SLS will likely never service the ISS if it flies- it is designed for deep space missions and constructing the Deep Space Gateway station in cislunar orbit. Ori

SLS will likely never service the ISS if it flies- it is designed for deep space missions and constructing the Deep Space Gateway station in cislunar orbit. Orion also is not ready for use, and even if it was it has only been flown on the Delta IV which is not human-rated. One other option is the Boeing CST-100, however after its engine test failure this last summer it likely won't fly this year either. But like Dragon it is thought to be almost ready.