Although there has been talk of turning the International Space Station over to commercial parties upon the end of it’s projected service life in 2025, a recent audit of that strategy carried out and released by NASA’s Office of the Inspector General seems to indicate that such an extension of the ISS lifespan is unlikely. Instead, as funding dries up for the orbital asset from both American and Russian governments, the behemoth structure will need to be de-orbited in a safe manner. The problem is … nobody’s quite sure how to do that yet.

The space station’s operational lifespan has already been extended to reach 2025, though the White House recently began discussing the idea of turning the aging station over to commercial investors who might be interested in continuing the ISS’s run of maintaining a continuously manned presence in space for nearly two decades. At first, it seemed like a logical idea — private space enterprises are rapidly becoming all the rage in the United States and beyond, with more than one private company already planning their own space stations for the decades to come. The problem, however, isn’t finding interested parties — it’s finding ones that can afford to keep the aging station operational.

“Component degradation, manufacturers no longer in business, and changes in technologies over the past 20 years on a one-of-a-kind on-orbit spacecraft like the ISS also present the risk of hardware becoming technologically obsolete,” their report says.

Currently, NASA pays between $3 and $4 billion every year to maintain the operational capacity of the ISS, and the costs associated with keeping things running smoothly will only continue to grow as the systems on board get older. That means private investors that are looking to take over the ISS would also need to be capable of absorbing that massive expenditure — and few private space companies net enough revenue to even consider such an investment. SpaceX, perhaps the highest profile private space company on the scene today, nets an estimated annual revenue of only about $1.8 billion, with the vast majority of those funds going toward paying for operations and project development.

So if America and Russia can’t find someone to take over the payments on the ISS, they’re left with only one other option: destroy it in a way that doesn’t put other orbital assets, or us earth-bound humans, at risk. That means an intentional and gradual de-orbiting of the platform that would ensure it re-enters the atmosphere and breaks up somewhere over the uninhabited Pacific Ocean. At almost 240 feet long, more than 350 feet wide, almost 70 feet tall and weighing in at around 925,335 pounds; a fair portion of the giant structure will likely survive re-entry and reach the Earth’s surface like a fiery meteorite (between 53,500 and 173,250 pounds worth by NASA’s estimate). Although that might sound simple, actually accomplishing such a task would be incredible complex — and when it comes to massive endeavors like this, complex means expensive.

NASA’s plan to de-orbit the space station has been roughed out, with much of the heavy mathematical lifting left to estimates for now. They’ve submitted their plan to Russia’s NASA equivalent Roscosmos for review, but some details are already available to the public: in particular, the how long it might take and how much NASA expects it to cost in order to de-orbit the station safely. They think the way to do it is gradually — over the span of two full years — and to the tune of about $950 million.

Compounding concerns about cost and timeline is the possibility that the ISS becomes too damaged to survive that 2-year timetable. NASA estimated the odds of a meteoroid strike causing catastrophic decompression in the International Space Station at around 1 in 120 — meaning a plan has to be established that would expedite that re-entry model into only a matter of months. Of course, the faster it’s done, the more it will cost to do safely.

Featured image: Backdropped against clouds over Earth, the International Space Station is seen from Discovery as the two orbital spacecraft accomplish their relative separation on March 7 after an aggregate of 12 astronauts and cosmonauts worked together for over a week. During a post undocking fly-around, the crew members aboard the two spacecraft collected a series of photos of each other’s vehicle. | NASA