General , Public Submissions  10 February, 2010 13:25

What's the weather like over Hellas on Mars?

5 VMC observations obtained early February 2010 show that clouds that form in the morning disappear in the afternoon. The attached image composite shows the five individual observations at different Martian day times.
An excellent study/composition of five VMC Mars Webcam images acquired between 3-8 February 2010 and submitted by Hannes Griebel. The images provide a visual record of the changing weather over Mars' Hellas basin at different times of the Martian day, and, as Hannes points out, they: "show that clouds that form in the morning disappear in the afternoon."

Click on the Full story link to access the high-resolution version and for details on Hannes' processing. Thanks for an excellent submission! -- Daniel

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Image Sets  10 February, 2010 01:37

New Images From 10 February 2010 Added

10-041_01.10.09_VMC_Img_No_1.pngNew images have been posted to the image database. These images are from the VMC observation on 10 February 2010, for more details on this observation hit the \"Full Story\" link below. To access the images click the link below. Also you can access the Celestia file to see where the images were captured and access the raw data in the zip file (for more details see Help us with the VMC)



10/02/2010 01:10-01:37 Gallery

Celestia Script

Raw Files Archive

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   Slideshow
Credit/caption: ESA/Mike Malaska, USA - cloud under changing lighting conditions Description Image submitted by Mike Malaska, Chapel Hill, NC, USA. Mike writes: Here is an image sequence of what I think is a cloud under changing lighting conditions at sunrise. To create this montage, I used Photoshop CS3. For each image, I used the floor of the crater near the terminator in image #5 as 'standard' and tried to adjust the exposure so that all the images in the sequence had the same level of exposure. The images were aligned, then cropped just enough to show some of the surface near the terminator. I added the date and time for the image in the sequence. All the frames have a 0.2-second delay, except the last frame (image 12) which has a 0.5-second delay before looping. Rick Hollar Image submitted by Heinke le Roux, Lindsay, Ont., Canada. Heinke writes: Today we went through one of those cosmological time alignments that happen once in a century... engineers just love these numbers!! ESA Mars Express, Venus Express and Rosetta spacecraft operations team members at ESA/ESOC, Darmstadt, Germany, on, of course, 7 August 2009. Public submission by Martin Ahr: I have created an animation from a VMC image series that was made on November 5, 2009. It shows what I believe to be clouds onto which the sun starts shining as the rotation of Mars brings them towards the sunlit side. There are clouds which appear to move also in a direction transverse to the direction of rotation of Mars, and some seem to disappear as the sun starts shining on them. For each frame of the animation, I combined three images from one of the exposure bracketing series into one HDR image. I tried to also use the fourth image having the shortest exposure time. However, the HDR program I used could not combine this image with the other three images, probably because the difference in brightness between the image and the other three images is very large. Since the sunlit side of Mars is overexposed in all three images used, it remains overexposed. However, the dynamic range of the HDR image is sufficient to cover the entire brightness range of the clouds. I then took the logarithm of the brightness values of the pixels in each HDR image to obtain images that can be displayed on a monitor while still showing the full dynamic range of the HDR images. Thereafter, I shifted the images such that Mars it at substantially the same position in each image, combined the images into an animation and rotated the animation such that the sunlight shines from the right. I tried several orientations, and, in my opinion, this one looks most natural. Unfortunately, Mars is moving out of the camera's field of view at the end of the series. Since the clouds are not shown any more in images No. 30 and later, I omitted these images. In the remaining images, I made the cut off portions transparent (which can be seen in the animation at the upper right part of Mars). GIF images can comprise only 256 different colors. Therefore, I converted the images to grayscale. This does not make much difference, since the color saturation in the original images is so low that colors are almost invisible. I used three computer programs for the processing: Fitswork for reading the raw data, extracting color information from Bayer patterns, shifting images and calculating logarithms of brightness values; FDRTools Basic for creating HDR images; and Gimp for combining the images into an animation, minor adjustment of the brightness of individual images and rotating the animation. This is a list of the VMC images used for the animation: Frame 1: 09-309_19.02.06_VMC_Img_No_3.raw,09-309_19.02.59_VMC_Img_No_4.raw,09-309_19.03.53_VMC_Img_No_5.raw; Frame 2: 09-309_19.05.39_VMC_Img_No_7.raw,09-309_19.06.33_VMC_Img_No_8.raw,09-309_19.07.26_VMC_Img_No_9.raw; Frame 3: 09-309_19.09.13_VMC_Img_No_11.raw,09-309_19.10.06_VMC_Img_No_12.raw,09-309_19.10.59_VMC_Img_No_13.raw; Frame 4: 09-309_19.12.46_VMC_Img_No_15.raw,09-309_19.13.39_VMC_Img_No_16.raw,09-309_19.14.33_VMC_Img_No_17.raw; Frame 5: 09-309_19.16.19_VMC_Img_No_19.raw,09-309_19.17.13_VMC_Img_No_20.raw,09-309_19.18.06_VMC_Img_No_21.raw; Frame 6: 09-309_19.19.53_VMC_Img_No_23.raw,09-309_19.20.46_VMC_Img_No_24.raw,09-309_19.21.39_VMC_Img_No_25.raw; Frame 7: 09-309_19.23.26_VMC_Img_No_27.raw,09-309_19.24.19_VMC_Img_No_28.raw,09-309_19.25.13_VMC_Img_No_29.raw. Image Credit: Martin Ahr, ESA