By Ed Stoddard

HOUSTON, Feb 16 (Reuters) - Astronauts worked to outfit Europe's new permanent space laboratory on Saturday as a busy visit by NASA's shuttle Atlantis to the International Space Station neared its end.

NASA is readying landing sites at both the Kennedy Space Center in Florida and Edwards Air Force Base in California to ensure a landing on Wednesday, as the U.S. military wants the shuttle landed by then so it can try to shoot down a disabled spy satellite with a missile.

In a news conference on Saturday with reporters on the ground in Europe and the United States, Atlantis commander Steve Frick said he had no worries about the U.S. military's high-tech shooting event.

"We don't have any concerns ... we're going to be safely on the ground before they take any action," Frisk said.

The Pentagon on Thursday said the Navy would try to shoot down the disabled satellite before it enters the atmosphere, using a modified tactical missile from a ship in the Pacific, to avert a potentially deadly leak of toxic gas from its fuel tank.

The Columbus module, the European Space Agency's $1.9 billion space lab, was launched aboard Atlantis last week and connected to the space station on Monday.

The external work on the lab during this mission was capped on Friday when spacewalking astronauts installed a solar observatory and an experimental facility on it.

Atlantis is scheduled to undock from the space station at 4:26 a.m. EST (0926 GMT) on Monday and is due to touch down on Wednesday at 9:06 a.m. (1406 GMT).

This mission, which has involved three space walks and been mostly trouble-free, has been heavily focused on Columbus, which gives Europe its first permanent presence in space.

The solar observatory installed on it contains instruments that will, among other things, measure aspects of the sun's energy and help scientists decipher the impact of solar activity on Earth's climate.

The other facility attached to Columbus' hull will be used to conduct a range of space-related experiments. These include exposing lichen and fungi to space conditions for about 1-1/2 years to test the limits of their survival.

The agency has nine construction missions remaining to complete the $100 billion outpost and two resupply flights planned before the shuttle fleet is retired in 2010.

NASA astronaut Dan Tani, who will be coming home aboard Atlantis after four months in orbit, at the news conference said he was looking forward to simple earthly delights.

"I'm looking forward to putting food on a plate and eating several things at once which you can't do up here," he said.

(Editing by Vicki Allen)

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