  The reason for the horizontal turn of the Tunguska-1908 bolide trajectory
remains difficult to understand. It finds explanation, however, in the New
Explosive Cosmogony of minor bodies as having been caused by an explosion of a
part (M up to 10^12 g) of the comet nucleus whose ices contained products of
its electrolysis, 2H2+O2. In detonation, this part was repelled from the more
massive unexploded nucleus remnant, changed the direction of its own motion by
~10^o and imparted its kinetic energy, in expanding and slowing down, to the
air in producing an effect of a high-altitude explosion. Because there are no
traces of a fall of the more massive remnant, one comes to the conclusion that
on passing through the Earth's atmosphere it again entered a heliocentric orbit
(the hypothesis of V.Vernadskiy, 1932). A search for this comet,
P/Tunguska-1908, among the 6077 known NEAs shows the 2005NB56 object to be the
most appropriate candidate for a number of its parameters (a size is ~ 170 m, P
= 2.106 y, e = 0.473 and i = 6.8^o). Back integration of its orbit made without
allowing for non-gravitational effects suggests that it had passed the Earth on
June 27, 1908 at a distance of 0.06945 AU. It is quite possible that a proper
inclusion of even fairly weak non-gravitational forces would make its orbit fit
in parameters that of the Tunguska bolide.
