By DANICA KIRKA, Associated Press LONDON (AP) — Richard Branson's space-tourism venture, Virgin Galactic, is planning to go public, creating the first listed human spaceflight firm. Virgin Galactic said Tuesday it is merging with Social Capital Hedosophia, whose CEO, Chamath Palihapitiya, will become chairman of the combined entity. The value of the merger was put at $1.5 billion. "We are at the dawn