(CNN) -- NASA engineers will repair small cracks found on the space shuttle Discovery's external fuel tank -- a development that could further delay its launch.
"The X-rays showed four additional small cracks on three stringers on the opposite side of the tank from Discovery, and managers elected to repair those cracks ..." NASA said in a statement. The work is expected to take two to three days.
Additional repairs may be needed, NASA said.
The cracks on support beams called "stringers" showed up during the latest round of image scans that NASA has been conducting to determine when the shuttle can take off, the space agency said Thursday.
The earliest possible launch date is February 3, according to the agency.
Earlier cracks found in the foam covering the fuel tank have repeatedly delayed the shuttle's final launch, originally scheduled for November 1.
Technicians repaired the cracks and reapplied foam insulation on aluminum brackets on the tank in November.
The foam cracked while the tank was being filled November 5 for the shuttle's planned launch to the International Space Station.
Discovery is scheduled to deliver a storage module, a science rig and spare parts to the orbiting facility.
The delay means the final launch of Endeavour, which is also scheduled to be the last launch of the space shuttle program, is likely to be delayed until April 1, said Bill Gerstenmaier, associate administrator for space operations.