WASHINGTON — NASA is setting its sights on an asteroid as the next big landing destination for astronaut explorers, but senior officials with two of the agency’s international space station (ISS) partners say the Moon should be the goal.

The most senior of these officials is Vladimir Popovkin, head of the Russian federal space agency, Roscosmos, who said lunar missions are his agency’s top priority for human exploration. Speaking May 22 at a roundtable of government space agency leaders at the Global Space Exploration Conference here, Popovkin said the space station partners should use the outpost to test technologies needed for a return to the Moon.

“We would like to see this phenomenal lab as a test bed that would allow us an opportunity to verify and test lots of technology that will be essential for us to be able to step up and reach deeper space,” Popovkin said through an interpreter.

Given that Roscosmos — like the rest of the world’s space agencies — faces financial and technical constraints that rule out near-term exploration of Mars or an asteroid, “we arrive at the conclusion that the Moon is supposed to be the next target,” Popovkin said. “And when we talk about the Moon, we are not talking about replicating what mankind has already achieved … we are talking about establishing permanent station bases on the surface.”

Without explicitly endorsing Popovkin’s call for permanent Moon bases, a senior official from the Japan Aerospace Exploration Agency (JAXA) agreed that space agencies across the globe should look to send human explorers to the Moon, and to use the space station to test the technology needed to get there.

The Moon “is the next destination for mankind,” said Yuichi Yamaura, associate executive director of JAXA. “We have a responsibility to continue the ISS program. That may be in preparation for human activity on the Moon.”

NASA Associate Administrator Robert Lightfoot said ISS offered “a great test bed for lunar technology,” but otherwise did not address calls to ramp up a lunar exploration campaign. He did not participate in a question and answer session held for press after the roundtable.

NASA is building the heavy-lift Space Launch System and a companion crew capsule known as the Orion Multi-Purpose Crew Vehicle for exploration of destinations beyond low Earth orbit. Development costs for these vehicles and supporting ground infrastructure will total about $3 billion in 2012.

The Moon is the initial destination for Orion, which is slated to loop around Earth’s nearest neighbor in 2017 without astronauts aboard and again in 2021 with a crew. But NASA has no plans to return to the lunar surface and instead hopes to send astronauts to a near-Earth asteroid.

Jean-Jacques Dordain, director-general of the European Space Agency, said the 19-member agency is working on an unmanned lunar lander that could be complete by 2018. Design work on the lander, backed by the German government, is under way at Astrium GmbH in Bremen, Germany. The craft is being designed to land at the Moon’s south pole, which is believed to have water-ice deposits that make it an attractive site for future astronaut landings.

In the near term, however, Dordain said his agency’s focus is the troubled ExoMars program, which would launch an orbiter toward Mars in 2016, to be followed by a lander in 2018. NASA last year withdrew from the program, leaving the European Space Agency short of the funds needed to carry out the campaign, even with Russia having agreed to launch the spacecraft.

Dordain cautioned that forging an international consensus on human exploration beyond Earth orbit will not be easy.

“Cooperation is difficult and is a slow process,” he said.

Dan Leone is a SpaceNews staff writer, covering NASA, NOAA and a growing number of entrepreneurial space companies. He earned a bachelor’s degree in public communications from the American University in Washington.