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MOM: Initial Mars operations, News and Mars photos after orbit insertion
vikingmars
post Oct 6 2014, 07:48 AM
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QUOTE (wildespace @ Oct 6 2014, 09:22 AM) *
...as we have seen from raw Mastcam and MAHLI images.
...is due to all the dust suspended in its atmosphere.

Thanks Wildespace : quite good interpretation if I may say !
BUT, please remember that :
1) Mastcam images are in raw format and must be calibrated for their colors ;
2) Dust clouds from space looks indeed yellowish, not white.
3) The color of the planet from space, as you say, is not as yellowish brown as it is seen from the ground...
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fredk
post Oct 6 2014, 02:51 PM
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QUOTE (wildespace @ Oct 6 2014, 07:22 AM) *
I think this has resulted in colours very close to the colours of the surface as we have seen from raw Mastcam and MAHLI images.

I remember reading in a few places that the pronouncedly red appearance of Mars when photographed from outside of its atmoshere is due to all the dust suspended in its atmosphere.


Mastcam cameras have a well-known "greenish cast" making the surface look yellowish.

If atmospheric dust reddened the planet, then the limbs should be redder than the centre of the disc, since you look through more dusty air near the limbs. Also the planet should look redder during global duststorms, but I haven't heard of a hue shift during duststorms.
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4throck
post Oct 6 2014, 04:22 PM
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The surface color seen from space suffers the effect of the atmosphere 2 times. Light must come down and then back up.
So any hue will be magnified on full disk images, more so if there's dust or anything that absorbs / reflects light.

The Red Mars from orbit is an accurate rendition of what you would see, the same way as astronauts see the Earth as a blue planet.
If really doesn't compare to what it looks like on the ground .

The limbs are also complicated because you have phase angle there. One thing is reflected light, another absorbed light, just to keep things simple. But you really have to take into account scatting, diffraction, etc, etc. Really not that simple.
And on Mars you have limb hazes and clouds, so a bluish color is to be expected there.

All this meaning that the MOM image is just fine. biggrin.gif


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fredk
post Oct 6 2014, 04:54 PM
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Another factor is the seasonal variation in atmospheric dust - some seasons are far dustier than others, even in the absence of duststorms.
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Bjorn Jonsson
post Oct 7 2014, 12:04 AM
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Also comparing Mars's global color with the Curiosity images might not be accurate. In addition to light coming down through the atmosphere and getting reflected back out of it (as pointed out above) and seasonal variations in dust, Mars' global color isn't totally uniform (although color variations aren't big) and the Curiosity images show just one location on the surface.

Regarding Mars' color as seen through a telescope: There is a lot of orange color but I have found it to be orange with a slight pinkish tint as well but this is extremely subjective. Of the various versions of the MOM image I have seen, Don Davis' version is probably closest to what I have seen through a telescope in terms of color (but again, this is subjective).
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djellison
post Oct 7 2014, 12:26 AM
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QUOTE (Bjorn Jonsson @ Oct 6 2014, 05:04 PM) *
...... this is subjective


Very very very subjective.
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4th rock from th...
post Oct 7 2014, 11:01 AM
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Completely subjective. And it changes with the telescope and magnification.

It's interesting that Mars seen with the naked eye (point souce) looks quite like Antares (that's why the star is called like that).
That comparison seems to be valid for most people and since a long time.


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fredk
post Oct 7 2014, 02:44 PM
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QUOTE (4th rock from the sun @ Oct 7 2014, 11:01 AM) *
Completely subjective.

A measurement of spectral irradiance, ie the spectrum of incident light, is completely objective. Of course that's not what people are referring to when talking about telescope views. But it's worth remembering that, in principle, the "colour" of Mars could be measured and reproduced. In practice this would be extremely hard (no display devices exist to reproduce all, or a large part of, a visible spectrum, etc, etc...). The matter of subjectivity of perception is separate from this.

But, getting back to the thread topic, it is easier to objectively discuss differences of colour. Long-term monitoring by MOM may tell us about seasonal variations on a global scale...
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Phil Stooke
post Oct 7 2014, 08:32 PM
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A new MOM image of Mars has been released - see Emily's blog for the link. Here I compare it with the Rosetta flyby image. Lots of small changes to be seen, and much that is the same including the distribution of clouds.

I wanted to add a Hubble view and a Mariner 7 view (incredible changes since Mariner 7) but I don't have time.

Towards upper right, a group of dark markings change very substantially. Look below them, there is a bright-toned curving patch on the surface in the Tartarus Montes area. That is where Mariner 4's first image of Mars was taken in 1965.

Phil

Attached Image


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vikingmars
post Oct 8 2014, 03:30 PM
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My interpretation of the new global Mars image taken by MoM and released by ISRO... Enjoy ! smile.gif
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ugordan
post Oct 8 2014, 07:09 PM
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My attempt at "un-enhancing" the image:
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Hungry4info
post Oct 14 2014, 02:46 PM
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Phobos (animation)
https://mtc.cdn.vine.co/r/videos/B745972857...10491926854.mp4


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Mr Valiant
post Oct 15 2014, 10:03 AM
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Through my telescope (8" Newtonian) the Mars I have observed is similar to ugordan's
image. Only difference is the Polar Cap always appears very bright, white and sharp edged.

Professional observations of Mars in daylight (sorry I don't have any links) reveal the
planet to be a tan colour, markings brown to dark grey.

Currently my scope is in pieces, gotta get it all together. Miss it.

p.s. Never saw any canals smile.gif
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vikingmars
post Oct 18 2014, 04:59 PM
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The last image from the Indian Mars Orbiter Mission (MoM) showing the huge Tharsis volcanoes with Olympus Mons on the left, close to the terminator... (with colors corrected) Enjoy smile.gif
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MahFL
post Oct 18 2014, 08:04 PM
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QUOTE (vikingmars @ Oct 18 2014, 05:59 PM) *
The last image from the Indian Mars Orbiter Mission .....


Do you mean the latest or the last one ?
Did the mission end ?

ADMIN NOTE: MahFl, I think that a quick look to either the mission website, Twitter feed, Facebook page, ISRO's website or any number of space news sites could have answered that question for you. MOM's mission continues as normal. At the very least check/Google before asking a quesion like that please.
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