An international symposium on gravitation physiology took start in Moscow today. Anatoli Grigoryev, Full Member of the Russian Academy of Sciences, Institute of Medical and Biological Problems Director, made an opening address to an impressive scholarly gathering. He took stock of problems science encounters in preparing a manned flight to Mars. Hard radiation and bad gravitation changes are the most formidable stumbling blocks. Be that as it may, we have no reason to bury the idea, Academician Grigoryev said in a communication headed, “Physiological Problems of Manned Martian Flight”.