* Astronomy

Russian space engineers think they are closing in on the cause of two dangerous  off-course Soyuz landings in the past year, but recent activities suggest there is still a dispute about the leading theory. Top space officials have asserted that the problemthe failure of one or more explosive bolts during reentryis already solved. But in fact, in a space walk from the International Space Station (ISS), scheduled for 23 December, astronauts will install an instrument that is supposed to confirm that theory, for which there is as yet no physical evidence.

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