For the past few years, tantalizing evidence has been found that Mars — thought to be long dead, dry, and lifeless — may have pockets of water just beneath the surface. To be clear, we know there’s water on Mars, in the form of ice. We see ice in the polar caps, and we’ve seen it revealed under the surface by small meteorite impacts.

The question is, is there liquid water?

New images by the Mars Reconnaissance Orbiter bring us a step closer to answering that question. A series of pictures of the 300 km (180 mile) wide Newton crater taken over the course of several years show dark deposits on the crater wall which change predictably with the seasons, clearly affiliated with some sort of material flowing downslope:

[Click to barsoomenate.]

The picture above shows Newton’s crater wall. It’s pretty steep, with about a 35° slope, and the dark deposits are labeled. This crater is located in the southern mid-latitudes of Mars, and this part of the crater faces north. That’s critical! Since it faces toward the equator, that means it’s facing the Sun in the summer, and so these deposits appear when the temperatures get warm.

NASA has created several animated gifs (too big to embed here) that show the growth and retreat of these features over time. You can easily see how these dark features change.

In the past, similar things have been seen in gullies on Mars. It’s not clear those are from water, since frozen carbon dioxide can also be thawing out and forming them. In those cases, the flows were seen on the cold-facing sides of crater walls, making it less likely they’re from water. These new formations are on the warm-facing side, making it more likely they are from water.

So what’s going on? (more…)

After nearly a year of trying to reestablish communications with the Spirit Mars rover, NASA has decided to suspend efforts. For all intent and purpose, Spirit is dead.

The rover sent its last message in March of 2010, and it was hoped that as Martian summer dawned at Spirit’s location, the solar cells might absorb enough energy to reawaken the plucky explorer. However, repeated attempts over several months have yielded no joy. And now, just months away from the launch of the much more ambitious "Curiosity" Mars Science Laboratory — a golfcart-sized rover with better range and instrumentation than any previous mission — communications satellites and Mars orbiters NASA uses to work with Spirit need to be transitioned to MSL.

This makes me sad, of course: Spirit was an amazing machine. But I have to admit, that sadness is offset by the incredible accomplishments of the rover. Designed to last for three months, Spirit kept on roving for over six years. Imagine having a car, a computer, that lasted for 25 times the warranty!

Or living to be 1500 years old. How much could you accomplish in that time?

Spirit’s made good use of its lifespan.

So while I’m sad about this, I know (as I wrote when we lost communication with Spirit last year) that this robot is one of the most successful NASA missions of all time. It’s hard not to anthropomorphize our work sometimes, and I think it’s appropriate to be sad. But I’m also very happy that Spirit could do what it did. It was a triumph of human engineering, human cleverness, and the very human need to explore what’s around the next corner… even when that corner is a hundred million kilometers away.

Speaking of weird impact craters on Mars…

Mars Express is a European Space Agency orbiter that’s been snapping away at the Red Planet since late 2003. In August 2010 it took this picture of a bizarre feature on Mars:

[Click to impactenate.]

I would’ve thought this was a canyon of some sort, but in fact it’s an elongated crater! Most likely some large object broke up as it entered the atmosphere of Mars, striking the surface at a low angle and creating a series of craters that merged to form this strange thing. Unlike the triple crater I mentioned last time, this one is pretty frakkin’ big: it’s 78 kilometers (almost 50 miles!) long, 10 km (6 miles) wide at one end and 25 km (15.5 miles) wide at the other. Whatever hit here was pretty big, certainly over a kilometer across before it broke up. Probably several.
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What the heck hit Mars and made this?

[Click to barsoomenate.]

This image is from my favorite Red Planet paparazzo, the HiRISE camera on Mars Reconnaissance Orbiter. It shows three craters, each about 1.5 to 2 km (0.9 to 1.2 miles) across… and they all formed at the same time!

How can I tell? Well, for one thing, if this were a coincidence, with three impacts happening at very different times, then you’d see overlap in the crater rims; the earliest crater would be partially obscured by the later crater, and that in turn by the most recent impact. But that’s not the case here, since the rims aren’t overlaying each other. In fact, the straight walls between them are exactly what you’d expect if you have impact explosions happening simultaneously: the expanding shock waves smack into each other and create a linear feature.

Not only that, but let your eye follow the straight lines between craters up and down, above and below the craters themselves and onto the landscape. You can see that the hellish expanding wall of fire etched itself onto the Martian surface well beyond just the crater rims, and those linear features match the crater wall orientation. I annotated the image here to show you what I mean; the red lines are just outside the linear features.

I can picture what must have happened, millions of years ago over Mars…
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Mars is a weird place. I mean, really. What kind of normal planet would have a huge flat valley cutting right through the north polar ice cap?

This picture [click to barsoomenate] is a combination of shots taken from 2002 – 2005 by the spacecraft Mars Odyssey, using a camera called THEMIS, which takes images in visible and infrared light. The valley is called Chasma Boreale (literally, northern chasm) and is formed by retreating ice in the cap. Over eons of time, as the cap evaporated and reformed, sand got caught in layers in the ice. Now, as the cap retreats again, the sand is released into the valley floor. You can see the layers in the valley wall in the image, and also dunes as the wind piles it up.

The valley is pretty deep: the walls can be as high as 1.4 kilometers (almost 0.9 miles)! That would be interesting to ski, especially in Mars’s lower gravity (0.38 of Earth’s). Of course, to get to this butterscotch valley, you’d have to travel through the seven levels of the Candy Cane forest, and through the sea of swirly twirly gum drops^*.

Image Credit: NASA/JPL-Caltech/ASU

^* Someone must get this joke.

As recently promised, the European Space Agency’s Mars Express probe made a very close pass of the small moon Phobos, taking incredibly detailed pictures of the spud-shaped rock. Emily Lakdawalla, as always with planetary missions, has the what-fors with this event.

When it was a mere 111 km (66 miles) from the moon, Mars Express took this amazing image:

Click it for the full-res version is a whopping 7800 x 5200 pixel, 13 Mb TIF barsoomenated version. The detail is incredible, with features as small as 8 meters (roughly 25 feet across). Since Phobos is about 27 km (17 miles) long, that’s a lot of detail!

But as regular readers know, I have a thing for 3D red/green anaglyphs, and as the probe passed the moon naturally took stereoscopic images. The folks at ESA put two together to make this jaw-dropping 3D shot of Phobos:

Click it to get 3800 x 2600 pixel, 13 Mb TIF version. You really want to. If you have red/green glasses, this is one of the best anaglyphs from space you’ll see. I’ve never seen something stick out of my screen like this! Also, the details were so sharp that if I shake my head back and forth (like gesturing "no") I can actually see Phobos rotate a little bit, due to the change of positions of my eyes! That was new to me as well, and is very cool. it really solidifies the illusion that you’re seeing an object three-dimensionally.

Mars is an astonishing place, and it’s easy to forget how interesting its two moons are (the other is Deimos, which is smaller than Phobos). Their origins are still something of a mystery, and the surface features on Phobos are not totally understood either. (more…)

The European Space Agency probe Mars Express has been orbiting the Red Planet for just over seven years now, returning vast amounts of information. It looks at Mars, of course, but also the two dinky and weird moons Phobos and Deimos. For example, a little while back it took this phenomenal shot of Phobos over the limb of Mars:

[Click to greatly barsoominate.]

That’s fantastic! Note how dark Phobos appears; it really is much less reflective than Mars. Its origin is unclear, but a popular idea is that it’s an asteroid Mars captured long ago. I’ve never been comfortable with this idea, since capturing an object is extremely difficult. An asteroid moving past a planet will just fly on by unless it is slowed considerably, and there aren’t many ways to do that. If it passes extremely close, the atmosphere of the planet might slow it sufficiently, but that results in a highly elliptical orbit that’s unlikely to last very long. Perhaps Phobos was a binary asteroid, and one of the two components absorbed the extra energy and was ejected, while the other settled into orbit and became Phobos. Maybe it got its start in some other way entirely.

We’ll hopefully learn more when the Russian probe (and lander with sample return!) Phobos-Grunt launches later this year. In the meantime, Mars Express is in an orbit that periodically brings it close to Phobos several times, and we’re entering a new season of passes right now. In fact, it just had a close encounter with Phobos, and word has it the flyby was a success! That means we’ll soon be getting more even interesting and beautiful images of this enigmatic little moon, so keep your eyes open for them.