NASA will run a series of fuel tank tests on the shuttle Discovery Friday to see if repairs have successfully fixed a series of cracks that have thwarted the mission's final run to space.
The tests are to take place at 7 am (1200 GMT) on the launch pad at NASA's Kennedy Space Center in Florida, the US space agency said in a statement.
NASA hopes the results will "help engineers determine what caused the cracks during Discovery's launch countdown on November 5," but warned that the findings would not be immediately released.
"Managers and engineers will review the data gathered from the test before determining the next course of action," NASA said.
The shuttle Discovery's final mission to the International Space Station has been delayed until February 3 at the earliest.
The aging shuttle's latest attempt to launch was scratched on November 5 when technicians found a hydrogen leak and later a series of long cracks on the shuttle's external fuel tank.
Experts are puzzled by the cracks, which were found on a pair of 21-foot-long (6.5 meter) U-shaped aluminum brackets called "stringers."
The February launch window stays open until the 10th, and if no launch can occur in that time frame, the next window opens February 27 through March 3.
The shuttle Endeavour is set to take off in April in what will be the last official shuttle launch scheduled for the US program.
A third shuttle launch could take place in the summer before the entire fleet is retired for good.
Explore further: Start of dwarf planet mission delayed after small mix-up