Emily LakdawallaOct 03, 2013

Super cool Phobos and Deimos animations from Mars Express

I've been delving in to the Mars Express image archive this week, checking out its images of Phobos, and found a couple of really cool time-series of images to assemble into animations. They are a little blurry because of the camera used to capture them -- I'll explain that in a moment -- but first, enjoy the views.

Here is one of Phobos traversing some cratered Mars terrain. Phobos is actually much darker than Mars; so we must be seeing it crossing Mars at local sunset or sunrise, with Sunlight barely creeping across the dusky landscape.

Phobos flies over Mars (HRSC animation)
Phobos flies over Mars (HRSC animation) Mars Express captured the 6 images in this animation on its orbit 6128 (October 10, 2008) using the Super Resolution Channel of its High Resolution Stereo Camera (SRC). Mars Express was 10,258 kilometers from Phobos when the series of images was taken. Phobos is visible against the backdrop of Mars. Phobos is much darker than Mars; the dark appearance of Mars suggests Phobos is near Mars' terminator (day-night boundary). ESA/DLR/FU Berlin (G. Neukum) / Emily Lakdawalla

This next one is even more awesome. I didn't notice it when I was looking for Phobos images, because according to the metadata it was targeted at Deimos. Yes, Deimos is here, a tiny little crescent; but then Phobos comes by, too. It's the second time Mars Express has captured such a mutual event on camera, but I've never seen a crescent-phase one like this. Except, of course, from Cassini, looking at mutual events of Saturn's lumpy little moons. So awesome.

High-phase Phobos and Deimos mutual event from Mars Express
High-phase Phobos and Deimos mutual event from Mars Express This 131-frame animation documents a "mutual event" of Phobos and Deimos -- the two appeared to pass by each other as the Mars Express orbiter moved along its own path. ESA/DLR/FU Berlin (G. Neukum) / Emily Lakdawalla

This animation was particularly fun to assemble because of the funny way that the raw images make the moons appear to bob up and down. That's an artifact of Mars Express' motion -- it's executing periodic tiny turns to maintain pointing centered close to Deimos -- but it's a funny effect. You have to remember that Mars Express' cameras are designed for a very orderly, predictable kind of imaging pointed downward at a planet that is supposed to be below it at all times. Attempting to catch motions of other things orbiting Mars is very much an off-label use.

Phobos and Deimos mutual event from Mars Express (raw)
Phobos and Deimos mutual event from Mars Express (raw) ESA / DLR / FU Berlin (G. Neukum) / Emily Lakdawalla

OK, now to explain why they're blurry. I did that in a blog post I wrote in 2009 about Mars Express' other mutual-event animation of Phobos and Deimos; I'll include its full text below for comparison to the 2012 images.

Phobos and Deimos mutual event from Mars Express
Phobos and Deimos mutual event from Mars Express Mars Express used the Super Resolution Channel (SRC) of its High Resolution Stereo Camera (HRSC) to take 130 images of Mars' moons Phobos and Deimos on November 5, 2009, beginning at 08:14 UTC. The images were taken over a period of 90 seconds at intervals of one second, speeding up to half-second intervals toward the end. The image resolution is 110 meters per pixel for Phobos and 240 meters per pixel for Deimos; Deimos was more than twice as far from the camera. ESA / DLR / FU Berlin (G. Neukum)

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