The most powerful rocket ever built will use four space shuttle engines and two solid rocket boosters to propel NASA astronauts to Earth orbit and beyond—and that translates into a lot of rocket fuel. The U.S. space agency recently finalized a $2.8 billion contract with Boeing to build the rocket's core stage, which will contain the hundreds of of metric tons of liquid hydrogen and oxygen needed to fuel the four main engines.
NASA is planning a test flight of the so-called Space Launch System (SLS) rocket in 2017. The test will demonstrate an initial 70-metric-ton lift capacity configuration of the rocket that will carry an uncrewed Orion spacecraft beyond low-Earth orbit. A successful test would pave the way for the rocket to evolve into history's most powerful launch vehicle with a lift capability of 130 metric tons, allowing human missions to near-Earth asteroids, the moon and Mars, according to The Register.
"Our teams have dedicated themselves to ensuring that the SLS—the largest ever—will be built safely, affordably and on time," said Virginia Barnes, vice president and program manager of Boeing SLS, in a press release. "We are passionate about NASA’s mission to explore deep space. It’s a very personal mission, as well as a national mandate."
The SLS represents NASA's first deep-space exploration vehicle for humans since the huge Saturn V rocket took U.S. astronauts to the moon more than 40 years ago. The initial 70-metric-ton configuration of SLS will have 10 percent more thrust than the Saturn V and once the 130-metric-ton configuration is completed, it will provide 20 percent more thrust than the Saturn V. That configuration should provide the necessary boost for human missions aimed at Mars. (For more on the latter possibilities, see IEEE Spectrum'sSpecial Report: Why Mars? Why Now?)
SLS makes good use of NASA's legacy technology in its design, including the using the high-efficiency RS-25 engines used by the space shuttle. NASA's new SLS rocket will also use larger versions of the space shuttle's twin solid-fuel boosters. The Orion spacecraft that will carry astronauts on their missions is inherited from NASA's previous Constellation program aimed at returning U.S. astronauts to the moon.
The NASA deal with Boeing makes the latter the prime contractor responsible for the SLS rocket's core stage. Standing 64.6 meters tall, the core stage will store the liquid hydrogen fuel and liquid oxygen oxidizer at cryogenic temperatures below -150 degrees C, as well as hold the rocket's main electronic systems and flight computer.
Boeing has also been given the job of studying the upper stage required for the 130-metric-ton version of the SLS rocket. That upper stage would provide the bigger boost necessary to send astronauts on deep space missions with two J-2X engines being developed by Pratt & Whitney Rocketdyne. The J-2X engines would also be fueled by liquid hydrogen and oxygen.
NASA representatives and the Boeing company recently met for the Critical Design Review board overseeing the SLS at NASA's Marshall Space Flight Center in Huntsville, Alabama on June 30 and July 1. The Critical Design Review represents the last major review before production begins on the core stage.
"Completing the CDR is a huge accomplishment, as this is the first time a stage of a major NASA launch vehicle has passed a critical design review since the 1970s," said Tony Lavoie, manager of the Stages Office at NASA's Marshall Space Flight Center, in a press release. "In just 18 months since the Preliminary Design Review, we are ready to go forward from design to qualification production of flight hardware."
NASA's human spaceflight program hasn't had much to cheer about in the past decade with the Constellation program's cancellation in 2010 and the subsequent retirement of the space shuttle fleet in 2011. But if NASA's budget and test launch schedule stays on track, the 130-metric-ton configuration of SLS could eventually blast off in 2021 with a payload that includes the Orion spacecraft and up to four U.S. astronauts.
Jeremy Hsu has been working as a science and technology journalist in New York City since 2008. He has written on subjects as diverse as supercomputing and wearable electronics for IEEE Spectrum. When he’s not trying to wrap his head around the latest quantum computing news for Spectrum, he also contributes to a variety of publications such as Scientific American, Discover, Popular Science, and others. He is a graduate of New York University’s Science, Health & Environmental Reporting Program.