Posted to sci.astro: From: Robert Clark (rgregoryclark@yahoo.com) Subject: Mars, the "Greenish" Planet? Newsgroups: sci.astro, alt.sci.planetary, sci.space.history, sci.astro.amateur, rec.arts.sf.science Date: 2002-12-11 18:31:56 PST Below I discussed the fact that Mars frequently presents a greenish tint to Earth bound observers. This had been attributed to an optical illusion but the best Hubble image taken of Mars also showed areas with a greenish hue: Hubble Captures Best View of Mars Ever Obtained From Earth http://oposite.stsci.edu/pubinfo/pr/2001/24/ Now the THEMIS camera on Mars Odyssey also shows an area on Mars with greenish patches: PIA03738: Candor Chasma on Mars, in Color http://photojournal.jpl.nasa.gov/catalog/PIA03738 Bob Clark ______________________________________________________ From: Robert Clark (rgregoryclark@yahoo.com) Subject: Re: First color images from 2001 Mars Odyssey? Newsgroups: alt.sci.planetary, sci.space.history, sci.astro, sci.astro.amateur Date: 2002-04-06 08:35:28 PST You wouldn't get the impression that Mars is a colorless world from this Hubble image either: Hubble Captures Best View of Mars Ever Obtained From Earth http://oposite.stsci.edu/pubinfo/pr/2001/24/ Impossible not to notice that the darker areas have greenish tinge to them. I found this web site that says this is common from telescope views from Earth but attributes it to an optical illusion: Mars "When Mars is viewed through a telescope, it looks like a red and orange disk. An observer can easily see white ice caps at the north and south poles of Mars. These caps grow and shrink throughout the Martian year, just as the polar caps of Earth do. The darker areas of Mars's surface may look greenish to the observer, but this is an optical illusion caused by the contrast in color between the dark patches and brighter areas. Scientists believe that the dark areas are regions of relatively unweathered bare rock, while the bright areas are regions with deposits of weathered material, especially fine dust." http://www.cosmiverse.com/reflib/marspage1.htm Whether this seasonal change is an optical illusion or not is something color light imaging from THEMIS could also address. I imagine examination of the spectra of this Hubble image also could address the question of whether these dark areas really are reflecting most strongly in the green part of the spectrum. rgregoryclark@yahoo.com (Robert Clark) wrote in message news:<832ea96d.0204021257.6ee68b47@posting.google.com>... > henry@spsystems.net (Henry Spencer) wrote in message news:<Gtwpt6.58@spsystems.net>... > > In article <1017689746.286824@server.gh.wh.uni-dortmund.de>, > > Holger Isenberg <H.Isenberg@ping.de> wrote: > > >> http://mars.jpl.nasa.gov/odyssey/ Pretty color pictures are probably > > >> not a high priority... > > > > > >Can you explain further? We send the first real color camera to Mars orbit > > >and its pictures are low priority in relation to 20 m/pixel b&w pictures, > > >which already had been taken back in 1972 by Mariner 9? > > > > They're (probably) low priority because they don't *tell* you anything > > new. It was established early that Mars is not a colorful place -- that > > is, its color doesn't *vary* much -- and that (conventional) color imaging > > thus doesn't add much information compared to B&W images. So tripling the > > data volume to bring back color isn't very attractive. > > > > Note that THEMIS is primarily an IR instrument. The visual part is mostly > > just a supplement to the IR imaging. > > I agree with you that the IR images should have higher priority but I > don't agree that color images wouldn't tell you very much. I copied > below a post discussing some questions that color imaging could > answer. Other questions that would be interesting to answer is what > are the colors of the dark streaks seen forming in current times? In > the MGS images they look just look black to varying shades of grey. > What about the color of the "dalmation spots" that some have claimed > to be indicative of life? > A region I'm especially interested in is Solis Lacus. This has long > been known to be a variable feature on Mars both seasonally and long > term. This is interesting because there are several lines of evidence > suggesting there could be near surface liquid water in Solis. Are the > known albedo changes in Solis accompanied by color changes? > This web page by the Association of Lunar & Planetary Observers lists > several variable features on Mars that very likely would also be > accompanied by color changes: > > 1998-1999 Aphelic Apparition of Mars: Part 3 > http://www.astroleague.org/marswatch/Newsletr/imv03i06.html > > Bob Clark > > ************************************************************** > From: Robert Clark (rgregoryclark@yahoo.com) > Subject: On the colors of Mars and the mystery of the "Sinton bands". > Newsgroups: sci.astro, alt.sci.planetary, sci.astro.seti, sci.bio.misc > Date: 2002-02-02 15:19:44 PST > > The color imager on Mars Odyssey should have about the same resolution > as the Viking orbiter, about 20 meters/pixel. > > A question about some features on Mars is whether some color > differences are real or are only apparent in comparison to surrounding > terrain. > > White Rock for example has been claimed to not really be white but > only lighter than the surrounding area. Will the color imager be able > to determine if it really is white? > > Another area where the interpretation of its color has been > controversial is the Syrtis Major region. It has long been known to > present an apparent bluish tint that appears to change seasonally. > William Sinton made some spectrographic observations of the area in > the 50's that appeared to show it's spectrum matched that of complex > organic molecules. This and the seasonal changes led Sinton to > originally propose the spectra were due to life. Will Mars Odyssey be > able to determine if Syrtis Major really does become blue seasonally? > Some of the bands Sinton observed have been explained as actualy due > to HDO in Earth's atmosphere. However, the bands at 3.4 microns which > are frequently seen in complex hydrocarbons have not been definitively > explained. Will the THEMIS infrared imager on Mars Odyssey finally be > able to resolve the mystery of the "Sinton bands"? > > The history of the Sinton bands is told in the second chapter of > Barry DiGregorio's book, _Mars: the Living Planet_, > http://www.amazon.com/exec/obidos/ASIN/1883319587/marsbugstheelect > > References on the Sinton bands: > > Home Page for IRTF Mars Image Gallery > Sinton bands in February 1995 IRTF images > http://marswatch.astro.cornell.edu/irtf.html > > 3-4m mm IMAGING SPECTROSCOPY OF MARS. > http://www.lpi.usra.edu/meetings/LPSC98/pdf/1658.pdf > > It's also discussed in the dissertation of David Klassen: > > Infrared Imaging Spectroscopy of Martian Volatiles > by David R. Klassen > http://elvis.rowan.edu/~klassen/papers/dissertation/chapter1.htm > > Bell et.al. have also proposed the aluminum mineral diaspore > for the origin of the "Sinton bands": > > SPECTROSCOPIC EVIDENCE FOR DIASPORE (a-AlOOH) ON MARS. > http://www.lpi.usra.edu/meetings/lpsc2000/pdf/1227.pdf > > > Bob Clark > **************************************************** _______________________________________________________________
sandstorms? combined with the oldskool theory of light diffraction / dust particle lightspectra adsorbtion etc.... [crackpot mode] no wait ETHER! The sandstorms cause atmospheric variations of etherdensity, more dense atmosphere, means less room for ether, hence less photondecay ---> redshift, perception as more greener light, part of the photons are absorbed as kinetic energy for the dust particles which accounts for the darker huey of the areas. Just a silly joke but still fun. /crackpot mode
Re: Mars the "Greenish" Planet? After discussing on sci.astro whether or not other telescopic or spacecraft images besides Hubble and THEMIS had shown greens or blues on Mars, I searched on the Viking archive for red, green, blue filter images that could be combined to give full color images: Viking http://www-pdsimage.jpl.nasa.gov/PDS/public/resources/cd_viking.html Below is a post to the Yahoo Cydonia group discussing one of the color images I produced: __________________________________________________ From: Robert Clark Date: Fri Jan 3, 2003 10:33 am Subject: Re: Mars the "Greenish" Planet? I found some images that provided a better image combination that covered the Kasei Vallis region of Mars. This report discussed using tri-color images of Mars in Kasei Vallis: Title: Multispectral Analysis of the Kasei Vallis - Lunae Planum Region of Mars Authors: Singer, R. B.; Cloutis, E.; Roush, T. L.; Mouginis-Mark, P. J.; Hawke, B. R.; Christensen, P. R. Affiliation: AAPLANETARY GEOSCIENCES DIV., HAWAII INST. OF GEOPHYSICS, UNIV. OF HAWAII, HONOLULU, HI 96822 Journal: LUNAR AND PLANETARY SCIENCE XV, P. 794-795. http://adsabs.harvard.edu/cgi-bin/bib_query?1984LPI....15..794S [full text] The report lists Viking image numbers 663A32, 663A36, and 663A38, found here: Index of /pdsa_data/vo_1024/f663axx http://starbase.jpl.nasa.gov/pdsa_data/vo_1024/f663axx/ After using NASAView to decode, then Gimp to combine the red, green, blue I got the color image attached. There are some pretty intense blues here. This does seem more realistic looking. But this was done without image processing, just straight combination of the red, green, blue images, so I can't be sure of the color accuracy. Bob Clark __________________________________________________ I'm looking for the programs that can perform the required image corrections mentioned in this documentation file: Archive of Digital Images from NASA's Viking Orbiter 1 and 2 Missions http://starbase.jpl.nasa.gov/pdsa_data/vo_1024/document/volinfo.txt "Images were acquired by the Viking Orbiters at approximately eight second intervals. In this time period, the viewing geometry changed enough so that the individual images that make up the color set can not be properly registered unless the images are geometrically rectified. The brightness of pixels in an image could be adjusted by choosing an exposure duration from a set of values between 0.003 to 2.66 seconds. The brightness values could also be adjusted by using a combination of three mode parameters: gain, offset, and light flood. The gain parameter specified the sensitivity of a VIS camera to light incident on the vidicon. There were two gain settings: 'low' and 'high'. The high gain mode had twice the sensitivity as the low gain mode. Thus, the low gain mode expanded the dynamic range of the camera by 100%. The exposure duration and the expected light level of a scene were the deciding factors for choosing high or low gain modes for an imaging sequence." And: "(1) Viking Orbiter images can be radiometrically calibrated by converting the digitized signal received from the camera (DN value) into a quantity that is proportional to the radiance reaching the sensor [2, 3, 4]. Each Viking Orbiter VIS camera was calibrated before flight. In addition, changes in the calibration over time have been estimated from analyses of images of deep space and dust storms. The radiometric calibration procedure applies additive and multiplicative corrections that account for the varying sensitivity of the vidicon across the field of view and over time. The calibrated values are proportional to radiance factor, which is defined as the ratio of the observed radiance to the radiance of a normally illuminated lambertian reflector of unit reflectance at the same heliocentric distance. (2) Geometric calibration of Viking Orbiter EDR images removes electronic distortions and transforms the point perspective geometry of the original image into a map projection [3, 4]. The electronic distortions are barrel-shaped distortions from the electron beam readout and complex distortions from interactions between the charge on the vidicon face plate and the electron beam. The electronic distortions are modeled by comparing the predicted locations of undistorted reseau marks with the actual locations in an image." Bob Clark f663a.kasaie.rgb.jpg Please Register or Log in to view the hidden image!
Re: Mars the "Greenish" Planet? Here's a link that contains the image: From: Robert Clark <bobbygc2001@y...> Date: Fri Jan 3, 2003 10:33 am Subject: Re: Mars the "Greenish" Planet? http://groups.yahoo.com/group/cydonia/message/21500 Bob Clark
