The Associated Press

CAPE CANAVERAL, Fla. (AP) -Space shuttle Endeavour's astronauts have tested their flight control systems for Friday's planned landing. They've also ejected a small research satellite into space.

Commander Mark Polansky and his crew released a small canister Thursday morning containing a navigation and rendezvous experiment prepared by University of Texas and Texas A&M researchers. In the afternoon, the astronaut will pop out an atmospheric density experiment.

Today should be the last full day in orbit for Endeavour and its seven astronauts, who put on a space station addition.

Over at the international space station, meanwhile, the major air-purifying system on the U.S. side has failed again. The crew is trying to fix the balky equipment.