Mariner 9 approaching Mars: a movie!
Posted by Emily Lakdawalla
09-12-2011 13:32 CST
Image magician Daniel Macháček has done it again. This time, he's celebrating the 40th anniversary of Mariner 9's arrival at Mars (November 13, 1971) with a morphed animation of the images that Mars' first orbiter took while approaching the planet. It is composed of 40 individual images, morphed together to smooth the animation. It's sped up 1200 times so that 1 second is equivalent to 20 minutes of real time, and the animation covers most of two days/sols. Mars was shrouded in a dust storm at the time, so details are hazy, but a few things are discernible. You can clearly see the little white dot of the southern residual polar cap, and tell from how much of the south polar terrain stays lit all the time that it's the height of summer in the southern hemisphere. As hazy features rotate into dawn, you can see a bright streak of a dust-filled Valles Marineris, followed by the triple dark dots of the peaks of the Tharsis Montes (which poke above the dust) and the trailing dot of Olympus Mons. As they rotate out of view a dimly dark streak appears with a circular light cutout -- that's Sinus Meridiani, near where Opportunity is now. An entire day passes and Valles Marineris and the great volcanoes return to the view before it fades out.
The view reminds me of the one from Mars Express' VMC, which also often show a hazy Mars. These were taken in the opposite season, though, at the height of northern summer, and the hazy appearance is mostly due to fog and water ice cloud, not dust. (I note here in passing an easy visual trick to figure out the approximate season -- if the Tharsis Montes are parallel to the dawn terminator, it's southern hemisphere summer; if they're at more like a 45 degree angle, it's northern hemisphere summer.)