A lack of suitable government or commercial rocket platforms in the United States has prompted a NASA advisory committee to recommend reducing America’s crew commitments to the International Space Station.

In July of 2011, NASA retired the last of its space shuttles and its only domestic means of putting astronauts into orbit. Since then, NASA has relied on Russia’s Soyuz missions to ferry Americans to and from the International Space Station with plans in the works for both NASA’s own Space Launch System (SLS) and for commercial space agencies like SpaceX to eventually take on the responsibility.

However, perpetual delays in the SLS program and foreseeable delays in the commercial sector are now prompting some to call for plans to reduce the American crew commitments to the space station to compensate for America’s lack of human-ready platforms. During a recent meeting Thomas Stafford, chairman of the ISS Advisory Committee, said,

For years, we have observed delays after delays in the development, flight test and qualification milestones in commercial crew, and therefore we believe the current schedule is optimistic,”

Current scheduling presupposes that commercial space ventures like Boeing and SpaceX will already be sending manned test missions into orbit later this year, in November and December respectively. However, Stafford and his committee agreed that this isn’t particularly likely. In fact, most within the industry expect crewed flights from either company to be delayed until well into 2019. In fact, NASA announced earlier this year that as a result of these anticipated delays, they may want to use the test flights of SpaceX’s Dragon capsule and Boeing’s CST-100 Starliner as ISS crew rotation missions.

According to Christina Chaplain, director of acquisition and sourcing management at the Government Accountability Office, it’s more likely that the two commercial space contenders won’t see certification for manned space travel until nearly a year after they’re currently projected. While test flights could potentially be used to rotate crews from the ISS, regular crew rotations using these platforms could not begin until they had been certified to do so. Chaplain said,

We found that the program’s own analysis indicates that certification is likely to slip into December 2019 for SpaceX and February 2020 for Boeing … According to NASA, both contractors assumed an efficiency factor in getting to the crewed flight test that the program office does not assume in its schedule.”

As a part of the recommended crew reduction, the ISS Advisory Committee also recommended training Russian cosmonauts on integral operations housed within the American portion of the space station, known as the U.S. Operating Segment (USOS). The USOS includes components sourced from the U.S., Europe, Japan and Canada, but are usually manned by Americans. If the United States were to reduce the crew on board the ISS, Russians would have to be ready and able to absorb the functional responsibilities of their lost American crew mates.