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Blue Origin has successfully tested its new hydrogen/oxygen rocket engine.

The competition heats up: Blue Origin has successfully tested its new hydrogen/oxygen rocket engine.

This would be the second new American rocket engine since the 1980s, following SpaceX’s Merlin engine. That it uses hydrogen/oxygen is also significant, as these fuels provide the highest ratio of power to weight. (As far as I remember, the shuttle was the only other spacecraft to use hydrogen/oxygen.)

Post corrected. Thanks Paul!

Pioneer cover

From the press release: From the moment he is handed a possibility of making the first alien contact, Saunders Maxwell decides he will do it, even if doing so takes him through hell and back.

Unfortunately, that is exactly where that journey takes him.

The vision that Zimmerman paints of vibrant human colonies on the Moon, Mars, the asteroids, and beyond, indomitably fighting the harsh lifeless environment of space to build new societies, captures perfectly the emerging space race we see today.

He also captures in Pioneer the heart of the human spirit, willing to push forward no matter the odds, no matter the cost. It is that spirit that will make the exploration of the heavens possible, forever, into the never-ending future.

Available everywhere for $3.99 (before discount) at amazon, Barnes & Noble, all ebook vendors, or direct from the ebook publisher, ebookit. And if you buy it from ebookit you don't support the big tech companies and I get a bigger cut much sooner.


  • Paul Howes

    Other way round, Bob! Highest power to weight ratio

  • Chris Kirkendall

    I thought one of the engines used on Apollo was a Hydrogen/Oxygen engine (maybe not the main engines on Saturn V though) – ?? Anyone know?

  • Patrick Ritchie

    LH2/LOX offers the highest ISP of commonly used rocket fuels.

    Lots of US engines us Hydrogen, but not so many first stages.

    Off the top of my head:

    J2 – used on upper stages of Saturn V
    RS-68 – Delta IV first stage
    RL10 – Used in the Centaur upper stages, Saturn I, Atlas, Titan etc… Still used on Atlas V and Delta IV upper stages.

  • Chris Kirkendall

    Thanks for that info Patrick – I figured someone here would know! This site is such a great resource – so many knowledgeable folks here. BTW – why are Hydro/Oxy engines used only for upper stages & not for main booster engines?

  • Patrick Ritchie

    Some first stages use LOX/Hydrogen, notably the RS-68 on the Delta IV and the SSME on the space shuttle.

    As to why LOX/LH2 is best suited for upper stages: as I understand it high thrust beats out efficiency on the first stage but lower gross weight and higher efficiencies win out once you’re in vacuum.

    This favors RP1 for first stages and LH2 for upper stages.

    This isn’t a hard rule and the devil is in the details. The Russians use RP1 on almost all their stages (I believe Energia was the exception).

  • Chris Kirkendall

    … high thrust beats out efficiency on the first stage but lower gross weight and higher efficiencies win out once you’re in vacuum.

    Makes sense to me – thanks !

    Come to think of it, with the weight of all the propellant & large 1st stage at the start of the launch, a little extra engine weight would probably be more or less negligible. Once most of that is consumed & the vehicle’s outside most of Earth’s atmosphere, the remaining stage(s) & fuel would weigh much less (booster stage long gone at that point), the engine weight probably accounts for a bigger % of the total remaining vehicle weight & therefore makes a bigger impact on performance…

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