Her comments came as NASA pondered whether to send astronauts out on an extra spacewalk to repair additional heat-protection damage on the first shuttle mission since the 2003 Columbia disaster.

Discovery is linked with the International Space Station and orbiting 220 miles above the Earth.

"Sometimes you can see how there is erosion, and you can see how there is deforestation. It's very widespread in some parts of the world," Collins said in a conversation from space with Japanese officials in Tokyo, including Prime Minister Junichiro Koizumi.

"We would like to see, from the astronauts' point of view, people take good care of the Earth and replace the resources that have been used," said Collins, who was standing with Japanese astronaut Soichi Noguchi in front of a Japanese flag and holding a colorful fan.

Collins, flying her fourth shuttle mission, said the view from space made clear that Earth's atmosphere must be protected, too.

"The atmosphere almost looks like an eggshell on an egg, it's so very thin," she said. "We know that we don't have much air, we need to protect what we have."

While Collins and Noguchi chatted, NASA officials were deciding whether a torn insulation blanket protecting part of the shuttle surface could rip off and strike a damaging blow to Discovery when it re-enters the atmosphere.

They said it could require another spacewalk to fix, which would take place on Saturday if needed. A decision was expected on Thursday afternoon.

Noguchi and astronaut Steve Robinson already have done three spacewalks, including a landmark walk on Wednesday to remove loose cloth strips protruding from Discovery's belly. NASA feared the strips could cause dangerous heat damage when the shuttle lands on Monday.

COLUMBIA TRIBUTE

The combined crew of Discovery and the space station, nine in all, paid tribute on Thursday to the Columbia crew and other astronauts who have died in space accidents. They took turns speaking while television shots from the shuttle showed it passing over a sunlit Earth, then into night.

"Tragically, two years ago, we came to realize we had let our God down. We became lost in our hubris and learned once more the terrible price that must be paid for our failures," said mission specialist Charles Camarda. "In that accident, we not only lost seven colleagues, we lost seven friends."

Columbia broke apart before landing on Feb. 1, 2003, and the seven astronauts on board died.

Loose insulation foam from the fuel tank struck the wing heat shield at launch 16 days before, causing a hole that allowed superheated gases to penetrate and destroy the shuttle when it descended into the atmosphere.

NASA spent 2 1/2 years and $1 billion on safety upgrades after Columbia, but videos showed loose tank foam at Discovery's launch last week. The agency suspended shuttle flights until the foam problem is fixed.

A report in The New York Times suggested NASA was not as careful as it could have been about the foam issue.

The Times said an internal NASA memo, written in December by a retired NASA engineer brought back to monitor the quality of the foam operation, complained that deficiencies remained in the way foam was being applied to the fuel tank and warned "there will continue to be a threat of critical debris generation."

A spokesman at Johnson Space Center in Houston told Reuters he had not yet seen the Times report and could not comment