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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.

Jerard Puckett
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dotancohen
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4 Answers4

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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.

Russell Borogove
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    I've heard the argument before that some of the manufacturing processes no longer exist -- do you know any examples of a manufacturing process that existed in the 1960's that couldn't be easily replicated today? – Johnny Dec 09 '14 at 19:31
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    @Johnny Not exactly an example of a process, but I imagine that part of the problem would be materials. Different materials behave differently, particularly under stress, and one can't necessarily substitute one material for another, so replacements would have to be found/designed, integrated, tested, ... Consider even something relatively trivial like ground-based RoHS compliance. As pointed out, many manufacturing tools were specific to the vehicles involved, and it's certainly no stretch to imagine that custom processes were involved as well, much knowledge of which has likely been lost. – user Dec 09 '14 at 20:02
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    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 (http://history.nasa.gov/SP-4206/ch7.htm); great big electromagnetic hammers (https://www.youtube.com/watch?v=5inJ7sDndBI). The book Stages To Saturn discusses about a hundred things like that, and probably ignores a thousand more. – Russell Borogove Dec 09 '14 at 20:31
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    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 http://arstechnica.com/science/2013/04/how-nasa-brought-the-monstrous-f-1-moon-rocket-back-to-life/2/ – oefe Dec 09 '14 at 20:53
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    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. – nobody Dec 09 '14 at 23:44
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    @Johnny, a big change is in the electronics. A modern cell phone can do almost everything the 4400-pound Instrument Unit could do, but you can't just tack a cell phone in place of the IU. You can't build an IU, either, because many of the discrete-logic components haven't been made since the 1960s, and before you could make them, you'd need to re-build the tooling for 60s-vintage semiconductor manufacturing. – Mark Dec 10 '14 at 22:52
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    Electronics are probably the easiest bit. We have plenty of experience in emulating old hardware, especially when the logical behavior is documented down to bit level. A modern cell phone with appropriate software can emulate that IU while staying in sleep mode, really. It could probably run a circuit simulation of an IU in real time. – MSalters Dec 11 '14 at 00:36
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    @MSalters How many phones would you want working in checked aggregate before you felt comfortable trusting your life to the millions of lines of unchecked code in them -- lines which don't do anything to solve the problems of navigation or life support, but could crash the phone all the same? – zxq9 Dec 11 '14 at 04:10
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    @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. – David Richerby Dec 11 '14 at 08:54
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    Indeed. More practically, the radiation-hardened PowerPC CPUs nowadays are standard parts, software-wise, and would be equally capable of emulating that IU while running e.g. VxWorks. – MSalters Dec 11 '14 at 09:49
  • I don't know if there's anything the designers of the IU might have liked it to do that it doesn't, that would justify writing all new software for it, but I wouldn't be surprised. But I guarantee that a modernized Apollo would have far more complex and sophisticated guidance software. – Russell Borogove Dec 11 '14 at 15:11
  • Another factor would be the very large number of off-the-shelf parts that went into the boosters and the spacecraft. Valves and other fittings; all manner of simple electrical parts like relays, connectors, switches; avionics of all sorts.. granted some of that was made for Apollo, but some was ordered from catalogs, and some of that group aren't available any more. Just another reason that you can't just unroll the blueprints and start ordering parts and assembling. – Jamie Hanrahan Dec 11 '14 at 19:46
  • @MSalters - Using modern electronics instead of the original is a no-brainer... but then what design changes do you have to make to the structure of the rocket to account for the much smaller components? You've now got new, untested components that have to survive the stresses of a rocket, as well as lots of empty space that used to be computer power. So you have to redesign all that, too... – Bobson Dec 12 '14 at 02:00
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    @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. – user Oct 17 '16 at 15:21
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    @MichaelKjörling - Exactly! Cascading changes like that make it much easier to just redesign from scratch (or close to it). – Bobson Oct 19 '16 at 00:40
  • I do not disagree yet suggesting that documentation is lost is like saying "the guy who knows where the Library of Congress is located is already retired". That's what databases are good for: to record the location of each documentation. Hard to imagine the NASA documents are not stored in an orderly fashion. – Joe Jobs Aug 03 '20 at 09:28
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    @JoeJobs NASA’s documents are stored in databases available to the public. But NASA alone didn’t build the Saturn V. – Russell Borogove Aug 03 '20 at 15:31
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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.
Hobbes
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    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.

     – Nickolai Dec 09 '14 at 17:26
  • There were plans to use a Saturn V to launch a mission for a manned Venus fly-by. Doesn't sound all that different compared to a trip to Mars. – user Dec 09 '14 at 18:15
  • That link also shows some of the changes that would be needed for an Apollo capsule to work for a year. They'd have to redesign many of the systems for that Venus flyby. – Hobbes Dec 09 '14 at 18:26
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    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. – Russell Borogove Dec 09 '14 at 18:35
  • @RussellBorogove I agree, it's a different type of mission (flyby vs landing), but it does show that the Saturn V did have the capability to go for longer trips. Given time to prepare, and the will to do it, I don't see why for example a two-launch mission where the initial launch parks a vehicle in Venusian orbit for rendevouz and docking Agena-style with a soon to follow manned capsule couldn't be done. You'd need a bit more fuel for inserting into and leaving Venusian orbit, but might make up for that by the two vehicles together allowing much larger (part inaccessible to the crew) payload. – user Dec 09 '14 at 20:08
  • Such a first launch could be just days ahead of the manned portion of the mission, if desired (so no change in launch windows or extra worrying about electronics). With careful choosing of the relevant transfer orbits, you could even design many failure modes such that if docking is impractical the mission becomes a flyby rather than a Venusian orbital mission, in much the same way as it was done with the early moon-bound Apollo missions choosing Earth-Moon free return trajectories going into the lunar transfer orbit for contingency if something went wrong. – user Dec 09 '14 at 20:11
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    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. – Russell Borogove Dec 09 '14 at 20:20
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    Why is ATK located in the worst place possible for building large rocket components? – Ryan Dec 09 '14 at 20:42
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    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. – Russell Borogove Dec 09 '14 at 23:23
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    @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. – David Richerby Dec 10 '14 at 01:26
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    @DavidRicherby: Or perhaps down the Mississippi River to the Gulf of Mexico. – Fred Larson Dec 10 '14 at 02:49
  • @ryan: I've added more details to my answer. – Hobbes Dec 10 '14 at 07:55
  • Why not give ATK money to build an SRB factory next door to KSC? – Vikki May 18 '19 at 22:45
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    The desert of Utah is a great place to test SRBs. Thiokol (the parent of ATK, now Northrop-Grumman) originally bought the Utah area for testing. Their main factory was in Huntsville, Alabama, until that plant was closed down around 1996. – IronEagle May 19 '19 at 05:46
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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.

Schwern
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    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. – FKEinternet Aug 08 '17 at 07:14
  • @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) – Schwern Aug 08 '17 at 09:31
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    @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. – Mark Apr 03 '19 at 21:42
  • 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. – The Rocket fan May 15 '22 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.

geoffc
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    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. – Hobbes Dec 10 '14 at 17:33
  • @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. – geoffc Dec 10 '14 at 19:31
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    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. – Hobbes Dec 16 '14 at 09:20
  • One absolutely would not reproduce the computer systems! The comparison between power, safety, capabilities ...... – Selene Routley Dec 16 '14 at 13:16