On the heels of awarding groundbreaking contracts to U.S. commercial space companies to ferry American astronauts to the International Space Station, NASA has released a request for proposals (RFP) for the next round of contracts for private-sector companies to deliver experiments and supplies to the orbiting laboratory.
Under the Commercial Resupply Services 2 RFP, NASA intends to award contracts with one or more companies for six or more flights per contract._