China and 15 other countries have joined NASA officials this week to consider how they might cooperate with U.S. plans for human exploration of the moon and Mars. The three-day Washington workshop was the first in a series of meetings sponsored by the U.S. space agency, NASA’s Michael O’Brien said on Thursday, the last day of the gathering. “It was somewhat precedent-setting for this particular meeting to have the Chinese there in attendance,” O’Brien said in a telephone news conference. China has its own space program and is not among the countries participating in the International Space Station.