A defense of the SLS over at an Alabama news outlet. Let the fisking commence:

In the newest incarnation of the 2017 federal budget, the U.S. Senate is asking for $19.3 billion for NASA, with $2.15 billion going to the super-heavy lift rocket, the Space Launch System. It’s the spiritual successor to the Saturn V rocket, the world’s last super-heavy lifter that launched humans to the moon.

“Spiritual successor“: The very first sentence reveals the fundamentally religious nature of the rocket worship.

The SLS relies on old-school NASA program management, with private companies responsible for elements of the rocket. Different pieces of the rocket are contracted out to the private sector, while NASA administers and oversees the entire project. Boeing is working on the massive core stage, Orbital ATK is building the solid rocket boosters and Aerojet Rocketdyne is building the RS-25 core stage liquid-fueled engines. As with most government programs, it is expensive with a lot of overhead and bureaucracy, but it is a proven way to build a big program – it’s how the Saturn V and the Space Shuttle were made.

Note, he says that as though they are good things. Both were ultimately unaffordable, and SLS will be no different, for the same reasons.

Some think that NASA should forego building a launch vehicle altogether, and instead buy launches from these private launch providers. In some sense, NASA is already doing that with the commercial crew and cargo programs – Boeing, SpaceX, Orbital ATK and Sierra Nevada have all been given contracts to fly supplies and crew to the International Space Station. This framework works well for low-Earth orbit (LEO). Going to LEO is something the U.S. has done for more than half a century, and it’s a service the private sector can routinely do and turn a profit on it. But deep space exploration is a whole other beast.

Sending large habitats, deep-space propulsion, Mars landers and Mars ascent vehicles needs a big rocket. Some argue that NASA could make due with a distributed launch approach – meaning that NASA could use multiple smaller rockets to launch pieces of a Mars mission that would be assembled in space. But that adds a lot of complication and risk. Furthermore, that would make an already extremely difficult mission that much harder.

This trope has been debunked numerous times, by both an analysis from Safety and Mission Assurance at JSC a few years ago, and more recently in the NextGen Space LLC report from last summer. As I wrote in my current project:

Let’s go back to the truck analogy. Suppose we build the house in the factory, ready to live in, and then deliver it to its final destination on a giant truck. It’s a very expensive payload, because of all the value added in the factory where it was built.

Now the success of getting your house to your building site is totally dependent on the truck not crashing somewhere along the way. Would you really want to make that bet? Because trucks do crash with some regularity. And if it happens, you’ve lost a hundred-thousand-dollar (or more) house.

That’s why we build houses on site from much smaller, less expensive parts, and we add value by assembling them there. That way, if you lose a shipment, it’s not that big a deal. You just send out another load of cheap cement or plywood or studs or drywall, or whatever.

This is the way we do things on earth. There is nothing magical about space that means we should do it any differently there, except that the one time we successfully did, half a century ago, what some would like to do again—send a handful of humans beyond earth orbit—we did it the crazy way, because we were in a hurry and didn’t know how to do it any other way, and we didn’t care what it cost, and we got away with it half a dozen times.

So what is the non-crazy way to manage risk? This is discussed extensively in the NextGen Space LLC report, starting on page 48. Specifically with regard to launch systems, the author, David Cheuvront (now retired from JSC, but based on work he did there half a decade ago) says:

The fundamental strategy to address the risk of launch vehicle failures is that no single launch failure should ever be catastrophic to Program success. This strategy is enabled by commercial acquisition and operation costs being nearly an order of magnitude lower than traditional approaches and is flowed through the entire architecture. The ELA features a large number of relatively low cost launches for each mission, potentially on some relatively immature new launch vehicles. This has raised concerns about what happens if one or more of these launches (or subsequent on-orbit operations) fail. This has been the subject of much investigation, both as part of this study and in prior studies by the author. A very effective strategy to manage this risk is to provide for contingency launches.

Using what is called “M of N” reliability techniques, any desired level of reliability (sometimes referred to as the number of 9’s) for any given number of required launches (M) can be provided by planning for some greater number of launch vehicles (N), assuming any reasonable level of inherent reliability of the base vehicle being used. The difference between N and M is the number of contingencies provided. Selection of the number of contingency launches should be based on the expected Probability of Success per launch, the required overall success probability for the mission set, and consideration for tolerance to payload loss and schedule risk. These parameters should be traded to identify the most cost-effective solution. This strategy…is effective when the consequence of losses, up to at least the planned number of contingency flights, is acceptable. [Emphasis added]

In other words, by planning for contingency flights, one can arbitrarily increase the probability of mission success, as long as (as I previously noted) there is no “irreplaceable” payload. But more importantly, reducing number of flights to “reduce risk,” as SLS proponents recommend, reduces vehicle reliability by reducing flight rate.

He goes on:

The largest thing that NASA has landed on Mars was the Curiosity rover – about the size of a compact car. What humans need for a Mars mission needs to be even bigger, and the landing equipment needed to land those large payloads will also be sizable. Shrinking them for even the heaviest launcher from the private sector would complicate things as well as add risk.

There is no need to “shrink” anything. A lander will fit perfectly fine on an existing launch system, as long as it’s fueled in orbit, and in fact Mars orbit is the most appropriate place to fuel it. The fuel should be delivered via electric propulsion from earth, if it’s not fueled from in-situ sources like Phobos or Deimos, or the Martian surface.

Another related argument is that NASA could instead pay a private company to develop the rocket themselves, which would be cheaper. Some point to SpaceX’s theoretical “Big Falcon Rocket,” or BFR as a super-heavy lift alternative. However, the BFR is still only rumors, although some expect Musk to detail more concrete plans about the rocket later this year. Regardless, there is currently no market for a super-heavy lift rocket for the private sector (Musk’s motivation comes from his desire to colonize Mars).

There is no doubt that a SpaceX BFR would be much less money than SLS, because a large part of the motivation for the SLS is to spend money in the right zip codes, though I don’t agree with the need for it.

NASA intends to fly the SLS roughly once per year, too low a rate for companies to leverage economies of scale to turn a profit. If a private company were simply given the money to build a super-heavy lifter, they would have to create the infrastructure and hire the workforce to support it – things that for the most part, NASA already has. Their only foreseeable customer for the super-heavy lifter would be NASA, who would be funding the rocket and looking over company’s shoulder to make sure the rocket is up to NASA’s high safety and reliability standards, adding cost. At the end of the day, maybe the price tag would be a lower, but if NASA builds it, it belongs to the public and can fly as long as NASA needs it to, without the profit incentive.

At the end of the day, if the super-heavy lift rocket is going to be the foundation of a decades-long effort to put boots on Mars, NASA is taking the proven, if expensive, way.

Note the assumption that it’s not programmatically insane to fly “roughly once per year,” with the concomitant low reliability, and the decades before there is any actual demonstrated reliability, along with the admission that it is expensive. The problem, of course, is that he begs the question with that last “if.” We don’t need a “super-heavy lift rocket,” and to make it the basis for a decades-long effort to repeat Apollo, except on Mars, will doom that goal to failure.

While NASA takes every chance to talk about the agency’s “Journey to Mars,” and the SLS is the foundation of that ultimate goal, the rocket is not only suited for that mission. A super-heavy lift rocket is an enabler. With something of that size, NASA and its international partners can go back to the moon (which for now, NASA has no intentions of doing), launch massive habitats like Bigelow Aerospace’s Olympus space station and send multiple planetary probes into deep space with a single launch. The lack of a mission isn’t the problem, to paraphrase a famous line from “Field of Dreams,” “If you build it, they will come.”

Very few launch vehicles have been built with an explicit mission in mind. The Saturn V was one of them.

The Shuttle also had an explicit mission in mind — to build a space station. But it was also designed to do (too) many other things (many of which were incompatible). The problem is that nothing has been proposed for the SLS that either can’t be done in other ways (for instance, a Falcon Heavy plus Centaur could do the exact same Europa mission), or that is worth the amount of money that the flight would cost.

Finally he addresses the “old technology” argument.

At face value, this seems to be the most valid criticism of the rocket. All of the propulsion architecture comes from the Space Shuttle program. The Shuttle used three RS-25 hydrogen/oxygen fueled engines and two towering, four-segment solid rocket boosters to lift off the planet. The SLS will use four RS-25’s and two five-segment solid boosters. In a sense, the SLS could be thought of a beefed up Shuttle in a vertical rocket stack.

Where the SLS is concerned, I can see how people could be disappointed that there’s not a whole lot “new” about it. Shouldn’t NASA be pushing the limits of space technology development? But many of those same people will also say that the SLS is too expensive. Well, developing new hardware would skyrocket the cost.

Only if it’s done the traditional NASA way. And there is no need to develop new hardware. That is already happening — at SpaceX, ULA and Blue Origin.

As I write in my latest project:

If the anthropologist’s proverbial objective Martian were to come to earth, it would probably look at the situation, and scratch its head (if it had one) with one of its tentacles (if it had any), and say: “¢–≈ß∂≥≥˚ ≠¡¡…•æ∆¶Ω ®$≠≠†µø¿¶ »æ£∞∂∏¢¡µδ –ø绣≈¢¢¶ œπ•αßœ«¶¶‰ ∫γ–‘√çα”.¹

He concludes:

At the end of the day, NASA went with the safe option. As a civilian government agency, NASA is very cautious (the term they like to use is risk-averse). The space agency has a lot of experience with the things that flew the Shuttle. They know what they can demand from the hardware, how hard to push it, and what can be improved. There’s also 16 RS-25 engines left, multiple solid rocket pieces, so why not use what we have?

That’s what the SLS is – a new rocket built on proven technology. It’s not going the be the shiniest, sexiest rocket out there, but it will get the job done.

But it won’t “get the job done” at a price we can afford, and there are other, more affordable ways to “get the job done,” that would allow us to shift funds to what we actually need to get the job done now, instead of in the mid-twenties.

¹Translation from the original Martian: “You people have numerous ways of getting things into space, relatively affordable and reliable, with prices dropping and reliability increasing almost yearly. Why are you spending so much money on a rocket that you don’t need, whose costs are much higher, will fly rarely, and whose demonstrated reliability won’t even be known for decades or centuries at any affordable flight rate, while not developing anything you actually need to get to my home planet from yours? It’s almost as though you don’t really want to visit me.”