CAPE CANAVERAL, Fla. - Lacking the proper laser tools, shuttle Discovery's astronauts performed a cursory wing inspection Sunday as they zoomed ever closer to the International Space Station.

The astronauts used their ship's 15-metre robot arm to beam down camera images of the upper edges of the wings so engineers back on Earth could check for any evidence of launch damage. Left unexamined were the lower edges of the wings and the nose cap, also particularly vulnerable hot spots during re-entry.

Astronaut Karen Nyberg, who helped operate the robot arm, said it was "just a quick inspection, as much as we could with what we have.''

The astronauts' laser-tipped inspection boom is at the space station, left there by the previous shuttle crew in March. They'll retrieve it after they arrive at the orbiting outpost Monday and perform a full survey once they depart.

Discovery did not have enough room for the boom because of the enormous Japanese lab that fills its payload bay.

About five pieces of insulating foam broke off Discovery's external fuel tank during Saturday's liftoff, and some of them may have hit the shuttle. NASA officials said they were not too worried because the foam losses occurred after the crucial first two minutes of the flight and therefore lacked the acceleration to do much, if any, damage.

What's more, the foam fragments looked to be thin and flimsy.

A big wedge of foam carved a hole in Columbia's wing in 2003 at liftoff and led to the shuttle's demise during re-entry.

Nyberg said neither she nor her crewmates saw anything wrong as they were surveying Discovery's wings.

Discovery's fuel tank was the first one built from scratch with all of the post-Columbia safety changes.

The seven shuttle astronauts, with help from the space station's three residents, will install Japan's $1 billion lab Tuesday. It's named Kibo, Japanese for hope.

The first part of Kibo _ essentially a storage shed _ is already at the space station, delivered by the last group of shuttle visitors. The compartment will be attached to the lab during Discovery's mission.

Shuttle commander Mark Kelly and his crew also are delivering a new pump for the space station's malfunctioning toilet. The Russian-built toilet has gone through three pumps in the past 1� weeks, and space officials are hopeful that this brand new one _ from a different manufacturing batch _ will do the trick.