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The SLS development budget is \$18 billion (currently \$10 billion are spent for SLS rocket), although another site shows even \$35B.

If I am not mistaken SLS is a new & improved version of Saturn V, so most of the research should exist.

The closest thing to SLS is Falcon Heavy. I know SLS is more powerful and can lift heavier payloads, but they are relatively similar. Since \$18B (or \$35B) is an amount that SpaceX can't afford, SpaceX must have spent less for Falcon Heavy.

So what makes SLS too expensive?

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    $\begingroup$ The only thing SLS and Saturn V have in common is scale. $\endgroup$ – Hobbes May 3 '16 at 17:27
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    $\begingroup$ While the core idea of your question is good, there's a lot of misconceptions. As Hobbes stated, it's not related to the Saturn V; they can both lift about the same amount to orbit, but that's all. Comparing it to the Falcon Heavy isn't terribly accurate; the Falcon Heavy's a good bit less powerful. $\endgroup$ – DylanSp May 3 '16 at 17:46
  • $\begingroup$ maybe SaturnV & SLS are totally different and that is the reason of high cost. But it does not explain why it is many time expensive than Falcon Heavy, which can be scale up I guess (by adding 2 more falcons) $\endgroup$ – dvdmn May 4 '16 at 2:46
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Pork. It is a jobs program not a technology program.

The SRB's are built by ATK, but the design ensured they needed to be reworked, so they could not just the existing Shuttle ones. Need an extra segment, which in SRB land means redoing the inner contour to control the burn rate to control thrust profile.

The switch between SSME to RS-68 to SSME (Yes, some of that was Ares-V, and some was SLS but basically same ideas) wasted a lot of time and money, but also meant that the SSME's could not simply be used. They needed a new digital controller upgrade. Which is probably good, but costs more in development costs.

The main barrel section is designed based on the ET from the Shuttle, but of course, needed new tools to build it since it is apparently just enough different.

The upper stage engine has been a total goat rodeo of indecision. J-2X, RL-10's, SSME, can someone please decide and stop switching. Each time money is spent, time is wasted, and little comes out of it.

In reality the true cost is in salary. So many people are employed in working on this, in by design inefficient fashion, so as to keep as many jobs as possible every time delay costs millions if not billions in salaries.

The reason other companies can launch for cheaper is that they employ fewer people. Raw material costs for launcher and fuel costs are a pittance. They are not manufactured out of solid gold. (By weight, simply building an SLS out of literal solid gold, might be cheaper than the current project. Anyone want to do the math?).

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    $\begingroup$ Your perspective is not without precedent, but it would be nice to see a cost breakdown to back it up. $\endgroup$ – called2voyage May 3 '16 at 16:46
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    $\begingroup$ $18 billion spent and no completed hardware? $\endgroup$ – geoffc May 3 '16 at 17:14
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    $\begingroup$ Some back-of-the-envelope math gives a dry mass for the core stage + upper stage of about 88,000 kg, though that doesn't include the SRBs; that's about $3.7 billion USD at current prices. $\endgroup$ – DylanSp May 3 '16 at 17:40
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    $\begingroup$ @DylanSp And you would need empty SRB weights anyway. So wow! Solid gold SLS would be cheaper, just in materials! $\endgroup$ – geoffc May 3 '16 at 17:48
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    $\begingroup$ The SLS SRBs also use a different propellant, PBAN, the Shuttle SRBs used ammonium perchlorate (with a small amount of PBAN as a binder). Basically the only thing in common is the casing. Another scam. Reference: nasa.gov/sites/default/files/atoms/files/… science.ksc.nasa.gov/shuttle/technology/sts-newsref/… $\endgroup$ – Organic Marble May 3 '16 at 23:09

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