The GAO is concerned (as well it should be, even though Congress doesn’t give a damn):
Space Launch System: “Based on current budget estimates, program officials have expressed concern that the first launch in 2017 could be delayed.” GAO says that the program will reach Key Decision Point-C (KDP-C) this month (April 2014) and at that point NASA will establish cost, schedule and performance baselines for the initial (70- ton) version of the launch vehicle. GAO highlights funding risks associated with the flat budget profile under which NASA plans to spend $6.8 billion between FY2014 and 2018, and calls the schedule “aggressive.” It also worries that two years after the program was established, “many of the SLS program contracts remain undefinitized.”
Orion: “The mass of the spacecraft remains a top program risk.” GAO says the spacecraft being designed to take humans beyond low Earth orbit aboard the SLS could be as much as 2,800 pounds overweight at launch for the first exploration mission (EM-1) in 2017. The maximum lift-off mass for that mission is 73,500 pounds, GAO states.
Well, one solution to the overweight problem would be to launch without crew. There’s no need to, since they can go up commercially. That way you can remove the escape tower, which adds many thousands of pounds to the vehicle. Not that it should even be built at all, of course.