Features of Experimental Studying of Comet Halley Dust Particles Elemental Composition

Abstract

Time-of-flight dust-impact mass-analysers PUMA-1,2 aboard VEGA spacecrafts were intended to investigate the properties of Halley comet dust component by means of direct measurements in the nucleus vicinity. More then 2000 mass-spectra were obtained by PUMA-1 and more then 500 ones were obtained by PUMA-2. Masses of studied particles are in the range 5 10-17 – 10-12 g. The spectra measured in time analyzer mode (zero mode) were the most convinient for data treatment; the number of these spectra was about 4–5% from the total number of PUMA spectra. The principal elements (H, C, N, O, Na, Mg, Al, Si, S, CI, Ca and Fe) and their most abundant isotopes were found. The isotopic composition of C, Mg, Si, S, CI and Fe is similar to mean cosmic isotopic abundance.The cometary dust particles contain a significant amount of light elements (H, C, N and 0). Their presence can be easily explained by the presence of organic compounds similar to observed in carbonaceous chondrites. The results of cometary dust composition measurements shows to a possible similarity of interstellar and cometary dust and can be explained by a model of cometary nuclei as aggregates of interstellar dust particles with no substancial chemical evolution.