21. The separation of small particles from meteor bodies, and its influence on some parameters of meteors

Symposium - International Astronomical Union ◽

10.1017/s0074180900019781 ◽

1968 ◽

Vol 33 ◽

pp. 207-216 ◽

Cited By ~ 2

Author(s):

A. N. Simonenko

Keyword(s):

A Priori ◽

Small Particles ◽

Earth’S Atmosphere ◽

Close Proximity ◽

Meteor Body ◽

Earth's Atmosphere

The separation of very small particles from meteor bodies as a part of the process of their ablation in the Earth's atmosphere is assumed by many investigators. But when the particle is small relative to the meteor body the path of the particle is a priori thought to be small relative to the length of the meteor path, i.e. the particle is expected to evaporate in close proximity to the point of separation. This assumption is not acceptable after McCrosky's work (1958) that has shown for one particular case the small particles (m = 10−5−10−6 g) go a long path before their mass is exhausted. The assumption made until now has caused incorrect conclusions, e.g. the luminosity at any point of the meteor path is proportional to the mass ablated from the meteor body at that point (Kramer, 1965).

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Observations of meteors in the Earth’s atmosphere: Reducing data from dedicated double-station wide-angle cameras

Astronomy and Astrophysics ◽

10.1051/0004-6361/201832927 ◽

2018 ◽

Vol 618 ◽

pp. A99 ◽

Cited By ~ 1

Author(s):

A. Margonis ◽

A. Christou ◽

J. Oberst

Keyword(s):

Software Package ◽

A Priori ◽

Radiometric Calibration ◽

Earth’S Atmosphere ◽

Meteor Streams ◽

Earth's Atmosphere ◽

The Right ◽

Right Ascension ◽

Median Deviation

Meteoroids entering the Earth’s atmosphere can be observed as meteors, thereby providing useful information on their formation and hence on their parent bodies. We developed a data reduction software package for double station meteor data from the SPOSH camera, which includes event detection, image geometric and radiometric calibration, radiant and speed estimates, trajectory and orbit determination, and meteor light curve recovery. The software package is designed to fully utilise the high photometric quality of SPOSH images. This will facilitate the detection of meteor streams and studies of their trajectories. We have run simulations to assess the performance of the software by estimating the radiants, speeds, and magnitudes of synthetic meteors and comparing them with the a priori values. The estimated uncertainties in radiant location had a zero mean with a median deviation between 0.03∘ and 0.11∘ for the right ascension and 0.02∘ and 0.07∘ for the declination. The estimated uncertainties for the speeds had a median deviation between 0.40 and 0.45 km s−1. The brightness of synthetic meteors was estimated to within +0.01 m. We have applied the software package to 177 real meteors acquired by the SPOSH camera. The median propagated uncertainties in geocentric right ascension and declination were found to be of 0.64∘ and 0.29∘, while the median propagated error in geocentric speed was 1.21 km s−1.

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Some General Considerations of the Heating of Satellites

Journal of Heat Transfer ◽

10.1115/1.4008216 ◽

1959 ◽

Vol 81 (4) ◽

pp. 308-314 ◽

Cited By ~ 1

Author(s):

Alfred J. Eggers ◽

Thomas J. Wong ◽

Robert E. Slye

Keyword(s):

Interplanetary Space ◽

Astronomical Unit ◽

The Sun ◽

Small Particles ◽

Radiation Heat ◽

Heating Rates ◽

Earth’S Atmosphere ◽

Auxiliary Power ◽

Earth's Atmosphere ◽

Escape Speed

Heating of satellites is treated in connection with flight in planetary atmospheres and in interplanetary space. Heating during entry into the earth’s atmosphere is generally more severe than that encountered during launch or exit, although it can be substantially reduced by employing blunt shapes and small entry angles. Decelerations and heating rates during entry can be further reduced by employing lifting satellites. These techniques in combination with known radiation, heat-sink, and ablation cooling techniques appear adequate to handle the entry problem at speeds up to escape speed. Return flights from distant planets like Saturn and beyond may be characterized by much higher entry speeds, and more advanced techniques for coping with the heating problem may be required. Heating during entry into the atmospheres of planets neighboring Earth tends to be more or less severe than that in the earth’s atmosphere depending on whether the planets are larger or smaller than Earth. Heating in interplanetary space due to solar radiation becomes severe only if a satellite approaches to within a small fraction of an astronomical unit of the sun, or if the vehicle has an inefficient radiation shield. A cooling problem is encountered in the outer portion of our solar system, and an auxiliary power source may be required to supplement the reduced amount of heat from the sun. The sputtering or erosion of material from the surface of a satellite, caused by impact at hypervelocities with small particles in space, may also pose direct or indirect heating problems. Further research is required to assess the magnitude of these problems.

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Observing meteors by creating artificial luminous clouds in the Earth’s atmosphere

Научные труды Института астрономии РАН ◽

10.51194/inasan.2021.6.2.004 ◽

2021 ◽

pp. 52-54

Author(s):

В.А. Леонов ◽

А.М. Пыжов ◽

А.И. Дробыжев

Keyword(s):

Ionization Potential ◽

Radar Observation ◽

New Method ◽

Atmospheric Gases ◽

Meteor Showers ◽

Earth’S Atmosphere ◽

Observation Methods ◽

Meteor Body ◽

Earth's Atmosphere ◽

Theoretical Assessment

В статье дается предварительная теоретическая оценка возможности применения нового способа наблюдения метеоров в атмосфере Земли с помощью искусственных светящихся облаков. При попадании метеоров в такие облака, образованные веществом с потенциалом ионизации в несколько раз меньшем потенциала ионизации атмосферных газов, происходит быстрая ионизация реагента облака за счет термического и ударного воздействия метеорного тела, приводящая к увеличению светимости метеорных следов. Предполагается, что такой эффект будет способствовать увеличению яркости слабых метеоров, находящихся на пороге обнаружения современных телевизионных камер. Это позволит проводить исследования метеоров и метеорных потоков, доступных ранее только радиолокационными методами наблюдения. The article provides a preliminary theoretical assessment of the possibility of using a new method of observing meteors in the Earth’s atmosphere using artificial luminous clouds. When meteors hit such clouds formed by a substance with an ionization potential several times lower than the ionization potential of atmospheric gases, the cloud reagent is rapidly ionized due to the thermal and impact effects of the meteor body, which leads to an increase in the luminosity of meteor tracks. It is assumed that this effect will increase the brightness of weak meteors, which are on the threshold of detection by modern TV cameras. This will make it possible to conduct studies of meteors and meteor showers that were previously available only by radar observation methods.

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