ИСТИНА

As follows from contemporary cosmogonic models, an accumulation of the asteroid parent bodies was stopped by the gravitational influence of Jupiter’s growing embryo and smaller Jupiter zone bodies (JZBs) or planetesimals ejecting by the proto-planet and penetrating through the asteroid belt at high relative velocities (kms per sec) (e. g., Safronov V. S., 1979, Asteroids/ Ed. Gehrels T., Tucson: Univ. Arizona Press, 975-991). JZBs invading the asteroid belt could gravitationally perturb the movement of approaching asteroid bodies or collide and crash with some of them. A large number of proto-asteroids or their fragments were probably swept out of the asteroid belt for the reason. Concurrently, the JZBs, more porous and fragile than asteroids or even having an internal water ocean (Busarev et al., 2005, this issue), were probably shattered to small debris or a dust due to the collisions. A consequence of the process may be a slow settling of the dust on asteroid parent bodies in the form of a surface layer of atypical content (including hydrosilicates). Accordingly, we have propounded a hypothesis (Busarev, 2004, LPSC 35th, #1026) on a postaccretionary period of the asteroid dust evolution. A confirmation of this supposition may be the space proximity of largest asteroids (1 Ceres, 2 Pallas and 10 Hygiea) having spectral characteristics of mineralogicaly primitive bodies to 4 Vega being probably highly differentiated. Other may be reflectance spectra of hydrated E-, M-, S- and V-type asteroids. From the present-day taxonomic classifications, albedos and shapes of reflectance spectra of the asteroids correspond to bodies compounded by high-temperature silicates (pyroxenes, olivines, etc.) or even metals. However, absorption bands present in reflectance spectra of the minor planets at 0.4-0.5, 0.6-0.9 and 3.0 μm are characteristic for hydrated silicates (Busarev, V. V., 2002, Solar Sys. Res. 36, 35-42; Rivkin, A. S. et al., 2000, Icarus 145, 351-368; Hasegawa et al., 2004, LPSC 35th, #1458). Thus the spectral features may be considered as markers of important evolutionary processes in the Solar system.