back to article Magnifico! Galileo satellite nudged back into correct orbit

The European Space Agency has managed to salvage one of two misplaced Galileo satellites that it is using to build an alternative to the US's GPS system. ESA launched the fifth and sixth satellite that will make up the Galileo constellation on August 22 – but the were sent into the wrong orbit. It was initially thought the …

  1. -tim
    FAIL

    Failure or test scenario?

    Why not just turn it on and see if the system works with sats that are in such wonky orbits? As long as the parameters for the orbit data can be sent in the constraints of the message format, the orbit won't matter much and they might learn something useful. I wonder why they were in a hurry to move the orbits since it takes far more fuel to move it quickly and it won't matter until more of the constellation is working.

    1. stizzleswick
      Boffin

      Re: Failure or test scenario?

      "Why not just turn it on and see if the system works with sats that are in such wonky orbits?"

      Because "in such wonky orbits," unfortunately, the orbit is likely to be rather unstable, making constant re-calibration necessary. In the intended orbits, the satellites already up can help guide the other satellites into their proper spots, without constantly spending reaction mass that was originally intended to do course corrections for the next 10 years.

      Basically, by right now spending approx. half of these two satellite's reaction fuel, they can save many times that for the (literally) up-coming satellites. The end result is most likely going to be that replacing these two birds earlier than planned is actually going to save the ESA some money. Sounds weird, but then again, this is Rocket Science ;) -- there are a couple of lessons available here (and the people at DASA are already working on them) which may make future additions to geolocation satellite systems more efficient.

      1. easyk

        Re: Failure or test scenario?

        Rocket Economics: The Dismal Rocket Science.

      2. JeffyPoooh
        Pint

        Re: Failure or test scenario?

        "...the satellites already up can help guide the other satellites into their proper spots..."

        If that's true, then it's weird. It implies a satellite to satellite link system. Or it implies that the ground system can't find their satellites through other means. Or it implies that the ground stations don't know where they are located.

        It's either weird, weirder, or weirdest. Or perhaps not precisely correct.

        1. stizzleswick
          Boffin

          Re: Failure or test scenario? @JeffyPoooh

          " It implies a satellite to satellite link system."

          Yup. The satellites are talking to one another. Helps a lot with calibration, too.

      3. -tim
        Boffin

        Re: Failure or test scenario?

        Being able to test an unstable orbit is a very good thing. So far many of the NavStar sats have ended up in less than perfect orbits and they have to be shut down if they don't go over the right earth based tracking systems. The Galileo system doesn't have that limitation so constant re calibration can be done and their prediction models can be updated to compensate for it which would give it a slight advantage over existing NavStar sats. The only way these sats would save fuel in upcoming launches is if they didn't but a decent multi-scheme GPS receiver on board. These stats aren't being positioned within the specs of a space based system (i.e. put them within a meter of so of their orbit), they are being put in an orbit that can be described by a 3d mathematical model using something like a 12th order polar coordinate polynomial. The orbits are already perturbed by the moon, Mars, Jupiter, Saturn and a few other factors that were detected by Gravity Probe B. Newtonian orbit wonkyness is trivial compared to the rest.

  2. Yet Another Anonymous coward Silver badge

    Whose boosters?

    >French launch company Arianspace admitted that its boosters were at fault.

    I thought the launch had used a Russian rocket launched from Ariane's site?

    The next launches will use proper French (well european) rockets

    1. Mark 85 Silver badge

      Re: Whose boosters?

      Only the first stage used Russian equipement. Here's the article on the failure: http://www.theregister.co.uk/2014/10/13/hardened_hydrazine_the_source_of_galileo_satnav_fail/

      1. MondoMan

        Re: Whose boosters?

        Actually, it was the *last* (fourth) stage that was Russian-built. The "Fregat" transfer stage/vehicle is apparently a generic "space tug" with a restartable engine that is intended to carry attached satellites to individual final orbits before releasing them.

        1. Anonymous Coward
          Anonymous Coward

          Re: Whose boosters?

          All four stages were Russian designed and built - first three are the Soyuz rocket system, fourth was Fregat. The Soyuz and Fregat vehicles are built by two different Russian companies.

          The fault was in the Fregat vehicle, simple version is this: They ran a liquid helium pipe (very, very cold) next to the hydrazine pipe, which resulted in the hydrazine fuel freezing solid and cutting off thrust.

          1. Anonymous Coward
            Anonymous Coward

            Re: Whose boosters?

            "...Russian... ...simple version is..."

            So it wasn't a stray empty vodka bottle left tucked into a corner?

  3. kyza

    Mad scientist words

    I'm fitting Passive Hydrogen Masers to all the sharks at my secret base near Oberpfaffenhofen.

  4. Suricou Raven

    How long before we see more ion engines?

    If the sats used those, theyd pack enough delta-V that a major orbital adjustment isn't much of a concern.

    1. David Harper 1

      Re: How long before we see more ion engines?

      As long as you don't mind waiting a couple of centuries :-)

      1. A Known Coward

        Re: How long before we see more ion engines?

        Ion engines aren't THAT slow. The Dawn probe has been zipping around the solar system on it's ION engines since it's launch in 2007. After a year of studying Vesta in 2011, it set course for Ceres and is due to arrive in 2015. By comparison to that journey, a small orbit change for a satellite is nothing.

  5. James Ashton

    What's the Impact on their Service Life

    Any word on how many years of operational life have been sacrificed? Maneuvering fuel is often the limiting factor for satellites and presumably they must have used plenty of it to make a substantial orbital change like this. Once the fuel tanks are nearly empty the birds can no longer maintain station. They're supposed to use the last of their fuel to move away to a graveyard orbit or deorbit to avoid being a hazard.

  6. David Goadby

    shorter life?

    Using so much propellant must shorten the life of the satellite as future corrections will need it.

    Why are the EU wasting out money on this in the first place?

    1. Yet Another Anonymous coward Silver badge

      Re: shorter life?

      Your entire civil aviation, maritime transport, emergency services, road pricing, traffic management relies on a system which a semi-friendly country can turn off the next time you don't allow GM foods or hormone dosed meat into the eu ?

      Or if you decline the opportunity to take part in their latest war then can not only call you cheese-eating surrender monkeys - but also shut down your transport infrastructure.

      1. Alan Brown Silver badge

        Re: shorter life?

        "Or if you decline the opportunity to take part in their latest war then can not only call you cheese-eating surrender monkeys - but also shut down your transport infrastructure."

        The USA has made it clear that if the EU doesn't shut down Galilleo "on demand", then they'll shoot the satellites down.

        You have to wonder how such a threat would go down against Glonass or Compass.

    2. John 98

      Same as the US could save loads of money by using Glasnost. Remember, the US has been known to put pressure on other nations in various ways including denying use (or the threatening to deny use) of GPS.

  7. Graham Marsden
    Coat

    Let me go!

    Bismillah, NO! We will not let you go...

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