WASHINGTON — The U.S. government must soon grapple with whether to keep operating the international space station (ISS), a $3 billion-a-year facility that will likely become less international the longer it flies, a pair of space policy experts said here Aug. 29.

“This is kind of like a smoker’s cough: Nobody wants to pay attention to it,” John Logsdon, founder of the Space Policy Institute at the George Washington University’s Elliott School of International Affairs, said on an Aug. 29 conference call with the media. 

“There’s clearly not enough money in the long-term outlook to do both a robust exploration program and continue to utilize and operate the space station at the $3 billion-a-year level,” Logsdon said. On top of that, he said, “Europe and Japan are not enthusiastic about spending money on the space station post-2020. Their governments had to be dragged to commit funds for the extension to 2020.”

Congress has authorized funding for ISS through 2020, but NASA wants to keep the station flying until 2028 or later. Earlier in August, Sam Scimemi, ISS director at NASA headquarters here, said program managers would like the White House, NASA and Congress to reach an accord about a post-2020 extension soon, as supporting investments for such a mission would have to begin as soon as 2015. 

Meanwhile, Congress has directed NASA to build a heavy-lift Space Launch System and Orion Multi-Purpose Crew Vehicle to send astronauts on missions beyond Earth orbit. Like ISS, NASA is spending roughly $3 billion on those programs — still insufficient to develop hardware such as landing and ascent vehicles needed for planetary surface expeditions. 

On the Aug. 29 conference call with Logsdon, Scott Pace, the current head of the Space Policy Institute and a former senior NASA manager, predicted that serious scrutiny of the ISS program would not begin until 2018. 

“I think … you will see [then] the beginnings of a senior review to make a decision about what will be in the 2020 NASA budget,” Pace said. “That review will be dependent on data that is being created now — or should be created now — on what is the scientific benefits, what are the technical benefits” of the space station. 

Now that construction on the orbital outpost is complete, NASA has stepped up plans for station-based research. The agency has also chartered the nonprofit Center for the Advancement of Science in Space to promote and manage non-NASA science aboard the space station.  Nevertheless, opportunities for science are limited, as crews must spend the bulk of their time keeping themselves alive, and the station spaceworthy. 

While ISS has undoubtedly been a diplomatic and technological success, “it’s not clear that it’s going to be a scientific success,” Pace said.

An administration official privately acknowledged that a post-2020 ISS mission hinges entirely on whether it can demonstrate, during the rest of this decade, some sort of return on the substantial taxpayer investment required to build it. 

As of 2012, at what could be called the beginning of the station’s time as a dedicated science research facility, the United States has spent upward of $100 billion on ISS since the early 1990s, including the cost of the 36 space shuttle flights necessary to assemble and support the hulking structure in low Earth orbit.

Upkeep costs about $3 billion a year, the bulk of which has gone to ISS prime contractor Boeing. And there is still more upkeep, maintenance and heavy lifting to be done going forward, according to Brad Cothran, Boeing’s ISS vehicle director. At NASA’s behest, Boeing has been studying which ISS subsystems will have to be serviced or replaced in order to keep the station flying through 2020. A formal report to NASA is expected in September, Cothran said, but a few things are already known. 

For example, sometime around the spring of 2015, the Italian-built Leonardo Permanent Multipurpose Module may have to be moved from its Earth-facing perch on the station’s Unity module to a forward-facing position on the Tranquility module. 

The are two reasons for relocating the Leonardo module, Cothran said. First, Russia is considering adding a second Multipurpose Laboratory Module and up to two 8-kilowatt Solar Power Modules to the station. Second, NASA has contracted with two commercial operators to take over the retired space shuttle’s cargo delivery duties, and by late 2017 or so, the agency plans to add a third vehicle for crew transport. That means the station needs more berthing and docking ports — four, to be precise, Cothran said. 

“Now you have a lot more different types of smaller vehicles that are coming up more often than one big bus, if you will, with the shuttle,” Cothran said. “So we had to make room for more docking ports, and to do that, we needed to move some more modules around.”

Whether the ISS can be pushed beyond 2020 is going to require another deep-dive study by Boeing — something Cothran does not expect will happen until at least the Oct. 1 start of the government’s 2014 budget year. 

In the meantime, while looking at what it takes to fly until the end of this decade, “we haven’t uncovered anything that says we can’t get to 2028,” Cothran said.

Dan Leone is the NASA reporter for SpaceNews, where he also covers other civilian-run U.S. government space programs and a growing number of entrepreneurial space companies. He joined SpaceNews in 2011.Dan earned a bachelor's degree in public communications...