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Ceres Low-Altitude Mapping Orbit (LAMO)
fredk
post Apr 23 2016, 02:25 PM
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QUOTE (nprev @ Apr 23 2016, 06:43 AM) *
Seems that there really is a serious proposal for a mission extension to visit another asteroid.

To be fair, that just refers to the original New Scientist story. It would be good to get independent confirmation, though NS is usually reliable in these matters.

I wonder how hard it would be for someone here to work out the delta v's for some potential new flyby targets. Do we have an estimate of the remaining delta v? Is there some minimal science that could be done in flyby?
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Mr Valiant
post Apr 23 2016, 03:44 PM
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I think we should squeeze as much data from Ceres as the mission allows.
SF has always viewed Ceres as a staging post between the inner and outer
Solar System. Initial results (brine/subsurface H2O) makes Ceres
appear as a nice, some may say, balmy stop over.
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Steve5304
post Apr 23 2016, 05:08 PM
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Why cant we just go an even lower descent on Ceres. Or are we not calibrated for that?

A new target does not make a lot of sense imo, it wont be anything bigger than a few football fields unless there is something i am missing
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HSchirmer
post Apr 23 2016, 05:31 PM
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QUOTE (fredk @ Apr 23 2016, 03:25 PM) *
To be fair, that just refers to the original New Scientist story. It would be good to get independent confirmation, though NS is usually reliable in these matters.

I wonder how hard it would be for someone here to work out the delta v's for some potential new flyby targets. Do we have an estimate of the remaining delta v? Is there some minimal science that could be done in flyby?


Eh, rough numbers - Dawn 425kg of xenon, and delta-v of 1000m/s uses about 25kg of xenon.
http://dawn.jpl.nasa.gov/mission/popups/faq_qa_M3.asp

Planned to use about ~275kg to get to vesta and then ~110kg to get to Ceres and spiral down to orbit.
Estimates were ~40kg of xenon would be left at the end of the Ceres orbit, that would be 1,600m/s.
Estimates for escape velocity from ceres low orbit, googling suggest around 400m/s.

Interesting, so Dawn might have enough xenon to break ceres orbit and still have over 1,000m/s of thrust left.
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mcaplinger
post Apr 23 2016, 06:29 PM
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QUOTE (HSchirmer @ Apr 23 2016, 04:57 AM) *
I'm betting on Pallas in 2018-2019.

Pallas is too inclined to the ecliptic to reach. From http://dawn.jpl.nasa.gov/mission/faqs.asp, Marc Rayman says

QUOTE
Pallas is highly inclined to the ecliptic plane. A lot of energy is needed to climb out of the ecliptic plane especially as far out of the plane as Pallas is. I DID try to design a mission to reach Pallas and it was impossible with the Dawn spacecraft even if we went nowhere else than Pallas.


BTW, you can't do effective gravity assists from small bodies. See "Tethers and asteroids for artificial gravity assist in the solar system", http://arc.aiaa.org/doi/abs/10.2514/3.25086?journalCode=jsr


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Disclaimer: This post is based on public information only. Any opinions are my own.
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Paolo
post Apr 23 2016, 07:31 PM
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QUOTE (mcaplinger @ Apr 23 2016, 08:29 PM) *
Pallas is too inclined to the ecliptic to reach.


for orbiting no doubt, but you can fly by it when it cuts through Dawn's orbital plane
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HSchirmer
post Apr 23 2016, 08:16 PM
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QUOTE (Paolo @ Apr 23 2016, 08:31 PM) *
for orbiting no doubt, but you can fly by it when it cuts through Dawn's orbital plane


Yep, which is why I said 2019; that's (roughly) when Pallas crosses the ecliptic plane.
-edit- actually Pallas crosses in 2017 and 2019...
And 2019 also happens to be when Pallas comes closest to Ceres.

It will be interesting to see whether the choice of words is significant,
e.g. "visit another asteroid" versus "orbit another asteroid"
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nprev
post Apr 23 2016, 08:37 PM
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Really can't see this as being anything other than a flyby, and with a limited chance of success at that given the age and health of the spacecraft. In fact, I would characterize it as a sort of enhanced end-of-mission disposal plan. Main goal does seem to be ensuring that Dawn doesn't impact Ceres and thus violate the planetary protection protocols.

NOTE: If this becomes confirmed as a real thing we'll split it off as its own thread. Main focus here will continue to be LAMO operations, of course.


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JohnVV
post Apr 29 2016, 05:18 AM
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LAMO - 77


a few , there is a interesting dip in the rim and ripples in the floor of the crater

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Bill Harris
post May 4 2016, 03:48 PM
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New LAMO Index map to LO-79 and a montage of Messor caldera (LO-1 + LO-77).

https://univ.smugmug.com/Dawn-Mission/Ceres-LAMO-Images/

--Bill


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Explorer1
post May 4 2016, 07:24 PM
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Interesting quote from this month's journal entry:
QUOTE
In an upcoming Dawn Journal, we will discuss how the last of the dwindling supply of hydrazine may be used for further discoveries.

Not ruling anything out apparently...
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atomoid
post Jun 6 2016, 10:43 PM
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No big releases, just looking forward to completing the secondary imaging campaign. Here's a partial Ahuna shot lamo84 crossed with the older composite for stereo.
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JohnVV
post Jun 17 2016, 03:25 AM
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it has been a bit

LAMO 107 -PIA20647.tif





centering in on the wasting area in between the two craters
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Phil Stooke
post Jun 22 2016, 09:39 PM
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A great new picture of Occator:

http://photojournal.jpl.nasa.gov/jpeg/PIA20653.jpg

Phil


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atomoid
post Jun 23 2016, 03:02 AM
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crossed with the other composite image it's hard to get a good result despite attempts to adjust for lighting differences.. but there is an intriguing morsel of relief in the main crater..
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