In an exclusive interview with NBC’s Lester Holt, which will air on NBC Nightly News on Tuesday, the crew — billionaire entrepreneur Jared Isaacman, retired Air Force Lt. Col. Scott “Kidd” Poteet and SpaceX engineers Sarah Gillis and Anna Menon — described the emotional side of their five-day journey.

The research in the Polaris program, planned to be three flights, is particularly focused on human health and the effects of spaceflight on the body. The current mission will be studied by Baylor College of Medicine, with the astronauts giving blood and going through extensive biomedical testing both before and after the flight.