Original sentence: However the cost estimates in Exploration Systems Architecture Study (ESAS) were based on the assumption that the EELVs would have to be launched from the Shuttle pad at Launch Complex 39, and that the Vehicle Assembly Building, Mobile Launcher Platforms, and LC-39 would have to be modified for the EELVs.The NASA study concluded that the cost and safety of the Ares was superior to that of either of the Evolved Expendable Launch Vehicle (EELVs)
Edited sentence: However the cost estimates in the study were based on the assumption that the EELVs would have to be launched from the Shuttle pad at Launch Complex 39, and that the Vehicle Assembly Building, Mobile Launcher Platforms, and LC-39 would have to be modified for the EELVs.The Exploration Systems Architecture Study concluded that the cost and safety of the Ares was superior to that of either of the Evolved Expendable Launch Vehicle (EELVs)