Back to the Future

This week, NASA launched the Orion spacecraft on a test flight. I have a conflicted viewpoint about this event. To me, Orion is both exciting and deeply disappointing.

On the one hand, Orion is NASA’s first entirely new spacecraft for human crews in over twenty years. There have been only seven in American history: Mercury (first successful flight in 1959), Gemini (1964), Apollo (1966), Skylab (1973), Space Shuttle (1981), Space Station (1992), and Orion (2014). Those dates have been getting unacceptably distant from one another, and it is wonderful to see NASA getting its game back on. Test flights are NASA’s business. The agency is supposed to operate in the proving ground of technology. I want to see it doing new things, and the Orion flight was a reasonable first step towards NASA getting back to its roots. Those roots, after all, were triumphant!

On the other hand, though, Orion falls far short of what NASA could, and should, do. The spacecraft is an improvement over the last capsule NASA designed – the Apollo Command Module – but it is an incremental improvement rather than a revolutionary one. As an example, one of the technological advancements NASA has been touting about Orion is its glass cockpit. But this is the era of the iPad: in such a mass- and volume-constrained environment as a space capsule, the glass cockpit is simply not innovative – it is obvious. (For examples of innovation in space vehicles, try inflatable habitatsrockets that fly back to their landing pads or crew shuttles that could land at any normal-sized airport runway.) To make matters worse, not only is Orion an incremental step in capability from the early ’70s, but its development is horrendously stretched. For reasons that are political, programmatic, and cultural, rather than technical, the next flight of Orion will be in 2018. A human crew will not use the capsule until after 2021, at which point it will be almost a decade old itself.

I think the most bitter disappointment is the concept of what Orion will do when it finally does have astronauts on board. The current plan is to build the world’s biggest rocket, the Space Launch System, and use it to send an Orion crew to asteroids and Mars. I’m all for visiting those places, but the “giant rocket with space capsule” architecture – the architecture of Apollo – is a recipe for one-shot visits to other worlds. After the first astronauts return from such “flags and footprints” missions, there is a very strong risk of program cancellation. I don’t want to see our space program cancelled.

An Orion capsule riding a Space Launch System rocket is not even close to how I would design a sustainable, long-term space program. A much better approach is to use many different spacecraft, and specialize them for individual purposes. Think of the Apollo Lunar Module: it was a flimsy, silly-looking vehicle that was exactly suited for the prospect of landing and taking off from the Moon’s surface. Instead of building on Apollo and Space Shuttle heritage to make an “all-purpose” space capsule, I would like to see NASA lean on its Space Station experience to design a set of interplanetary transport spacecraft. These vehicles would stay in space for their whole lives: we would assemble them in space, launch them out of Earth orbit rather than from Earth’s surface, and we’d never use them to carry astronauts up from and down to the ground. Whenever they need more fuel, we’d send only the fuel up to them – not a whole new vehicle. When we need to rotate astronaut crews, we could always hire SpaceX.

That sort of multi-vehicle concept offers some big advantages. First of all, it’s much more flexible than giant, infrequent, one-shot missions. Second, it’s far more efficient and cost-effective. Think about this: 20% of Orion’s mass is its heat shield, a component only needed for the last ten minutes of its mission. If Orion is returning from Mars, then that means our Mars return rocket needs to be huge in order to push that heavy heat shield on its half-year-long journey back to Earth. And if the heat shield and Mars return rocket need to be huge, then the Earth departure rocket needs to be enormous. Instead, though, we could forget sending the heat shield to Mars in the first place. Forget having the vehicle that goes to Mars also be responsible for landing on Earth. When the astronauts come back from Mars, you just send a little rocket with a little capsule into Earth orbit – just enough to bring the astronauts to the ground. The lightweight interplanetary spacecraft stays in space.

In 2011, when Congress ordered NASA to begin work on the Space Launch System, internal NASA studies came out that agree with my assessment. Multi-vehicle approaches that we can re-fuel and re-use in space are more efficient and cheaper than SLS. They will also get astronauts to other worlds much sooner. Most importantly, such approaches won’t be reliant on one-and-done missions. They will be much more likely to keep our explorers in space.

That is why, while I applaud NASA’s successful demonstration of the ability to launch new vehicles, I hope the agency moves on quickly from Orion, and begins work on a new fleet of exploration vehicles to stay in space.

One thought on “Back to the Future”

  1. SLS will almost certainly be cancelled. This is a case of using the wrong technology because its expedient rather than appropriate to the assigned task. There is absolutely no way that SLS will ever be less expensive to operate than STS, apart from developmental costs. Since there’s no funding available for payloads given the exorbitant cost of the launch system, what is it going to launch? Nothing.

    SLS will not, absent an inordinate expenditure of resources, meet its design objectives.


    RS-25D – $72M per copy. NASA is going to dump 4 perfectly serviceable RS-25’s into the ocean with every SLS launch. It’s monumentally wasteful.

    SRM – Requires a re-design and re-certification of the motor for manned space flight.


    RS-25E – For all intents and purposes rating an entirely new engine for manned space flight. Supposedly, this variation of the RS-25 would only cost $39M, although that is only speculation on the part of the manufacturer. $156M for 4 engines you’re going to dump into the ocean instead of $288M. If that is really what the new RS-25E’s would cost, that’s certainly more economical, but nowhere good enough.

    ASRM – Can’t get to 130mT without a fifth RS-25, which would require a complete redesign and recertification of the launcher for manned space flight. Again, ASRM is a complete redesign and recertification.

    8.4M tank – Can’t hold enough fuel for 5 RS-25’s.

    The STS launch hardware was designed for maximum performance and salvageability. SLS was supposed to be economically expendable and use more cowbell, rather than attainment of maximum possible design efficiency, to achieve performance objectives. The requirements for those two launch systems are opposed to one another.

    What’s actually needed?

    NASA needs to accept the fact that, with respect to efficiency, most launch system performance profiles look remarkably similar to the LOX/RP-1 and commit to designing and building high performance kerolox-fed motors to use as the first stage of any launch system.

    The so-called F-1B immediately comes to mind. Same or better performance as F-1A with a vastly simplified, and therefore less expensive, design. The number of parts in the new F-1B design is dramatically less than the parts in the original F-1 design. In short, it may not be the most efficient motor but five F-1B’s produce enough thrust to eliminate the complexity of SRM’s and SSME’s.


    – RP-1 tank doesn’t have to be as voluminous as the LH2 tank

    – Better mass fraction

    – Fuel is not cryogenic

    – Less risk of fire

    – SRM’s impart loads to the main tank that are eliminated using an all-liquid engine design

    – SRM’s can’t be continuously throttled or shut off

    If NASA can replicate the functionality of Saturn V, not the vehicle but the lift capability, then it will have a launch system that is right at the edge of the purported, though not realistically achievable, Block II performance capability of SLS.

    If J-2X development continues, then a suitable second stage motor would be available to fulfill the design requirements. We’ve already wasted the money on the test stand and motor development, so we might as well use the test stand for what it was designed for and get some return on our investment.

    The third stage motor would not be a Saturn program derivative, rather four RL-60/MB-60 would seem to be a more appropriate choice than J-2X for a variety of reasons.

    If this sounds an awful lot like a Saturn V, there’s a reason for that. Saturn V was specifically designed to launch spacecraft beyond earth orbit. That is the stated purpose of SLS, is it not?

    We’re replicating the capability using modern manufacturing techniques for the motors and tankage, using simplified motor designs made possible by materials, computer, and sensor technology not available during the Saturn V program, and ultimately creating a launch system that does not have the high cost of reusable components built into it and simultaneously.

    If SpaceX’s first stage recovery technology comes to fruition, it may be possible to recover the first stage for reuse if it proves economically feasible. IIRC, recertification of flight hardware was the most costly part of the STS program. The second stage recovery technology is an awful lot like what’s required to salvage the orbiter from STS. In other words, second stage recovery may be possible, but it’s likely to be prohibitively expensive.

    We have to decide whether or not we actually want to go to Mars. From the DRM’s I’ve seen, the low end of the mass requirement is 1200mT. That would mean 12 Block II SLS launches. In other words, $1.8B just for the new RS-25E’s that don’t exist. SLS simply does not and will not have the payload capacity. The vehicle I propose would provide the payload capacity that SLS won’t at a much lower operating cost and lower or equal developmental cost, the trade-off being the time to first launch.

    To wrap it up, if we want to achieve the result that we say we want to achieve, flight certification of the F-1B, J-2X, and a new 10M core rocket are what we need. The alternatives simply cost too much to certify and operate.

    The means to leave our planet were devised decades ago and the solutions were practical rather than political, even if driven by political agendas. Once upon a time Congress created goals for NASA and it was up to the men and women of our space program to figure out how to achieve them. The SLS program is Congress telling NASA how to get to other planets. Apart from some members of Congress being space cadets, what does Congress know about how to create a launch system for interplanetary travel? So far as I can tell, absolutely nothing. I know we’re destined to try every dumb idea that we know won’t work before we accept the solution, but the solution is there for everyone to see.

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.