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Thread: Dawn at Vesta

  1. #1
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    Dawn at Vesta

    According to the BBC Dawn has sent back signals confirming it's in orbit:

    Probe orbits asteroid Vesta

  2. #2
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    Dawn herself confirms
    http://twitter.com/#!/NASA_Dawn

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    !

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    I've been following the progress of Dawn since launch. I get all the emails from the Dawn mission site, so I was very happy to hear that Dawn had entered orbit around Vesta successfully!

    I'm looking forward to seeing the great images we can expect shortly as Dawn lowers its orbit.

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    Nice image released today. Phil has a blog entry about it here.

    Emily has been strangely silent about it (the approach and entry in to orbit), even though she's been back from vacation. I expect she'll have a rather nice write-up when she gets to it, though!

    CJSF
    Last edited by CJSF; 2011-Jul-18 at 09:10 PM.
    "Soon the man who sweeps the room brings the secret telegram, 'COMMENCE OFFICIAL INTERPLANETARY EXPLORATION.' "
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  6. #6
    Big article with new images from orbit:
    http://www.nasa.gov/mission_pages/da...20110718.html#

    How come all the images appear a bit blurry? They're not as crisp and detailed as I was hoping they'd be at this point.

    ---

  7. #7
    Quote Originally Posted by Vilkata View Post
    How come all the images appear a bit blurry? They're not as crisp and detailed as I was hoping they'd be at this point.
    They're taken with the framing camera, a wide angle instrument. They're scaled up...you can see some pixelation left over.

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    Quote Originally Posted by CJSF View Post
    Nice image released today. Phil has a blog entry about it here.

    Emily has been strangely silent about it (the approach and entry in to orbit), even though she's been back from vacation. I expect she'll have a rather nice write-up when she gets to it, though!

    CJSF
    Seems I was right. Here's Emily's Planetary Society blog entry.

    CJSF
    "Soon the man who sweeps the room brings the secret telegram, 'COMMENCE OFFICIAL INTERPLANETARY EXPLORATION.' "
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  9. #9
    So, what's the data on surface composition?

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    Quote Originally Posted by Winner View Post
    So, what's the data on surface composition?
    They just achieved orbit 2 days ago. I suspect they haven't even started collecting that data yet, let alone transmit it to Earth, process it, and then do the human analysis. This is a year long mission (at least), they are not going to do everything in the first three days.
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  11. #11
    Quote Originally Posted by Swift View Post
    They just achieved orbit 2 days ago. I suspect they haven't even started collecting that data yet, let alone transmit it to Earth, process it, and then do the human analysis. This is a year long mission (at least), they are not going to do everything in the first three days.
    Of course, I was just wondering if they've done some analysis during the approach phase.

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    Quote Originally Posted by Winner View Post
    Of course, I was just wondering if they've done some analysis during the approach phase.
    I couldn't find the details for this mission, but generally NASA/JPL don't do anything more than some minor testing of the scientific instruments during the flight. The images so far have been done with what is essentially their navigation camera. Now that they are in orbit, the scientific package will be warmed-up, tested, and calibrated (if appropriate for the particular instrument). Once they are satisfied everything is working (and that can sometimes take a couple of weeks), they will start the serious data collection. Data processing and analysis starts immediately after that, but can take a while too.

    One other thing (from Emily's blog, linked above) - they are currently in orbit, but not the "survey orbit"; in other words, they want to slowly move closer, to get better resolution. That also will take several weeks.

    Given both of these considerations, I suspect it will be several weeks more till we start seeing serious amounts of data.
    Last edited by Swift; 2011-Jul-19 at 01:35 PM. Reason: added paragraph
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    From the UT article:

    “We will not have a steady stream of images until we are in one of our three science phases,”
    ... “When we are in transit from one place to another we thrust, stop, turn, image, turn, transmit, turn, thrust, and several days later repeat. All time spent not thrusting is time taken away from science later.”

    [Prof. Chris Russll, Dawn’s Science Principal Investigator of UCLA]
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  14. #14
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    Some more details from this R&D Magazine on-line article:
    Although orbit capture is complete, the approach phase will continue for about three weeks. During approach, the Dawn team will continue a search for possible moons around the asteroid; obtain more images for navigation; observe Vesta's physical properties; and obtain calibration data.

    In addition, navigators will measure the strength of Vesta's gravitational tug on the spacecraft to compute the asteroid's mass with much greater accuracy than has been previously available. That will allow them to refine the time of orbit insertion.

    Dawn will spend one year orbiting Vesta, then travel to a second destination, the dwarf planet Ceres, arriving in February 2015. The mission to Vesta and Ceres is managed by JPL for the agency's Science Mission Directorate in Washington. Dawn is a project of the directorate's Discovery Program, which is managed by NASA's Marshall Space Flight Center in Huntsville, Ala.
    At night the stars put on a show for free (Carole King)

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  15. #15
    New photo taken July 18th, released yesterday.
    http://dawn.jpl.nasa.gov/feature_sto...back_photo.asp

    ---

  16. #16
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    Quote Originally Posted by CJSF View Post
    Emily makes an interesting observation: Vesta's lumpier and less spherical than some moons having lesser diameters.

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    She has explained that is likely because the other satellite's have a high ice content, which deforms easier.

    CJSF
    "Soon the man who sweeps the room brings the secret telegram, 'COMMENCE OFFICIAL INTERPLANETARY EXPLORATION.' "
    -They Might Be Giants, "Destination Moon"

  18. 2011-Jul-23, 06:19 AM

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    That ice/rock thing puts the whole "dwarf planet" thing into question.

  20. #19
    Quote Originally Posted by parallaxicality View Post
    That ice/rock thing puts the whole "dwarf planet" thing into question.
    You mean the hydrostatic equilibrium part of the definition? It's true that a lumpy, misshapen rocky object can be much heavier than an icy one that's formed itself into a sphere, but it's not like there's any particular mass you can draw a line at. In this case, it seems likely that Vesta was big enough to pull itself into a sphere, its current condition being a result of impacts after it had completely solidified.

  21. #20
    Fascinating pictures from the spacecraft so far, I eagerly await the rest of the photographs.

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    Would Vesta look different in color, or would it be more or less a colorless lump of rock like the Moon? I ask because this fuzzy picture of Ceres looks tantalizingly colorful.

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    In terms of scientific discoveries, I would assume that the observations of Dawn's orbit around Vesta will tell a lot about density, mass distribution and the like.

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    Quote Originally Posted by IsaacKuo View Post
    Would Vesta look different in color, or would it be more or less a colorless lump of rock like the Moon? I ask because this fuzzy picture of Ceres looks tantalizingly colorful.
    Hubble took similarly looking fuzzy photos of Vesta. So probably Vesta nad Ceres are gray and peperred with craters. Of course, you can hope for more interesting features on Ceres.

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    The collision that created the big crater at the south pole did not heat up the planet sufficiently to restore hydrostatic equilibrium even temporarily. My intuition says that it should have, so obviously I need to recalibrate my intuition...

    At any rate, is it possible with the instruments on Dawn to get an idea of what latitude the collision actually happened at? It's very unlikely to have happened exactly at the south pole, and if it happened elsewhere, forces would tend to tilt the planet until the crater was centered on the nearest pole, since that's the minimal energy state.

    Assuming Vesta had a magnetic field in its early days, there should be magnetic grains in the rocks that would show the orientation of the field at the time the rocks cooled. But that would require measuring the rocks in situ, which Dawn is incapable of. So any ideas based on what instruments Dawn has?

  26. #25
    ^
    I'm guessing a magnetometer was very high on the team's wish list (it could also clinch the existence of a ionic mantle in Ceres), but was probably excluded partly for cost, and perhaps (though I'm no expert) possible interference from the ion drive with any readings.

  27. #26
    The magnetometer was removed as a cost-cutting measure to prevent it from staying cancelled, IIRC.

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    New Event Time NASA To Unveil Vesta Images At News Conference
    Monday Aug 1 at noon EDT (changed from 2:00pm)

    Update -- New Event Time NASA To Unveil Vesta Images At News Conference WASHINGTON -- NASA will host a news conference on Monday, Aug. 1, at noon EDT, to discuss the Dawn spacecraft's successful orbit insertion around Vesta on July 15 and unveil the first full-frame images from Dawn's framing camera. The news conference will be held in the Von Karman auditorium at NASA's Jet Propulsion Laboratory (JPL), 4800 Oak Grove Dr., Pasadena, Calif. Journalists also may ask questions from participating NASA locations or join by phone.

    To obtain dial-in information, journalists must contact JPL's Media Relations Office at 818-354-5011 by 8 a.m. PDT
    on Aug. 1.

    NASA Television and the agency's website will broadcast the event. It also will be carried live on Ustream, with a live chat box available, at:


    http://www.ustream.tv/nasajpl2

  30. #29
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    Quote Originally Posted by Garrison View Post
    Image of the Dark Side of Vesta Captured by Dawn on July 23, 2011
    Dark side?
    It's a rotating body, how can it have a dark side?

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    Quote Originally Posted by NEOWatcher View Post
    Dark side?
    It's a rotating body, how can it have a dark side?
    Just the "side" that happened to be in shadow. A bit sloppy, there.

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