In the video above, NASA Deputy Associate Administrator Dan Dumbacher lays out the nominal launch schedule for the heavy-lift Space Launch System (SLS). There will be an unmanned test in 2017, followed by a test with a crew aboard four years later. SLS will then be launched every other year (2023, 2025, etc.). Dumbacher says that NASA is examining whether the system could be launched once a year.
In a separate interview with the Houston Chronicle, former NASA manned space flight director Chris Kraft says that SLS will never become a reliable human-rated booster even if the space agency can manage one launch per year.
Kraft also says that the costs of building and operating SLS, along with the low flight rate, will prevent NASA from actually doing anything in deep space.
“The problem with the SLS is that it’s so big that makes it very expensive. It’s very expensive to design, it’s very expensive to develop. When they actually begin to develop it, the budget is going to go haywire. They’re going to have all kinds of technical and development issues crop up, which will drive the development costs up. Then there are the operating costs of that beast, which will eat NASA alive if they get there. They’re not going to be able to fly it more than once a year, if that, because they don’t have the budget to do it. So what you’ve got is a beast of a rocket, that would give you all of this capability, which you can’t build because you don’t have the money to build it in the first place, and you can’t operate it if you had it.
Kraft suggests using existing, proven boosters such as the Atlas V, Delta IV and Ariane 5 to begin a deep-space exploration earlier.