How NASA's new SLS megarocket stacks up against its legendary predecessor the Saturn V

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How NASA's new megarocket stacks up against its legendary predecessor

"It's a great pickup truck. I'm glad we built it. And I'm ready to fly."

mashable.com

NASA's SLS rocket as it starts rolling out to its Kennedy Space Center launchpad. Credit: NASA / Ben Smegelsky

When NASA blasted its colossal rocket to the moon in July 1969, the denizens of Earth watched the 363-foot-tall behemoth on televisions in department stores, on a giant screen in Central Park, and in living rooms in Tokyo and Paris. Still today, it's the most powerful rocket ever successfully flown.

This rocket, the Saturn V, could propel the weight of some four school buses to the moon. It sent astronauts to the chalky lunar surface six different times. And it hauled America's first space station, Skylab, into orbit around Earth.

Now half a century later, NASA is on the cusp of launching its new powerful megarocket to the moon, a class of rocket the aerospace industry calls a "super heavy-lift launch vehicle." Indeed, this rocket, the Space Launch System (SLS), is set to supersede Saturn V as the most powerful vehicle ever blasted into space. Yet it's not a "better" rocket. It's designed to do different, and unprecedented, things. Namely, NASA intends SLS to carry the resources and people needed to establish a permanent presence on the moon, and maybe even blast astronauts to Mars.

"It's a great pickup truck. I'm glad we built it. And I'm ready to fly," John Blevins, the chief engineer for NASA's SLS rocket, told Mashable.

Flying back to the moon is crucial for the future human exploration of deeper space. A looming exploration problem is how the fragile human body will hold up to the likes of space radiation and isolation. Missions to the moon will inform NASA how to keep people safe, and how to ensure their survival in an inhospitable world where astronauts will likely have to harvest water ice from the moon's shadowy craters.

"These are crucial lessons before we put them on a rocket and send them to Mars," Paula do Vale Pereira, an assistant professor of aerospace engineering at the Florida Institute of Technology, told Mashable.

How NASA's new SLS rocket (left) stacks up against the Saturn V and the Statue of Liberty. Credit: Bob Al-Greene / Mashable

Why not resurrect Saturn V?​

After NASA's legendary Apollo missions ended, the space agency no longer needed a colossal moon rocket. Instead, NASA put effort into constructing the International Space Station, and built the Space Shuttle to bring astronauts and infrastructure to Earth's orbit, some 250 miles above the surface.

But NASA turned its eyes back to human exploration of deep space in the aughts, and they considered rebuilding a Saturn V rocket, or using integral rocket parts from the Apollo era. Saturn V, of course, was already proven. It had already done the job.

"We looked at resurrecting that," said NASA's Blevins.

Yet rebuilding Saturn V would have required reaching back many decades into technology and rocket materials that were no longer around. NASA, and its contractors, would have to resurrect parts and processes. So the agency scrapped any Saturn V plans. "It was better to just move on," said Blevins.

Instead, the agency designed the SLS with key, tried-and-true components — notably the engines — of the Space Shuttle. After all, NASA engineers understand those engines better than any other. And they are mighty powerful.

The Saturn V rocket blasting off in 1967. Credit: NASA

SLS isn't just one rocket​

Saturn V was a single rocket design with a primary overall mission: Safely getting NASA astronauts to the moon and back without killing anyone.

But SLS can be reconfigured in six different ways for six different missions. The rocket, for example, will at times carry astronauts to the moon; and at other times it will haul cargo, such as parts for a moon base, to the lunar surface.

"We're more like a fleet of rockets," explained Blevins. "SLS is a platform. Saturn V was a targeted mission."

The different SLS configurations are designed around the 212-foot-tall, orange central rocket booster, which is called the "core stage." It's the backbone of the vehicle. The majority of a rocket is composed of giant fuel tanks, and the SLS is no different. Its great aluminum core stage, which fuels four Space Shuttle engines, holds 537,000 gallons of liquid hydrogen and 196,000 gallons of liquid oxygen.

The orange rocket stage will fire for over eight minutes before its fuel is spent. By then, it will have accomplished its job. It will have blasted its precious cargo — whether the Orion spacecraft or other cargo — into space.

But that's not the only essential thing pushing SLS beyond Earth.

Six different SLS rocket configurations. Credit: NASA / MSFC

The two powerful boosters​

Unlike the Saturn V, the SLS has two rocket boosters strapped to the side of its backbone. These are called "solid rocket boosters" — because they use solid fuel compounds — and they give SLS a potent push through the atmosphere.

NASA created these boosters from the Shuttle design. But on the SLS, they're bigger. These 17-story rockets carry 25 percent more fuel than the Shuttle's, and provide 75 percent of the SLS's thrust, or force pushing down against Earth, during the first couple of minutes the SLS speeds through the atmosphere.

Engineers testing an SLS solid rocket booster in the Utah desert. Credit: Northrop Grumman

"We take [boosters] to the max," said Blevins. "These are the largest solid boosters ever built."

Between the core stage and the two boosters, the SLS will produce 8.8 million pounds of thrust, which is 15 percent more thrust than the Saturn V. That will allow NASA to send loads of moon-bound cargo, and spacecraft, beyond Earth's orbit and en route to the moon.

"It has so much more thrust than any other rocket that has been sent to space," said the aerospace engineer do Vale Pereira.