(08/20/1996) -- Atlantis, with its new external tank/solid rocket booster stack, rolls out to Pad 39A on August 20, 1996, in preparation for launch of STS-79 on the fourth Mir docking mission. Atlantis will return Astronaut Shannon Lucid to Earth after her record-breaking stay by an American on the Russian space station. Lucid has completed 21 weeks in space this week. Astronaut John Blaha will trade places with Lucid for a planned four-month stay aboard Mir. Atlantis will also carry the first SPACEHAB Double Module