CometWatch – 15 August

Rosetta navigation camera (NAVCAM) image taken on 15 August 2014 at a distance of about 91 km from comet 67P/C-G.

Full-frame NAVCAM image taken on 15 August 2014 from a distance of about 91 km from comet 67P/Churyumov-Gerasimenko. Credits: ESA/Rosetta/NAVCAM

Full-frame NAVCAM image taken on 15 August 2014 from a distance of about 91 km from comet 67P/Churyumov-Gerasimenko. Credits: ESA/Rosetta/NAVCAM

Comments

21 Comments

  • idjles says:

    Where can i find information about the timing and maneuvers during your “pyramidal orbit” . You made big media events about the large burns, but what about your 60° burns? How do you measure the precise distance to the comet? Radar? Cameras? What is your accuracy at 100km? Have the perturbations in the trajectories given you good info about the density profile of the comet? Have you had to do micro-adjustments to the paths because of such perturbations?

    • Margarita says:

      The Planetary Society blog has a full schedule at the end of the blog post of 15th August.
      Here is the URL, if links are permitted:
      http://www.planetary.org/blogs/emily-lakdawalla/2014/08150814-finding-my-way-around-cg.html

      • Margarita says:

        This is what the other Emily listed at the Planetary Society
        Beginning on Sunday, Rosetta will transition to a slightly lower orbit, at around 80 rather than 100 kilometers, and it will spend the rest of August surveying from that altitude. Here’s a timeline of the upcoming events. Stay tuned for more great photos!

        First triangular “orbit” averaging 100 km, August 6 to 17
        August 6: arrival, begin first leg
        August 10: begin second leg
        August 13: begin third leg
        August 17-24: transfer to 50 km
        August 20: turn at 80 km
        Second triangular “orbit” averaging 50 km, August 24-Sep 3
        August 24: begin first leg
        August 27: begin second leg
        August 31: begin third leg
        September 3-10: transfer to global mapping orbit at 30 km
        September 10-24: global mapping at 30 km
        September 24-29: night excursion and transfer to 20-km orbit
        (September 25: announcement of landing site selection?)
        September 19-October 10: close observations at 20 km
        October 10- : close observations at 10 km
        November 11: Philae lands

  • raymundo dionicio says:

    The belly of duck/ET
    That ‘mare’ just at the middle
    seems promising for landing.

    Orbits shouldn’t get along at all
    with 67P shape so its going to be more
    of the comet hitting Philae than
    some kind of landing.

    This belly surface looks less weatherized
    than that of the head of even
    the back of duck/ET.

    The ‘snow’ in the neck
    sounds to me the more promissory,
    but this area is closer to what Philae
    was designed to land on.

    🙂

    • Donald Q says:

      The problem is you would be landing in a thick layer of dust, probably not optimal for research. Easy, safe…assuming you could stick your harpoons in it, but not very exciting science-wise.

      • raymundo dionicio says:

        Fully agree with you…
        Are this harpoons
        ‘fisher’ kind?,
        ‘batman’ kind?
        slooow motion kind?

  • Jacob nielsen says:

    The comet has a low density of app. 0,1. Does anyone know if this might be explained by a popcorn or styrofoam -like structure filled with voids?

    • Marco Parigi says:

      Yes. Sizeable voids under the surface would explain a lot. Firstly, the low density of course. Then the “jets” where most of the out gassing occurs. Voids would be where gas pressure would build up, burst through a soft spot in the surface. If the voids were tiny, you would expect lots of tiny jets. Hartley and other nuclei had sizeable discrete jets. Of course, the pressure below the jet and the temperature would imply the liquefaction of water, which would explain some of the minerals found in stardust.

  • doomsdayy says:

    nice post health in your hands

  • Ross says:

    Gotta love that hexagonal crater with a flat floor at the right edge of the smooth plain. In fact, several craters appear on the rim of the central smooth plain, and one of these craters (about 4 o’clock position) have a crater on its rim, all with flat, smooth floors and sharp ridges. Only pattern I’ve seen this occur in is electric discharge machining.

    I’m sure Rosetta will make its revolutionary discoveries soon enough.

    • raymundo dionicio says:

      Some chimneys seem four sided.

    • Dave Higgins says:

      Hi Ross,
      many features look like the result of electric discharge machining, some photos show paired deep parallel sided holes, like a plunge cut. Also some of the rocks on the floor of some of the flat areas even look a bit like the shape of the comet and consistent with the shapes produced in labs when discharging into sand or rock.
      regards

  • Neil says:

    After all that sleep, Sleeping Beauty/Rosetta is alive a kicking. Full credit to the Rosetta teams and to all the other wondrous projects ESA has operating and planned either by itself or in partnership with other agencies.

    Have you got a chemistry profile yet on the “head” and “body”?

  • Clive Hartland says:

    Has any set sequence of the ‘Tumbling path’ been ascertained yet, or is it random?
    I read that this is a recent Comet in our Solar system, I wonder why it now decides to enter our system and where was it before?

    Clive

  • Clive Hartland says:

    I have a question about the 2 discoverers of the Comet 67P/ C – G.
    Have they any involvement in the present Rosetta probe workings?
    They must be amazed at seeing close up of the comet they discovered.
    It would be interesting to hear of any comments about it that they may have made.

    Clive

  • Clive Hartland says:

    I have since found out that the Comets path going near Jupiter changed its course as Jupiters mass is so large and its gravitational pull so great it could deviate the Comets track!
    Also the Comet may not be visible to the naked eye and you would need a telescope to see it!

    Clive

  • Jacob nielsen says:

    Yes, to me it looks like “tuff”: the material that form the “icing” on Yucatan, Mexico. So exiting to follow here, what goes on in the inside in this micro gravitation environment.

  • Clive Hartland says:

    Thank you Emily, I was pleased to read through the 2 Links you gave.
    I am enthralled by the happenings and to see something that no man has set eyes on before.

    Clive

  • Dave Higgins says:

    (Editted)
    Re the density, I have looked at all the photos, especially where there are steep carved escarpments and also at the striated part of the head (that looks like its been exposed to erosion) and I can see no loose conglomerated of ice snow and boulders.
    The comet looks like homogeneous hard rock, no ice and no Styrofoam type porosity.
    It makes the low specific density hard to believe, Have you been able to re-access the mass and density of the comet from the pull of the comet?
    Will you be able to do this before the lander is launched?

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