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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 NTRS2017

Meteoroids are Dangerous to Spacecraft

Meteoroids put dents in Shuttle windows much like bouncing gravel puts dents in your car's windshield. However, meteoroids move at such high speeds that they can partly vaporize the surfaces they strike! A dust particle (smaller than a meteoroid) hit the STEREO spacecraft and produced this fountain of smaller particles. When a meteoroid breaks up, its "shrapnel" can also be dangerous. Even when meteoroids don't damage a spacecraft, they can cause problems. Here, a small meteoroid bumped a camera on the Lunar Reconnaissance Orbiter (LRO), causing wiggles in this scan of the lunar surface. Meteoroids and pieces of space junk create rough edges on the outside of the Space Station that can damage space suits. The astronauts' gloves had to be thickened to help prevent them from ripping.

Moorhead, Althea V.↗
DOE OSTI2023

Rapidly evolving aerosol emissions are a dangerous omission from near-term climate risk assessments

Abstract Anthropogenic aerosol emissions are expected to change rapidly over the coming decades, driving strong, spatially complex trends in temperature, hydroclimate, and extreme events both near and far from emission sources. Under-resourced, highly populated regions often bear the brunt of aerosols’ climate and air quality effects, amplifying risk through heightened exposure and vulnerability. However, many policy-facing evaluations of near-term climate risk, including those in the latest Intergovernmental Panel on Climate Change assessment report, underrepresent aerosols’ complex and regionally diverse climate effects, reducing them to a globally averaged offset to greenhouse gas warming. We argue that this constitutes a major missing element in society’s ability to prepare for future climate change. We outline a pathway towards progress and call for greater interaction between the aerosol research, impact modeling, scenario development, and risk assessment communities.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1974

Our contaminated atmosphere: The danger of climate change, phases 1 and 2

The effects of increased concentrations of atmospheric particulate matter on average surface temperature and on the components of the earth's radiation budget are studied. An atmospheric model which couples particulate loading to surface temperature and to changes in the earth's radiation budget was used. A determination of the feasibility of using satellites to monitor the effect of increased atmospheric particulate concentrations is performed. It was found that: (1) a change in man-made particulate loading of a factor of 4 is sufficient to initiate an ice age; (2) variations in the global and hemispheric weighted averages of surface temperature, reflected radiant fluz and emitted radiant flux are nonlinear functions of particulate loading; and (3) a black satellite sphere meets the requirement of night time measurement sensitivity, but not the required day time sensitivity. A nonblack, spherical radiometer whose external optical properties are sensitive to either the reflected radiant fluz or the emitted radiant flux meets the observational sensitivity requirements.

Cimorelli, A. J.↗
NASA NTRS1984

Predicting dangerous ocean waves with spaceborne synthetic aperture radar

It is pointed out that catastrophes, related to the occurrence of strong winds and large ocean waves, can consume more lives and property than most naval battles. The generation of waves by wind are considered, Pierson et al. (1955) have incorporated statistical concepts into a wave forecast model. The concept of an 'ocean wave spectrum' was introduced, with the wind acting independently on each Fourier component. However, even after 30 years of research and debate, the generation, propagation, and dissipation of the spectrum under arbitrary conditions continue to be controversial. It has now been found that spaceborne SAR has a surprising ability to precisely monitor spatially evolving wind and wave fields. Approaches to overcome certain weaknesses of the SAR method are discussed, taking into account the second Shuttle Imaging Radar experiment, and a possible long-term solution provided by Spectrasat. Spectrasat should be a low-altitude (200 to 250 km) satellite with active drag compensation.

Beal, R. C.↗
NASA NTRS1988

On the danger of redundancies in some aerospace mechanisms

An attempt is made to show that redundancies in some aerospace mechanisms do not generally improve the odds for success. Some of these redundancies may even be the very cause for failure of the system. To illustrate this fallacy, two designs based on the Control of Flexible Structures I (COFS I) Mast deployer and retractor assembly (DRA) are presented together with novel designs to circumvent such design inadequacies, while improving system reliability.

Chew, M.↗
NASA NTRS1988

The dangers of underestimating the importance of data adjustments in band ratioing

The practical importance of simple data adjustments for path (atmospheric) radiance and sensor calibration offsets prior to band ratioing has often been overlooked or misjudged. This paper describes and demonstrates the critical nature of data adjustments for the production of useful ratio images, including ratio images derived solely from long wavelength bands. A simple bispectral graphic model is used for illustrating and evaluating the impact of data offsets upon ratio images. Orthogonal indices, used as alternatives to band ratios, are shown to be sometimes less sensitive to topographic influences than ratios of unadjusted data but not less sensitive than ratios of properly adjusted data.

Crippen, Robert E.↗
NASA NTRS1988

Lightning danger and advanced warning times obtainable from field mills

The rate of charge moment generation derived from Maxwell current densities at the ground is compared with the rate of charge moment removal by lightning for the initial stages of a small thunderstorm cell. It is shown that the current moment in the cell increased with time at a rate of 4.5 (A m/s) during the first seven minutes following detection of electrical activity on the ground. At the time of the first lightning flash which neutralized 0.48 (kC m) a charge moment of over 8 (kC m) had been separated. Theoretical and practical implications of these measurements are discussed.

Nisbet, John S.↗
NASA NTRS1928

A dangerous seaplane landing condition

A peculiar phenomena in seaplane landing is observed and reported. The seaplane having executed a normal fast landing at low incidence, a forward movement of the control stick effected an unusual condition in that the seaplane left the water suddenly in an abnormal attitude. The observations describing this phenomena are offered as a warning against possible accident and as a conjectural cause of seaplane landing accidents of a certain kind.

PRESSURE DISTRIBUTION - FLOAT BOTTOMS↗
NASA NTRS1931

The dangerous flat spin and the factors affecting it

This report deals first with the fundamental data required for the investigation. These are chiefly the aerodynamic forces and moments acting on an airplane in a flat spin. It is shown that these forces and moments depend principally on the angle of attack and on the rotation about the path axis, and can therefore either be measured in a wind tunnel or calculated from wind-tunnel measurements of lift, drag and moment about the leading edge of the wing of an airplane model at rest. The lift, drag and moments about the span axis are so greatly altered by the rapid rotation in a flat spin, that they can no longer be regarded as independent of rotation. No substantial change in the angles of attack and glide occurring in a flat spin is involved. The cross-wind force, as compared with the lift and drag, can be disregarded in a flat spin.

Fuchs, Richard↗