Next-gen Rockets

Right now, companies around the world are building a new breed of super launcher that will have the capability to take bigger payloads in greater numbers beyond low Earth orbit (LEO) than ever before.

Known as heavy-lift rockets, these behemoths are essential if we are to continue our unmanned exploration of the Solar System as well as taking humans to new destinations. But there’s a reason the last such vehicle, the Saturn V, was retired over 40 years ago; these massive launchers are not only expensive but complicated and a huge engineering challenge, too. Now, however, it’s time to take up the mantle again as we re-evaluate our missions into the cosmos.

The Saturn V was a technological marvel; never before had such a huge undertaking been attempted. With Kennedy’s mandate set in 1961 to land Americans on the Moon by 1969, NASA was in need of a giant rocket that would be capable of taking a spacecraft beyond low Earth orbit and to the Moon. Smaller rockets, like those used to launch the Mercury and Gemini missions, simply didn’t have the muscle. The Apollo missions required more fuel and a bigger payload, including a lunar lander, command module and return capsule, that those earlier rockets simply couldn’t handle. The only way to get this amount of equipment to the Moon was to launch it in one go atop a rocket taller than a 36-storey building, the Saturn V.

With 13 successful launches under its belt, the Americans conquered the logistics of heavy-lift launchers with the Saturn V. Over in the Soviet Union, however, things did not go quite as smoothly. Around the same time the Saturn V was being built the Soviets were designing a comparable mega rocket of their own known as the N1. The comparison between the N1 and Saturn V shows just how difficult it is to build a rocket of this sort, and how challenging it can be to get one flying. When designing the Saturn V, NASA decided to go with a first stage that used five engines to provide the necessary thrust to reach orbit. The Soviets, on the other hand, went with a much more complex first-stage design. The N1 rocket, although similar in size to the Saturn V, had 30 separate hi-tech engines, and this complicated arrangement would prove detrimental. After four failed launch attempts, the N1 was retired. It highlighted just how difficult it was to build a rocket of this magnitude, and further cemented the Saturn V as an engineering masterpiece.

So now, with a variety of new super launchers being built around the world, the lessons learned from history, both the good and the bad, must be adhered to. Progress has been slow and steady, but in the coming years we’ll be seeing new concepts and developments, and even some flights, as mega rockets once again become one of the major ways to access space. But just why are these heavy-lift rockets so important?

”In our studies we’ve found that [heavy-lift rockets] provide us with a capability for multiple deep space exploration missions,” says Michael Wood, chief engineer at Boeing, the company contracted to build the core stage and upper stage of NASA’s huge Space Launch System (SLS). “Overall they are the fastest and most economical approach to put crewed habitats and science payloads in destinations we want with a flexible capability almost independent of the destination location. They are designed for that very specific purpose of deep space exploration where other rockets are not.”

There are several mega rockets currently in development. These include NASA’s Space Launch System (SLS), SpaceX’s Falcon Heavy and Russia’s Angara 7, all of which we’ve taken a closer look at in this feature. However, other global space agencies also have their own tentative plans to build rockets of this sort, such as China’s Long March 5. For any nation or agency to undertake deep space missions, they’ll need a mega rocket to launch any accompanying spacecraft.

Rockets use a form of propellant, either solid or liquid, to take off against the Earth’s gravity and get into space. Rockets that are placing a payload into orbit around the Earth need to move fast enough sideways so that the payload is constantly falling towards our planet and therefore encircles it – an orbit. To escape Earth’s gravity, however, a rocket must accelerate a payload beyond the escape velocity of Earth. To conquer the Earth’s gravitational pull you need to travel about 40,000 kilometres per hour (25,000 miles per hour). This enables you to travel into deep space.

The larger a rocket, the bigger the payload that can be taken into space and the more fuel it can carry. But on a specific rocket, an increase in the size of a payload decreases the amount of fuel it can take. Therefore, for some deep space missions, like NASA’s JUNO spacecraft that is currently on its way to Jupiter, they must rely on innovative power and propulsion methods in order to carry a large amount of scientific equipment. JUNO, for example, is almost entirely solar powered and is designed to make very slow progress towards Jupiter as it is not carrying much fuel – it launched in August 2011, and will not arrive at the planet until August 2016, using a boost from an Earth flyby in October 2013 to give it the speed to reach the gas giant. A bigger rocket enables such a payload to take more fuel, and therefore lowers the travel time to deep space locations.

When building rockets it can be useful to copy some of the designs that have previously been successful. NASA’s SLS, for example, will use hardware utilised by the Space Shuttle, Saturn V and Ares (cancelled in 2010). Similarly, SpaceX is using its Falcon 9 rocket as a base from which to build its Falcon Heavy. Essentially, the Falcon Heavy is three Falcon 9 rockets strapped together and, as the latter has been successful, it is hoped the former will not encounter too many problems.

The Falcon Heavy, when it comes into operation (which is expected to be some time in 2014), will be the largest rocket currently in operation. “Falcon Heavy will carry more payload to orbit or escape velocity than any vehicle in history, apart from the Saturn V Moon rocket,” SpaceX CEO Elon Musk stated in a press conference in April 2011. SpaceX has been vocal in its ultimate goal of not only reducing the cost of going to space, but taking humans to deep space destinations as well. With the Falcon Heavy it will ultimately be able to achieve its goals.

But the Falcon Heavy will only carry the mantle of the biggest rocket until NASA’s SLS launches in 2017. ”This is the largest rocket ever, not just that we’ve developed but that the world has developed,” says Wood. “It’s got about 8.4 million pounds [3.8 million kilograms] of thrust, and with a horsepower of 13,000 locomotives you get an idea of the power we’re talking about. The SLS is the biggest rocket by far. It’s got capability to lift 154,000 pounds [70,000 kilograms] to orbit, equivalent of about 12 elephants, and we’ve never done anything on this scale. It’s designed to have capability to power humans and habitats and space systems beyond our Moon and into deep space, so it’s quite a capability that we are developing for humankind.” Many people, however, wonder why it has taken such a long time to regain this capability since Saturn V was retired in 1973. By the time the SLS flies it will be almost 45 years since the last Saturn V launch, and it won’t evolve into a capability bigger than the Saturn V until the 2030s. As Michael Wood explains, though, our manned missions into Earth orbit for the last three decades have been vital in our understanding of manned exploration, and will enable us to carry out these new missions into the unknown.

“As I see the space exploration history and how we’ve proceeded, we have purposefully decided to look at deep space exploration in methodical means, meaning that people needed to learn to live and operate and build in space,” says Wood. “So coming out of the Saturn Apollo missions, NASA went for a means of low Earth orbit transportation [the Space Shuttle] to build a long-term habitat which was known as the International Space Station. This allowed us to collaborate on a global scale with other international partners to learn how to live and operate in space for extended periods of time. To mount the next expeditions, whether it’s to the Moon or an asteroid, and ultimately on to Mars, we need to learn to live and operate in space for extended periods of time and it’s a natural stepping stone, establishing some kind of a low camp if you will in LEO and building out from there to other destinations. It’s kind of required that knowhow that we’ve gained through the ISS.”

The most exciting prospect of heavy-lift launch vehicles is, of course, manned missions to asteroids and to Mars. The latter is now widely regarded as NASA’s long-term goal, which required the construction of the SLS. The Orion space capsule, which will be used to return astronauts to Earth at the conclusion of any such mission and possibly also be used as an exploratory spacecraft to asteroids, will fly in September 2014 on a Delta IV rocket to test its capabilities. When it eventually flies on the SLS, in December 2017, NASA will be ready to outline its plans to reach asteroids and Mars. Missions to Mars will require significant infrastructure including landing vehicles and an orbiting spacecraft.

Heavy-lift rockets are the future, and they are an absolutely essential means of travel if we are to continue manned exploration of the Solar System. These vehicles are already in development, and they will continue to be built and tested in the coming years. There is no turning back now; when these rockets are completed they will fly both unmanned and manned vehicles on missions the likes of which we have never seen before.

SQL - 16 | 0,472 сек. | 6.94 МБ