There are many benefits of launching a rocket from the equator, but to get there a team of engineers from across the globe had to come together to build the first – and only – floating launch pad.
Made up of three elements, including a Zenit-3SL rocket, a marine segment, and home port, the Sea Launch System has made the trip to the equator 35 times since its creation in 1995.
The Sea Launch came together as a joint venture between multiple countries after a push from the U.S. State Department hoping to prevent a brain drain from Russia following the fall of the Soviet Union.
“The benefit the Sea Launch System and the Zenit-3SL rocket brings is the combination of western style customer interfaces both in payload processing and program interfaces and the heritage of Russian and Ukrainian launch vehicle design,” says John Riedman, systems engineer at Energia Logistics. “This combination provides the transparent interactions that our customers expect.”
By Land & By Sea
Providing support to the marine segment at sea, the Sea Launch System’s home port sprawls across 17 acres in Long Beach, California. The facility is staffed 24 hours a day, seven days a week, and serves as the base of operations for both the Sea Launch Commander and the Launch Platform Odyssey.
Also home to the Payload Processing Facility (PPF), the port receives customers’ spacecraft that is prepared for launch on the Zenit-3SL launch vehicle, which is capable of launching up to 6,160 kg.
“The performance benefits of the Zenit-3SL rocket is that each spacecraft is launched into an optimized orbit into its desired inclination so that it does not need to execute a plane change maneuver when transferring to its final orbital location,” explains Riedman. “Therefore they have more fuel on-board to dedicate to maintaining orbital position and extending the lifetime on orbit.”
When all systems are ready to head to sea, the rocket is moved to the Launch Platform Odyssey, a former North Sea oil drilling platform floating on two large pontoons, each similar in length to a Trident submarine. The platform is one of the world’s largest self-propelled, semi-submersible vessels, and includes an environmentally controlled hangar where the rocket is stored horizontally until it is righted and rolled out to the launch deck.
“As the engine thrust reaches 100 percent we release the rocket from the posts and they rise up and close back into the launch pad before the main engine’s 1.6 million pounds of thrust lifts the vehicle off of the launch platform. This automated process protects our launch platform from damage,” explains Riedman.
The process begins with a three day countdown to launch, and takes place on the Odyssey’s counterpart, the Sea Launch Commander.
The Commander serves as the assembly and command ship (ACS), and is approximately 221 meters long, 32 meters wide, and has a displacement of more than 34,000 tons. Communicating with the launch platform via line-of-sight radio links, the launch platform is evacuated 24 hours before launch.
“The Sea Launch Commander has to be at least 5 kilometers away from the launch platform for safety reasons,” says Riedman. Although failure is something the system has rarely encountered.
“We never use the word sink in our industry,” says Riedman, and to make sure they never have to, the launch platform uses multiple systems to maintain its stability, even during periods of significant mass movements.
The first of these systems is the use of ballast water (water a ship takes on in order to keep its balance). Taking on this water shifts the platform’s weight from 30,000 tons to 50,000 tons, allowing the launch vehicle to account for a mere one percent of the total mass of the launch platform.
A series of pumps then shifts the water between the platform’s tanks to help maintain the static angle of the launch deck. Additionally, the platform has a positioning system, the same type of systems used in the North Sea for drilling platforms to hold the station over the drill head.
“It’s floating and maintaining its location using a dynamic positioning system which is a series of thrusters in each pontoon that help it hold station,” explains Riedman. “It can also use the main propellers if it needs additional thrust to fight any currents.”
A global positioning feed from a satellite provides additional support, allowing the platform to hold within ±50 meters of a single location. “It’s surprising how stable it is. You can barely tell that you are on the sea,” says Riedman.
All of these systems work in conjunction to keep the Launch pad stable, but getting them to work together was not an easy task. During the development phase, the stability of the launch platform and the effects of the motion on both the load and on the launch vehicle as it was lifting off the pad, was a major engineering challenge.
“We had to work with a lot of analytical data and try to convert the effects of wave height, wind, and other expected motions on the launch platform,” explains Riedman. “A lot of integration work was done in the development stage to create and validate those models to ensure that we were going to have mission success.”
The Sea Launch System has now been a part of 35 missions, and with the benefit of experience, the team has determined that many conservatisms went into the analytical models of the past.
“Today we can calculate loads based on the actual environment, receiving information in real time,” says Riedman. Now deep into the operational stage, most glitches have been worked out, but the biggest challenge remains.
“Anytime we have an integrated issue, that’s our biggest challenge,” says Riedman. “Developing the processes and language so that you can fully understand the issue, bring together the right specialists, develop the resolution plan, verify it, and then determine that you are okay for launch. That is probably the biggest engineering challenge that remains on this program.”
With multiple engineering cultures, and languages, the integration of a Western, Russian, and mariner mentality has been difficult, and adding to that pressure are government concerns about transferring technologies between the organizations.
Yet Riedman explains that while the integration of cultures is their biggest challenge – it also provides one of biggest benefits. “By bringing together the technical marine, rocket, and systems integration cultures, as well as the Norwegian, Russian, Ukrainian, and U.S. cultures, the teams come up with innovated solutions and approaches that focus on mission success.”
Filed Under: Aerospace + defense