MOSCOW, April 12 (RIA Novosti) - President Dmitry Medvedev has congratulated space and missile industry workers on their professional holiday - Cosmonautics Day, the presidential press service said on Sunday. "The conquest of outer space became one of the brightest and most unforgivable pages of the 20th century history. The flight by Yuri Gagarin on April 12, 1961 opened a new epoch in the civilization's development," Medvedev's message read. "The first step in outer space was made thanks to the talent of our outstanding designers and the courage of cosmonauts. And we are rightfully proud of the fact that this...