Nov 242012
A chart from a NASA briefing from May of this year giving a quick look at three planned configurations of the Space Launch System which some/many in NASA hope to get built and flown in the coming years.
When transitioning from the Block 1 to Block 1A configurations, the plan is to replace the Shuttle-derived five segment solid rocket boosters with all-new advanced boosters, either liquid or solid. But history has shown that if what you’ve got *now* more or less works, replacing it with an expensive new rocket is a somewhat politically dubious prospect.