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Dawn approaches Ceres, From opnav images to first orbit
Gladstoner
post Mar 8 2015, 11:59 PM
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It appears the released crescent images were vertically inverted. Here they are right side up:

Attached Image


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Gladstoner
post Mar 10 2015, 08:15 AM
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PIA19310b_lg at 200% with unaltered pixels:

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Attached Image


At 2x, it is easier for my eyes, at least, to make out maximum detail.
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mcgyver
post Mar 12 2015, 01:00 PM
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This thread can be closed in favour of thread about Ceres orbiting: http://www.unmannedspaceflight.com/index.p...mp;#entry218672
This would improve forum readibility.

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JohnVV
post Mar 15 2015, 07:23 AM
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PDS has a shape file
ftp://naif.jpl.nasa.gov/pub/naif/DAWN/misc/ceres/


hipass of the baked dem ( 0 to 360 mapping)
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algorimancer
post Mar 16 2015, 03:38 PM
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For anyone comfortable with R, here is some R code to read and view the shape files -- it will open a window with an interactive 3D viewer of the shape data, allowing you to use the mouse and mouse wheel to rotate or zoom the data. For context, I have it also plotting the X, Y, and Z axes in red, green, and blue (respectively); blue should be the North-South axis.

To use it, you'll need to have R installed (or RStudio, which is my preference). Once R is installed, install the rgl package.

Extract the downloaded shape files within a directory of your choice, then you can use the following code to view the shape file in R:


#BEGIN R CODE...

#Run this line once. Specify the directory where the shape files (such as "ceres_opnav5_128.txt") are stored
setwd("C:\\Downloads\\Ceres3D")

#Run the next block once (imports the rgl library, defines functions)
#BEGIN...
library(rgl)
#Given filename, reads shape file
#Returns list containing N=#vertices, M=#plates, vertices as N-row X 3-col matrix
# (1 vertex per row, each vertex being an x,y,z coordinate),
# plates as M-row X 3-col matrix (each row being a vector containing the 3 vertex integer indices
# defining the corners of a triangular plate, listed by convention in CCW order)
ReadShapeFile<-function(filename)
{
N=scan(filename,n=1,what=integer())
vertsM=matrix(scan(filename,n=4*N,skip=1),byrow=TRUE,nrow=N,ncol=4)[,-1]
M=scan(filename,n=1,what=integer(),skip=1+N)
platesM=matrix(scan(filename,n=4*M,what=integer(),skip=1+N+1),byrow=TRUE,nrow=M,
ncol=4)[,-1]
list(N,M,vertsM,platesM)
}
MyView3D<-function()
{
sFileName=file.choose()
shape=ReadShapeFile(sFileName)
open3d()
par3d(windowRect=c(100, 100, 600, 600))
rgl.pop(type="lights")
rgl.light(theta=-60,phi=0,ambient="#010101",specular="#000000",diffuse="#CFCFCF")
bg3d("slategray")
material3d(col = "black")
rgl.triangles(shape[[3]][as.vector(t(shape[[4]])),],col="grey")
rgl.lines(c(-510,510),c(0,0),c(0,0),col="red")
rgl.lines(c(0,0),c(-510,510),c(0,0),col="green")
rgl.lines(c(0,0),c(0,0),c(-510,510),col="blue")
}
#....END

#Run the next line each time you want to view a 3D shape file
MyView3D()

#To save a snapshot of the current view, set the filename and run the following line
FileTitle="ThisFileName"
rgl.snapshot(file=paste(paste(FileTitle,".png"),sep=""))

#...END R CODE


And here's an example of what you'll see when you get it working:
Attached Image


You can also resize or maximize the window (it defaults to a smallish size).

These shape files may strain your system -- I'm using a 64-bit computer with 32G of ram, and having no difficulties. Your mileage may vary.
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Phil Stooke
post Mar 16 2015, 09:00 PM
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A nice new thing at LPSC - a map of Ceres in false colour using the RC1 images - yes, that was multispectral. There's a lot of variation across longitudes. Nothing released officially yet, of course. This was on a poster.

Phil


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... because the Solar System ain't gonna map itself.
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Jackbauer
post Mar 17 2015, 09:06 AM
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From the 46th Lunar and Planetary Science Conference :

http://www.hou.usra.edu/meetings/lpsc2015/pdf/sess630.pdf
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Habukaz
post Mar 17 2015, 11:13 AM
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The Sander crater on Mercury contains very bright hollows in a way that reminded me about the brightest spots on Ceres:



High resolution views of the crater can be found here: [1] [2]

(the image above was cropped from here)


--------------------
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Habukaz
post Mar 17 2015, 02:38 PM
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Some interesting yet confusing tweets from the LPSC:

QUOTE
#LPSC2015 #Ceres Bright spot in center of basin, seen even above rim, so believe it's outgassing (needs higher res to get spectral info)


https://twitter.com/Laurent_Montesi/status/...830420697387008

QUOTE
Icy plume possibly seen on limb of Ceres. Exciting! #LPSC2015


https://twitter.com/MonicaGrady/status/577830943995621376


Is this based on RC2 observations, or OpNav 4-5? I got the impression from the press conference where the RC2 rotation animation was presented that cryovolcanism was low on the list for possible explanations for the brightest spots - and now it suddenly ranks high again?


--------------------
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jgoldader
post Mar 17 2015, 03:10 PM
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QUOTE (Habukaz @ Mar 17 2015, 09:38 AM) *
Some interesting yet confusing tweets from the LPSC:


Wow. This holds up, it's game-changing for planetary exploration.
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TheAnt
post Mar 17 2015, 03:28 PM
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QUOTE (Habukaz @ Mar 17 2015, 03:38 PM) *
Some interesting yet confusing tweets from the LPSC:

Is this based on RC2 observations, or OpNav 4-5? I got the impression from the press conference where the RC2 rotation animation was presented that cryovolcanism was low on the list for possible explanations for the brightest spots - and now it suddenly ranks high again?


I think this reflect different ideas and opinions among different people. There might even be one or two who is like me - though I am certainly not a planetary scientist - who look into a problem from several different perspectives in a single month.
The first tweet go a reply with the alternative explanation that: "'''its a granite compounded with ice , a remnant of impact object of the crater."

My best guess is that the idea is based on that image used in the rotation where the bright spot stayed very bright even on the terminator.

So what we're seeing in those tweets is an ongoing debate on how to interpret what we've seen at moderate resolution.
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Ken2
post Mar 17 2015, 06:13 PM
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QUOTE (Habukaz @ Mar 17 2015, 06:38 AM) *
Some interesting yet confusing tweets from the LPSC:



https://twitter.com/Laurent_Montesi/status/...830420697387008



https://twitter.com/MonicaGrady/status/577830943995621376


Is this based on RC2 observations, or OpNav 4-5? I got the impression from the press conference where the RC2 rotation animation was presented that cryovolcanism was low on the list for possible explanations for the brightest spots - and now it suddenly ranks high again?



I wonder what they are referring to - it's quite a couple tweets!

I took look at the white spot picts again to see any possible plume pixels and the only thing I can see is these 5 pixels (yellow circle in inset image). However if you align it to the previous frame in the rotation movie (the main image), I think they correspond to the high point of the crater rim (yellow arrow). Note, I have cranked up the exposure to max to bring out the dim pixels.

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ngunn
post Mar 17 2015, 06:40 PM
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Monica Grady refers to a feature seen on the limb rather than the terminator so maybe those aren't the right images to look in??
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Gladstoner
post Mar 17 2015, 07:13 PM
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QUOTE (ngunn @ Mar 17 2015, 01:40 PM) *
Monica Grady refers to a feature seen on the limb rather than the terminator so maybe those aren't the right images to look in??


That could explain why a few frames -- including one or two with the bright spot on the limb -- were left out of the released rotation sequence.
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belleraphon1
post Mar 17 2015, 10:41 PM
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A bit more detail on what was presented at LPSC regarding white spots...

Bright spots on Ceres could be active ice
http://www.nature.com/news/bright-spots-on...=TWT_NatureNews

The pictures reveal the spots even when they are near the edge of Ceres, when the sides of the impact crater
would normally block the view of anything confined to the bottom. The fact that something is visible at all
suggests that the feature must rise relatively high above the surface.

"What is amazing is that you can see the feature while the rim is still in the line of sight,” said Andreas Nathues,
a planetary scientist at the Max Planck Institute for Solar System Research in Göttingen, Germany."

Craig



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