The SLS is the same heavy lift launcher concept used in the Constellation program which was cancelled because: "The U.S. human spaceflight program appears to be on an unsustainable trajectory. It is perpetuating the perilous practice of pursuing goals that do not match allocated resources.” Such is the case today.

NASA’s Space Launch System and Multi-Purpose Crew Vehicle Program (SLS/MPCV) will fail because…mission costs are too high, the MPCV crew module has an unsolvable water recovery issue, and there is no commercial application.
The following SLS/MPCV “operation” cost estimates were presented to the Congressional Budget Office after it failed to make the Congress aware of the prohibitive cost to operate expendable heavy lift vehicles.
·         The NASA human exploration budget will be flat lined at $2.8b for the foreseeable future. One report indicates a development cost of $38b and another reports that the first development version launch of the SLS could not take place until December 2017 and the 130mt production versions (crew and cargo) are not expected to unveiled until August 2032. This SLS development program scenario based on 13 flights over a 21 year period would have extreme difficulty maintaining the manufacturing labor force for such a low flight rate. However, it is the introduction of the cargo vehicle which forecast that it will require two launches of these mammoth vehicles to accomplish one mission. The SLS is the same heavy lift launcher concept used in the Constellation program which was cancelled because: "The U.S. human spaceflight program appears to be on an unsustainable trajectory. It is perpetuating the perilous practice of pursuing goals that do not match allocated resources.” Such is the case today.
·        NASA has failed to reduce the mission operation cost of the SLS/MPCV. The following $4.2b estimate of annual operations cost for the SLS indicated it will cost more to manufacture the expendable vehicles, plan the mission, and conduct flight operation than NASA has budgeted for human exploration. NASA is assuming that future budgets will be increased to cover mission operations. THIS WILL NOT HAPPEN!