 Van den Berg was assigned as Payload Specialist on STS @-@ 51B Challenger ( April 29 – May 6 , 1985 ) . STS @-@ 51B , the Spacelab @-@ 3 mission , was launched from the Kennedy Space Center , Florida , and returned to land at Edwards Air Force Base , California . It was the first operational Spacelab mission . The seven @-@ man crew aboard Challenger conducted investigations into crystal growth , drop dynamics leading to <unk> material processing , atmospheric trace gas spectroscopy , solar and planetary atmospheric simulation , cosmic rays , and laboratory @-@ animal and human medical monitoring . 
