Dusts cosmic

The substances we can use come primarily from the earth. In its movement around the sun, the earth sweeps through space and collects material from meteors and some cosmic dust, but the amount of gathered material is small compared with the amount present in the earth. We shall consider the material of the earth and see how it is put to use by mankind. 

Stardust February 7, 1999, saw the start of NASA s Stardust mission the cometary probe, the first mission to collect cosmic dust and return the sample to Earth, has a time-of-flight mass spectrometer (CIDA, Cometary and Interstellar Dust Analyser) on board. This analyses the ions which are formed when cosmic dust particles hit the instrument s surface. In June 2004, the probe reached its goal, the comet 8 IPAVild 2, getting as close as 236 km The CIDA instrument, which was developed at the Max Planck Institute for Extraterrestrial Physics in Garching (near Munich), studied both cometary dust and interstellar star dust. 

The extinction curve of light which has passed through dust clouds tells us which particles are present in the cosmic dust ... 

The micrometeorites that melt during passage through Earth s atmosphere tend to solidify as spheres. These are termed cosmic spherules. The mineralogy of these spherules is given in Table 13.2. Their high iron and nickel content make them much denser (3 to 6g/cm ) than continental rock ( 2.7g/cm ). Like aeolian particles, cosmic dust deposited on the sea surface eventually settles to the seafloor via pelagic sedimentation. 

Cosmic dust Particles with an interstellar origin that range in size from a few molecules to 0.1 mm in diameter. 

Love, S. G. and Brownlee, D. E. (1993). A direct measurement of the terrestrial mass accretion rate of cosmic dust. Science, 262, 550-3. 

Martin, P. G., 1978. Cosmic Dust, Oxford University Press, London. 

Terrestrial and extra-terrestrial none igneous rock vein Earth s surface fumaroles cosmic dust ... 

Another more esoteric use for polystyrene PolyHIPE materials was suggested by Williams et al., and involves the intact capture of microparticles of cosmic dust [147],... 

Schmitz, B., Peucker-Ehrenbrink, B., Linstrom, M. and Tassinari, M. (1997) Accretion rates of meteorites and cosmic dust in the early Ordovician. Science, 278, 88-90. 

Figure 5.3 3He contents in sediments are plotted against 3He/4He ratios. The curve can be interpreted to be a mixing curve between helium in cosmic dusts (4He = 0.1 cm3STP/g,... 

If we assume that a fallout rate of cosmic dusts has been constant and 3He in sediments is entirely due to cosmic dusts, a 3He concentration in sediment can be expressed as a function of sedimentation rate (r) and of a cosmic dust fall-out flux (F),... 

Here, it would be worth emphasizing that the preceding estimate of 3He fall-out rate was made only from measurements of 3He content in sediment samples with known sedimentation rate, but did not require knowledge of a cosmic dust fall-out rate or 3He content in cosmic dusts. Moreover, the plot (Figure 5.4) enables us to make an objective appraisal for an averaging value of fall-out rate as well as for the underlying assumption on a constant fall-out rate. 

Esser and Turekian (1988) estimated an accretion rate of extraterrestrial particles in ocean bottom and in varved glacial lake deposit on the basis of osmium isotope systematics and concluded a maximum accretion rate of between 4.9 x 104 and 5.6 x 104 tons/a. The discrepancy between this estimate and those derived from helium can easily be attributed to the difference in the size of the cosmic dust particles under consideration. Cosmic dusts of greater than a few ten micrometers may not be important in the helium inventory of sediments because the larger grains are likely to lose helium due to atmospheric impact heating (e.g., Brownlee, 1985). Stuart et al. (1999) concluded from studies on Antarctic micrometeorites that 50- to 1 OO-qm micrometeorites may contribute about 5% of the total flux of extraterrestrial 3He to terrestrial sediments. Therefore, the helium-based estimate deals only with these smaller particles. 

Micrometorites are generally larger than cosmic dust particles, some up to a few hundred micrometers. Some of them show partially melted features but still contain measurable amount of noble gases. 

Anderson, D. L. (1993) Helium-3 from the mantle Primordial signal or cosmic dust Science, 261, 170-6. 

Brownlee, D. (1985) Cosmic dust Collection and research. Ann. Rev. Earth Planet. Sci., XIII, 147-73. 

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