<p>CAPE CANAVERAL, Fla. (AP) With security tighter than usual, space shuttle Columbia streaked toward a Florida touchdown Saturday to end a successful 16-day scientific research mission that included the first Israeli astronaut.</p>
<p>The early morning fog burned off as the sun rose, and Mission Control gave the seven astronauts the go-ahead to come home on time. ''I guess you've been wondering, but you are 'go' for the deorbit burn,'' Mission Control radioed at practically the last minute.</p>