Aug 22, 2023 - Science

Space industry eyes next generation fuels to send rockets to new heights

Illustration of a rocket with wake behind it forming a circular arrow repeat symbol

Illustration: Natalie Peeples/Axios

Demand for reusable rockets that will launch more satellites to space and support lofty ambitions to travel farther from Earth are shaping the future of the space industry.

Why it matters: Companies are rethinking how to best power rockets that get spacecraft to orbit, and they're using new fuels to make it happen.

What's happening: In July, China's Landspace successfully launched a rocket powered by a mixture of liquid methane and oxygen for the first time in history.

  • SpaceX's next-generation Starship rocket, which is designed to carry payloads to deep space, RocketLab's Neutron, Blue Origin's New Glenn, and ULA's Vulcan Centaur are all fueled by methane.
  • All of these rockets are expected to be reusable — but they haven't been successfully launched yet.

How it works: Modern rockets propelled by liquid fuel largely use either a mixture of kerosene and oxygen (kerolox) or hydrogen and oxygen (hydrolox).

  • But kerolox doesn't burn clean, limiting the reuse of rockets propelled by the fuel. And extensive infrastructure is needed for storing and moving liquid hydrogen.
  • Methane, however, is a cleaner and more efficient fuel than kerosene.
  • It's also possible methane could be made on Mars from hydrogen and carbon dioxide, eliminating the need to carry heavy fuel there from Earth.

Zoom in: Methane is taking over as the fuel of choice for many new rockets coming online in the coming years.

  • "We've seen over the past two decades just a huge increase in interest in using methane as a rocket fuel," Stephen Heister, professor of engineering at Purdue University, tells Axios. "In most instances, it's replacing kerosene, which was used in the Apollo program."
  • During Apollo, methane wasn't as available as it is today, Heister said. But, he added, liquid methane has become more available with increased natural gas production and refining.
  • Methane also produces about 10% more thrust than kerosene, Heister said. "If you're using the same flow rates of propellants, you would get 10% more thrust, and that's hard to argue against."

Yes, but: As the space industry grows and more launch providers come online, concerns are mounting about the environmental impact of these rockets and their fuel.

  • Methane burns more cleanly than kerosene, but it's possible that during transport, gas pipes could leak methane into the atmosphere, fueling climate change.

What to watch: Researchers are studying other possible rocket propellants beyond methane.

  • A biofuel based on a molecule produced by a species of bacteria is in the early stage of development, and another hybrid, biofuel rocket engine was tested last year.
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