SpaceX Heavy Best Option to Replace SLS for EM-1 Mission in 2020

SpaceX also has the second mission for the Falcon Heavy scheduled for April, 2019. There should be a third Falcon Heavy mission a few months later. If NASA is serious about completing the Exploration Mission-1 in June 2020, then SpaceX could be the only option. The Space Launch System will not be ready for its first launch in 2020 and could easily slip to 2022 or 2023. The Delta IV Heavy would be better to launch the Orion capsule because it has the same upper stage as the Space Launch System (SLS). However, it would probably take two years for a United Launch Alliance Delta IV Heavy to be prepared for launch. It seems only SpaceX has the flexibility and responsiveness to make the adjustments for the two heavy launches that would be needed for Exploration Mission-1 in 2020. SpaceX would need to make quite a few modifications. They would need a larger faring and they would need to adapt the upper stage. It seems SpaceX can complete the greater amount of work on the NASA schedule while ULA would not be able to get a Delta IV Heavy together on short notice. If SpaceX shows they can launch the SLS mission with two Falcon Heavy launches and the Europa mission with an extra gravity assist then there would be no reason for the much more expensive SLS.
SOURCES- NASA Written By Brian Wang