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PETER JENNISKENS PAUL WERCINSKI JOE OLEJNICZAK GARY ALLEN PRASUN N. DESAI GEORGE RAICHE DEAN KONTINOS DOUG REVELLE JASON HATTON RICHARD L. BAKER RAY W. RUSSELL MIKE TAYLOR FRANS RIETMEIJER 《Earth, Moon, and Planets》2004,95(1-4):339-360
The imminent return of the Genesis Sample Return Capsule (SRC) from the Earth’s L1 point on September 8, 2004, represents
the first opportunity since the Apollo era to study the atmospheric entry of a meter-sized body at or above the Earth’s escape
speed. Until now, reentry heating models are based on only one successful reentry with an instrumented vehicle at higher than
escape speed, the 22 May 1965 NASA “FIRE 2” experiment. In preparation of an instrumented airborne and ground-based observing
campaign, we examined the expected bolide radiation for the reentry of the Genesis SRC. We find that the expected emission
spectrum consists mostly of blackbody emission from the SRC surface (T∼
∼2630 K@peak heating), slightly skewed in shape because of a range of surface temperatures. At high enough spectral resolution,
shock emission from nitrogen and oxygen atoms, as well as the first positive and first negative bands of N2+, will stand out above this continuum. Carbon atom lines and the 389-nm CN band emission may also be detected, as well as
the mid-IR 4.6-μm CO band. The ablation rate can be studied from the signature of trace sodium in the heat shield material,
calibrated by the total amount of matter lost from the recovered shield. A pristine collection of the heat shield would also
permit the sampling of products of ablation. 相似文献
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N. G. Barri 《Earth, Moon, and Planets》2008,102(1-4):395-401
This work is devoted to modeling of the transverse scattering of meteoroid fragments in the atmosphere by adopting supersonic
gas dynamics around a system of bodies. Artem’eva and Shuvalov (1996, Shock Waves, 367) and Zhdan et al. (2004, Dokl. Phys.,
315–317) found that the transverse force decreases with the increase of the distance between fragments, that is, fragments
do not separate in a transverse direction under the action of constant repulsion force. This work on the decreasing transverse
force uses the values of the transverse force coefficient by Zhdan et al. (2004, Dokl. Phys., 315–317) obtained from numerical
modeling for spheres in a supersonic flow to derive the analytical solution of the dynamic equation for a fragment. The new
model of layer-by-layer scattering of meteoroid fragments moving as a system of bodies is constructed on the basis of the
analytical solutions derived in this work and the numerical data by Zhdan et al. (2005, Dokl. Phys., 514–518). 相似文献
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J. M. TRIGO-RODRíGUEZ J. LLORCA J. BOROVIČKA J. FABREGAT 《Earth, Moon, and Planets》2004,95(1-4):375-387
A detailed analysis of a photographic spectrum of a Geminid fireball obtained in December 14, 1961 at the Ondrejov Observatory
is presented. We have computed a synthetic spectrum for the fireball and compared it with the observed spectrum assuming chemical
equilibrium in the meteor head. In this way we have determined relative chemical abundances in meteor vapors. Comparing the
relative chemical abundances of this Geminid meteoroid with those obtained from meteoroids associated with comets 55P/Tempel-Tuttle
and 109P/Swift-Tuttle we found no significant chemical differences in main rock-forming elements. Despite of this similarity,
the deepest penetration of the Geminid meteoroids and their ability to reach high rotation rates in space without fragmentation
suggest that thermal processing is affecting their physical properties. We suggest that as consequence of space weathering
a high-strength envelope is produced around these particles. In this picture, heating processes of the mineral phases could
result in the peculiar properties observed during atmospheric entry of the Geminid meteoroids, especially their strength,
which is evidenced by its resistance to ablation. Finally, although one meteoroid cannot be obviously considered as representative
of the composition of its parent body, we conclude that 3200 Phaethon is able to produce millimetre-size debris nearly chondritic
in composition, but the measured slight overabundance of Na would support a cometary origin for this body. 相似文献
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Z. Ceplecka P. Brown R. L. Hawkes G. Wetherill M. Beech K. Mossman 《Earth, Moon, and Planets》1995,71(3):395-404
Large Near-Earth-Asteroids have played a role in modifying the character of the surface geology of the Earth over long time scales through impacts. Recent modeling of the disruption of large meteoroids during atmospheric flight has emphasized the dramatic effects that smaller objects may also have on the Earth's surface. However, comparison of these models with observations has not been possible until now. Peekskill is only the fourth meteorite to have been recovered for which detailed and precise data exist on the meteoroid atmospheric trajectory and orbit. Consequently, there are few constraints on the position of meteorites in the solar system before impact on Earth. In this paper, the preliminary analysis based on 4 from all 15 video recordings of the fireball of October 9, 1992 which resulted in the fall of a 12.4 kg ordinary chondrite (H6 monomict breccia) in Peekskill, New York, will be given. Preliminary computations revealed that the Peekskill fireball was an Earth-grazing event, the third such case with precise data available. The body with an initial mass of the order of 104 kg was in a pre-collision orbit with a = 1.5 AU, an aphelion of slightly over 2 AU and an inclination of 5. The no-atmosphere geocentric trajectory would have lead to a perigee of 22 km above the Earth's surface, but the body never reached this point due to tremendous fragmentation and other forms of ablation. The dark flight of the recovered meteorite started from a height of 30 km, when the velocity dropped below 3 km/s, and the body continued 50 km more without ablation, until it hit a parked car in Peekskill, New York with a velocity of about 80 m/s. Our observations are the first video records of a bright fireball and the first motion pictures of a fireball with an associated meteorite fall. 相似文献
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