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
It is surprisingly difficult to find any reliable estimates on SLS launch costs.
The lowest -- and least believable -- is from Space.com 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!
Operations & Maintenance
SLS (1st stage, 2nd stage, upper stage)
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.
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 ...
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:
$ 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.