IPB

Welcome Guest ( Log In | Register )

15 Pages V  « < 9 10 11 12 13 > »   
Reply to this topicStart new topic
Ceres Low-Altitude Mapping Orbit (LAMO)
nprev
post Mar 27 2016, 11:45 AM
Post #151


Senior Member
****

Group: Admin
Posts: 8432
Joined: 8-December 05
From: Los Angeles
Member No.: 602



Definitely a possibility. There are very few similar features on Ceres, and Occator is by far the largest and most prominent. I would expect such features to be more common if they were purely endogenic, but of course that's just an opinion.

Alternatively, this may mean nothing more than that the icy crust is extremely thick and/or lacks deep cracks almost everywhere but a few select spots like this. Insufficient data at this time.


--------------------
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.
Go to the top of the page
 
+Quote Post
David Palmer
post Mar 31 2016, 09:16 AM
Post #152


Junior Member
**

Group: Members
Posts: 33
Joined: 16-June 14
From: Sweet Home, Oregon
Member No.: 7202



As far as the origin of the mysterious pyramid-shaped mountain (Ahuna Mons), I find it to be a bit too much of a coincidence that there is a relatively young crater of approximately the same size right next-door, and can't help but suspect that there is a connection. And I would like to suggest the following model: as the largely-water-ice crust of Ceres has continued to thicken over time (due to the internal heat source gradually running down), cracking of the crust has occurred, some of which would be polygonal in shape, and I would suggest that the crater-creating impact occurred right next to one such polygonal section, and the resultant pressure impulse in the subsurface ocean (slightly) popped that section up through the surrounding crust. And since that time, continued freezing in the subsurface ocean has pushed the polygonal section further upwards, in response to vertical pressure created by expansion of the freezing water below, and due to the fact that the cracks defining its edges (cracks which became vertical faults) de-coupled it from the surrounding crust and allowed it to move fairly independently of that crust. So this mountain is basically what is referred to as a "horst" in Earth geology, but because of the differences in crustal composition and dynamics here, there are no surrounding "grabens," and Ahuna Mons doesn't take the shape of the linear ridge that is typical of terrestrial horsts.
Go to the top of the page
 
+Quote Post
JohnVV
post Apr 1 2016, 01:26 AM
Post #153


Member
***

Group: Members
Posts: 845
Joined: 18-November 08
Member No.: 4489



LAMO 53

a few renders at a low angle




Go to the top of the page
 
+Quote Post
Gladstoner
post Apr 1 2016, 07:28 AM
Post #154


Member
***

Group: Members
Posts: 687
Joined: 3-January 08
Member No.: 3995



A summary of the formation of salt deposits as I imagine it. Many, if not all points here have or may have been mentioned or thought of already.

1. Ceres originates as accretion of rocky material and water.

2. Early, heavy meteoritic bombardment depletes crust and/or mantle of water. This possibility was mentioned somewhere recently; I had suspected this as well since the rough terrain seems to preclude water ice.

3. Differentiation of ice and rock/metal leaves ocean and/or water-rich zone in mantle, which probably occurred during bombardment mentioned above.

4. Interior water progressively freezes out, leaving increasingly concentrated salts in the remaining brine. I am reminded of pegmatites in terrestrial magmatic systems.

5. Some brine migrates toward the surface, often drying out and leaving behind deposits of salt. These are often exposed by impacts and mass wasting.

6. In some cases, the effects of large impacts manage to penetrate deep enough to reach some remaining brine at the water-rich level.

7. The highly fracture central rebounds of the large impacts provide conduits for the movement and ascent of brine. Occator is probably the most recent example of this process. Older craters, like Dantu and Ezinu, seem to show signs of reduced or extinct activity. Interestingly, these types of craters seem to be clustered over a broad area, but this may be a bias of impact occurrence and observation so far on our part, at least:

Attached Image


8. Ahuna Mons may be an example of a process similar to that of the Occator central uplift, but occurring in different conditions.

9. Other large salt-rich spots, like Haulani and Oxo Craters, are probably chance impacts into particularly salt-rich material.
Go to the top of the page
 
+Quote Post
Ken2
post Apr 4 2016, 04:58 PM
Post #155


Junior Member
**

Group: Members
Posts: 48
Joined: 20-December 14
Member No.: 7370



Just FYI, an interesting new study (see link) to help explain the very long runouts of the crater wall landslides all over Ceres.

Vibrations make large landslides flow like fluid
Go to the top of the page
 
+Quote Post
Gladstoner
post Apr 6 2016, 07:22 PM
Post #156


Member
***

Group: Members
Posts: 687
Joined: 3-January 08
Member No.: 3995



For those who haven't seen the 'Unveiling Ceres' animation:

http://photojournal.jpl.nasa.gov/catalog/PIA20537

Some video screen captures:

Haulani Crater:

Attached Image


Oxo Crater:

Attached Image


Urvara Basin central peak:

Attached Image
Go to the top of the page
 
+Quote Post
Explorer1
post Apr 7 2016, 04:26 PM
Post #157


Senior Member
****

Group: Members
Posts: 1724
Joined: 13-February 10
From: Ontario
Member No.: 5221



New Dawn journal from Marc Rayman: http://dawnblog.jpl.nasa.gov/2016/03/31/da...nal-march-31-3/
Go to the top of the page
 
+Quote Post
JohnVV
post Apr 9 2016, 11:01 PM
Post #158


Member
***

Group: Members
Posts: 845
Joined: 18-November 08
Member No.: 4489



just a few from LAMO 63


Go to the top of the page
 
+Quote Post
JohnVV
post Apr 12 2016, 07:52 PM
Post #159


Member
***

Group: Members
Posts: 845
Joined: 18-November 08
Member No.: 4489



a bit out of order
LAMO 55





Go to the top of the page
 
+Quote Post
Ken2
post Apr 13 2016, 04:18 PM
Post #160


Junior Member
**

Group: Members
Posts: 48
Joined: 20-December 14
Member No.: 7370



QUOTE (Explorer1 @ Apr 7 2016, 08:26 AM) *


Based on that - it looks like the wheels are still holding out and hydrazine is still left. I think the project should seriously consider going to a lower orbit now to image the key sights at an even higher resolution. At this point it is 100% bonus time and the 2x-4x higher resolution would be invaluable for science - especially of the white spots. Now is the time - is there planetary society petition or something to try and make this happen?
Go to the top of the page
 
+Quote Post
Explorer1
post Apr 13 2016, 06:55 PM
Post #161


Senior Member
****

Group: Members
Posts: 1724
Joined: 13-February 10
From: Ontario
Member No.: 5221



It's not a technical reason they're remaining at this altitude. I recall the entire point of stopping at LAMO was to prevent Dawn prematurely crashing into the surface (you really don't want to run into Ahuna Mons by accident!)
Higher orbits are stable enough to stay for a much longer timescale, enough to sterilize the spacecraft (though nearly a decade in space ought to be enough time, IMHO!).
We might just have to wait for Dawn 2....
Go to the top of the page
 
+Quote Post
elakdawalla
post Apr 13 2016, 07:00 PM
Post #162


Administrator
****

Group: Admin
Posts: 5170
Joined: 4-August 05
From: Pasadena, CA, USA, Earth
Member No.: 454



QUOTE (Ken2 @ Apr 13 2016, 09:18 AM) *
I think the project should seriously consider going to a lower orbit

The project's plans have been made years in advance based upon countless hours of work of the science team and navigators, and represent's the project's best plans for achieving all the science goals of the mission within constraints of capability, budget, planetary protection, and everything else. The people who know the mission best have determined its course. We'd have no interest in petitioning them to change their plans, and wouldn't expect the project to listen to us if we did.


--------------------
My blog - @elakdawalla on Twitter - Please support unmannedspaceflight.com by donating here.
Go to the top of the page
 
+Quote Post
scalbers
post Apr 13 2016, 08:13 PM
Post #163


Senior Member
****

Group: Members
Posts: 1361
Joined: 5-March 05
From: Boulder, CO
Member No.: 184



We could always respond to the blog post and contact Marc as individuals on our own behalf whether that could possibly be considered.


--------------------
Go to the top of the page
 
+Quote Post
Gladstoner
post Apr 13 2016, 08:36 PM
Post #164


Member
***

Group: Members
Posts: 687
Joined: 3-January 08
Member No.: 3995



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.
Go to the top of the page
 
+Quote Post
Ken2
post Apr 15 2016, 07:23 AM
Post #165


Junior Member
**

Group: Members
Posts: 48
Joined: 20-December 14
Member No.: 7370



QUOTE (elakdawalla @ Apr 13 2016, 11:00 AM) *
The project's plans have been made years in advance based upon countless hours of work of the science team and navigators, and represent's the project's best plans for achieving all the science goals of the mission within constraints of capability, budget, planetary protection, and everything else. The people who know the mission best have determined its course. We'd have no interest in petitioning them to change their plans, and wouldn't expect the project to listen to us if we did.



A few counterpoints and I'll drop the subject

- Unlike almost every other mission which has time to plan and execute extended mission plans / pitch them to NASA HQ (Deep Impact,Stardust,Cassini, Messenger final imaging etc etc), Dawn has a very short window and can't reasonably go through that process. Missions are focused on the prime mission and don't do much if any extended mission studies until very late in the game - and given how little resources Dawn had left to just complete the prime mission means it is unlikely that much effort was able to be spent on an extended mission.

- Dawn saves hydrazine when on it's ion engines so can afford to lower it's orbit with a low hydrazine cost.

- Planetary protection arguments for a nuclear free Dawn are dubious at best when we routinely crash lunar orbiters and recently Messenger into mercury. Even so, a much lower orbit would still yield plenty of sterilization time.

- A Dawn2 is very unlikely to happen in the foreseeable future, we have a ~half billion dollar asset in good health there now and we have only have months to get an extended mission done

- The planetary society is very influential in US planetary circles

- Dawn is a tax payer funded mission and we as tax payers should want to get the most bang for our buck - and high value more risky extended mission science is has a good ROI.

In any event it just seems an unnecessary shame - much higher resolution images would be very valuable and should be doable.
Go to the top of the page
 
+Quote Post

15 Pages V  « < 9 10 11 12 13 > » 
Reply to this topicStart new topic

 



RSS Lo-Fi Version Time is now: 3rd July 2020 - 09:12 PM
RULES AND GUIDELINES
Please read the Forum Rules and Guidelines before posting.

IMAGE COPYRIGHT
Images posted on UnmannedSpaceflight.com may be copyrighted. Do not reproduce without permission. Read here for further information on space images and copyright.

OPINIONS AND MODERATION
Opinions expressed on UnmannedSpaceflight.com are those of the individual posters and do not necessarily reflect the opinions of UnmannedSpaceflight.com or The Planetary Society. The all-volunteer UnmannedSpaceflight.com moderation team is wholly independent of The Planetary Society. The Planetary Society has no influence over decisions made by the UnmannedSpaceflight.com moderators.
SUPPORT THE FORUM
Unmannedspaceflight.com is a project of the Planetary Society and is funded by donations from visitors and members. Help keep this forum up and running by contributing here.