back to article Comet-chasing Rosetta spies SWEATY prey

The European Space Agency's (ESA) Rosetta comet-chaser has clocked 67P/Churyumov–Gerasimenko "releasing the equivalent of two small glasses of water into space every second" - enough to " fill an Olympic-size swimming pool in about 100 days". Graphic showing rate of water vapour outgassing from the comet It's going to take a …

  1. Rustident Spaceniak

    With all this transpiration -

    Does anyone know how much of the volatile material will recondense on the comet nucleus after it has passed the sun and vanishes into the black yonder, only to return after many years? You'd think that with so much sweating and possible later dirty rain on the comet, its surface composition will change over the eons.

    1. aBloke FromEarth

      Re: With all this transpiration -

      Here's an article about Halley's comet that discusses mass loss:

      Apparently, some of a comet's mass (including water etc) will come off, usually in the time it spends in the inner solar system (where it's warmer - further out it's completely frozen). As it leaves the inner solar system, the evaporate gradually refreezes.

      As a comet loses its ice, the darker coloured rock surfaces are exposed, so it gains more solar heat and so could theoretically change its orbital path over time.

      IANAA (I Am Not An Astrophysicist)

  2. Andrew Commons

    Re Bootnote

    Surely the rate at which a comet passes water is more properly measured in terms of the concepts expressed in this El Reg piece:

    So instead of 'Olympic Swimming Pools' maybe 'Cats urinating per minute'?

    1. Anonymous Coward
      Anonymous Coward

      Re: Re Bootnote

      No, the rate would be cats urinating, full stop. But the rate when it's nearer the sun, now, that might be measured in giraffes urinating.

      1. Andrew Commons


        Of course, the urethra squared law.

    2. Tom 38 Silver badge

      Re: Re Bootnote

      Surely this is more elegantly expressed in cans of coke per second, viz ~ 1 Cc/s.

      1. Elmer Phud

        Re: Re Bootnote

        "the equivalent of two small glasses"

        Hmm, need a standard for 'small glass'.

        Shot glass?

        Reused Nutella jar?

  3. Cubical Drone

    I hate it when I have moist out gassing!

    1. Anonymous Coward

      Have an upvote sir... and you owe me a new keyboard... brew everywhere!

  4. John 110

    Does this mean....

    Does this mean that we don't have to invade Earth and steal the water, we actually flew past gallons on the way in!!


    Somebody find me the keys for the saucer, I'm off home.

    1. Elmer Phud

      Re: Does this mean....

      " we actually flew past gallons on the way in!!"

      Don't count your space chickens -- these may be U.S. gallons.

  5. Martin Budden

    When Rosetta gets really close, will there be enough out-gassing to cause a noticeable "upward" pressure affecting Rosetta's course?

    1. Anonymous Coward
      Anonymous Coward


      I hope they've rust proofed it as it's a long way to go with a can of the above.

      1. Rustident Spaceniak

        Re: WD40

        Ever seen one of the French cars near the launch site? It was specified to survive that.

  6. Dr Patrick J R Harkin

    Glasses per socond?

    But how long to cover Wales to the depth of a double-decker bus?

  7. Please answer me

    Why is it going to take until August to reach the comet - surely this probe is travelling at about 30000 MPH even with my bad maths that means it's gonna be there in hours not months?

    1. Tom 38 Silver badge

      There are two reasons why it will take so long:

      a) The comet isn't sitting still - it is also going very fast.

      b) Generally when you approach an object you want to land on, it is advisable to be going significantly less than 30000 MPH or parking dings may occur.

  8. Please answer me

    Why is it going to take until August to get to the comet - surely the craft is going at about 26000 MPH - It'll be there in hours?

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