Is SpaceX changing the rocket equation?
1 visionary + 3 launchers + 1,500 employees = ?
- By Andrew Chaikin
- Air & Space magazine, January 2012
South African-born entrepreneur Elon Musk, 40, ended up in the United States because, he says, it's where great things happen. Musk is gambling that his company, SpaceX, can change the world with its Falcon rockets and Dragon capsules by carrying cargo, and eventually people, to orbit.
Space X
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Instead, from the very beginning, SpaceX designed its Falcon rockets with commonality in mind. Both of Falcon 9’s stages are powered by RP1 and liquid oxygen, so only one type of engine is required. Both are the same diameter and are constructed from the same aluminum-lithium alloy, reducing the amount of tooling and the number of processes and resulting in what Musk calls “huge cost savings.”
No choice was more critical than the Merlin rocket engines used to power Falcon 9. SpaceX propulsion chief Tom Mueller and his team selected an engine type called the pintle that was pioneered by Mueller’s former employer, TRW, which used it for the descent stage of the Apollo lunar module. Unlike most rocket engines, in which droplets of fuel and oxidizer are sprayed into the combustion chamber through an injector plate resembling a shower head, the pintle uses a needle-like injector that’s more like the nozzle on a garden hose. It’s not only less expensive to make, Mueller says, but it is also less susceptible to combustion instability, a runaway buildup of energy within the thrust chamber that has vexed engineers since the dawn of the Space Age (it added years and many millions of dollars to development of the giant F-1 engines for the Saturn V moon rocket, for example). Combustion instability can make an engine undergo what veterans dryly call an RUD, for Rapid Unscheduled Disassembly; civilians would call it blowing up. Even the Merlin had a couple of RUDs in the early days of development. “There are a thousand things that can happen when you go to light a rocket engine,” Mueller says, “and only one of them is good.”
That, of course, was hardly news by the time SpaceX got started; studies had shown that over the previous two decades, the vast majority of rocket failures were due to engine malfunctions. And so, before attempting the multi-engine Falcon 9, Musk began with the smaller and less expensive Falcon 1, which uses a single Merlin engine in its first stage. Test launches of this 70-foot rocket, beginning in 2006, were SpaceX’s baptism by fire. Only after three failed attempts did the Falcon 1 become the first privately built liquid-fuel vehicle to reach orbit, in September 2008. Musk and his team were both elated and sobered. “We knew it would be hard,” Mueller says, “but it was harder than we thought.”
The rest of the aerospace world took notice. With the early Falcon 1 failures, says Stern, Musk “showed spine, showed he would spend his own money, showed he would stick with it.” And the lessons learned from Falcon 1 smoothed the path for Falcon 9, whose successful maiden launch, in June 2010, impressed observers accustomed to watching other would-be rocket startups, from AMROC in the 1980s to Kistler in the 1990s, fail before getting anything into space.
The Falcon 9 was designed from the beginning to be human-rated, meaning an increased focus on reliability. The rocket’s avionics and controls are triple-redundant (as will be some sensors in the human-rated version of the Atlas V), and the flight computers, which run on Linux, will “issue the right commands even if there’s severe damage to the system,” Musk says. The choice of nine engines for the first stage was made with reliability in mind: From the moment of liftoff, Falcon 9 can suffer an engine shutdown and keep flying; after about 90 seconds, it can tolerate a second engine shutdown. Even if an engine explodes, says Mueller, the others will not be affected.
Of course, SpaceX goes to great lengths to prevent such a scenario. Part of the Merlin’s qualification testing involves feeding a stainless steel nut into the fuel and oxidizer lines while the engine is running—a test that would destroy most engines but leaves the Merlin running basically unhindered. Every Falcon upper and lower stage is test-fired in Texas before it’s cleared to fly. “It’s very common to do component and system-level testing…. That’s very typical in aerospace, ” says Alan Lindenmoyer of Houston’s Johnson Space Center, who has been working with SpaceX since 2005 as manager of the agency’s Commercial Crew and Cargo program. “But to actually put a vehicle together and do system-level testing of the rocket is not. That’s a level of rigor you don’t typically see.” On the pad at Cape Canaveral, Florida, the rocket undergoes an additional brief firing a few days before launch. And just before liftoff, for a few moments after the engines are lit, their performance is analyzed by the Falcon’s computers before hold-down clamps are released and the rocket is allowed to rise.
The Merlin engine itself has undergone a number of improvements, including reducing the number of parts and increasing its power and efficiency. According to Mueller, the 140,000-pound-thrust Merlin 1D, designated the production model for Falcon 9, has the highest thrust-to-weight ratio of any rocket engine ever made.
Significantly, the Merlin engines—like roughly 80 percent of the components for Falcon and Dragon, including even the flight computers—are made in-house. That’s something SpaceX didn’t originally set out to do, but was driven to by suppliers’ high prices. Mueller recalls asking a vendor for an estimate on a particular engine valve. “They came back [requesting] like a year and a half in development and hundreds of thousands of dollars. Just way out of whack. And we’re like, ‘No, we need it by this summer, for much, much less money.’ They go, ‘Good luck with that,’ and kind of smirked and left.” Mueller’s people made the valve themselves, and by summer they had qualified it for use with cryogenic propellants.
“That vendor, they iced us for a couple of months,” Mueller says, “and then they called us back: ‘Hey, we’re willing to do that valve. You guys want to talk about it?’ And we’re like, ‘No, we’re done.’ He goes, ‘What do you mean you’re done?’ ‘We qualified it. We’re done.’ And there was just silence at the end of the line. They were in shock.” That scenario has been repeated to the point where, Mueller says, “we passionately avoid space vendors.”
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Comments (25)
Excellent article. I really hope they succeed.
Posted by Bill Hensley on November 16,2011 | 02:04 PM
Yes, and excellent article. I am just amazed at SpaceX's accomplishments. I have new appreciation for the Merlin 1D engine. You read once that the engine has more power to weight than any other engine and you think "that's incredible!", and then you read that this engine is so reliable it is designed to be used for dozens of flights, and that by itself is also incredible. But you would think that such durability would come at the price of extra weight, a trade-off, either/or, but no they did BOTH!
Their rocket is not just cheaper, but clearly superior by design. The author talks about inevitable failures, well SpaceX has already had 3. Let's hope that is all SpaceX has to endure.
Posted by Roy_H on November 16,2011 | 09:23 PM
Former NASA associate administrator Alan Stern says rockets are expensive largely “because the system allows it.”
This statement caused a guffaw of derisive laughter!
"Because we have our heads up our asses" is more accurate, but then, this is a (former) government employee.
"they have an incentive to reduce their cost,” Stern says, “but it’s at the margin.”
Which is to say, they don't really have an incentive.
Posted by IcePilot on November 16,2011 | 09:41 PM
SpaceX wins even if it fails.
Excellent article.
Posted by PhillyJimi on November 16,2011 | 01:51 AM
Very nice article. I was a little kid in the 60s and avidly watched every Gemini and Apollo flight. I'm a little too young to remember Mercury, though. When the Shuttle first flew, I marveled at the feat of engineering that could create a reusable space plane. Alas, the Shuttle's initial promise of making space flight routine never came to pass.
SpaceX has brought back the Wow! factor for me. I watched Dragon's first test flight last December with more excitement than I've had for any flight since the heyday of the 60s and early 70s. And the fact that the first flight was only two orbits, and a few hours from launch to splashdown, gave me an inkling of what those early Mercury flights must have been like.
I'm eagerly anticipating the next flight, and I'm going to be holding my breath and crossing my fingers. It will be the most important launch in decades; perhaps since the 1988 return to flight following the Challenger disaster.
Posted by rickl on November 17,2011 | 09:09 PM
Fascinating article not only on SpaceX and Musk but the rocket business - thanks for having this on the web in addition to the magazine - I am going to send this link around.
Posted by Bill Brandt on November 20,2011 | 11:55 AM
A smarter man than I, Dr. Hawking, has said it clearly: 'humans get off Earth, and prosper there, or there are no humans'. This is God's work. Again, Dr. Hawking said it clearly: the most important thnig going on on this planet, bar none.
Posted by john werneken on November 21,2011 | 07:50 AM
Argh. Why the obsession with Mars? There's absolutely nothing of value there, it's hideously far away, tremendously difficult to get anything there, and any trips to the surface will be one-way for a _long_ time. Grab a few asteroids, divert them into a high earth orbit, and tunnel into them like crazy.
According to NASA, even a small metallic asteroid would have roughly $20 _trillion_ worth of industrial and precious metals. And getting stuff down is a lot easier than getting stuff up.
Posted by Jared on November 21,2011 | 11:14 AM
Jared, the answer to your question is delta V and chemistry.
It takes marginally less delta V to reach Mars insertion orbit than it does to reach any of the nearer asteroids.
It takes significantly less delta V to do a Martian insertion orbit if you can aerobrake to shed velocity. This is not an option with an asteroid.
Moving an asteroid to high earth orbit would require staggering amounts of delta-v, and it would require building something on the asteroid to throw reaction mass off of it at a high velocity. Your options for that boil down to building a mucking huge magnetic cannon and throwing slag off the asteroid at high velocity - and the people working on that job are going to be on that asteroid for somewhere close to 5 to 6 years at a minimum doing the orbital transfer. Which means you have to have the life support and oxygen for them to breath.
Mars is a first step in that process, because Mars has carbon dioxide and water and oxygen bound to iron that can all be released and sent to said asteroid refining station - once you build a launch facility on Mars, getting from Mars to the asteroid belt is much cheaper. It's the access to oxygen and volatiles that's key here - getting oxygen and water from Mars to the asteroids is approximately equal to the difference in squares between their orbital energy requirements. Mars' orbital velocity is just about 4 km/sec. Earth's is 7.5. 7.5^2 is 56.25m 4^2 is 16. 56-16 is roughly a factor of 40 decrease in the amount of energy needed. (This is ignoring atmospheric effects on the rocket, which skew the cost difference higher for launching off of earth.)
Posted by Ken Burnside on November 21,2011 | 12:33 PM
Wonderful article. I hope they make it! I'd love to go up someday...
Posted by eternalgreenknight on November 23,2011 | 07:35 AM
> It takes marginally less delta V to reach Mars insertion orbit than it does to reach any of the nearer asteroids.
Nope. There's an entire group called Apollo asteroids, which regularly cross Earth's orbit.
> Moving an asteroid to high earth orbit would require staggering amounts of delta-v
Nope. The trick is to apply small amounts of delta-v well in advance. With the right asteroid on the right trajectory, a VASIMIR engine powered by a nuclear plant and a couple dozen tons of reaction mass running for a few _months_ will do the trick. There's a nice little 27 MT asteroid, called 99942 Aphonis, scheduled to make a close approach in 2029 that requires just 1.4kps adjustment to be captured. (Source: http://ramblingsonthefutureofhumanity.blogspot.com/2010/06/asteroid-capture-into-earth-orbit.html)
> Mars is a first step in that process, because Mars has carbon dioxide and water and oxygen bound to iron that can all be released and sent to said asteroid refining station
Ha! There is precisely zero prospect of making even a single Mars-to-orbit launch, let alone an entire _system_ for industrial purposes. And anyway, comets have water and plenty of oxygen as well. They come barreling inwards all the time, grab one of them too.
Yes, capturing large bodies is marginally harder than sending a single ship to Mars. But once done, it's _done_, and you don't have to ship anything out past lunar orbit. You don't have to wait years for optimum orbital arrangements (Mars can get as far as 400 million km away, you know) for regular shipments. And you don't have to try and fight against another pointy gravity well; 40 times easier than Earth launches is still pretty far away from "easy", especially when any replacement parts are, on average, 200 Mkm and 6 months to a year away.
And hell, if you want to go to Mars, I can't think of any better way than to have an entire industry already running in Earth orbit to build and fuel a ship to get you there.
Posted by Jared on November 23,2011 | 10:02 AM
> Earth's is 7.5. 7.5^2 is 56.25m 4^2 is 16. 56-16 is roughly a factor of 40 decrease in the amount of energy needed
I think you mean 4, not 40.
Posted by Jared on November 23,2011 | 11:44 AM
Musk should put that much effort into his car company...Tesla Motors. Instead they pretty much use an existing Lotus car without the internal combustion engine..far from innovative. C'mon Elon...let's see something special from Tesla!
Posted by Boris Gunjevic on November 23,2011 | 05:58 PM
"Former NASA associate administrator Alan Stern says rockets are expensive largely “because the system allows it.”
This statement caused a guffaw of derisive laughter!"
Understand them for what they are, though. NASA is a govt agency, and their projects are driven primarily by politics. The rockets and spacecraft must be public successes for the politicians who vote them.
Of course they still do fail occasionally, but they are going to do any inefficient procurement they feel they need to to make it safer for the boss in DC.
That makes me worry some about NASA getting their fingers into SpaceX engineering decisions on manned projects.
Posted by bruce on November 26,2011 | 12:29 AM
Author Andrew Chaikin could not possibly have painted a more succinct yet complete picture of the current condition of the US Space Program. As a skeptical rocket scientist-type, I was ready to disagree, point-by-point. I can’t! He nailed it.
My best possible wishes go with Elon Musk and the SpaceX folks since they now carry our dreams.
Also, the comments this article generated fascinated me. Asteroid rendezvous, Moon-Mars missions, and getting a self-sustaining colony off planet are all exactly the efforts our species needs to chase. Unfortunately, we have to get out of this gravity well first. To borrow and paraphrase -- LEO is halfway to anywhere in the Solar System.
Well done, Mr. Chaikin. Bring us more.
Posted by Charles Justiz on December 7,2011 | 05:48 PM
NASA is set to spend at least $5 billion for Lockheed-Martin to develop the Orion capsule alone. Congress has mandated that NASA spend at least $10 billion (and likely closer to $40 billion) to develop the Stupid Launch System, a rocket in search of a payload and a mission. They want a really big rocket in the worst way and that's exactly how they're going about getting it. At least until the inevitable overruns and delays causes the SLS to get canceled.
By way of contrast, SpaceX has spent less than a billion dollars developing the Falcon 1, Falcon 9, the Dragon capsule including all of the R&D for the rockets and engines, building the manufacturing capability, conducting flight tests, flight control centers, software development, launch prep and launch pads in multiple locations, etc.
Posted by Larry J on December 9,2011 | 03:39 PM
Boris Gunjevic,
You are thinking of the old Tesla Roadster that is no longer in production. They have been working hard on the design and mass production of the Model S (a luxury sedan that is half the price of the roadster). The Model S is slated to be released sometime near July 2012 and provides options for both a 300 mile range battery and a 4.5 second 0-60.
http://www.teslamotors.com/models
Posted by Mark Turney on December 10,2011 | 04:47 PM
"With the right asteroid on the right trajectory, a VASIMIR engine powered by a nuclear plant and a couple dozen tons of reaction mass running for a few _months_ will do the trick."
Why not just use the asteroid itself for the reaction mass? If you have a nuclear plant, it could power a machine to dig up and pulverize the material, then accelerate it through a magneto hydrodynamic tube.
Posted by Timothy Brummer on December 19,2011 | 11:15 PM
Tesla Motors help jump start the electric car by making it sexy and highly efficient. The point was to change the industry, and I think they succeeded. It is still a car many people would love to have, especially in all its new iterations.
That aside, many fault Musk for being a dreamer, but without vision we would never have gone to the moon, or done the things that make our society great. We need more Elon Musk's with vision and the acumen to back it up, the money doesn't hurt either...lol God knows a society of clock punchers waiting for the dustbin of history is not a better option.
I think as long as the politics or cheap Chinese knockoffs don't derail them, that they will make a better mousetrap, for the early failures MAKE them more aware and humble.
Posted by Jake Dhillon on December 22,2011 | 06:21 PM
Musk says:
“If you were sitting at an executive meeting at Boeing and Lockheed and you came up with some brilliant idea to reduce the cost of Atlas or Delta, you’d be fired,” he says. “Because you’ve got to go report to your shareholders why you made less money. So their incentive is to maximize the cost of a vehicle, right up to the threshold of cancellation.”
This is blatantly false. ULA is working with XCOR on developing a vastly cheaper upper stage for use on both rockets. This has been publicized in the media; there's no way Musk would not know that. I'm surprised that Chaiken seems unaware of it.
Posted by M. Lurkster on December 27,2011 | 11:15 PM
Jared - Spot on. Think of it this way - what product will be produced on Mars and sold for a profit on Earth? Nothing, short of 20 years of Lunar/asteroid/dead comet resource exploitation.
Posted by Dan Steele on May 18,2012 | 10:13 PM
"According to Mueller, the 140,000-pound-thrust Merlin 1D, designated the production model for Falcon 9, has the highest thrust-to-weight ratio of any rocket engine ever made."
That's wrong.
Just look at the old Soviet and Russian rocket engines:
RD-253 - thrust-to-weight ratio was 172:1
RD-270 - thrust-to-weight ratio was 201:1
RD-701 - thrust-to-weight ratio was 212:1
Posted by Shpankov on June 26,2012 | 10:22 AM
One point that should be made, and Andrew just briefly mentioned, is the average age of SpaceX employees. It is under 30, last time I looked.
That is exactly how NASA started in late 1950s and 1960s --- this makes a huge difference in energy and enthusiasm.
That is also the secret ingredient of many Silicon Valley firms -- ironically corporate America fights that business model.
Posted by G. Beat on June 26,2012 | 12:04 PM
Shpankov:
I think the article was just misquoting him, other quotes state that its the highest thrust-to-weight ratio of any RP-1 fueled rocket engine ever made. Which to my knowledge is actually correct.
I should also note that the RD-270 and the RD-701 never flew and only ever had ground tests done to them. (Granted the Merlin 1D has not flown yet, but it already has flights manifested for early next year.)
You also appear to have the thrust-to-weight ratio of the RD-253 wrong. The best thrust that that engine generates is 1.83 MN in vacuum and the weight of the engine is 1260 kg which gives a thrust to weight ratio of roughly 148. So actually the Merlin 1D will have the highest thrust to weight ratio of any rocket ever flown, once it flies.
Posted by Matthew Lindner on June 30,2012 | 09:39 AM
I'm too old to ever be an astronaut. Rollercoasters make me sick anyway. Zero-g wouldn't be much fun for me. But thanks to pioneers like Elon Musk our future generations will get the opportunity. Probably just as well since we are falling through the universe on a rock. If we are even half as intelligent as we like to imagine then planning for the future by investing in state of the art rocketry is a good way to prove it. Investing in the longterm survival of the human race is the most humanitarian act possible. Its possible longterm benefits are incalculable. Astronomical in fact. www.facebook.com/groups/ElonMusk
Posted by Universe Daily on March 12,2013 | 04:14 AM