Archive for November, 2011
Worlds of Stone: 11/23/2011
As part of the current show (Worlds of Stone) at Pacific Science Center we’re updating the images we show from NASA’s MESSENGER and Dawn missions on a weekly basis. I’ll try to show them to you the week after we use the in the planetarium.
Dawn
Vesta
NASA Caption
Date acquired: November 8, 2011
Release Date: November 22, 2011
This Dawn image shows a young, fresh crater, which is about 7 km in diameter, in the lower right part of the image. This crater has both dark and bright rays fanning out from it. The bright rays extend much farther from the crater than the dark rays, which are located close to the crater rim. Rays around a crater are formed when relatively small sized pieces of material are ejected by the impact that formed the crater. When larger pieces of material are ejected they can form secondary craters. Clusters and chains of sub-kilometer diameter secondary craters occur roughly 15 km to 20 km away from the rim of the 7 km crater. They are called secondary craters because the blocks that formed them were ejected from a crater formed by a primary impact. Sometimes blocks fall back into the initial crater. Many of these blocks can be seen on the floor and walls of the 7 km diameter crater. These blocks are several tens of meters in size.
Image Credit: NASA/ JPL-Caltech/ UCLA/ MPS/ DLR/ IDA
Alice Says:
Pretty good description of crater rays and why this is cool by NASA. Why is it cool? Because it has dark AND light rays. Looks pretty neat to me.
Vocabulary from above: “sub-kilometer diameter” – craters that are less than a kilometer across.
Interpretation notes: “Why do you think there are two colors of rays?” “Were the rays made by the same impact or two events?” “Why do you think that” Which craters in this picture happened before or after the main crater on the right?”
MESSENGER
Mercury
Released November 22, 2011
Date acquired: October 28, 2011
Of Interest: This image, taken with the Narrow Angle Camera (NAC), shows a pair of secondary crater chains. These features are formed when ejecta from a primary impact is thrown outward from the growing crater cavity. As chunks of ejecta fall back to the surface, they can form chains of secondary craters that often overlap.
Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
Alice Says:
Just like in the Dawn image above, we’re talking about “secondary craters” – craters formed by stuff tossed up by an impact. This is, believe it or not a crater chain, but the impacts are so close together it makes what looks like a single gouge.
Interpretation notes: “What do you think this is?” “How do you think this shape could have been made?” “What do you think did this?” “What about this picture is interesting to you?”
Want More?
Worlds of Stone at Pacific Science Center
~ A l i c e !
Worlds of Stone: 11/08/2011
As part of the current show (Worlds of Stone) at Pacific Science Center we’re updating the images we show from NASA’s MESSENGER and Dawn missions on a weekly basis. I’ll try to show them to you the week after we use the in the planetarium.
Dawn
Vesta
NASA Caption
Released November 7, 2011
PASADENA, Calif. — These Dawn FC (framing camera) images show part of Vesta’s equatorial region, which contains a prominent, deep impact crater (lower center of image) and large troughs (linear depressions). The various colors correspond to the height of the area that they color. For example, the white areas in the bottom corners of the image are the highest areas and the blue areas along the top of the image are the lowest. The prominent impact crater is set into a topographically high area defined by the red and white color-coding. Above this area there are a number of deep troughs represented by green and blue color-coding. A conspicuous trough on the left, which looks like it could be quite deep in the albedo image, is shown by the color-coding in the topography image to be only a little shallower than the area surrounding it.
Image Credit: NASA/ JPL-Caltech/ UCLA/ MPS/ DLR/ IDA
Alice Says:
This is a standard terrain image with rainbow colors corresponding to elevation. Pink and white are high elevations, blue and green are low. There’s a weirdness in this one though – the colors go in this order: blue, green, yellow, orange, pink, brown, white. Orange and brown look almost the same.
My favorite feature here is the line running up to the left from the big crater in the middle. Due to the weirdness with the scale, I can’t tell if this is a ridge or a valley. What do you think? I have an e-mail out to JPL.
MESSENGER
Mercury, or a puddle?
Released November 8, 2011
Date acquired: October 31, 2011
Of Interest: This eastward-looking image shows a wider view of the beautiful unnamed crater highlighted in yesterday’s featured image (center). The complicated folds and fractures that deform the once smooth floor of the Caloris basin can also be seen.
This image was acquired as a high-resolution targeted observation. Targeted observations are images of a small area on Mercury’s surface at resolutions much higher than the base maps. It is not possible to cover all of Mercury’s surface at this high resolution during MESSENGER’s one-year mission, but several areas of high scientific interest are generally imaged in this mode each week.
Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
Alice Says:
If this image doesn’t take your breath away I can’t help you. Those craters look like raindrops in a puddle to me. This picture is so beautiful. Mercury looks like a PLANET here, not just a desolate collection of black-and-white photos. Of note: the bright areas are not highlights, they are crater rays – new dirt (“regolith”) kicked up by recent impacts.
Want More?
Worlds of Stone at Pacific Science Center
~ A l i c e !
Worlds of Stone: 10/25/2011
As part of the current show (Worlds of Stone) at Pacific Science Center we’re updating the images we show from NASA’s MESSENGER and Dawn missions on a weekly basis. I’ll try to show them to you the week after we use the in the planetarium.
Dawn
Vesta in enhanced color
NASA Caption
Released October 25, 2011
Date acquired: August 11th 2011
Instrument: Dawn FC (framing camera)
PASADENA, Calif. — This Dawn FC (framing camera) composite images show the spectacular spectral diversity of Vesta’s surface. This image shows a Red-Green-Blue color composite image of Vesta. The images from these 3 filters were combined into this one RGB composite image, which enhances Vesta’s coloration..
Image Credit: NASA/ JPL-Caltech/ UCLA/ MPS/ DLR/ IDA
Alice Says:
In short, this is a false-color image. I’ve chosen one of the two that was originally part of this release. I chose this one because it is what I would call “less false” color. Instead of an image with crazy colors depicting specific minerals, I thought it would be interesting to look at a picture that gives us a bit of a sense of what color Vesta might be rather that the greyscale images we’ve been seeing so far.
MESSENGER
What made that funny crater shape on Mercury?
Released October 23, 2011
Date acquired: October 10, 2011
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Of Interest: The large crater here was formed by a very low angle, or oblique, impact. Although impacts at most angles produce circular craters, impacts with incidence angles <15º (from the horizontal) will create elliptical craters. This crater is superposed on an older, circular crater.
Alice Says:
NASA’s explanation is good. I picked this image because it’s a great way to engage with the geology of Mercury.
Here’s a teachable moment: ask guests why the crater might have such a strange shape.
And what about that ridge in the middle? Often when you have a peak in the middle of a crater it’s a “splashback” – like those in slow-motion images of milkdrops.
Want More?
Worlds of Stone at Pacific Science Center
~ A l i c e !
