HOUSTON -- The day after the U.S. space agency unveiled a lunar exploration strategy calling for a Moon base, NASA Deputy Administrator Shana Dale stressed that Earth's nearest neighbor remains only a stepping stone to more distant destinations.

"The Moon in our vision is but part of a grander scheme that will eventually take humans to Mars and beyond," Dale said in a Dec. 5 speech opening the Second Space Exploration Conference here.

Dale said the global exploration strategy unveiled Dec. 4 at NASA's Johnson Space Center was still very much "a work in progress" but nonetheless distilled several main themes that will drive the agency's exploration plans going in forward, including looking at the Moon as "a foothold to further exploration" and using the Moon as "a unique laboratory" to enable science.

She also stressed that international collaboration would remain a big part of NASA's strategy, telling the audience that space exploration would provide a "challenging, shared and peaceful activity" that will "enhance [the] collective security" of the participating nations.

She said NASA received input from more than 1,000 individuals and 14 national space agencies in preparing its exploration strategy.

When the conference ends Dec. 6, Dale said, NASA will host a meeting here of an international coordination team that has already met three times to discuss shared exploration goals.