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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 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS1999

Global Lightning Variations Caused by Changes in Flash Rate and by Changes in Number of Thunderstorms

Observations from the Optical Transient Detector in space are used to examine the response of the number of storms and the total flash rate to thermodynamic forcing of deep convection on the diurnal and annual time scales. On the diurnal time scale, the flash rate appears to track with cloud buoyancy, and storm numbers dominate later in the cycle. On the annual time scale, almost all of the total lightning response is due to changes in the number of storms, with a negligible contribution from flash rate.

Williams, E.↗
NASA NTRS2005

Space Technology 5: Changing the Mission Design without Changing the Hardware

The Space Technology 5 (ST-5) Project is part of NASA's New Millennium Program. The validation objectives are to demonstrate the research-quality science capability of the ST-5 spacecraft; to operate the three spacecraft as a constellation; and to design, develop, test and flight-validate three capable micro-satellites with new technologies. A three-month flight demonstration phase is planned, beginning in March 2006. This year, the mission was re-planned for a Pegasus XL dedicated launch into an elliptical polar orbit (instead of the Originally-planned Geosynchronous Transfer Orbit.) The re-plan allows the mission to achieve the same high-level technology validation objectives with a different launch vehicle. The new mission design involves a revised science validation strategy, a new orbit and different communication strategy, while minimizing changes to the ST-5 spacecraft itself. The constellation operations concepts have also been refined. While the system engineers, orbit analysts, and operations teams were re-planning the mission, the implementation team continued to make progress on the flight hardware. Most components have been delivered, and the first spacecraft is well into integration and test.

Carlisle, Candace C.↗
NASA NTRS2019

Changing Climate, Changing Data: Exposing Climate Data to New Users Through GeoPlatform.gov’s Resilience Community

Over 700 climate related datasets were curated by subject matter experts into 9 thematic areas as a part of the Climate Data Initiative (CDI). NASA was tasked with maintaining the collection’s data inventory and supporting web pages at data.gov/climate. Today, the Data Curation for Discovery (DCD) team at MSFC continues to support the CDI collection. In order to expose the collection to a new and growing user community, the DCD team has partnered with GeoPlatform.gov to develop the Resilience community. The Resilience community serves as an interactive, topically-focused web portal that further promotes and shares CDI web content, datasets, services, maps, and other tools relevant to global resilience and change. This poster focuses on the team’s efforts to leverage GeoPlatform’s semantic applications to link CDI objects within the platform to improve discoverability. This poster also provides insights as to how this effort may serve as an example for building and expanding future Geoplatform.gov communities..

Sisco, Adam↗
NASA NTRSDate not supplied

Decadal Changes in the Antarctic Sea Ice Response to the Changing ENSO in the Last Four Decades

Variation of the sea ice fraction (SIF) over the Ross/Amundsen/Bellingshausen Sea (RAB) is investigated focusing on the decadal difference in time-lagged response to ENSO between the late 20th century (1980-2000, L20) and the early 21st century (2001-2021, E21). Moving correlation of the ENSO index against the SIF and sea surface temperature (SST), respectively, over the RAB region indicates that they are more strongly linked in the L20 than in the E21, with a time lag of up to two seasons. Time-lagged regressions onto the mature phase of El Niño reveal that the SIF decrease and SST increase over the RAB is relatively weaker in the E21 and most pronounced at a shorter time-lag of 0-4 months. In contrast, the SIF melt in the L20 continues to grow and reaches its peak at approximately two season lag (5-7 month). Near-surface wind, upper-level circulation and geopotential height, and wave activity in response to the ENSO in the L20 explain that they create a zonally oriented system of high- and low-pressure areas with a two-season lag, enhancing the poleward meridional flow that plays a key role in sea ice melt in the Ross and Amundsen Sea during El Niño. However, in the E21, this pattern is no longer active at the same lag, and the circulation determines the region of maximum sea ice melt east of the pattern observed in the L20. This study suggests that stronger ENSO on average and higher frequency of eastern Pacific ENSO occurrence in the L20 are associated with this decadal change in the lagged response of the RAB SIF to ENSO.

Young-Kwon Lim↗
NASA NTRS1998

Changes in gravitational state cause changes in ocular torsion

Gravity-responsive eye torsion was studied simultaneously in both eyes during parabolic flight to determine the effects of weightlessness. Observed effects were that torsional position of eyes in the 1G states between parabolas was offset from the baseline positions obtained prior to the onset of parabolas, responses to hyper- and hypogravity were seen in most subjects, and responses were consistent within subjects but varied between subjects.

NASA Discipline Neuroscience↗
NASA NTRS2019

The Changing Changing-Look AGN 1ES 1927+654

We report on X-ray follow-up observations of the March 2018 nuclear transient event AT2018zf (ASASSN-18el) from an ongoing campaign that includes XMM-Newton, NuSTAR, Swift, and high cadence (daily-to-weekly) NICER observations. The event was associated with the Seyfert galaxy 1ES 1927+654, a "True Type-2" that, nevertheless, showed an X-ray spectrum typical of an unobscured Type 1 AGN. Optical monitoring revealed the emergence of broad Balmer emission lines following the outburst, suggesting a transition from a Type 2 to a Type 1 AGN on timescales consistent with the light-travel time between the central black hole and the broad line region. The optical outburst was followed by a dramatic shift in the X-ray spectrum as the hard X-ray luminosity of the corona plunged by >2 orders of magnitude and the spectrum became dominated by a 10^6 K thermal component. The subsequent X-ray evolution of 1ES 1927+654 includes an additional two-order of magnitude decline in overall luminosity, followed by an extended period of quiescence, and re-brightening to levels that make it the brightest AGN currently in the X-ray sky. Throughout its evolution, the source has displayed X-ray flux variability of factors of several on timescales less than hour, and of ~100 on timescales less than a day. The X-ray spectrum varies along a consistent luminosity-dependent track, wherein increases in flux are accompanied by a spectral hardening. We seem to be witnessing the onset of an instability in the pre-existing AGN disc and corona, followed by a still-continuing re-emergence of the corona. If the initial transient is identified as the tidal disruption of a star, it is possible that this was the instigator of this unique behavior.

Loewenstein, M.↗