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Ceres Low-Altitude Mapping Orbit (LAMO)
Mariner9
post Apr 15 2016, 07:46 AM
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Hey, I dream about higher resolution pictures of Occator as much as the next guy. However, I think something is being assumed here, namely that the primary purpose of the LAMO has been achieved by completing the higher resolution imaging of Ceres. But that is only part of the LAMO science objective. If I recall correctly the main point of the low orbit is to gather a good data set for the Gamma Ray and Neutron Detector. From what I remember reading years ago about a similar instrument on Mars Odyssey, the more orbits you collect data the better your composition data becomes. Lots of math algorithms crunching lots of science numbers from lots of data points yielding a higher and higher resolution composition map. So the longer they can maintain Dawn in a stable orientation to collect it's data, passing multiple times over the same terrain, the better their composition map becomes.

I think the Dawn team intends to keep that data set expanding as long as possible. Trying to power Dawn down to a lower orbit, as juicy as those new pictures sound, would put an end to the LAMO data collection for the GRAND instrument.

Again, most of this is my recollection, explained with lots of hand waving and general vague notions.
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Holder of the Tw...
post Apr 15 2016, 08:44 PM
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Ending the mission early would sacrifice filling in as much of the south polar region as possible. It will be November before the solstice arrives and Ceres begins to get primary illumination in the southern hemisphere. For several months after that there will be more and more of the southern polar areas coming out of shadow where they are locally depressed (like basins). If those areas don't get photographed in the coming months, it could be decades. That plus what Mariner9 mentioned.
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Gladstoner
post Apr 15 2016, 09:28 PM
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QUOTE (Gladstoner @ Apr 13 2016, 02:36 PM) *
Speaking of waiting until Dawn 2, a couple questions:

1. Can Dawn directly determine the nature of a water-rich layer within Ceres, e.g. with gravity data? Or will this have to wait for a future mission?

2. Have theoretical constraints on the nature of such a layer been determined? The rough, 'rocky' terrain seems to preclude a pure layer, while the scattered deposits of salts seem to imply some differentiation from a homogeneous rock/ice mixture.


I gather we'll have to wait for seismology on future missions.
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David Wright
post Apr 16 2016, 03:04 AM
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I spotted an interesting light-colored patch inside one of the smaller craters in LAMO 68. If I lighten the shadows I see this lobate object on a north-facing slope:

Attached Image


What do you think? It doesn't look like an artifact to me.

David
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JohnVV
post Apr 16 2016, 03:31 AM
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not much lighter
px value of 24 in a 23 background

false color
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David Wright
post Apr 16 2016, 05:45 PM
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I agree it's not much. But look at two other high latitude craters:

PIA20409
Attached Image


and PIA20407
Attached Image


The (admittedly faint) shadow detail in the first seems real, esp. compared to the second.
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JohnVV
post Apr 16 2016, 05:55 PM
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seeing as the images on the photo journal are normalized 5% to 95% 8 bit jpg's
and the pds img files are 16 bit unsigned
http://sbn.psi.edu/archive/dawn/fc/
we really will need to see the EDR's to get any details
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JohnVV
post Apr 18 2016, 05:13 AM
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LAMO 68 is at the edge of getting good looking mesh



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fredk
post Apr 20 2016, 04:47 PM
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New Scientist reporting that there's a proposed extension to a third asteroid.
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antipode
post Apr 20 2016, 10:13 PM
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QUOTE
Given the small amount of xenon fuel remaining, the list of potential destinations is probably not too long


Not to mention the fact that there are only 2 reaction wheels left.

I would love to see this happen, but dont see how it could.

A flyby of 3 Pallas was once mooted - now THAT would have been exciting. Sadly that cant happen now. Discovery proposal anyone?

P
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Explorer1
post Apr 21 2016, 02:15 AM
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There must be something on a very similar orbit to Ceres; the delta-v remaining is pretty low by now. It would be great to see but Dawn isn't really built to do flybys, is it? Wonder how much Dawn can actually accomplish on a short time scale with a moving target (just tempering my enthusiasm...)
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Mariner9
post Apr 21 2016, 03:52 AM
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The target asteroid only needs a similar orbit if the purpose is to match velocity and achieve orbit around it. If just a flyby is all that is required, then the target could be in a very different orbit from Ceres that Dawn could intersect at the appropriate time.

I rather doubt they would go to the effort to escape Ceres just to do a flyby, because as it has been pointed out the spacecraft was designed with orbital studies in mind.
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JohnVV
post Apr 23 2016, 03:39 AM
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Release LAMO 71
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nprev
post Apr 23 2016, 05:43 AM
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Seems that there really is a serious proposal for a mission extension to visit another asteroid.

Be interesting to see how this plays out in terms of getting an extension given the spacecraft's overall health. The strongest argument in favor of this may be to prevent Dawn from crashing into Ceres at EOM.


--------------------
A few will take this knowledge and use this power of a dream realized as a force for change, an impetus for further discovery to make less ancient dreams real.
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HSchirmer
post Apr 23 2016, 12:57 PM
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QUOTE (nprev @ Apr 23 2016, 05:43 AM) *
Seems that there really is a serious proposal for a mission extension to visit another asteroid.

Be interesting to see how this plays out in terms of getting an extension given the spacecraft's overall health. The strongest argument in favor of this may be to prevent Dawn from crashing into Ceres at EOM.


Well, perhaps a fly by of a short period comet is possible, more interesting would be a gravity assist from a comet,
but since the spacecraft is designed to survey from orbit, and the only thing big enough to orbit seems to be Pallas,
I'm betting on Pallas in 2018-2019.
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