, magnetics, and radiation testing and results of a Lockheed Martin high-power micro pulse tube cryocooler. The thermal performance of the microcooler was measured in vacuum for heat reject temperatures between 185 and 300 K. The cooler was driven with a Chroma 61602 AC power source for input powers ranging from 10 to 60 W and drive frequency between 115 and 140 Hz during thermal performance testing. The optimal drive frequency was dependent on both input power and heat reject temperature. In addition, the microphonics of the cooler were measured with the cooler driven by Iris Technologies LCCE-2 and HP-LCCE drive electronics for input powers ranging from 10 to 60 W and drive frequency between 135 and 145 Hz. The exported forces were strongly dependent on input power while only weakly dependent on the drive frequency. Moreover, the exported force in the compressor axis was minimized by closed loop control with the HP-LCCE. The cooler also survived a 500 krad radiation dose while being continuously operated with 30 W of input power at 220 K heat rejection temperature in vacuum. Finally, the DC and AC magnetic fields around the cooler were measured at various locations.

Rodriguez, Jose I.↗
NASA NTRS2018

Simulation and Analysis of Opportunistic MSPA for Multiple Cubesat Deployments

We describe a software approach for simultaneous demodulation and decoding of multiple frequency- multiplexed spacecraft across multiple ground stations. The approach involves the use of a single ground antenna with wide enough aperture to receive multiple angularly adjacent spacecraft simultaneously. This technique uses a wide-band RF signal digitizer coupled with easily and cheaply duplicated software-receiver modules to independently process the frequency-channelized downlink signals from the spacecraft. This approach relaxes the need for realizable modems at each antenna, for example in the Deep-SpaceNetwork (DSN), and can also function as a delayed data retrieval method for cubesat missions with routine science data return. Thus, we hope that this solution can enable more efficient utilization of DSN assets. We concentrate on a simulation similar to the proposed Exploration Mission 1 (EM-1) mission from a geometric perspective. To that end, the simulated scenario involves ten secondary cubesats deployed and tracked for a span of four days (the modeled motion over the first four days of the mission does not include any Trajectory Correction Maneuvers (TCMs) that may be necessary as the cubesats approach the moon). Transmissions from the cubesats may be received through a combination of DSN ground sites based on visibility. The cubesats are assumed to utilize typical cubesat transmit powers and a waveform similar to that of the Iris radio. One cubesat is chosen as the “target” and is considered tracked by all ground-stations throughout the simulation (i.e., it is consistently at the center of the main lobe of each ground station antenna when the ground station is in view of the cubesat in terms of elevation angle). The simulation effort involves synthesizing a wideband signal that includes the ten cubesats across a large bandwidth due to each cubesat having its own center-frequency in X-band, near 8.4 GHz. Each signal is characterized by its own Doppler-frequency shift and free-space path-loss computed through the underlying geometry of the simulation as well as the cubesat transmit power. Finally, each cubesat signal experiences a unique antenna gain at each ground station due to the underlying antenna pattern and spacecraft-ground station geometry. We establish two interesting findings: First, the link-budget for the EM-1-like scenario is almost completely limited by the angle between the center of the antenna main beam and the cubesat, which means that the signal-to-noise ratio is wholly adequate for demodulation and decoding at the simulated bitrates unless the cubesat exits the main beam. Secondly, and fortunately due to the use of a software radio architecture, we show that it is possible to successfully receive signals from most cubesats for the entire 4-day simulation. Due to the signal-to-noise ratio being sufficient for demodulation even after the side-lobe’s 17dB reduction in SNR, the software radio can still demodulate such cubesats as long as the radio is capable of re-establishing carrier lock as the cubesats leave the main beam and enter the side-lobe. Considering that the target application utilizes offline processing, a loss of lock can be detected and lock can be re-established by iterating over the data. Extensive simulations demonstrate these results.

Abraham, Douglas S.↗
NASA NTRS2018

Maturation and Status of the Lockheed Martin Micro1-2 Cryocooler

This paper describes the maturation and status of the Lockheed Martin “High Power” Micro1-2 pulse tube cryocooler. This cryocooler, which was qualified to technology readiness level 6 in 2014, is the baseline cooler for the Jet Propulsion Laboratory (JPL) Mapping Imaging Spectrometer for Europa (MISE) instrument aboard the Europa Clipper mission, and the Johns Hopkins University Applied Physics Laboratory (JHU-APL) Gamma Ray and Neutron Spectrometer (GRNS) aboard the planned Psyche asteroid mission. This paper will describe enhancements to the cryocooler made for the MISE program, specifically modifications to maximize the cooler efficiency at low heat rejection temperature (220 K) and to increase the operating frequency. The paper will also describe minor modifications for the GRNS program, specifically modification of the coldfinger for low thermal emissivity and the addition of a cold tip interface tab. Finally, the paper will describe modifications made for operation with 150 K heat rejection temperature and 35 K cold tip temperature for the Deep Space Cooling System (DSCS) project with Iris Technology.

Frohling, K.↗
NASA NTRSDate not supplied

Observations and 3D MHD Modeling of Small-scale Solar Prominence Oscillations

Small scaleoscillations were recently observed in prominences with high resolution Hinode/SOT and IRIS SJI in unprecedented detailand identified as fast magnetosonic waves. The high-resolution observations provide evidence of flows of cool material, fluid instabilities such as Kelvin-Helmholtz and Rayleigh-Taylor, and the spectroscopic information provides evidence of Doppler shifts, heating, and cooling of the prominence material. Recently nonlinear fast magnetosonic waves were observed withperiods in the range of 5–11 minutes and wavelengths in the plane of the sky (POS) of ~2000kmand flows, and the flows in narrow threads withPOS speed ∼16–46 km/s. Thenonlinear fast magnetosonic waves and flows were modeled using 2.5D MHD (Ofman & Kucera 2020). Here, we extend the studyof the nonlinear fast magnetosonic waves using more realistic 3D MHD model. The model includes the 3D structure of the density and the magnetic fieldas well as mode coupling anddemonstrate the propagating density compressions associated with the nonlinear fast magnetosonicwaves, as well as the guided modesin the pillar. The 3DMHD modelingimprove understanding ofthe POSeffects in limb prominence oscillations observations.The results of the modeling are useful for coronal seismology of the prominence structure.

Leon Ofman↗
NASA NTRSDate not supplied

Direct Evidence for the Dynamic Chromospheric Origin of Solar Coronal Plumes

Coronal plumes are long ray-like open structures in coronal holes, and have been considered as possible sources for the fast solar wind. Their origin in the largely unipolar coronal holes has long been a mystery. Earlier spectroscopic and imaging observations have revealed blue-shifted plasma and propagating disturbances (PDs) in plumes that are widely interpreted in terms of flows and/or propagating slow-mode waves, but these interpretations (flows vs waves)are under debate. Recently we discovered an important clue about plume internal structure: dynamic filamentary features called “plumelets”, which account for most of the plume emission. Here we present high-resolution observations from SDO/AIA and IRIS that revealed numerous quasiperiodic tiny jets (so-called “jetlets") associated with transient brightening and plasma heating at the chromospheric footpoints of the plumelets. By analogy to larger coronal jets, these jetlets are most likely produced within the plume base by magnetic reconnection between closed and open flux at a stressed 3D null point. The jetlet-associated brightenings are in phase with plumelet-associated PDs, and vary with a period of ∼3 to 5 minutes, which is remarkably consistent with the photospheric/chromospheric p-mode oscillation. This reconnection at the open-closed boundary in the chromosphere/transition region is likely modulated or driven by local manifestations of the global p-mode waves. We discuss how these quasiperiodic jetlets extend upward to become plumelets, contribute mass to the solar wind, and may be sources of switchbacks recently detected by the Parker Solar Probe.

Pankaj Kumar↗
NASA NTRS2020

Sample Transponder Implementations for PN DDOR

The design philosophy and recommended standards for PN DDOR transponders are proposed in RFM 20-04. The referenced document illustrates how to pick a chip rate, roll-off factor, and other PN parameters for a PN DDOR transmitter. The document also proposes various recommendations for these parameters. This document expands upon RFM 20-04 and presents two PN DDOR transmitters that were designed and tested at JPL. First the IRIS cubesat radio is presented with an 8 MHz spread spectrum DDOR signal. Next the Univeral Space Transponder (UST) transmitter is presented with a 32 MHz spread spectrum DDOR signal. These transmitter designs show that the proposed recommendations are reasonably implemented with current technology.

Volk, Christopher P↗
NASA NTRS2021

A 1-D Submm-wave Leaky-Wave Phased Array using MEMS Phase Shifters

Beam-scanning of submillimeter-wave spectrometers and radiometers have traditionally been implemented using mechanical scanning mechanisms due to the absence of lowloss electronic phase shifters. Recently developed waveguideintegrated MEMS phase shifters are paving the way to realize electronic beam-steering using submm-wave phased arrays. In this work, two phased array demonstrators are presented that operate from 500GHz to 600GHz. A 20 dB directivity 8 ? 1 leaky-wave antenna array will be demonstrated, using fixed waveguide feeding networks, to be capable of ?20? scanning with a scan loss less than 1:7 dB. Secondly, an equivalent but smaller 17 dB directivity 4 ? 1 array will be integrated with MEMS phase shifters to demonstrate a dynamic scanning capability over a ?9:5? range. The antenna array is based on closely sampled square waveguides, terminated with a double-iris, in close proximity of a low permittivity superstrate in order to reduce the grating lobes at larger scanning angles. Measurements are expected to be presented at the conference.

Chattopadhyay, Goutam↗
NASA NTRS2022

Quasiperiodic Energy Release and Jets at the Base of Solar Coronal Plumes

Coronal plumes are long, ray-like, open structures, which have been considered as possible sources for the solar wind. Their origin in the largely unipolar coronal holes has long been a mystery. Earlier spectroscopic and imaging observations revealed blue-shifted plasma and propagating disturbances (PDs) in plumes that are widely interpreted in terms of flows and/or propagating slow-mode waves, but these interpretations (flows vs waves) remain under debate. Recently we discovered an important clue about plume internal structure: dynamic filamentary features called “plumelets”, which account for most of the plume emission. Here we present highresolution observations from the Solar Dynamics Observatory’s Atmospheric Imaging Assembly (SDO/AIA) and the Interface Region Imaging Spectrograph (IRIS) that revealed numerous, quasiperiodic, tiny jets (so-called “jetlets”) associated with transient brightening, flows, and plasma heating at the chromospheric footpoints of the plumelets. By analogy to larger coronal jets, these jetlets are most likely produced within the plume base by magnetic reconnection between closed and open flux at stressed 3D null points. The jetlet-associated brightenings are in phase with plumelet-associated PDs, and vary with a period of ∼3 to 5 minutes, which is remarkably consistent with the photospheric/chromospheric p-mode oscillation. This reconnection at the open-closed boundary in the chromosphere/transition region is likely modulated or driven by local manifestations of the global p-mode waves. The jetlets extend upward to become plumelets, contribute mass to the solar wind, and may be sources of the switchbacks recently detected by the Parker Solar Probe.

jets↗
NASA NTRSDate not supplied

Navigation Performance of the BioSentinel Deep Space CubeSat Mission

The BioSentinel mission was recently launched aboard the SLS launch vehicle (LV) as part of the Artemis- 1 campaign. The BioSentinel navigation team successfully tracked and guided the spacecraft through a lunar gravity assist to its destination Earth-trailing heliocentric orbit. This 6U CubeSat carries live yeast cells to analyze the effects of radiation at large distances from Earth, becoming the first biological payload in Deep Space. Prelaunch activities included mission design updates, orbit determination rehearsals and the development of a tracking schedule in coordination with the Artemis-1 payload office and the Deep Space Network (DSN). An important influence on the trajectories of Artemis I secondaries was the uncertainty associated with deployment from the Interim Cryogenic Propulsion System (ICPS), the upper stage of the SLS LV. The ICPS was rotating at a rate of 1 rpm; there was also an uncertainty in the spin axis attitude, which translated into an unknown clock angle of deployment. The variability in this angle and magnitude of deployment implied the existence of a non-negligible risk of a lunar impact, which was evaluated for various potential launch dates. We present the results of Monte Carlo analyses and compute the pertinent maneuvers to avoid it. In addition, we present a comparison with the actual deployment once the mission launched by reconstructing our trajectory with tracking data. On November 16th 2022 BioSentinel successfully deployed from ICPS and the navigation team started to receive 2-way Doppler and Sequential Ranging data from the DSN. We processed early data to try to obtain a first ephemeris using Initial Orbit Determination (IOD) methods such as the least squares. Soon after deployment, the spacecraft was tumbling and entered safe mode, creating a period where the tracking data were sparse. The mission team recovered the spacecraft and after four tracking passes, we solved for a first ephemeris that was sent to the DSN for better tracking of the spacecraft. After propagating this first ephemeris solution, we determined that we avoided impact with a margin of a few hundred km from the lunar surface. More tracking data over the next few days (from DSN as well as ESA antennas) allowed for a more refined orbit solution predicting a periselene altitude of 406 km and a lunar eclipse lasting 36.5 minutes. Therefore, BioSentinel operators aborted any correction maneuvers. This periselene altitude also gave us the necessary energy to achieve a heliocentric orbit. The next challenge was due to the necessary adjustments in our orbit determination method due to the large energy boost resulting from the lunar flyby. After a series of tracking passes we were able to get a nominal solution that resulted into a stable trajectory. This paper discusses in detail the navigation performance using the X-band IRIS transponder, as well as the challenges and lessons learned prior to and during this deep space, CubeSat mission.

Andres Dono Perez↗
NASA NTRSDate not supplied

Small Events Involve the Entire Solar Atmosphere

Here we discuss and analyze observations centered on a bipolar region of enhanced-network magnetic flux near disk center on SOL2017-03-17T14:00-17:00. The comprehensive data set comprises observations from SDO:HMI,AIA; Hinode:SOT, XRT; DST:IBIS, FIRS; ALMA; and IRIS, thus providing a variety of plasma diagnostics spanning the photosphere to the corona. We confirm the correspondence between the broadest width of the hydrogen-α spectral line and the hottest temperatures observed in millimeter wavelengths, which persist for the duration of cotemporal observations. We use these data to study the existence and persistence of oscillatory power with periods in the 3 to 5 minute range. Previous studies have found conflicting results on the existence of these modes in the ALMA data, which we suggest is linked to the spectral windowing due to requisite calibration observations. We also find that spatial maps of oscillatory power at 3mm display the pattern of magnetic shadows and halos typically displayed by other chromospheric diagnostics. Finally, numerous transient brightenings were observed across the data set, and here we highlight transient brightenings within a set of thin filamentary features. One interesting event shows initial heating in the cooler (ALMA, 7000 K) before showing in the hotter (XRT, 3 MK) data series.

Adam Kobelski↗
NASA NTRSDate not supplied

Even Small Events Involve the Entire Solar Atmosphere

The connection between the photosphere, chromosphere, and corona is essential for understanding the energy flows throughout the solar atmosphere. Here we discuss and analyze observations centered on a bipolar region of enhanced-network magnetic flux near disk center on SOL2017-03-17T14:00-17:00. The comprehensive data set comprises observations from SDO: HMI, AIA; Hinode: SOT, XRT; DST: IBIS, FIRS; ALMA; and IRIS; thus providing a variety of plasma diagnostics spanning the photosphere to the corona. Numerous transient brightenings were observed across the data set, and here we highlight transient brightenings within a set of thin filamentary features. One interesting event shows initial heating in the cooler (ALMA, 7000 K) before showing in the hotter (XRT, 3 MK) data series. These brightenings showcase how even small events involve large ranges of the solar atmosphere.

chromosphere↗
NASA NTRSDate not supplied

Neuro-Vestibular Examination During and Following Spaceflight (Vestibular Health)

BACKGROUND Adaptation to microgravity during spaceflight causes neurological disturbances that are either directly or indirectly mediated by the vestibular system. These disturbances can include space motion sickness, spatial disorientation, and cognitive impairment, as well as changes in head-eye coordination, vestibulo-ocular reflexes, and control of posture and locomotion. Otolith-mediated reflex gains appear to adapt rapidly during spaceflight and after landing. However, animal studies have shown that structural modifications of the vestibular sensory apparatus develop during long-duration spaceflight. To date, no studies have characterized the severity of vestibular syndromes experienced by astronauts as a function of the duration of spaceflight or whether the effects are caused by changes at the peripheral end organs, midbrain, cerebellum, or vestibular cortex. OBJECTIVES We will investigate temporal vestibular changes in crewmembers of short, 6-month, and one-year missions to identify trends in adaptation of vestibular health and performance in orbit and after landing. We will also determine whether the vestibular organs and/or the central vestibular system undergo structural changes during long-duration exposure to microgravity, which could cause vestibular disorders when transitioning to a different gravitational environment. METHODS Recordings of eye, head, and body movements, as well as subjective reports of perception of motion, will be used to determine the presence of abnormal eye movements, dysmetria, motion sickness symptoms, and illusions of motion during head or body movements. This includes characterization of temporal trends in central compensation for vestibular (otolith) asymmetry. Pre-flight data will be collected 90 days before launch. In-flight examinations will be performed early in the mission (Flight Days 1 and 30) and once every two or three months thereafter. Post-flight examinations will be performed on the following days after return (R) from the mission: R+0, R+4, R+9, and R+30. Ground-based control tests have been performed on healthy volunteers in the laboratory to estimate mean normative responses. RESULTS Data collection for this study is ongoing. Data processing techniques are being refined. Our eye tracking method for measuring three-dimensional eye movement takes advantage of modern computer vision software (OpenCV) and advances in the field of iris recognition to improve measurement of ocular-counterolling. RELEVANCE If the observed symptoms in crewmembers are more deleterious after the year-long missions than those documented after 6-month missions, then relevant countermeasures will be required to maintain the health and operational performance of astronauts during longer missions. Depending on the etiology of the vestibular syndrome revealed by these tests, countermeasures will be proposed based on vestibular rehabilitation therapies currently used in patients with vestibular disorders, such as habituation, gaze stabilization, and/or balance training exercises.

T R Macaulay↗
NASA NTRS2023

Slow Solar Wind Connection Science during Solar Orbiter's First Close Perihelion Passage

The Slow Solar Wind Connection Solar Orbiter Observing Plan (Slow Wind SOOP) was developed to utilize the extensive suite of remote-sensing and in situ instruments on board the ESA/NASA Solar Orbiter mission to answer significant outstanding questions regarding the origin and formation of the slow solar wind. The Slow Wind SOOP was designed to link remote-sensing and in situ measurements of slow wind originating at open–closed magnetic field boundaries. The SOOP ran just prior to Solar Orbiter's first close perihelion passage during two remote-sensing windows (RSW1 and RSW2) between 2022 March 3–6 and 2022 March 17–22, while Solar Orbiter was at respective heliocentric distances of 0.55–0.51 and 0.38–0.34 au from the Sun. Coordinated observation campaigns were also conducted by Hinode and IRIS. The magnetic connectivity tool was used, along with low-latency in situ data and full-disk remote-sensing observations, to guide the target pointing of Solar Orbiter. Solar Orbiter targeted an active region complex during RSW1, the boundary of a coronal hole, and the periphery of a decayed active region during RSW2. Postobservation analysis using the magnetic connectivity tool, along with in situ measurements from MAG and SWA/PAS, showed that slow solar wind originating from two out of three of the target regions arrived at the spacecraft with velocities between ∼210 and 600 km s −1 . The Slow Wind SOOP, despite presenting many challenges, was very successful, providing a blueprint for planning future observation campaigns that rely on the magnetic connectivity of Solar Orbiter.

Slow solar wind↗
NASA NTRSDate not supplied

Biosentinel: Update on Extended Mission Operations

BioSentinel has achieved unprecedented performance of an SLS secondary payload due to preparation, planning, and a robust design. Following the conclusion of the primary science mission in April 2023, the Linear Energy Transfer (LET) Spectrometer has continued to collect solar and galactic radiation data from its unique location in heliocentric orbit. The free space dataset offered by the BioSentinel LET is a valuable source of data for both model validation and future mission planning. As the spacecraft travels farther from Earth it is poised to provide longitudinally distributed measurements of solar particle events during solar maximum. Flight heritage has now been gained on many of the novel spacecraft components. The spacecraft bus continues to operate within the design envelope. The 3D-printed cold gas propulsion system provides momentum unloading from the reaction wheels. The power system has maintained power positive levels during flight. The IRIS radio communicates on a weekly basis with the Deep Space Network. The extended mission operations are allowing the team to characterize the performance of the spacecraft components over longer durations of operations. NASA Ames led development of the BioSentinel spacecraft and mission operations. The novel subsystems and COTS components that comprise the BioSentinel bus can serve as a template for future deep space missions. With over a year of continuous operations, the data will inform the next generation of interplanetary smallsat missions.

BioSentinel↗
DOE OSTI2021

EarthScope Seismic Station A21K (A21K-6) Field Campaign Report

Seismic station A21K has been successfully operating over the last five years. The station was constructed on 4/24/2014 by creating a borehole using an auger drill and inserting a PVC pipe casing. Roughly one month later, on 6/2/2014, the seismometer, weather station (Vaisala WXT520 meteorological sensor), enclosure, and electronics were installed. Collected data is being reported in real-time and is publicly available. On rare occasion, the station has required in-person service/maintenance visits, occurring on 4/29/2015 (fix faulty cable), 4/5/2016 (swap VIE), and 8/4/2017 (general check-up visit while in the area). This station is one in a 280-station seismic array/grid that make up the EarthScope: Transportable Array (USArray) project, funded by the National Science Foundation. USArray is operated by the Incorporated Research Institutions for Seismology (IRIS), a nonprofit 503(c) Corporation founded in 1984, that is a consortium of over 100 US universities dedicated to the operation of science facilities for the acquisition, management, and distribution of seismological data.

North Slope of Alaska, seismology, Earth system↗
DOE OSTI2020

A Case Study on the HACCmk Routine in SYCL on Integrated Graphics

As opposed to the Open Computing Language (OpenCL) programming model in which host and device codes are generally written in different languages, the SYCL programming model can combine host and device codes for an application in a type-safe way to improve development productivity. In this paper, we chose the HACCmk routine, a representative compute-bound kernel, as a case study on the performance of the SYCL programming model targeting a heterogeneous computing device. More specifically, we introduced the SYCL programming model, presented the OpenCL and SYCL implementations of the routine, and compared the performance of the two implementations using the offline and online compilation on Intel (R) Iris (TM) Pro integrated GPUs. We found that the overhead of online compilation may become significant compared to the execution time of a kernel. Compared to the performance of OpenCL implementations, the SYCL implementation can maintain the performance using the offline compilation. The number of execution units in a GPU are critical to improving the raw performance of a compute-bound kernel.

Compilation modes↗