As use of the International Space Station (ISS) increases, demand for cargo resupply, cargo recovery, and reboost services is expected to increase. The K-1 vehicle represents a viable solution for such missions.

For an ISS resupply mission, RPK would switch out the K-1's payload module for an ISS Cargo Module. The ISS Cargo Module can carry experiment racks, equipment, and supplies to the ISS. In addition, pre-packaged cargo modules (such as medical units or laboratories) can stand ready at RPK's launch site for quick response in case of emergency.

With the ISS Cargo Module, RPK can provide safe and efficient rendezvous and berthing with the ISS and meet the ISS Visiting Vehicle requirements.

The K-1 will be able to deliver up to 6,118 lbm (2,775 kg) of pressurized cargo to the ISS and return up to 6,118 lbm (2,775 kg) of recoverable downmass. The K-1 is also capable of providing up to 25 miles (40km) reboost and attitude control for the ISS, an important feature for maintaining the ISS orbit.

Use of the K-1 for select ISS missions would represent significant cost savings for NASA and its partners, who must balance diminishing budgets with increasing demands. At the same time, routine K-1 missions to the ISS would expand research opportunities and scientific utilization.