<p><strong>U.S. astronaut <a href="http://www.jsc.nasa.gov/Bios/htmlbios/magnus.html">Sandra Magnus</a> participates in a fit check of her Russian Sokol spacesuit in Moscow on March 29. Magnus was a mission specialist for <a href="http://www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/">STS-135</a>, the final flight of the <a href="http://science.nationalgeographic.com/science/space/space-exploration/space-shuttle-program.html">space shuttle</a> <em>Atlantis</em>. The shuttle's successful landing today at 5:57 a.m. ET wrapped up the very <a href="http://news.nationalgeographic.com/news/2011/07/110707-space-shuttle-launch-final-mission/">last mission of the U.S. space shuttle program</a>.</strong></p><p>During the 13-day mission, Magnus and her three crewmates delivered supplies and spare parts to the International Space Station, ran an experiment for robotically refueling spacecraft, and retrieved a failed ammonia pump module. Each of the shuttle astronauts had to be fitted for a Russian spacesuit in case they needed to evacuate the station via a Soyuz capsule.</p><p>"Every vehicle has its life," Magnus said in a Reuters interview shortly after landing. "We've known the shuttle is going to retire for a very long time."</p><p>Still, she added, "it's hard to say goodbye. It's like saying goodbye to an old friend."</p><p>(Also see <a href="http://news.nationalgeographic.com/news/2011/07/pictures/110720-best-unforgettable-space-shuttle-pictures/">"The Most Unforgettable Space Shuttle Pictures."</a>)</p>