Why replacing the Russian RD-180 engines is so difficult, and so senseless
By Dimitri Elkin and Woodrow Clark
The list of collateral damage from the geopolitical standoff between US-Russia continues to grow.
The latest victim is the successful rocket engine joint venture that lifts most of the American commercial and military satellites into space. America's access to space depends mainly on the Atlas V rocket that is jointly produced by Boeing and Lockheed Martin, working together since 2006 as the United Launch Alliance ("ULA"), and which is powered into space by the powerful engine that is RD-180, produced by Russia's NPO Energomash.
The Atlas is not the only rocket available to give America assured access to space. There is the powerful Delta IV rocket produced by Boeing. And also the Falcon 9 produced by SpaceX - neither of which utilizes a Russian engine. But the Delta is large and expensive, while the Falcon 9 is less powerful and cannot deliver heavy loads to high orbits.
The use of Russian advanced engines dates back to the early 1990s, but even further for over several decades as the US and Russia began collaborating in the 1975 with the joint Soyuz-Apollo mission. The advanced Atlas V rocket with its RD-180 engine completed testing in 2001, and since then, it has powered over 50 American missions to space, including many military ones. Despite the spotless safety record and compelling cost, what used to be the poster child for US-Russian cooperation is now under attack as a threat to US national security.
Conservative American politicians, including Arizona Senator John McCain, have been criticizing US-Russian space cooperation for many years. But because of the RD-180 engine's lower cost and safe performance, the ULA had long been impervious to criticism.
However, after the annexation of Crimea, the use of Russian engines came under close scrutiny from both sides. A Pentagon study led by retired Air Force Maj. Gen. Mitch Mitchell concluded that losing access to the Russian-made engines would delay as many as 31 missions and would cost the United States as much as $5 billion. The Russians likewise hurt their own cause when the chief of Russia's NPO Energomash, Mr. Dmitry Rogozin, sent out a tweet on May 13, 2014, saying that cooperation on the RD-180 engine would only be possible if it is not used in the interest of the US Pentagon.
Then came the American sanctions, and Mr. Rogozin, was included in the list of sanctioned officials. On April 30, 2014, this gave the American private company, SpaceX grounds to file a lawsuit against the U.S. Air Force, claiming that it had entered into an illegal contract with the ULA, since it buys engines from a supplier headed by a sanctioned individual. By December 2014, the United States Congress enacted a ban for future use of the RD-180, beyond the launches already scheduled until 2018.
Replacing Russian space technology turned out to be easier said than done. In November 2015, the ULA refused to submit a proposal to launch US Air Force GPS navigation satellites, on the grounds that it could not guarantee the availability of engines. This left SpaceX as the only contender for American space travel, a monopoly position that made many in the US government uncomfortable.
With a possible replacement for RD-180 years away, Lockheed and Boeing pushed aggressively to have the ban lifted. Richard Shelby, a Republican Senator from Alabama, called the ban reckless. "Banning the use of RD-180 until the US has a domestically produced engine with similar capabilities undermines national security," he said. In December 2015, the US Congress voted to lift RD-180 ban as it was overturned as part of a government spending bill.
But this only inflated controversy further.
On January 27, 2016, the Senate Armed Services Committee had a hearing on the use of Russian-made rocket engines. Senator McCain accused the United Launch Alliance of extortion and questionable dealings with Russians. The US Airforce Secretary Deborah Lee James appealed to the complexity of the task that depended on "hard science," rather than on political wishes. The US Airforce Secretary entreated the Senate, arguing that instead of investing money to replicate the Russian engine, America should be investing in the development of the Vulcan, a new space vehicle for which a new engine would be an integral part.
This seems like a straightforward enough plan, but there are complications. First, there is no agreement on who (government, private sector) will provide the several billion dollars required to develop a new engine. Should it be the Pentagon? The Airforce? The United Launch Alliance? Both Boeing and Lockheed Martin expressed reservations about writing a blank check for a risky technical project. Second, until a US booster is ready, the United States will be forced to rely on the Russian engine, since neither the Falcon nor the Delta present an economically competitive option today. Air Force Secretary James publicly stated that the congressional mandate to stop using Russian-made engines by 2019 is extremely tight.
As remarkable as it may seem, US space technology is trailing that of Russia by a considerable margin, and closing this gap can be done only slowly and at a great expense to the US taxpayers. But thirdly, it might be reasonable to step back, and ask the most basic question: what is so special about the Russian RD-180 engine, such that no existing American competition (US private or public) can match its performance? The answer to this question puts a lot of issues in perspective. But to properly answer that question, it is necessary to take a brief excursion into rocket engine science, and the history of space competition between the US and the Soviet Union over the last half century.
ROCKET SCIENCE IN A NUTSHELL
A rocket moves forward because it spews out heated gases from its nozzle in the opposite direction. In fact, anything can travel in space that has something to throw in back of it. For example, you can fly in space on a cart loaded with stones. The cart will accelerate when a stone is thrown backwards. The cart can attain a greater speed by one of two ways: throwing heavier rocks; or throwing them faster. A rocket is fundamentally no different from a cart loaded with stones. The weight of the stones is the amount of fuel loaded on a rocket. The speed of the throw is the speed of the exhaust.
Just like a cart with stones, the rocket's top speed depends on two things: how much fuel it has to spit out; and at what speed. In mathematics, this is known as the fundamental equation of rocket travel, devised by the father of Russian rocket science, Konstantin Tsiolkovsky, in 1911.
There is a third way of making a rocket go faster and further: reduce the weigh of the rocket. This strategy was played out in the recent dramatic movie The Martian, when Matt Damon's character, faced with a fixed amount of fuel and the need to lift himself into Mars' orbit, reduced the weight of the rocket by cutting off part of his ship. Keep in mind that NASA was featured as a key dramatic element in that film. And even cited with strong cooperation by NASA to the film producers. But this could only happen in the movies when they get "creative". In reality, there are two issues: how to make engines more powerful; and how big of a rocket do you want to build?
The issue of how much speed a rocket can attain becomes especially critical when a spaceship needs to travel beyond the earth's orbit. To reach the moon, the spaceship needs not just a first cosmic velocity of 7.9 km per second that will keep the rocket orbiting the earth, but also the need for the so-called "second cosmic velocity" of 11.2 km per second.
During the space race for the moon in the 1960s, the US and the USSR faced the same issue as to how to make a more powerful engine that could propel a spacecraft to the second cosmic speed. The advantage of the Russian RD-180 engines over American rockets stemmed from the way the two nations chose to reach the moon.
THE SECRET OF THE CLOSED CYCLE
The heart of the rocket engine is a combustion chamber where fuel and oxygen are mixed and burned: the rocket needs to carry not only fuel, but also oxygen required for burning in order to propel through space. But the fuel loaded on a rocket is measured in hundreds of tons, and the pressure in the burning chamber is high. So, to inject fuel from the tank into the combustion chamber is a demanding task, especially if when the scientific fact to consider is that a rocket burns over 2 tons of fuel per second. To mix the fuel and oxygen, every rocket has a second smaller burning chamber called a pre-burner, which provides the power for fuel injection. In the standard design used by both the USSR and the US from the 1950s, the heated gas from the pre-burning chamber is spit outside and its energy is wasted, losing up to 25% of fuel and power.
There is however potential to inject the heated gas from the first chamber into the main channel. This type of rocket engine design is called the closed cycle, which could boost engine power by 25%. But it will also increase pressure and the temperature of the combustion process.
During the Apollo program, the US engineers concluded that a closed cycle engine was not possible. The pressure and the temperature were simply too high to control. They stuck with the open cycle design, and compensated for the loss of efficiency with rocket size. The result was Saturn V, a massive rocket powered by five very large open cycle engines.
Russian engine designers of the 1960s took a different view. They believed that a closed cycle engine was possible, and were able to achieve it through a combination of material science and clever thermodynamics. For example, the fuel oxygen mix is injected in the combustion chamber in a thin layer over the walls of the chamber, creating the effect of evaporation, and lowering the temperature of the combustion chamber walls.
To compete with the US Saturn V, the USSR designed an N1 rocket powered by 30 closed cycle engines. But Russia did not get the entire rocket done in time. Americans beat Russians to the moon. Russians then chose to drop their aspirations for a manned moon mission.
The Soviet N1 rocket never became operational, but it served a useful purpose: it proved that a closed cycle engine can work. In the early 1970s, the unused stock of closed cycle engines was put in high security storage, where they remained unseen for 20 years.
THE ENGINE THAT CAME FROM THE COLD
US-Russian space cooperation began in 1993 at the end of the Cold War, when Vice President Gore and Prime Minister Chernomyrdin agreed on technical and commercial cooperation between the US and Russia. At this time, the US Department of Defense was seeking a new launch vehicle, and the Gore-Chernomyrdin Commission through their trade agreement allowed Lockheed Martin to search throughout the former Soviet Union for a more powerful engine.
When Americans came across the stored rocket engine of the N1 rocket and saw the specifications, they initially thought it was a mistake - the Russian engine's performance was unusually high. However, the US scientists quickly realized the scientific and technological value of the Soviet achievement. In 1995, Lockheed Martin chose the RD-180, a derivative of the N1 engine, as the main engine for the US Atlas rockets.
The first American rocket powered by the Russian RD-180 engine took off in May 2000 from Cape Canaveral, Florida. When Boeing and Lockheed Martin merged their space launch programs under the United Launch Alliance, the RD-180 became its main engine. It was a dramatic success of the free market and governments together in the new Russian-American cooperation.
Developed for the US and USSR Cold War space race, the RD-180 technology turned out to be well suited for the new challenges in the space age. The development of communication technologies demanded the launch of a larger number of smaller satellites. The RD-180 remained unchallenged by delivering an unmatched combination of power and cost, all based on the closed cycle rocket engine design developed in the 1960s by the then USSR.
The closed cycle engine is not the only viable technology for a space engine developed during the Cold War era. The good old open cycle technology is still in use in the area of manned space flights, where as it should be that safety trumps the consideration of cost. Consider also China as the Martian film illustrated. Chinese rockets use open cycle propulsion. However the heavy lifting tasks that require numerous launches, means that the RD-180 will not have any equals for the foreseeable future. The ULA was so satisfied with the RD-180 engine's performance that it did not consider replacing it, until the Crimea crisis of 2014 occurred. As in the past, clearly governments such as China and Russia pay for taking the lead in science, whereas the US private sectors do not see the markets yet. SpaceX in the US is heavily funded now by US government funds.
REINVENTING THE COSMIC WHEEL
Last month the US Airforce commissioned two possible replacements for RD-180. The first one is called BE-4 by Blue Origin, a space venture backed by Amazon founder Jeff Bezos. The second alternative is AR1, developed by Aerojet Rocketdyne, a California based manufacturer of rocket engines. Both BE-4 and AR-1 are based on the closed cycle design, but fueled differently. AR-1 will be fuel by liquid kerosene, similar to RD-180. BE-4 will use methane. If successful, these two engines may provide America with a rocket booster that will meet or exceed the specification of RD-180.
The problem is that nobody can say with certainty, how quickly or how successfully the new engine developments will be achieved. Both Blue Origin and Aerojet are trotting down the same path that the USSR space scientists took in the 1960s. While the Americans have the benefit of knowing that a closed cycle engine is technologically possible, the process of development will be risky and expensive. The pressure and temperature involved in a closed cycle engine require very large testing stands, and potentially a very high tolerance for failure, before the right design can be pinned down. The Russian N-1 rocket exploded four times during the tests. It would be unlikely that the US would go through the new engine development without similar costly hiccups.
Already there are skeptical voices that suggest that the 2019 deadline for a new engine seems to be ambitious. The Wall Street Journal recently leaked a study by an independent panel that suggested that pushing domestic replacement to 2025 would be less risky, and would save taxpayers billions of dollars.
The irony is that the US is about to spend billions on trying to fix something that is fundamentally not broken. The Atlas V rocket continues to lift US satellites into space - case in point is the recent NASA launch took place in Florida last month. The supply of RD-180 remains secure, and despite the political noise, there is no indication that Russia has any serious intention of using this as political leverage. Russia's space industry needs the revenue from RD-180 as much as America needs this product. The breakdown of the Russian-American rocket engine joint venture is rather unfortunate. Few of American foreign partners have been as reliable as Russia's space experts. When the American space program needed help, Roskosmos always delivered, noted Susan Eisenhower in Partners in Space: US-Russian Cooperation After the Cold War. But in today's Washington, politics trumps reality, and the decision to phase out RD-180 seems to be a fait accompli.
Shouldn't we pause and to ponder what if the relationship between US and Russia may someday improve? But instead of exploring options of finding common ground in the future, the American politicians pursue what is politically expedient in the current electoral cycle. But what makes sense politically, often fails technologically, like the October 2014 attempt to supply the International Space Station with an Antares rocket that was jointly produced by the US and Ukraine. A US-Ukrainian rocket seemed like a nice geopolitical snub to the Russians, but the rocket exploded during the takeoff. This is a space race between America and Russia starting all over again?
It certainly looks that way. But unlike the first space race, when both the USSR and the US reached for new horizons, the second space race seems to be about repeating old accomplishments. Even in the best case scenario, should the US succeed with developing a new closed cycle engine, Americans will not be breaking any new technological ground, but will simply be replicating proven Soviet technology, that by then will be more than fifty years old.
It is hard to think of a pricier way of reinventing the wheel. Especially today when Russia and the US have so many global security issues that they hold in common.