NASA intends to use future U.S. commercial crew vehicles to carry not only its astronauts, but also those of its Russian partner, to the International Space Station (ISS), said Dan Hartman, deputy space station program manager, at a NASA Advisory Council (NAC) meeting on Monday (July 28).

Different international vehicles routinely transport crew and cargo to and from the ISS, a laboratory circling some 250 miles above Earth. Currently, the U.S. commercially provided Orbital Sciences Corporation’s Cygnus and SpaceX’s Dragon, Russia’s Progress, Japan’s H-II Transfer Vehicle (HTV) and Europe’s Automated Transfer Vehicle (ATV) provide cargo resupply to the space station. ATV-5, scheduled to lift off today from Europe’s Spaceport in Kourou, French Guiana, is the last of its kind.

Russia’s Soyuz, however, remains the world’s sole operational crew vehicle, on which NASA must continue to rely until U.S. commercial alternatives are ready.

“We’re going to stay mixed” though, Hartman said at a meeting of NAC’s Committee on Human Exploration and Operations at NASA’s Langley Research Center in Virginia. NASA’s plan is for some NASA astronauts to continue launching on the Soyuz from Kazakhstan and some Russian cosmonauts to be launched from the United States by private companies, he explained. The idea is to barter: “It would be just a seat for a seat.”

Soyuz spacecraft not only transport crews to and from ISS, but serve as “lifeboats,” always docked to the ISS as an emergency evacuation route if needed. The number of crew aboard the ISS is, in part, limited by how many Soyuz seats are available for evacuation. Each Soyuz can accommodate a three-person crew. If two Soyuz are attached, six people can be in residence. Soyuz spacecraft can remain attached to the ISS for as long as six months, setting up what is now the routine 4-6 month crew rotation schedule. SpaceX, at least, is designing its Dragon V2 so that it could serve as a lifeboat as well. Other commercial crew competitors may have similar plans.

Hartman’s point was that in an emergency, it might not make sense to have all the Russians leave on one spacecraft and the Americans and others on a separate spacecraft because a mixture of experience may be needed to conduct operations. “When you have these rescue vehicles on orbit and you have to leave the station…it doesn’t make much sense for three Russians to leave and expect the four Americans onboard to operate the Russian segment [of the ISS] and vice versa, right?” Hartman said.

NASA plans to award at least one contract under the Commercial Crew Transportation Capability (CCtCap) phase of the commercial crew program in August or September 2014. NASA officials are prohibited from providing any details of the bids that have been submitted, including which companies made the bids. NASA is funding three companies in the current phase of the program, CCiCap (Commercial Crew Integrated Capability) – Boeing, Sierra Nevada and SpaceX. Under CCtCap, at least one crewed flight test to the space station is required before certification is granted. NASA hopes that at least one U.S. commercial crew vehicle will be ready to transport astronauts to the ISS by late 2017.

President Obama has proposed extending ISS operations until at least 2024. The governments of NASA’s space station partners—Russia, Europe, Canada and Japan—have not formally accepted yet.

“I don’t think we need that answer from them for another year or so,” Hartman said. Other NASA officials have said they do not expect answers from the partners for several years and today’s strained U.S.-Russian geopolitical relationship complicates future planning on many fronts.

Presently, three Russians, one European and two Americans are living and working aboard the space station.