As the crew of U.S. space shuttle Endeavor prepare for landing, NASA mission managers are closely monitoring a cold front that could affect Sunday's entry and landing at the Kennedy Space Center in Florida.

Forecasters are predicting the front could bring rain, possible thunderstorms and crosswinds that would violate the shuttle's flight rules into the Florida spaceport area, according to updates posted Saturday night at NASA's official website.

The two landing opportunities at Kennedy Space Center are at 1:19 pm and 2:54 pm EST on Sunday (1819 and 1954 GMT).

Should mission managers wave off landing in Florida, there are two chances at Edwards Air Force Base in California at 4:25 pm and 6:00 pm EST. The California forecast is favorable.

NASA's ground control center on Saturday declared the shuttle's heat shield healthy and safe for entry and landing. The report followed a review of imagery obtained by the Orbiter Boom Sensor System Friday after Endeavor undocked from the International Space Station.

In preparation for landing, Endeavor's crew tested the ship's flight control surfaces and reaction control system thrusters. Both systems functioned well and are ready to support entry activities.

The crew also deployed a small satellite designed to test space environment effects on new solar cell technologies. The Picosat satellite was deployed at 3:34 pm EST while the shuttle was over the southern Pacific Ocean. It will remain in orbit for several months.