China’s space officials said Thursday they welcomed scientists from across the world to apply to study the lunar rock samples the Chang’e 6 probe brought back to Earth in a historic mission, but noted there were limits to that cooperation, specifically with the U.S. Officials said at a televised press conference in Beijing meant to introduce the mission’s achievements that any cooperation with the U.S. would be hinged on removing a U.S. law that bans direct bilateral cooperation with NASA, the space agency. “If the U.S. truly wants to hope to began regular aerospace cooperation, I think they should take the appropriate measures to remove the obstacle,” an official said.