NASA officials say possible rains and low clouds may force the delay of Tuesday's scheduled launch of the space shuttle Discovery. In Miami, VOA's Brian Wagner reports the shuttle is set to deliver a new module to expand the International Space Station.

NASA officials said Monday there were no technical issues to resolve before the scheduled launch of Discovery on Tuesday from Kennedy Space Center. But officials say forecasts show bad weather is likely, and they reduced the chance of liftoff to 40 percent.

Shuttle weather officer Kathy Winters says stormy weather may move through the space center around the time of the late morning launch.

"This is the time period we are worried about, with a chance for isolated showers in the area, also some cumulus cloud development, and that scattered [cloud] deck at 30,000 feet could be varying between scattered and broken at that time," said Kathy Winters. "With that, we have a 60 percent chance of KSC [Kennedy Space Center] weather prohibiting launch."

If the weather does not permit launch on Tuesday, officials say they will try again on Wednesday or Thursday.

NASA test director Stephen Payne said thunderstorms had caused minor delays in preparations on Sunday, but he said crews had completed all necessary work on the shuttle.

"At this point in the count[down] we are on schedule, our systems are all good," said Stephen Payne. "We are in great shape. There are no issues we are tracking."

Payne said that engineers have made slight changes to the shuttle's launch schedule to prevent the formation of ice, which they say causes foam insulation to break off the fuel tank during launch. A piece of falling foam damaged Endeavour's thermal protection system during launch in August, and damage from foam debris is blamed for the break-up of the shuttle Columbia during re-entry in 2003.

The Discovery will be carrying a crew of seven astronauts who will deliver a new module to the International Space Station. The new module is one of several that international partners plan to add to the orbiter to double the interior capacity of the station to allow six astronauts to live and work.

The Discovery crew is scheduled to return to Earth on November 6.