Mars Orbiter Mission images Mars' moons, including the far side of Deimos
There has not been very much news out of the Mars Orbiter Mission since the Siding Spring flyby last October. Today I'm excited to show you some previously unreleased images from Mars Orbiter Mission, containing Mars' moons Phobos and Deimos, which were also taken in October. Some of these photos were included in a Lunar and Planetary Science Conference abstract (PDF), which also mentioned that the Mars Colour Camera has returned a total of 250 images as of the time of the abstract submission. I contacted the Mars Colour Camera's head scientist, Ashutosh Arya, for permission to post the images of Mars' moons here, and he kindly shared these versions with me. According to a second abstract submitted to LPSC (PDF), the Mars Colour Camera team does eventually plan to make all images public in a format compatible with NASA's Planetary Data System, although they did not specify a schedule for the data release.
Mars orbiter Mission saw Phobos above Mars at 11:25 UT on October 14, 2014. Stickney crater is at the lower right. Resolution of the image is about 550 meters per pixel; Phobos is roughly 25 kilometers wide.
Phobos over Mars, from Mars Orbiter Mission
Mars orbiter Mission saw Phobos in front of Mars at 11:25 UT on October 14, 2014. Stickney crater is at the lower right. Resolution of the image is about 550 meters per pixel; Phobos is roughly 25 kilometers wide.
The moon Phobos, 25 kilometers in diameter, is much darker than bright, dusty Mars, as seen in this image captured by the Phobos 2 spacecraft on February 28, 1989. Phobos 2 took a total of 13 color sets of images of Phobos before contact was lost on March 27, 1989.
And now, here's Deimos from Mars Orbiter Mission. It's okay, I don't blame you if you're underwhelmed by these pictures; it looks like a wad of chewing gum. But stick with me and I'll explain why these pictures are significant. Arya sent me these four pictures:
Four views of the anti-Mars side of Deimos by Mars Orbiter Mission
Mars Orbiter Mission captured these four images of Deimos about 12 seconds apart at 13:06 UT on October 14, 2014. The images have a resolution of about 300 meters per pixel; Deimos is roughly 13 kilometers wide.
I enlarged them 400% and stacked them to try to make something of them. If nothing else, the stacking reduced the artifacts of the Bayer color interpolation in the originals.
ISRO / processed by Emily Lakdawalla
Mars Orbiter Mission photo of the far side of Deimos
Like most solar system moons, Deimos always keeps the same hemisphere facing Mars. It's rare for spacecraft to view the hemisphere that faces away from Mars, but Mars Orbiter Mission's long, elliptical orbit permits it to do that. This image is a composite of four different exposures, stacked and enlarged 400%.
These photos don't look like much, but they are of a face of Deimos that we almost never see: the anti-Mars side, from a perspective just a little below the equator. (Many many thanks to Phil Stooke for helping me understand the orientation of this photo. Without him it would still look like a wad of chewing gum to me.)
I know of only one other photo taken from a similar perspective:
NASA / JPL / O. de Goursac
Deimos over Pasteur crater, Mars
The moon Deimos over Pasteur crater, Mars. Taken as part of a transit sequence on January 2, 1978.
Most Mars missions operate in orbits much lower than that of Deimos. Since Deimos keeps the same face pointed at Mars all the time, any spacecraft that orbits below it only sees the Mars-facing hemisphere; it never sees half of Deimos. Mars Global Surveyor, Mars Odyssey, Mars Express, Mars Reconnaissance Orbiter -- they always only see half of the moon. Even the Viking Orbiters, which reached periapses outside Deimos' orbit, usually saw the leading and trailing hemispheres. Mars Orbiter Mission, with its uniquely elliptical orbit reaching to 77,000 kilometers above Mars, does get to face the far side of Deimos. And it gets color photos! I fervently hope that they will be able to get some pictures of Deimos from closer range, to achieve a better color portrait of the far side of Deimos.
To place the Mars Orbiter Mission images in context, here are the best Deimos images from Mariner 9 (yes, Mariner 9 data is still relevant today, for Mars' outer moon):
NASA / JPL / Emily Lakdawalla
Five views of Deimos from Mariner 9
Mariner 9 was the first spacecraft to capture detailed views of Mars' two moons. These five images were captured between December 20, 1971 and February 20, 1972. They showed a strangely smooth world with a linear ridge running across it.
And here is every single Viking Orbiter image targeted at Deimos. (It doesn't include sequences, like the color picture above, that were aimed at Mars but happened to have Deimos in the field of view.) This is what we are working with, when it comes to photographic maps of the far side of Deimos. Whatever Mars Orbiter Mission can add will be a bonus!
NASA / JPL / Emily Lakdawalla
Every Viking Orbiter image of Mars' moon Deimos
Mars' outer and smaller moon Deimos appears in 111 Viking Orbiter images gathered between August 16, 1976, and October 18, 1978. Targeting Deimos was a challenge, and it was often cut off at the edge of the frame.