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Why is the US developing a new rocket and spacecraft as opposed to building the Saturn V and Apollo stacks again?

The SLS / Orion development programs certainly can't cost less than the unit cost of building more Saturn Vs and Apollo spacecraft which are already designed, tested, and proven.

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  • $\begingroup$ Saturn V/Apollo were single-purpose craft, Skylab and ASTP notwithstanding. A real Mars mission would have required a C-8/Nova configuration, at the very least. Neither was tested. $\endgroup$
    – Deer Hunter
    Dec 9, 2014 at 19:33
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    $\begingroup$ Taking apart an F-1 to see what makes it tick: arstechnica.com/science/2013/01/… Trial and error in design (baffles, and hand-drilled holes): arstechnica.com/science/2013/04/… $\endgroup$
    – user6893
    Dec 11, 2014 at 12:08
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    $\begingroup$ Related: Could the museum Saturn V's be refitted for one more flight? $\endgroup$
    – dotancohen
    Apr 3, 2019 at 14:46
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    $\begingroup$ @DeerHunter: Why not simply use more than one Saturn V? $\endgroup$
    – Vikki
    May 18, 2019 at 22:43
  • $\begingroup$ The SLS is not much more than a modernized Saturn. $\endgroup$
    – Fattie
    Jan 18, 2021 at 20:44

4 Answers 4

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Hobbes' answer focuses on why we might want to build SLS. There are also significant barriers to rebuilding Saturn/Apollo.

In addition to the (vast) amount of existing technical documentation on those designs, there's a (probably vaster) pool of knowledge that the individuals who actually built the things collected during the process. Nearly all of those people are dead or retired now.

Most of the individual manufacturers, subcontractors, and sub-subcontractors involved have merged or collapsed, and their internal process documents may have been lost; their documentation may have been very carefully stored in a warehouse somewhere, but the guy who knows where has retired as well!

Building Apollo and Saturn required particular manufacturing processes which are now obsolete. The tools needed to make the tools to make the rockets no longer exist.

To rebuild Saturn/Apollo, we'd first have to rebuild a substantial slice of the US aerospace industry as it existed circa 1965, and all that just to be able to carry out the same kind of missions we lost interest in 40 years ago.

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    $\begingroup$ Some things that might, or might not, be easily replicated today: explosive forming of fuel tank dome sections in a 60,000 gallon water tank (history.nasa.gov/SP-4206/ch7.htm); great big electromagnetic hammers (youtube.com/watch?v=5inJ7sDndBI). The book Stages To Saturn discusses about a hundred things like that, and probably ignores a thousand more. $\endgroup$
    – Russell Borogove
    Dec 9, 2014 at 20:31
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    $\begingroup$ There was a huge amount of manual labor involved, which would be unaffordable today. The rocket engines alone were welded from thousands of parts. See arstechnica.com/science/2013/04/… $\endgroup$
    – oefe
    Dec 9, 2014 at 20:53
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    $\begingroup$ 50 years later, probably quite a few people with key knowledge have died, not just retired. And the ones who are still alive have probably forgotten a few things. $\endgroup$
    – nobody
    Dec 9, 2014 at 23:44
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    $\begingroup$ @zxq9 I don't think MSalters is suggesting that one should literally use a mobile phone for the Instrument Unit. The point is just that, in computational terms, the functionality of the IU is simple enough that the whole computer could be simulated on any modern computer. $\endgroup$
    – David Richerby
    Dec 11, 2014 at 8:54
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    $\begingroup$ @Bobson Of course, the power usage of the electronics provided much-needed heating of the spacecraft as well (compare the environment on Apollo 13 after they shut down all the heat-dissipating electronics). If we take Wikipedia's figures at face value, the IU generated up to 6.7 kW of heat (had up to 16 cooling plates per stage, with each cooling plate capable of dissipating 420 watts). If you remove that, lots of other things are going to need to be or benefit from being redesigned based on the new thermal environment. $\endgroup$
    – user
    Oct 17, 2016 at 15:21
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There are several reasons:

  1. We can do better these days. Saturn and Apollo were designed in the early 1960s, so the design tools used were mainly pen and paper, with some primitive computer tools thrown in here and there. These days CAD can be used to create a design that performs far better (because you can design parts closer to the strength they need, for example). Similarly, you'd want to replace all electronics from Saturn/Apollo anyway with modern equipment.
  2. Politics. Unfortunately, the US Congress plays a large role in the design of SLS: choosing components based on where key manufacturers are located. ATK is an infamous example: they're located in the worst place possible for building large rocket components. The SRBs are transported on rail cars from Utah to Florida, and unavoidable tunnels through a mountain range in the route dictate the maximum length and diameter of the cargo. As a result, the SRBs have to be built in segments, adding a weak point to the design. Nevertheless, ATK solid boosters appear on every new design because of political factors.
  3. Performance. This applies more to the spacecraft than the launcher: Apollo was designed for short trips to the Moon, and would have to be redesigned to support longer trips. Orion also has about 3 times the interior volume of Apollo.
    Edit: there were some proposals to use Apollo for longer missions, see the comments. But those comments show that lots of systems would have to be changed to support long missions. These missions also needed a redesign of the S-IVB third stage, to allow its fuel tanks to be converted to habitable space in-flight.
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    $\begingroup$ Your first two points are spot on, but I disagree with 3. Saturn V could lift 120 tons to LEO, SLS Block I can only lift 70, even block II will only be able to lift 130. Saturn V could definitely be used to build a Mars-bound spacecraft. And I'll add one: 4. Many of the companies who built various part and pieces of the Saturn V no longer exist, so you need to find a new supplier or, if no new suppliers exist, redesign that assembly. $\endgroup$
    – Nickolai
    Dec 9, 2014 at 17:26
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    $\begingroup$ Note that the proposed Venus flyby doesn't have the mass budget for either a lander or enough fuel to enter and leave Venusian orbit -- it's an 8-month trip for a visit measured in hours, instead of a week-long trip for a day or two on the moon. It's hard to see any reason for a manned mission like that to Mars, let alone Venus. $\endgroup$
    – Russell Borogove
    Dec 9, 2014 at 18:35
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    $\begingroup$ My point is that a proposal to use a Saturn V for Venus flyby doesn't really speak to S-V's capabilities, any more than New Horizons demonstrates that Atlas V is a suitable launcher for a manned/orbital/landing Pluto mission. $\endgroup$
    – Russell Borogove
    Dec 9, 2014 at 20:20
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    $\begingroup$ They're in Minnesota, the northernmost part of the US, almost equally distant from both oceans. For equatorial-velocity reasons, we launch from as far south as possible, and for safety reasons, we do it on the Atlantic coast: Kennedy Space Center in Florida. The Pacific Northwest is further away from Kennedy, but at least a West-coast site would offer the possibility of shipping parts via the Panama canal. $\endgroup$
    – Russell Borogove
    Dec 9, 2014 at 23:23
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    $\begingroup$ @RussellBorogove ATK is headquartered in Minnesota but they have a large number of facilities spread across the US and Canada: the aerospace part of the business is in more than 20 states. I believe their solid rocket motors are actually made in Promontary, Utah: see ATK's website. But if they were made in Minnesota, they could be shipped via the Great Lakes and the St Lawrence Seaway. $\endgroup$
    – David Richerby
    Dec 10, 2014 at 1:26
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NOTE All dollar values are in present day values accounting for inflation.

Another reason we're not reusing the Saturn V is the same reason it was cancelled in the first place: cost. The SLS is supposed to be half the cost per launch. Whether that works out remains to be seen.

The Saturn V was expensive. The Saturn V program cost \$47 billion over 10 years for 13 launches which works out to something like \$3.6 billion per launch. But the \$3.6 billion figure includes development costs. Without dev costs, it's a mere \$1.2 billion per launch.

The assumption of many people is we can just dust off the plans and crank out Saturn V's without sinking any money into it. Other answers have covered that's impossible, substantial cost would have to go into creating new facilities, re-creating manufacturing techniques, and re-engineering, not to mention the greatly increased cost of modern labor and re-engineering to modern safety margins.

The SLS program claims they will be able to get the cost down to $500 million per launch. Many find this number to be fantasy. Maybe SpaceX could, but a large government contract is more likely to balloon. Nevertheless, this is the number they sold the government on and it is less than half what the Saturn V cost.

Here I am going into speculation, but taking a page from aviation another consideration is how much room for future improvement there is left in the design. The F-1 engine was late 50s technology. The Saturn V was straining the limits of technology in the 60s. After 13 launches NASA had enough experience with the rocket to make launches as efficient and safe as they were going to get. The SLS, as a new design, will have a lot of room for improvement and flexibility. It's not just about getting us to Mars, it's about providing the US with versatile heavy lift capacity for decades to come.

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    $\begingroup$ The Shuttle program also claimed it would get costs down to $657 per pound (2013 dollars) where the actual incremental cost was about $8000 per pound in 2011, and $27,000 per pound when amortizing the development and maintenance costs. The Shuttle was also originally supposed to fly once a week, but only flew 135 missions over the program's 30 year duration, averaging about once per 3 months. So yeah, there's a good reason many people consider the $500 million per launch number to be fantasy. $\endgroup$
    – FKEinternet
    Aug 8, 2017 at 7:14
  • $\begingroup$ @FKEinternet Note: the Shuttle was designed for a scenario that didn't happen. It was called a "shuttle" because it was supposed to shuttle to space station Freedom. That station never happened, it eventually became the smaller ISS. So the shuttle had nothing to shuttle to. The expected pace of launches that would have made the reusable design worthwhile didn't happen. We'll see if the SLS is given enough work, or can compete with the Falcon Heavy. (Vintage Space video on the shuttle) $\endgroup$
    – Schwern
    Aug 8, 2017 at 9:31
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    $\begingroup$ @Schwern, the lack of a space station wasn't the only Shuttle design scenario that didn't happen. It was designed to do on-orbit servicing of satellites (only used for Solar Max and Hubble), it was designed to retrieve satellites (four times), it was designed for single-orbit polar missions (never happened), and so on. $\endgroup$
    – Mark
    Apr 3, 2019 at 21:42
  • $\begingroup$ If you made and launched a Saturn V rocket for the same price NASA flew the space shuttle then there could have been a Saturn V rocket launching ever six months. $\endgroup$
    – The Rocket fan
    May 15, 2022 at 10:49
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A different approach might be to rebuild the Saturn V, with modern techniques, not as a one for one rebuild, but rather take the good parts, and make them better.

For example, the F-1 engine of the first stage, (5 used, 1.5 million lbs thrust) is being reconsidered as a more modern version with higher thrust. The nozzle was meticulously assembled in painstaking fashion. It consists of cooling tubes that fuel flows through to keep it from melting. Nowadays a 3-D Printed version while expensive in capital costs (3-D printer that big for something like Inconel boggles the mind at cost) but still might be cheaper than the labour it takes to build the old way.

The J-2 engine of the second stage (5 used, 232 Klbs thrust) and third stage (1 used) has been redeveloped as the J-2X for the Constellation program and then dropped.

The overall design of the various stages is still of interest. Even if the very specific minutaue of the control systems is not.

There is no need to reproduce the identical computer systems as they used back then. Modern computers are cheaper, and easier to program as SpaceX has shown with their development from scratch of the Falcon 9 computer control system.

The trick would be not to redevelop anything that does not need it, nor to hew exactly to the original design.

Now in theory that might work. In practice, if NASA is doing it, it is hard to imagine it happening in a cost effective fashion.

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    $\begingroup$ You could argue that that's what they're doing now. Only instead of basing the new rocket on Saturn V, they're basing it on the Shuttle, with engines that are a lot more recent than the F-1 so they'll be a lot easier to adapt. $\endgroup$
    – Hobbes
    Dec 10, 2014 at 17:33
  • $\begingroup$ @Hobbes Somewhat. But the form factor and all aerodynamics change and new SRB's (one extra segment different fuel, etc). So less commonality. If they really wanted to use Shuttle, Shuttle C would have been the cheaper way to go. No more Orbiter refurb costs which ate a big chunk of the recurring costs. $\endgroup$
    – geoffc
    Dec 10, 2014 at 19:31
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    $\begingroup$ If you used this approach, you'd soon run into the question, "which parts are good and which parts need to be improved". To answer this, you're going to need to analyze every part, and you'll need to delve deep into the design history. We still have drawings of the final parts, but did NASA record why a part was designed as it was? I.e. do we know what issues they ran into back then and the decision tree that led them to choose solution X instead of Y? If you're not careful, you end up redesigning everything anyway. $\endgroup$
    – Hobbes
    Dec 16, 2014 at 9:20
  • $\begingroup$ One absolutely would not reproduce the computer systems! The comparison between power, safety, capabilities ...... $\endgroup$
    – Selene Routley
    Dec 16, 2014 at 13:16

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