T-38 Talon aircraft. Training was conducted in the waters of the Weightless Environment Training Facility and in the Boeing KC-135 Stratotanker known as the Vomit Comet that flies a trajectory that gives the sensation of being in space. She completed her astronaut training in August 1998. On September 28, 1998, she returned to Annapolis along with fellow astronaut alumni Jim Lovell, Charles O. Hobaugh, David Leestma, John M. Lounge, Bryan D. O'Connor and Pierre J. Thuot, for a celebration of the life of Mercury Seven astronaut Alan Shepard, who had died two months before. In early 2001, Nowak became pregnant with twins. At the Astronaut Office, Nowak specialized in the operation of the Space Shuttle's robotic arm. She also served with the CAPCOM Branch, the astronauts that worked with the mission control center as the primary communicators with the spacecraft. She performed this duty during the STS-100 mission in April 2001, when the crew of the installed a robot arm in the International Space Station (ISS). In October 2001, she gave birth to twin daughters. Nowak and her husband alternated their work schedules so one of them was always with the children. This arrangement lasted until Richard was recalled to active duty in 2002 to participate in Operation Enduring Freedom, which effectively left Nowak a single mother with three young children. On December 12, 2002, NASA announced the crew for STS-118, a mission scheduled for November 2003. Scott Kelly would be the mission commander, Hobaugh the pilot, and the mission specialists would be Nowak, Scott Parazynski, Dafydd Williams, and Barbara Morgan. The Space Shuttle Columbia disaster on February 1, 2003, killed seven astronauts on the STS-107 mission, including three from Nowak's 1996 astronaut class. It was NASA's practice to provide the families of astronauts who had died with a personal casualty assistance officer, and Nowak performed this duty for the family of her close friend Laurel Clark. Clark's widower, Jonathon Clark, a former NASA flight surgeon, recalled that: The disaster resulted in a series of schedule and hardware changes. The task of testing all the changes was assigned to STS-114, the Return to Flight mission, but the list of changes that required testing grew so large that a second Return to Flight mission was added to the schedule to accommodate them. Despite the numbering, this mission, STS-121, would be the second mission flown after the Columbia disaster. STS-121 was primarily