Rand Simberg of Transterrestrial Musings wrote an opinion article for the Washington Examiner which exposes fundamental flaws in the Congressionally mandated Space Launch System, the successor to the cancelled Constellation program.
The new vehicle will use left-over engines from the Shuttle orbiters that are now being retired. There's only one problem. Unlike the Shuttle, which reuses the engines each time, the new vehicle will be completely expendable. There are only enough engines for it for four flights, and there are no plans to reopen the production lines at Pratt & Whitney Rocketdyne to produce more, even if their cost wouldn't be prohibitive.
In other words, NASA plans to spend $10 billion to develop a vehicle that has no defined payload, and will only fly four times. Each flight of this vehicle will cost the taxpayers $2.5 billion dollars, while doing absolutely nothing to advance our progress in conquering space.
Why is NASA doing this? Because Congress insists that they "follow the law," and Congress wrote a law last year that NASA must spend a specified amount of money on a heavy-lift vehicle, using existing contracts and contractors. Why did Congress write that law? They will tell you that they wanted to ensure that the nation maintained forward direction and leadership in space, but if you look at the people who wrote the law (Sens. Bill Nelson (D) of Florida, Kay Bailey Hutchison (R) of Texas, Orrin Hatch (R) of Utah, Richard Shelby (R) of Alabama) you will be struck by the amazing coincidence that they all have major Shuttle contractors in their states. In fact, they are surprisingly up front about it.
Simberg's article refers to an Orlando Sentinel investigation by Mark K. Matthews. That article begins:
NASA's latest plan to replace the space shuttle would spend at least $10 billion during the next six years to test-fly a rocket made of recycled parts of the shuttle — with no guarantee the rocket would ever be used again, according to documents obtained by the Orlando Sentinel.
NASA is proposing a so-called "shuttle-derived test flight campaign" to provide the agency with a rocket it can use to test its nascent crew capsule — and keep shuttle workers and the aerospace industry busy — while the agency figures out what it really wants in a next-generation "heavy-lift" rocket that could go to the moon or beyond.
The article notes that SLS postpones the answer to a fundamental question: "What's the mission of NASA's human-spaceflight program?"
The answer would seem to be directing pork to the districts of those on congressional space subcommittees.