ISSN:
1572-9664
Keywords:
Al2O3 particles
;
aluminum particles
;
cosmic dust
;
high eccentricity orbits
;
micro-craters
Source:
Springer Online Journal Archives 1860-2000
Topics:
Energy, Environment Protection, Nuclear Power Engineering
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract A total of 87 microcraters 〉30 μm in diameter that were found in gold substrates exposed on the trailing edge of the non-spinning Long Duration Exposure Facility (LDEF) yielded analyzable projectile residues in their interiors. Using qualitative SEM-EDS analysis methods, some 60 of these craters were formed by natural cosmic-dust particles, while 27 residues (31%) were assigned to orbital debris (Hörz et al., 1993). The far majority of the orbital-debris impacts, 24 (89%) of the 27 events, contained only aluminum in their X-ray spectra. The present study evaluates these aluminum-rich residues in detail and employs a windowless X-ray detector, which permits for the analysis of low-Z elements and specifically of oxygen. This makes it possible to discriminate between oxidized (Al2O3) and metallic (Al) projectiles from dramatically different sources, the former produced during solid-fuel rocket firings, the latter resulting from explosively or collisionally disrupted spacecraft. Of the 24 craters analyzed with the windowless detector, 13 (54%) contained Al2O3 and 11 (46%) yielded structurally disintegrated Al metal. The oxidized residues preferentially occur in the smaller craters, all 〈60 μm in diameter. Corresponding particles on LDEF's trailing edge are 〈35 μm in diameter. Some 70% of this particle population is composed of Al2O3. Although solid-fuel rocket exhaust products are typically 〈5 μm in size, they tend to coagulate into crusts at the rocket nozzle to be shed occasionally as relatively large, aggregate particles. Structurally disintegrated, metallic fragments compose one-third of all particles 〈35 μm, but they dominate all particles 〉35 μm, and thus all craters 〉60 μm. These findings clearly establish that solid-rocket exhaust particles, as well as explosively or collisionally produced debris, exist in low-inclination, high-eccentricity orbits in sufficient quantities that they must be accounted for in models describing the present and future orbital-debris population at typical Shuttle and Space Station altitudes.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1015689229412
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