back to article China launches 'pollution-free' rocket

China used its latest green rocket design to carry 20 micro-satellites into space on Sunday. Xinhua news agency reports the Long March–6 was successfully launched from the Taiyuan Satellite Launch Centre in north China’s Shanxi Province. While it won’t earn a Greenpeace sticker, the Long March–6 is about as environmentally …

  1. Ru'

    At least one nation seems serious about space exploration.

  2. Your alien overlord - fear me

    If it cares about pollution, should Beijing businesses be run on Long March-6's?

    1. Kharkov
      Facepalm

      A Rocket in every factory...

      Now I have an image in my head of a Long-March 6 in every Beijing factory. A couple of thousand factories, all powered by an LM-6 in every yard. And every couple of weeks, a rocket pops free of its mountings...

  3. hplasm Silver badge
    Boffin

    Pollution free?

    Kerosene? Surely LOX and LH are the most pollution free.

    Excluding whatever Carbon Boots are used to produce the liquids in the first place, natch.

    1. Grikath Silver badge

      Re: Pollution free?

      I think you'll find the creation of LOX and especially LH requires quite a bit of energy....

      Compared to the other hypercholic stuff they use in rockets, kerosene is almost like pure mountain air.

      1. Martin Budden

        Re: Pollution free?

        I think you'll find the creation of LOX and especially LH requires quite a bit of energy....

        ....which could very easily be green energy e.g. hydro, geothermal, etc.... and China are famous for making affordable solar panels.

  4. VinceH Silver badge

    "Chinese media have reported plans for a more ambitious mission to the dark side of the Moon before 2020."

    Do you mean the far side?

    1. John Robson Silver badge

      Dark - as in dark ages - as in the less studied (at least when it was named) side.

      It's not quite as light bathed as the earthside (which recieves earthlight as well as sunlight) but it is pretty close...

  5. LesC
    Mushroom

    If that's a current long march the luminous flame means hydrocarbons not being burned efficiently if they were the flame would be blue with shock diamonds. . LOX & RP-1 have been propellants since the early days of rocketry and was used on the Saturn 5. Kerosine or JP fuels tend to sludge up rocket engines. When the fireball is burning nicely this'll burn to CO/CO2/H20 probably with some remaining unburned hydrocarbons as it'll run slightly rich to keep the temperatures down. And some NOX.

    Best propellant combo are liquid hydrogen and LOX but the thought of all that seriously cryogenic LH2 sloshing about puts the rocketeers off.

    A Big Bang as that's what you get if these things spontaneously self-disassemble.

    1. Sorry that handle is already taken. Silver badge

      Liquid rocket engines tend to be run fuel rich for a number of reasons. Performance is one of them - you get better efficiency by not burning cleanly, since the efficiency is inversely proportional to the molecular weight of the exhaust products. Lots of CO and H2 in the exhaust of a hydrocarbon burning rocket by design.

      1. Anonymous Coward
        Anonymous Coward

        you get better efficiency by not burning cleanly,

        Bowing down before the rocket scientists, could I humbly ask why efficiency improves? I follow the logic about keeping combustion temps down, but surely the less efficient the burn, the more fuel & structure weight you're having to lift. Is it really more efficient to lift fuel and then hose a proportion of it out the back end unburnt?

        1. lawndart

          There are two measures with a rocket engine.

          Firstly there is thrust.

          Then there is fuel consumption.

          With conventional rocket engines one is inversely proportional to the other. Thrust means you cannot achieve fuel consumption efficiency as the exhaust velocity is relatively low.

          You want a lot of thrust when you launch from Earth as you have to push your entire rocket up against gravity, and quickly enough that it doesn't topple over when you lift off the pad; consequently you want to shove as much propellant mass out of the nozzle as possible, even if you don't clean burn the entirety of your propellant. Rocket nozzles are optimized for certain flight regimes and the first stage is usually burning most efficiently not that far from the pad.

          This is where the kerosene/RP1 comes in for big lifting because it is vastly denser than that other major rocket fuel, hydrogen.

          Fuel consumption kicks in when you are at altitude and moving fast. You use your second and subsequent stages to burn much lighter propellant, such as liquid hydrogen.

          The critical value here is exhaust velocity. The hydrogen, being as light a molecule as you can get, is kicked out at a much higher velocity and so is much more efficient as a fuel - the efficiency is measured as the log of the exhaust velocity.

          The downside is the thrust is small compared to the Kerosene/RP1 propellant and your LHyd/LOx rocket may not even have enough thrust to get off the ground, so is useless as as first stage.

          One way round the thrust/efficiency conundrum is to go nuclear. You can shove the hydrogen fuel out the reactor nozzle at ludicrous velocities, hundreds of times more efficiently as a chemical rocket and get big thrust as well.

          The problem is that as soon as you mention nuclear some people start frothing at the brain and automatically hitting the downvote button.

          1. Anonymous Coward
            Anonymous Coward

            Ah! I remember some more about this from reading Sutton & Biblarz!

            The efficiency of a rocket engine is known as the Specific Impulse or Isp. It's related to how much exhaust can be ejected, and how fast. If a rocket generates lots of smaller molecules in its exhaust (CO is smaller than CO2, H2 is smaller than H2O), then any heat energy can be better used to make those smaller molecules move faster. The equation for kinetic energy is 0.5*m*v^2, so for the same amount of energy and a lower mass of molecule, you get a much larger velocity. More exhaust velocity == more Isp = VROOOM!

            Of course you have to burn some fuel and oxidiser to get the heat in the first place, so you can't get even more thrust by just ejecting cold H2 gas (thought it is surprisingly effective).

            I think the "clean" bit is because it's not using carcinogenic hydrazine-based fuels N2H4 / UDMH and N2O4. A lot of China's rocket tech is soviet based, and the Russians rockets often used these, at least in the past, because they were storable (not-cryogenic) and so better for use in ICBMs :(

            1. Anonymous Coward
              Anonymous Coward

              @lawndart & Dantium

              Thank you. Again, I prostrate myself before you higher beings.

              1. lawndart

                Re: @lawndart & Dantium

                Oops. That should read "You can shove the hydrogen propellant out the reactor nozzle at ludicrous velocities, hundreds of times more efficiently as a chemical rocket and get big thrust as well."

                With a nuclear engine the fuel is whatever material you are burning in the reactor (uranium/plutonium etc.)

            2. LesC
              Mushroom

              Clark's excellent "Ignition" goes into all this in detail, a quick google will get you a PDF. A must read, a basic grasp of maths and chemistry is handy but not vital. There are quite a few amusing moments too.

              Plenty epic fail on YouNyancat. Rocketry fails provides the best Guy Fawkes fireworks!

              Explosion - due to a tank of HTP and one rat.

      2. Dan Paul

        Remember the noise when you light a cutting torch?

        You always want to light the rich burn mixture first and then slowly trim O2 to the right ratio or the damn thing goes "POP" like the torch, only a lot louder and with far more dire consequences.

        As said elsewhere, the right final flame color is blue with shock lines in it. We don't typically see that here on Earth launches because we often use solid fuel boosters to get the bird off the ground. Since they burn ammonium perchlorate and latex rubber with carbon black in them, they smoke like a volcano and obscure the LOx/H2 flames.

    2. PNGuinn
      Joke

      Pollution free rochet or rocket)

      Why not diesel and liquid oxygen? We all know that with a little added German software knowhow that burns incredibly cleanly....

  6. Elmer Phud

    Mini-satellites

    Momentarily donning an aluminum or aluminium hat --- what about when 200 or so mini-sats finally combine and produce one big fuck-off military-spec satellite hunter?

    Sky falling in, etc etc.

    1. John 62

      Re: Mini-satellites

      Forget micro-meteorites the size of a pea blasting an hole in a satellite's side, what about a micro-satellite about the size of a backpack colliding with your mil-comm-sat?!

  7. Santa from Exeter
    Alien

    FTFY

    China has already landed a rover on the Moon, the third nation to do so after Russia and the USA.

    Lunokhod 1 - USSR - 1970

    Apollo Rover - USA - 1971

    1. Anonymous Coward
      Anonymous Coward

      Re: FTFY

      China has already landed a rover on the Moon,

      What, the Roadkill Rabbit, or whatever, that promptly keeled over? I understand the pain and loss of the Chinese proletariat - I've had Chinese made stuff that only lasted that long.

      Although I suppose they're still doing better than Beagle 2.

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