Nasa has given the green light for Discovery to attempt a landing on Monday, after an inspection showed no signs of damage to the space shuttle.
A heat shield scan has shown there is no damage to the space shuttle
Engineers reviewed images from an inspection of the orbiter's wings and nose cap conducted by Discovery's crew.
The shuttle has been docked with the International Space Station (ISS) for most of its 13-day mission.
Six astronauts are on board, after German astronaut Thomas Reiter was left behind for a six-month ISS stay.
The shuttle detached itself from the space station on Saturday, and had been kept just 74km (46 miles) from the platform so it could return if any serious damage came to light.
The shuttle is now expected to land at the Kennedy Space Center in Florida at 0914 EDT on Monday. The crew will fire the shuttle's engines at 0807 to begin the orbiter's descent.
The landing will bring to an end a mission that the US space agency (Nasa) hopes will help reduce safety concerns over the shuttle programme that have been heightened since the loss of the Columbia ship.
Discovery's mission is just the second to be carried out since Columbia broke up on re-entry into the Earth's atmosphere in February 2003, killing all seven crew on board.
DISCOVERY SHUTTLE FLIGHT
Mission known as STS-121
Discovery's 32nd flight
18th orbiter flight to ISS
Landing: 0914 EDT (1314 GMT), Monday 17 July
Location: Kennedy Space Center
Crew: Lindsey, Kelly, Fossum, Nowak, Wilson, Sellers
Accident investigators said that disaster had been caused by insulating foam falling from the vehicle's external fuel tank during launch and striking the orbiter's wing, compromising the heat shield needed to protect it during re-entry.
Discovery's heat shield scan was done with the same laser and camera system which was used to check for possible damage from flying debris during launch earlier in the flight.
It checked for micrometeoroid impacts that could have occurred during the stint in space.
The mission has included three spacewalks and repairs vital to resuming building work on the ISS.