back to article ESA to try tank-to-tank fuel switch on sat that wasn't designed to do it

The European Space Agency is planning what it thinks is a world-first transfer of fuel between tanks on an orbiting satellite that wasn't designed to do the job. The agency's venerable XMM-Newton X-ray 'scope has been orbiting Earth since 1999, thanks in part to daily engine burns that keep its orbit stable. While the 'scope …

  1. Richard 12 Silver badge

    What were the other tanks for?

    The ESA page doesn't say, does anyone know and have a link?

    1. Paul Crawford Silver badge

      Re: What were the other tanks for?

      At a guess I would say for attitude control thrusters that unload momentum from the reaction wheels to keep their speed within sensible bounds.

      Some satellites use torquing coils to do that instead of chemical engines (basically pull against the Earth's magnetic field as needed) - not sure if there are any special reasons for XMM not using that, or maybe it has both and they managed to hardly ever use thruster fuel?

  2. Pascal Monett Silver badge
    Thumb Up

    Here's hoping it works

    Good ol' square-peg-round-hole problem. If anyone can solve it, it's the engineers at NASA.

    Good luck !

    1. Anonymous Coward
      Anonymous Coward

      Re: Here's hoping it works

      I think you'll find this is a European Space Agency project Pascal. Unless I missed a sarcasm tag somewhere.

    2. allthecoolshortnamesweretaken

      Re: Here's hoping it works

      Hey, ESA has steely-eyed missile men & women too!

      1. Yet Another Anonymous coward Silver badge

        Re: Here's hoping it works

        The main difference being that while NASA would make a film sending Bruce Willis up to it, ESA would make a film with Benedict Cumberbatch thinking how to solve it from the ground

        1. Mark Dempster

          Re: Here's hoping it works

          >The main difference being that while NASA would make a film sending Bruce Willis up to it, ESA would make a film with Benedict Cumberbatch thinking how to solve it from the ground<

          Actually they made that film (Space Cowboys) which starred Clint Eastwood & several other well-known pensionable actors. Utter rubbish if you look at it with an even slightly critical eye, but quite enjoyable otherwise

          1. Yet Another Anonymous coward Silver badge

            Re: Here's hoping it works

            Are you one of those conspiracy nuts who think that NASA faked Armageddon on a sound stage somewhere?

  3. Adam 52 Silver badge

    According to ESA, design life was 10 years not 2, which partly explains how they've managed to eek it out so long.

    And just one engineer brought back from retirement.

    1. Cuddles

      Eek!

      Eke.

      That aside, I hope I'm not the only one imagining a guy stepping out on a spacewalk with dirty overalls over his spacesuit and a length of rubber hose in hand.

      1. Mark 85

        Re: Eek!

        That aside, I hope I'm not the only one imagining a guy stepping out on a spacewalk with dirty overalls over his spacesuit and a length of rubber hose in hand.

        Harry Tuttle?

      2. John Brown (no body) Silver badge

        Re: Eek!

        "That aside, I hope I'm not the only one imagining a guy stepping out on a spacewalk with dirty overalls over his spacesuit and a length of rubber hose in hand."

        <long slow suck of air through teeth>

        That'll cost ya!

    2. Yet Another Anonymous coward Silver badge

      XMM is an x-ray telescope with a small optical camera (which I briefly worked on nearly 20years ago) so no liquid coolant so generally a very long life.

      With x-ray telescopes the life is generally limited by the operating system you wrote the data analysis software packages on. It's cheaper to launch a new spacecraft than to port all the analysis stuff from VMS to Ultrix, to Solaris, to Linux to Windows10

      1. Number6

        It's cheaper to launch a new spacecraft than to port all the analysis stuff from VMS to Ultrix, to Solaris, to Linux to Windows10

        Having got it working on Linux, why would you need to move it again? Especially to Windows 10.

        1. Yet Another Anonymous coward Silver badge

          So scientists can anayse the data on their phones. (x-ray astronomers aren't cool enough for iPhones)

  4. Anonymous Coward
    Anonymous Coward

    How?

    If tank-to-tank transfer wasn't designed in then I'd love to know how it is even remotely possible to retro-fit it - why would there be a path from one tank to another for any other purpose?

    Is there an engine that shares both the non-empty tanks and the main tank?

    Will shifting the fuel around affect the orbit?

    God*, I love this stuff!

    *Just a figure of speech.

    1. imanidiot Silver badge

      Re: How?

      Probably it's using a fuel selector and cutoff valves in a "non approved" manner. (Fuel flows out of full tank through normal "output" line, gets to tank selector valves, gets blocked from flowing to normal place, flows into empty tank through "output" line of empty valve.) There's a lot of valving and piping for redundancy in case a valve gets stuck. I can imagine that some imaginative use of valves can create a route from a full to an empty tank. All you then need is a pressure differential to get things flowing.

      1. Anonymous Custard

        Re: How?

        It won't be a retrofit (a bit tough to do for a satellite in orbit, at least now the shuttle's are museum displays), but I'd imagine it'll be lowering the pressure in the main tank as much as they can, overriding some interlocks and forcing a valve or three open to create a path for the flow between the tanks, presumably via pipework that isn't normally supposed to be open via that route/condition.

        But it's also wonderful to see yet another piece of space hardware far outliving its designed lifetime, although the cynic in me does have to wonder if they are applying Mr Scott's principle on their lifetime estimates...

        1. Complicated Disaster

          Re: How?

          Of course design lifetime for this sort of mission is to do with the funding for the ground segment operational expenses as well as the actual lifetime of the craft.

    2. Alister
      Boffin

      Re: How?

      What they're going to do is eject the fuel into space from the other tanks (at a low delta V) and then swing round and suck it all back into the main tank...

      No seriously, That's what they'll do, honest...

  5. Michael H.F. Wilkinson Silver badge
    Thumb Up

    Best of luck to the ESA team

    Ingenuity at its best. I love the way these engineers try to get the most out of a design

  6. Daedalus
    Boffin

    Er, there's a better way...

    If you can get an engine with fuel up there alongside the satellite (which is probably spinning to maintain direction, just to complicate matters) you don't need to transfer fuel. Just use the engine you brought along to keep the satellite in orbit. All you need then is a way of attaching the engine+fuel to the satellite.

    1. Kubla Cant

      Re: Er, there's a better way...

      Not, I suspect "better" in the sense of cheaper, easier, simpler or quicker.

      1. Daedalus

        Re: Er, there's a better way...

        After you've gone to all the trouble of doing the rendezvous, anything else is basically a rounding error. You need an engine with fuel to do the rendezvous. All I'm saying is that you might as well use the hardware you brought along to do the job rather than inventing some new, wonderful and potentially disastrously misconceived scheme.

    2. Anonymous Coward
      Anonymous Coward

      Re: Er, there's a better way...

      it'd affecting the pointing capability though- How badly would depend on how that attitude control system works.

  7. Gene Cash Silver badge

    Related: NASA will try to refuel Landsat 7

    Note that Landsat 7 wasn't designed to be refueled, so they're going to have to robotically deal with the "permanently sealed" tanks.

    "NASA has a builder to construct a five-ton spacecraft to catch up with the aging Landsat 7 Earth observation satellite and refuel it in 2020, employing robotic tools mastered in years of rehearsals on the International Space Station."

    http://spaceflightnow.com/2016/12/09/nasa-selects-builder-for-robotic-satellite-servicing-mission/

  8. Herby
    Joke

    Fueling....

    Will that be Regular or Hi-Test?? Sorry no Diesel today.

    Can I clean the windshield?? By the way, your oil is fine.

    Sorry, couldn't resist...

  9. John Smith 19 Gold badge
    Go

    Tricky.

    Short of some kind of servicing mission (no way that's going to happen less than 5 years) or they come up with some clever operations hack.

    Which looks like what they are planning to do.

    Over the years ESA and NASA have come up with some amazing (and amazingly complex) procedures to make probes and satellites either do things they were not designed to do or compensate for parts that have failed, through a mix of very clever simulations followed by software uploads to implement the plan.

    I suspect that this will involve some clever valve sequencing coupled with some patches to override certain safety features to do with tank pressurization.

    I'll with them good luck

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