Mark Vassallo is an Amphibian Researcher at the Detroit Zoo.
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Tracy Caldwell Dyson, Astronaut, compares the excitement of "launch" versus "landing".
Tracy Caldwell Dyson, Astronaut, her connection to American Sign Language and why she decided to be the first person to sign on the International Space Station.
Tracy Caldwell Dyson, Astronaut, describes preparing for and experiencing her first space walk.