The International Space Station (ISS) is not going to last forever. At some point, it will have to be de-orbited, or perhaps turned over to private companies to run. When that happens, though, is up for debate.

Yesterday, the House Science and Technology's Subcommittee on Space discussed the various options available to Congress. Some suggested continued support of the ISS would delay NASA’s other goals, like getting humans to Mars, while others said work on the ISS was vital for future spaceflight.

"Tax dollars spent on the ISS will not be spent on destinations beyond low Earth orbit, including the Moon and Mars," Texas Republican and subcommittee chair Brian Babin said, reported Space.com. "What opportunities will we miss if we maintain the status quo?"

At the moment, the ISS is used for a wide range of research, including studying Earth-bound diseases and assessing the impact of long-term spaceflight on the human body. Hundreds of experiments are run on the station every year, with many teams waiting for their chance to perform research up there.

However, about half ($3.5 billion) of NASA’s budget for human exploration is spent every year on running the ISS. So there is an argument to be made that, without it, more funds would be available for other missions.

That’s a tricky argument, though. The ISS is hugely valuable, and you can’t just up sticks and leave. When NASA does eventually stop running it, either de-orbiting the station or handing over to private companies, it will need to be a smooth transition. And there are of course the other countries involved to consider too, including Russia, Japan, Canada, and those in ESA.

"Applications [from commercial space companies] with strong market potential are emerging," said Mary Lynne Dittmar, executive director of the Coalition for Deep Space Exploration. "Abandoning the ISS too soon will most certainly guarantee failure."

NASA is already involved in a number of public-private partnerships on the station. Astronauts have been operating a 3D printer from company Made In Space on the ISS for the last few years, while an experimental inflatable private module – the Bigelow Expandable Aerospace Module – was installed last year.

The ISS is expected to remain under public ownership until at least 2024, and possibly as late as 2028 or 2030. But NASA has already tentatively looked at greater private involvement, potentially with a company taking over. One, Axiom, said earlier this year it was looking at using parts of the ISS to create a new private space station.

Two private companies, SpaceX and Boeing, are expected to start flying astronauts to the ISS from next year. What happens in the future, though, remains to be seen.