When NASA Administrator Mike Griffin meets with other space agency heads during the Paris Air Show this week, he will find colleagues who face many of the same challenges he does, but who also are looking to him for leadership. And while each of the partners needs NASA’s help in some key areas — particularly with regard to the international space station — it should not be forgotten that NASA needs its partners as much as they need the United States.

NASA has downplayed this meeting as merely a chance for Mr. Griffin to meet and greet the other agency heads for the first time in his new role as head of the U.S. civil space program. It is nonetheless an important opportunity for Mr. Griffin to send a message that NASA is serious about living up to U.S. President George W. Bush’s January 2004 pledge that the United States will meet its obligations to its partners in the space station program.

All of the partners have expressed understanding about the delays caused by the destruction of the shuttle Columbia and to some extent the scaling back of the program by Mr. Griffin’s predecessor. Certainly, each nation involved in the program has suffered its own delays and many have scaled back their own ambitions.

But there is great concern in Europe and Japan about when and how NASA will be able to launch hardware like the European Space Agency’s Columbus module, the Japanese Experiment Module and the centrifuge that Japan took on at the request of the United States. There is equal concern about how much they will be able to get from that hardware once it is launched.

Of course, no one will know the answers to those questions until NASA has successfully launched the shuttle a couple of times without major problems cropping up.

But in the meantime, the partners are nervous and want assurances that they will be able to get personnel and experiments to and from the station regularly well into the next decade and take full advantage of a facility that has soaked up an enormous amount of taxpayers’ money with very little to show for it so far.

Since taking the top NASA job, Mr. Griffin has said publicly several times that the United States will live up to its commitments, but he still needs to define for the partners what that means. Easing their concerns about the station would also be a first step toward a larger challenge: convincing them that the United States can be a reliable partner for the future.

It won’t be easy.

With the station program now in its third decade, the United States has earned a reputation for arbitrary, unilateral decision making. While the other partners have always looked to NASA for leadership, they also sometimes have bristled at being informed about decisions rather than consulted. As a result, no other nation has made serious overtures about working with NASA on exploration beyond Earth orbit. Many European officials have made it clear in public statements that they want much more say in any future joint work with the United States than they have ever had in the international space station program.

There also is growing concern that U.S. export control laws, particularly the International Traffic in Arms Regulations (ITAR), make it too difficult to work with the United States or U.S. companies. Some European companies have started to look for alternatives to their U.S. suppliers, but only as a last resort.

The solution to the export control problem, of course, does not rest on Mr. Griffin’s shoulders — that one will be for Congress and the White House to sort out. But it will nonetheless cast a substantial shadow in many of the meetings he will have in Paris.

Realizing President Bush’s vision for future space exploration will require the efforts and resources of many nations. While it is possible that NASA by itself will get astronauts back to the Moon by the end of the next decade without a major budget increase, there is little in the agency’s recent history to suggest that is likely to happen. And going to Mars alone is an even bigger stretch.

China, Russia, Japan, Europe and even India are all catching up to U.S. technology. It is possible — and maybe even likely — that they could decide to go to the Moon or Mars without the United States. That would be a shame because the greatest chance for a truly extraordinary century of solar system exploration is a strong, unified international effort.

But that won’t happen until the United States learns to act like a true partner. Mr. Griffin can start off in that direction in Paris by soliciting help and consensus from his partners rather than announcing decisions as his predecessors have.