So, as some of us may know, NASA axed the Ares I/IV/V program in 2010; the V in particular would have had taken too long to develop, and would not have been ready until the mid to late 2020s. The I had actually already flown, in the form of a single prototype, and a May 2010 launch of a V first stage with a I upper stage was planned (Something of a proto IV). The Ares V would have been able to carry a larger payload than any other missile (188 metric tons to LEO [Low Earth Orbit]) aside from the USSR's proposed Energia-Vulcan (200 metric tons to LEO) and NASA's Nova Mars-variant design proposals (of which one of the smallest would have lifted OVER 300 metric tons to LEO! All of these variants would have also been taller than the Saturn V and the Ares IV [which would have become the tallest had it been built]. Their costs were unfortunately equally impressive (in the bad way))*. It by far dwarves the lifting capacity of the most powerful missiles built to date including the Saturn V (120 metric tons to LEO), the Energia (100 metric tons to LEO, only flown in 2 test flights), and the N-1 (4/4 failures, 90-100 metric tons to LEO).
Ok, so it was too expensive and slow to develop. So what now?
Some people were advocating going with a Shuttle derived launch system, resulting in the Space Launch System (SLS).
The SLS comes in a number of upgradeable designs, meaning there wouldn't need to be the Ares I & V [the Ares IV was really an Ares I 2nd stage on an Ares V 1st stage), which would make its development cheaper. It also re-used existing shuttle technology, again, giving it a lower base R&D price-tag. Its lifting capacities are a bit more modest, clocking in at 70-80 metric tons for the 'light' version scheduled for 2017, and 130 to LEO for the 'heavy' version which is not expected to be ready before 2031. But wait(!) Something doesn't smell right about this.
Apparent issues:
1) The heavy lifting version would be done AFTER the Ares V would have been!
2) You still have to start development from scratch, and the Ares I already had a successful prototype flight! (note that BOTH the Ares I & V were axed, not just the V)
3) To add insult to injury, you have a significantly lower maximum lifting capacity.
The overall budget had better be less than the Ares missiles' remaining R&D budget or this should be axed now before any more tax dollars get wasted on it.
*There were other proposals, but those were ones that had the highest likelihood of actually getting constructed; they actually intended to build the Nova line because the Saturn V wasn't originally thought to be capable of actually getting something to land on the moon. There have been some sketchier designs with high LEO payload limits, like a nuclear N1 which barely made it over 300 tons to LEO, and a Nova variant which could put a whopping 455 tons to LEO, again, taking the cake for greatest payload to LEO).
*Incidentally, the most powerful civilian missile to fly will be the Falcon Heavy prototype in 2013, however, this is "only" 55 metric tons to LEO; though that will also make it the most powerful launch vehicle in service until the 70 ton version of the SLS flies in 2017, IF it manages to not get axed by then.
