Backgrounder: Crew members of U.S. space shuttle Discovery's STS-124 mission

CAPE CANAVERAL, the United States, May 31 (Xinhua) -- U.S. space shuttle Discovery will leave for the International Space Station (ISS) here at 5:02 p.m. EDT (2102 GMT) Saturday.

There are seven astronauts aboard the shuttle on this construction mission for the station.

Mark Kelly: mission commander. As a U.S. Navy Commander, Kelly has logged over 4,500 flight hours in more than 50 different aircraft.

Kelly is a veteran of two spaceflights. He served as the pilot of shuttle Endeavour's STS-108 in 2001 and shuttle Discovery's STS-121 in 2006, and has logged more than 25 days in space.

Kenneth Ham: pilot. As a U.S. Navy Commander, he has logged over 3,700 flight hours in more than 40 different aircraft.

Selected by NASA in 1998, Ham served as the ground communicator on several space shuttle missions. This will be his first spaceflight.

Karen Nyberg: mission specialist. She is a scientist in research of human thermoregulation and experimental metabolic testing and control, specifically related to the control of thermal neutrality in space suits.

Selected as a mission specialist by NASA in 2000, Dr. Nyberg was assigned technical duties and was chosen to join the crew of STS-124. This will be her first time into space.

Ronald Garan: mission specialist. As a U.S. Air Force Colonel, Garan has logged over 4,500 hours in more than 30 different aircraft. He was selected as a pilot by NASA in 2000. This will be his first spaceflight, and he will serve as a mission specialist for ascent and reentry and perform three spacewalks.

Miachael Fossum: mission specialist. An Air Force test pilot, Fossum has logged over 1,000 hours in 34 different aircraft. He was employed by NASA as a system engineer and was chosen for astronaut training in 1998. Fossum completed his first space flight on a shuttle mission in 2006, logging over 306 hours in space, including over 21 hours in three spacewalks. On this mission, he is assigned as the lead spacewalker.

Akihiko Hoshide: mission specialist from the Japan Aerospace Exploration Agency (JAXA). In February 1999, he was selected by JAXA as one of three Japanese astronaut candidates for the ISS.

He was trained at the Yuri Gagarin Cosmonaut Training Center in Russia, and then in the United States for shuttle training. His main task on this mission is to help set up Japan's Kibo science module.

Gregory Chamitoff: mission specialist. He is a scientist and was employed by NASA in 1995, developing software applications for spacecraft attitude control.

He was selected as an astronaut in 1998. This will be his first spaceflight. He will replace an ISS resident and stay up there for six months as a flight engineer.