SLS vs Falcon

SLS vs Falcon - Which Rocket is a Better Choice for our Journey to Mars?

SLS vs Falcon - Which should we choose for Mars?

You have to wonder ...

With the successful landing of the SpaceX Falcon 9 first stage, the excitement and enthusiasm over the capabilities of commercial space companies is contagious.

And it makes you think -- Would this rocket be a better choice for NASA's Journey to Mars? Can commercial companies outperform , at least financially, the stated choice for getting humans to Mars -- the Space Launch System?

To understand that question, we need to understand the true costs of SLS vs Falcon.

Determining True Costs


SLS Reference Configuration

click for larger image

​It is surprisingly difficult to find any reliable estimates on SLS launch costs

​The lowest -- and least believable  -- is from Senior writer Mike Wall at $500 million per launch

This is an unofficial estimate.  And it's not clear whether it actually includes the $30 billion development cost of the SLS.

It clearly, though, does not include annual operation costs or payload costs.

How do I know? 

Well figure this ...

The combined development cost of the SLS and Orion is $30 billion -- or about $3 billion a year spread out over at least 10 years. If you consider the operational life cycle of the program will be 30 years, similar to the Space Shuttle, then, assuming just one launch per year, the pro-rated cost is $1 billion a year.

That's just for development - it does not include operating costs.

Let's add those in...

There are no figures showing what the operational costs will be, But let's take the Space Shuttle figures as and example of what large, complex launch systems have cost NASA in the past.

The shuttle launch operations varied from about $3 - $5 billion a year. Granted, the shuttle itself, being reusable, had some hefty maintenance costs, but even if you conservatively estimate those costs at $2 billion, then the annual operating costs would have been around $2 billion.

Assume the SLS operating costs would be similar.

That means, again at just one launch per year, the annualized development and maintenace cost of SLS - excluding any development costs for specialized cargo or Upper Stage components  -- would be at least $3 billion.

And we're still missing the actual production costs of the SLS laumch vehicle and the Orion capsule, estimates of which are around $1 billion each.

We're starting to talk about some real money now!​


Annualized Cost

Development Costs

$1 billion

Operations & Maintenance

$2 billion

SLS (1st stage, 2nd stage, upper stage)

$1 billion

Orion Capsule

$1 billion


$5 billion

​These costs are more in line with what John Strickland, a member of the board of directors of the National Space Society and an Advocate with the Space Frontier Foundation, estimated and are the most expensive estimates found.

One question you may ask, though, is the impact the revised 2016 NASA budget has on these estimates.

None - really.

The 2016 US Omnibus Bill allocated $2 billion to SLS development​. This was an increase from the $1.36 billion NASA requested.

While good news overall for NASA, the increase in budget allocations does not change the total program budgetary estimate​.

It simply means development​ can proceed more quickly than previously estimated.

Worst case, more money  will actually increase the overall program funding. The prorated, annualized development costs will go up -- not down.​

But let's get back to the comparison of SLS vs Falcon.

Let's be conservative and simply ignore the development and annual operating costs. Let's also ignore the development and production costs of the Orion capsule and any modifications to the upper stages and focus simply on the production costs of the SLS core stages.

The result - a minimum $1 billion per launch.​


Falcon Heavy capabilities

click for larger image

​What about SpaceX and the Falcon Heavy?

Development and operating costs are not publicly known but the production costs have been quoted by SpaceX at $135 million for the most expensive variant of the Falcon Heavy.

That's a little bit more than 7 times less than SLS, but there;s more to it than that ...

Performance Analysis

​Simply comparing launch costs does not let us accurately determine which system would, overall, be a better choice financially.

To do that, we need to also look at the performance characteristics of each rocket.

The most ambitious estimate for SLS is that it will be able to deliver 130 metric tonnes to LEO. That's 130,000 kilograms.

SpaceX estimates the Falcon Heavy currently will deliver 53,000 kilgrams, or 53 metrics tonnes, to the same orbit.

So SLS will deliver more in one launch, but let's take a look at the actual cost per kilogram:


Launch Cost

kg delivered

$ per kg to LEO









​Even ignoring the operational and development costs (which are inherently built into SpaceX per launch cost), the Falcon Heavy will deliver payloads to LEO 3 times more cheaply than SLS.

Which leaves us with two clear conclusions:

  • ​The SLS is a ridiculously expensive way to get into space, and
  • SLS is draining away funding that could be used to speed the development of private rockets and end payments to the Russians for crewed launches.

NASA, and NASA Administrator Charlie Bolden​ in particular, has stated their commitment to engaging private enterprise for space operations and launch services.  

But there's a caveat ...​

They stop at LEO.

In other words, NASA will lead the way into deep space, as stated in their Journey to Mars overview, using SLS as their primary launch vehicle, but contracting for private services beyond LEO is not currently on their radar As Bolden stated In an interview with NPR's Science Friday on December 16:

... eventually we want to bring them up with us to cislunar​ space and on to Mars ...

... implying that NASA will already be functioning in cislunar space and Mars with their current vehicle of choice -- the Space Launch System.

​What do you think? SLS vs Falcon. Which should we use? Leave your comments below.


  1. Adrienskis 25 August, 2017 at 12:03 Reply

    Something the author missed is that SLS block 1 crew, the one that is set to launch crewed in 2023, maybe, has a cargo capacity of 70 tons to LEO when expendable. Falcon Heavy’s EXPENDABLE capacity to LEO is 69 Tons. One costs over a billion per launch, the other will launch you for the billing price of 180 million per launch, that’s what NASA, and thus the taxpayer, would have to pay for SpaceXs launch services.

  2. G 15 April, 2016 at 21:08 Reply

    This comparison makes no sense. Falcon heavy isn’t in the same lift category as SLS, let alone type of lift category. While Falcon heavy can put 53 tonnes into LEO, it is not very good at GTO mass or mass to TLI and TMI.

    SLS is designed to send a large mass to TLI/TMI, something the Falcon Heavy is not designed for.

    • Jack 5 December, 2016 at 02:08 Reply

      Your right. The Falcon Heavy is more like a Delta 4 Heavy & trying to compare it to SLS is stupid. A proper comparison would be between SLS & the future SpaceX BFR booster which will use 42 raptor engines & unlike SLS it will be reusable & capable of returning to the launch pad. SpaceX is better than NASA in many ways but they don’t have anything that will actually rival the SLS yet.

  3. JohnnySpacer 16 February, 2016 at 21:04 Reply

    I believe SpaceX is working on a larger more powerful engine called the Raptor. I will place money on the table that SpaceX launches its BFR (Big Falcon Rocket) powered by Raptor engines before NASA rolls an SLS to the launch pad.

  4. Jesse 29 December, 2015 at 14:43 Reply

    Space X. NASA should research engines, space flight health and safety, orbital building and repair. Rescue and Military Defense of Space should also be one of NASA’s goals to help maintain stability of enterprise and mining in the Solar System.

  5. who am i 23 December, 2015 at 08:34 Reply

    just send falcon heavy 3 times for same amount of SLS carriage or put 2 extra stage 1 for “Falcon too heavy” to carry 80 tons 🙂

    • Bob the Rocket Guy 18 April, 2019 at 09:56 Reply

      Sure, because launching 3 times, docking in orbit, assembling a vehicle in LEO, and then going translunar is WAY easier.

  6. Peter Bilski 23 December, 2015 at 07:16 Reply

    Obviously we could reasonably suspect that NASA will be able one day match SpaceX reusable technology.
    If landing safely SLS alternate all calculations above ? Time will show…

  7. Robert Hutchison 22 December, 2015 at 15:17 Reply

    I often wonder why they do not use a rocket (probably with modifications, after all it was last launched in the 70s) of the Saturn V, the most successful one in history, everyone of them worked?

    • Joel Ammons 22 December, 2015 at 15:20 Reply

      But in our infinite wisdom, we decided to stop in favor of developing the Space Shuttle — and then promptly lost the blueprints for the Saturn V.

      • Terry B 26 December, 2015 at 15:19 Reply

        That’s exactly what I was going to point out. Maybe a search for the blue prints must be gathering dust somewhere?
        A combination between Space X, Virgin and the Russians with support from NASA would be good to see, though getting them to work together for a common goal, no matter how important would be unlikely.

    • Bracy Harvey 7 February, 2016 at 19:06 Reply

      SLS is essentially a Saturn V clone. It has a similar design, payload capacity, and probably a similar cost to operate. The only difference is that it uses some updated tech. It uses LH2/LOx and SSSRBs instead of RP1/LOx fit it’s first stage. Orion is just an updated Apollo, except that it has had some significant improvements unlike SLS.

    • Jack 5 December, 2016 at 02:19 Reply

      The Saturn V had 2 partial failures throughout the Apollo program but thanks to a great team on the ground & in space they found a way around those problems to continue the mission. Apollo 12 was struck by lightning twice (thats right, twice!) which almost caused electrical failures & Apollo 13 experenced a booster falure on the way up but the other 4 boosters were enough to continue the mission.

Leave a reply