The NASA expert said the astronauts - crew commander Pavel Vinogradov and flight engineer Jeffrey Williams - would photograph the surface of the shuttle with two 800 and 400 mm digital cameras to see if its thermoprotection tiles had been damaged.
This will let experts on the Earth know about possible damage before the shuttle flies back and prevent any repetition of the February 2003 Columbia tragedy, the official said.
The NASA source said Vinogradov and Williams would have to assume immobile positions to make clear shots, and added that the astronauts had been trained to keep still in conditions of zero gravity because portholes on the ISS module had no handles.
The NASA official said Discovery would turn over before docking with the ISS and fly 200 meters (656 feet) under the ISS with showing the side of its undercarriage for the pictures to be taken.
Members of the eleventh ISS crew - Sergei Krikalyov and John Phillips - performed a similar mission in May 2005 when Discovery made its first test flight after the Columbia tragedy. The astronauts' photo allowed experts to identify damaged areas on the thermoprotection of the spacecraft and fix them in orbit.
