For over two decades, the RD-180 rocket engine, designed and manufactured in Russia, has been the propulsive force behind the first stage of the American Atlas III and Atlas V rockets. This powerful engine, with its dual combustion chambers and nozzles, has enabled the launch of numerous military, commercial, and scientific payloads. Despite its foreign origins, the RD-180 has proven to be a reliable and high-performing engine that has played a critical role in American spaceflight.
Origins in the Soviet Space Program
The RD-180 traces its roots back to the Soviet Energia rocket, which was developed in the 1970s and 80s to launch the Buran space shuttle. The Energia’s strap-on boosters were powered by the RD-170, a massive four-chamber engine that was at the time the most powerful liquid-fueled rocket engine ever built.
In the early 1990s, after the dissolution of the Soviet Union, the Russian engine manufacturer NPO Energomash began looking for commercial customers for its rocket engine technology. Engineers at Energomash scaled down the RD-170 into a two-chamber version called the RD-180. This new engine generated about half the thrust of the RD-170 while keeping the same efficient staged combustion cycle.
Partnership with the United States
In the mid-1990s, American aerospace company General Dynamics (later acquired by Lockheed Martin) was searching for a powerful engine for its new Atlas III rocket. Impressed by the capabilities of the RD-180, General Dynamics partnered with Energomash and American engine maker Pratt & Whitney to import the engines for use on the Atlas III.
The Russian government approved the deal, and Lockheed Martin set up a joint venture called RD AMROSS with Pratt & Whitney and Energomash to manage the supply of RD-180 engines. Under this arrangement, Energomash would build the engines in Russia and ship them to the United States, where Pratt & Whitney would inspect them before integration with the Atlas rockets.
The first Atlas III launch with an RD-180 engine took place in May 2000. The engine performed flawlessly, demonstrating its immense power and reliability. With this successful debut, the RD-180 began its long career powering American rockets.
Technical Capabilities
The RD-180 is renowned for its remarkable performance and advanced design. With a thrust of 860,000 pounds (3,830 kN) at sea level, it is one of the most powerful engines in the world. The engine achieves this impressive thrust by burning a mixture of refined kerosene (called RP-1) and liquid oxygen in a staged combustion cycle.
In a staged combustion engine, the propellants are first burned at a low temperature in preburners to generate hot gas to drive the turbopumps. The gas is then injected into the main combustion chamber to burn with the rest of the propellants at high temperature and pressure. This allows for very efficient combustion and high engine performance.
The RD-180 is unique among staged combustion engines in that it uses an oxygen-rich preburner, whereas most other engines use a fuel-rich mixture. The high-pressure, high-temperature oxygen poses a challenge for engine components, but Energomash solved this problem by developing a special heat-resistant alloy and coating all oxygen-touching surfaces with it.
Another key feature of the RD-180 is the single turbopump that feeds propellants to both combustion chambers. The single-shaft design is very compact and lightweight. The two nozzles can gimbal, or pivot, independently to steer the rocket during ascent.
Overall, the RD-180 achieves a remarkable thrust-to-weight ratio and fuel efficiency, surpassing any other kerosene-fueled engine at the time of its introduction. These capabilities have made it an attractive choice for the Atlas rockets.
Powering the Atlas V
After the successful debut on the Atlas III, the RD-180 was selected to power the Common Core Booster (CCB) first stage of Lockheed Martin’s next-generation Atlas V rocket. The Atlas V was developed under the US Air Force’s Evolved Expendable Launch Vehicle (EELV) program to provide assured access to space for military payloads.
The first Atlas V launch took place in August 2002. Since then, the rocket has launched over 90 times with a near-perfect success record. The RD-180 has been a key factor in this reliability, performing flawlessly on every mission.
The Atlas V quickly became a workhorse for the US military, launching critical national security payloads like GPS satellites, missile warning satellites, and classified spy satellites. NASA has also relied on the Atlas V to launch many scientific spacecraft, including the Curiosity and Perseverance Mars rovers, the Juno Jupiter orbiter, and the OSIRIS-REx asteroid sample return mission.
In the commercial sector, the Atlas V has launched several communications and Earth observation satellites. The rocket has also sent cargo resupply missions to the International Space Station under NASA’s Commercial Resupply Services program.
Throughout this diverse launch history, the RD-180 engine has demonstrated its versatility and reliability. The engine’s robust design and substantial performance margins have allowed the Atlas V to successfully fly in a variety of configurations and weather conditions.
Geopolitical Challenges
Despite the RD-180’s technical merits and successful track record, the engine has faced political challenges due to its Russian origins. Concerns about relying on a foreign supplier for such a critical national security capability have been raised repeatedly in the US Congress.
These concerns came to a head in 2014 after Russia’s military intervention in Ukraine and annexation of Crimea. In response to US sanctions, Russian government officials threatened to cut off the supply of RD-180 engines for US military launches.
Although the threat was not carried out, it highlighted the potential vulnerability of depending on Russian engines. The US Congress began to push for the development of a domestic replacement for the RD-180.
United Launch Alliance (ULA), the joint venture between Lockheed Martin and Boeing that operates the Atlas V, responded by partnering with Blue Origin to develop the BE-4 engine. This new liquefied natural gas-fueled engine is slated to power ULA’s next-generation Vulcan rocket, which will eventually replace the Atlas V.
At the same time, Aerojet Rocketdyne proposed its AR1 engine as a drop-in replacement for the RD-180 on Atlas V. However, ULA ultimately chose to proceed with the BE-4 and Vulcan.
As a stopgap measure, Congress approved a limited number of additional RD-180 engine imports to support national security launches until a domestic alternative becomes available. However, the political controversy surrounding the engine has continued.
Phasing Out the RD-180
With the development of the Vulcan rocket and BE-4 engine progressing, ULA has begun the process of phasing out the Atlas V and RD-180. The company has stated that it plans to retire the Atlas V by the mid-2020s after fulfilling its remaining launch commitments.
ULA has already taken delivery of the final batch of RD-180 engines from Russia. These engines will support Atlas V launches through the transition period to Vulcan.
The phaseout of the RD-180 marks the end of an era in American spaceflight. For over 20 years, this powerful Russian engine has been a key enabler of US space capabilities. Its performance and reliability have set a high bar for future American rocket engines to meet.
Legacy and Impact
The RD-180 story is a fascinating case study in the globalization of the space industry and the complex interplay of technology, politics, and national security. On one hand, the engine represents a remarkable technological achievement and a successful international partnership. On the other hand, it illustrates the risks and challenges of relying on foreign suppliers for critical capabilities.
From a technical perspective, the RD-180 has had a significant impact on American rocket engine development. Its staged combustion cycle and oxygen-rich preburner design were groundbreaking features that pushed the boundaries of engine performance.
American engine manufacturers have learned valuable lessons from studying and working with the RD-180. This knowledge has informed the design of new US engines like the BE-4 and AR1. In a sense, the RD-180 has helped to advance the state of the art in American rocket propulsion.
Beyond the technical realm, the RD-180 has also had an important strategic impact. The engine’s capabilities have been a key factor in the success and reliability of the Atlas V, which has been a critical asset for US national security and space exploration.
However, the RD-180 experience has also exposed the vulnerabilities of relying on foreign suppliers for such important capabilities. It has underscored the need for the United States to maintain a strong domestic industrial base for space technology.
Summary
The RD-180 rocket engine has had a remarkable journey from its origins in the Soviet space program to its long career powering American rockets. Along the way, it has demonstrated impressive capabilities, supported groundbreaking missions, and sparked heated political debates.
As the era of the RD-180 comes to a close, its legacy will endure. The engine’s technical achievements will continue to influence rocket design, and its strategic impact will shape American space policy for years to come. The story of the RD-180 is ultimately a testament to the power of international collaboration in spaceflight, as well as the ongoing challenges of ensuring national self-sufficiency in space.
While the RD-180 will soon fade into history, the lessons learned from its development and use will continue to guide the future of American rocketry. As the United States enters a new era of space exploration and competition, the experience with the RD-180 will undoubtedly inform decisions about how to build and sustain the next generation of powerful, reliable, and homegrown rocket engines.
