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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS2008

Mitigating Aviation Communication and Satellite Orbit Operations Surprises from Adverse Space Weather

Adverse space weather affects operational activities in aviation and satellite systems. For example, large solar flares create highly variable enhanced neutral atmosphere and ionosphere electron density regions. These regions impact aviation communication frequencies as well as precision orbit determination. The natural space environment, with its dynamic space weather variability, is additionally changed by human activity. The increase in orbital debris in low Earth orbit (LEO), combined with lower atmosphere CO2 that rises into the lower thermosphere and causes increased cooling that results in increased debris lifetime, adds to the environmental hazards of navigating in near-Earth space. This is at a time when commercial space endeavors are posed to begin more missions to LEO during the rise of the solar activity cycle toward the next maximum (2012). For satellite and aviation operators, adverse space weather results in greater expenses for orbit management, more communication outages or aviation and ground-based high frequency radio used, and an inability to effectively plan missions or service customers with space-based communication, imagery, and data transferal during time-critical activities. Examples of some revenue-impacting conditions and solutions for mitigating adverse space weather are offered.

Tobiska, W. Kent↗
NASA NTRS2011

More Surprises from the Moon

Even with the naked eye, the dark, extensive plains of the lunar maria can be clearly seen on the surface of the Moon. The maria formed after meteorite impacts created large craters that later filled with lava flows. Mare volcanism is the dominant type of volcanic activity on the Moon and the lavas are made up of basaltic rocks. However, non-mare volcanic deposits, though rare, have been observed on the lunar nearside. The deposits are distinguished from the maria because they are compositionally more evolved rich in silica, potassium and thorium. The deposits are limited in surface extent and it was unknown whether similar non-mare volcanism occurred at all on the Moon s farside. Writing in Nature Geoscience, Jolliff et al. report using Lunar Reconnaissance Orbiter images and compositional data to identify the rare occurrence of more compositionally evolved volcanic deposits in an isolated area on the Moon s farside. In the 1960s and 1970s, rock and soil samples were collected by the Apollo and Luna missions, by the USA and USSR respectively. This material represents a geologic treasure trove that continues to provide a wealth of information about the Moon and its evolution, and it was a very small fraction of these samples that gave the first hint that non-mare volcanic activity might have occurred. The samples contained fragments of complex volcanic rocks that were unrelated to the maria basalts. Violent bombardment of the Moon by meteorite impacts has caused significant mixing of the rocks at its surface, so the fragments could have had a source hundreds or thousands of kilometres away. The origin of the fragments was unknown. Several decades later, the Lunar Prospector mission used a gamma-ray spectrometer to map the distribution and abundance of various elements, including thorium, on the Moon s surface. The maps identified a distinct and large area of high thorium concentration, as well as several smaller, but equally peculiar areas of high thorium concentration on the nearside of the Moon (Fig. 1). The rocks that contained high thorium contents also exhibited geomorphological and spectral features that were typical of volcanic deposits, and so the thorium hotspots were thought to represent non-mare volcanism on the nearside of the Moon. A relatively large region with extremely high thorium concentrations - the Compton-Belkovich thorium anomaly - was also identified on the Moon s farside. This thorium hotspot was particularly unusual because it was completely isolated, alone on the farside of the Moon, far from the nearest maria. No high-resolution image data were available for this region, so a definitive interpretation of the source of this isolated anomaly has been impossible.

Petro, Noah↗
NASA NTRS2017

Chapter 15: Potential Surprises: Compound Extremes and Tipping Elements

The Earth system is made up of many components that interact in complex ways across a broad range of temporal and spatial scales. As a result of these interactions the behavior of the system cannot be predicted by looking at individual components in isolation. Negative feedbacks, or self-stabilizing cycles, within and between components of the Earth system can dampen changes (Ch. 2: Physical Drivers of Climate Change). However, their stabilizing effects render such feedbacks of less concern from a risk perspective than positive feedbacks, or self-reinforcing cycles. Positive feedbacks magnify both natural and anthropogenic changes. Some Earth system components, such as arctic sea ice and the polar ice sheets, may exhibit thresholds beyond which these self-reinforcing cycles can drive the component, or the entire system, into a radically different state. Although the probabilities of these state shifts may be difficult to assess, their consequences could be high, potentially exceeding anything anticipated by climate model projections for the coming century.

Kopp, R. E.↗
NASA NTRS2018

Surprising Results from Large Crowds Using Micro-Purchase Challenges - Using Contests on Freelancing Communities to Source Innovative, Impactful and Cost-Effective Solutions

Our world is more connected than ever before. The new digital economy is empowering platforms and crowds to become a progressively strategic way for organizations to innovate ahead of their competition. Existing research shows the effectiveness and quality of solutions crowdsourcing yields, yet few organizations genuinely understand it nor are leveraging those solutions to unlock the full range of benefits. Moreover, early adopters often face structural and financial barriers towards evangelizing digital platforms at scale within their organizations. NASA is an exception - being an advocate of the field since 2010, it has paved the path for large organizations to follow. An empirical analysis is conducted on NASA's Center of Excellence for Collaborative Innovation (CoECI) micro-purchase challenges on a crowd-based platform to assess the cost-savings, quality of work, time for work turnaround and brand effects of using this problem-solving mechanism. The results proved to provide a tangible impact on all four parameters. As such, micro-purchases could become a compelling entry-point for organizations who are willing to experiment and subsequently build a convincing business case to present to stakeholders. The paper concludes with NASA's learnings, supplemented by literature, on how to redesign business processes, change conventional thinking and create an organization that will transform its future with crowds.

Tang, Sarah↗
NASA NTRS2020

Chandra spectral measurements of the O supergiant ζ Puppis indicate a surprising increase in the wind mass-loss rate over 18 yr

New long Chandra grating observations of the O supergiant ζ Pup show not only a brightening of the X-ray emission line flux of 13 per cent in the 18 yr since Chandra’s first observing cycle, but also clear evidence – at more than 4σsignificance – of increased wind absorption signatures in its Doppler-broadened line profiles. We demonstrate this with non-parametric analysis of the profiles as well as Gaussian fitting and then use line-profile model fitting to derive a mass-loss rate of 2.47±0.09×10−6Myr−1, which is a 40 per cent increase over the value obtained from the cycle 1 data. The increase in the individual emission line fluxes is greater for short-wavelength lines than long-wavelength lines, as would be expected if a uniform increase in line emission is accompanied by an increase in the wavelength-dependent absorption by the cold wind in which the shock-heated plasma is embedded.

David H. Cohen↗
NASA NTRS2024

Evidence for Surprising Heavy Nitrogen Isotopic Enrichment in Comet 46P/Wirtanen's Hydrogen Cyanide

46P/Wirtanen is a Jupiter-family comet, probably originating from the solar system's Kuiper Belt, that now resides on a 5.4 yr elliptical orbit. During its 2018 apparition, comet 46P passed unusually close to the Earth (within 0.08 au), presenting an outstanding opportunity for close-up observations of its inner coma. Here we present observations of HCN, H13CN, and HC15N emission from 46P using the Atacama Compact Array. The data were analyzed using the SUBLIME non-LTE radiative transfer code to derive 12C/13C and 14N/15N ratios. The HCN/H13CN ratio is found to be consistent with a lack of significant 13C fractionation, whereas the HCN/HC15N ratio of 68 ± 27 (using our most conservative 1σ uncertainties), indicates a strong enhancement in 15N compared with the solar and terrestrial values. The observed 14N/15N ratio is also significantly lower than the values of ∼140 found in previous comets, implying a strong 15N enrichment in 46P's HCN. This indicates that the nitrogen in Jupiter-family comets could reach larger isotopic enrichments than previously thought, with implications for the diversity of 14N/15N ratios imprinted into icy bodies at the birth of the solar system.

Short period comets↗
NASA NTRS2026

Surprisingly Enriched CO and CH4 in Halley-type Comet 13P/Olbers: Clues to Its Interstellar Heritage

The native ice composition of Halley-type Comet 13P/Olbers (hereafter 13P) was measured post-perihelion, on UT 2024 August 16 using iSHELL, the 1–5 μm cross-dispersed, high-resolution facility spectrograph at the NASA InfraRed Telescope Facility. At that time, the heliocentric distance (Rh) of 13P was 1.37 au and the geocentric distance (Δ) was 1.99 au. Using a slit that delivered spectral resolving power RP λ/Δλ 4.5 × 104, two instrument settings targeted rovibrational emissions of seven parent molecules released into the coma through sublimation of ices in the nucleus. These settings provided broad and contiguous or nearly contiguous spectral coverage, one simultaneously measuring H2O, CO, and OCS, and the other simultaneously measuring CH4, C2H6, CH3OH, and H2CO. Meaningful abundances were obtained for all seven species. Our study revealed substantial enrichments of CO and CH4, the two most volatile species systematically targeted at IR wavelengths in comets. Relative to their respective mean abundance ratios among measured comets from the Oort cloud reservoir, CO in 13P was enriched by a factor of about six and CH4 was enriched by a factor of about three. Together with near-average abundances measured for CH3OH and C2H6, this suggests large endowments of CO and CH4 on interstellar grains, yet it could indicate inhibited surface chemistry on the pre-cometary grains subsequently contained in the nucleus or 13P. Assuming that this represents the primordial composition of 13P, it could reflect very low temperatures in its natal environment (∼10 K or lower).

Michael A Disanti↗
NASA NTRS1998

Aiding Vertical Guidance Understanding

A two-part study was conducted to evaluate modern flight deck automation and interfaces. In the first part, a survey was performed to validate the existence of automation surprises with current pilots. Results indicated that pilots were often surprised by the behavior of the automation. There were several surprises that were reported more frequently than others. An experimental study was then performed to evaluate (1) the reduction of automation surprises through training specifically for the vertical guidance logic, and (2) a new display that describes the flight guidance in terms of aircraft behaviors instead of control modes. The study was performed in a simulator that was used to run a complete flight with actual airline pilots. Three groups were used to evaluate the guidance display and training. In the training, condition, participants went through a training program for vertical guidance before flying the simulation. In the display condition, participants ran through the same training program and then flew the experimental scenario with the new Guidance-Flight Mode Annunciator (G-FMA). Results showed improved pilot performance when given training specifically for the vertical guidance logic and greater improvements when given the training and the new G-FMA. Using actual behavior of the avionics to design pilot training and FMA is feasible, and when the automated vertical guidance mode of the Flight Management System is engaged, the display of the guidance mode and targets yields improved pilot performance.

Feary, Michael↗
NASA NTRS1994

Gamma-ray constraints on supernova nucleosynthesis

Gamma-ray spectroscopy holds great promise for probing nucleosynthesis in individual supernova explosions via short-lived radioactivity, and for measuring current global Galactic supernova nucleosynthesis with longer-lived radioactivity. It was somewhat surprising that the former case was realized first for a Type II supernova, when both Co-56 and Co-57 were detected in SN 1987A. These provide unprecedented constraints on models of Type II explosions and nucleosynthesis. Live Al-26 in the Galaxy might come from Type II supernovae, and if it is eventually shown to be so, can constrain massive star evolution, supernova nucleosynthesis, and the Galactic Type II supernova rate. Type Ia supernovae, thought to be thermonuclear explosions, have not yet been detected in gamma-rays. This is somewhat surprising given current models and recent Co-56 detection attempts. Ultimately, gamma-ray measurements can confirm their thermonuclear nature, probe the nuclear burning conditions, and help evaluate their contributions to Galactic nucleosynthesis. Type Ib/c supernovae are poorly understood. Whether they are core collapse or thermonuclear events might be ultimately settled by gamma-ray observations. Depending on details of the nuclear processing, any of these supernova types might contribute to a detectable diffuse glow of Fe-60 gamma-ray lines. Previous attempts at detection have come very close to expected emission levels. Remnants of any type of age less that a few centuries might be detectable as individual spots of Ti-44 gamma-ray line emission. It is in fact quite surprising that previous surveys have not discovered such spots, and the constraints on the combination of nucleosynthesis yields and supernova rates are very interesting. All of these interesting limits and possibilities mean that the next mission, International Gamma-Ray Astrophysics Laboratory (INTEGRAL), if it has sufficient sensitivity, is very likely to lead to the realization of much of the great potential of gamma-ray spectroscopy for understanding supernovae.

Leising, Mark D.↗
NASA NTRS1996

Two-Photon Ghost Image and Interference-Diffraction

One of the most surprising consequences of quantum mechanics is entanglement of two or more distance particles. The two-particle entangled state was mathematically formulated by Schrodinger. Based on this unusual quantum behavior, EPR defined their 'physical reality' and then asked the question: 'Can Quantum-Mechanical Description of Physical Reality Be Considered Complete?' One may not appreciate EPR's criterion of physical reality and insist that 'no elementary quantum phenomenon is a phenomenon until it is a recorded phenomenon'. Optical spontaneous parametric down conversion (SPDC) is the most effective mechanism to generate an EPR type entangled two-photon state. In SPDC, an optical beam, called the pump, is incident on a birefringent crystal. The pump is intense enough so that nonlinear effects lead to the conversion of pump photons into pairs of photons, historically called signal and idler. Technically, the SPDC is said to be type-1 or type-2, depending on whether the signal and idler beams have parallel or orthogonal polarization. The SPDC conversion efficiency is typically on the order of 10(exp -9) to 10(exp -11), depending on the SPDC nonlinear material. The signal and idler intensities are extremely low, only single photon detection devices can register them. The quantum entanglement nature of SPDC has been demonstrated in EPR-Bohm experiments and Bell's inequality measurements. The following two experiments were recently performed in our laboratory, which are more closely related to the original 1935 EPR gedankenezperiment. The first experiment is a two-photon optical imaging type experiment, which has been named 'ghost image' by the physics community. The signal and idler beams of SPDC are sent in different directions, so that the detection of the signal and idler photons can be performed by two distant photon counting detectors. An aperture object (mask) is placed in front of the signal photon detector and illuminated by the signal beam through a convex lens. Surprisingly, an image of this aperture is observed in the idler beam, by scanning the idler photon detector in the transverse plane of the idler beam, if we are sure that the idler photon detector 'catches' the 'twin brother' of the signal, which can be easily performed by a coincidence measurement. This effect is even more striking when we found that the object-lens-image relationship satisfies the Gaussian thin lens equation. The second experiment demonstrates two-photon 'ghost' interference-diffraction. The experimental set up is similar to the image experiment, except that rather than a lens and an aperture it is a Young's double-slit (or a single-slit) inserted into the path of the signal beam. We could not find any interference (or diffraction) pattern behind the slit. Surprisingly, an interference (or diffraction) pattern is observed when scanning the detector in the idler beam, if we are sure that the idler photon detector 'catches' the 'twin brother' of the signal.

Shih, Y. H.↗
NASA NTRS2012

Martian and Asteroid Dusts as Toxicological Risks for Human Exploration Missions

As the lunar dust toxicity project winds down, our attention is drawn to the potential toxicity of dust present at the surface of more distant celestial objects. Lunar dust has proven to be surprisingly toxic to the respiratory systems of test animals, so one might expect dust from other celestial bodies to hold toxicological surprises for us. At this point all one can do is consider what should be known about these dusts to characterize their toxicity, and then ask to what extent that information is known. In an ideal world it might be possible to suggest an exposure standard based on the known properties of a celestial dust without direct testing of the dust in laboratory animals. Factors known to affect the toxicity of mineral dusts under some conditions include the following: particle size distribution, particle shape/porosity, mineralogical properties (crystalline vs. amorphous), chemical properties and composition, and surface reactivity. Data from a recent Japanese mission to the S-type asteroid Itokawa revealed some surprises about the dust found there, given that there is only a very week gravitational field to hold the dust on the surface. On Mars the reddish-brown dust is widely distributed by global dust storms and by local clusters of dust devils. Past surface probes have revealed some of the properties of dust found there. Contemporary data from Curiosity and other surface probes will be weighed against the data needed to set a defensible safe exposure limit. Gaps will emerge.

James, John T.↗