Because the planets are so terribly old, and impacts so rare, I still have this (very slight) prejudice that craters are old too. The Moon was bombarded billions of years ago, and the craters on Earth are mostly so old that they’ve eroded away. Heck, even a "new" crater like the one in Arizona is tens of thousands of years old.
Getting the age of a crater can be tricky. But sometimes it’s so easy it’s literally a matter of keeping your eyes on one spot. Like this spot on Mars:
That image (highly color enhanced; click here for a grayscale version) shows a crater seen by a camera on the Mars Reconnaissance Orbiter in 2011. We can tell it’s young because it’s still surrounded by the ejecta blanket; material that blasted out of the crater and settled around it. That stuff tends to erode away (or get covered in dust and sand by Martian winds) relatively quickly.
But in this case, we know just how young it is: it wasn’t seen in images taken of the same spot by a camera on board the Odyssey Mars probe… in 2009! In other words, this crater is less than three years old!
That’s so cool. And it speaks to the power of having multiple, sustained missions to other worlds. Things change. If we take one picture and then walk away, we’ll miss a lot.
Image credit: NASA/JPL/University of Arizona
We have a fleet of spacecraft at Mars right now, including the amazing Mars Reconnaissance Orbiter and its equally amazing HiRISE camera, capable of taking very high-res pictures of the planet below.
The folks managing HiRISE just released a new picture of Mars showing the location of Curiosity, and it’ll wow you for sure:
Wow!* [Click to enaresenate.]
The colors have been enhanced in this image – which actually makes things very interesting. As I’ve pointed out before, most of Mars is covered in basalt, a blue-gray rock. When you hear about sand on Mars, it’s usually coarse-grained stuff made up of eroded basalt. However, there’s also much finer-grained dust which is high in iron oxide – rust – and it’s that which gives Mars its characteristic ruddy color.
That fine dust covers everything, making the planet red/orange/ochre. But there’s wind on Mars, and it can blow the dust around, revealing the grayer basalt underneath (like the dust devils do). And if there’s no natural wind, why, the thrusters from the rockets of a sky crane hovering over the surface as it lowers a one-ton rover to the ground will do just fine.
That part is actually pretty obvious in the picture. The thrusters blew around the dust, revealing the rock underneath, giving the landing site a bluer cast in the image (remember, it’s color enhanced). In the first images from the rover you can see that as well, but not as clearly as here. In fact, in the high-res version you can see the streaks from the individual rockets under the sky crane immediately around the rover, which then fanned out to produce the larger region of disturbed dust.
And as an added bonus, the rover itself can be seen sitting pretty right in the middle!
Note that this is a small, small portion of a vastly huger picture from HiRISE showing an incredible slice of Mars. The colors and landscape in that (also enhanced) picture are jaw-dropping, and you should take a look.
Wanna see more? I created a gallery of my favorite images of and from Curiosity from its first week on Mars.
Image credit: NASA/JPL/University of Arizona
A new picture returned from the HiRISE camera on the Mars Reconnaissance Orbiter shows an overview of the Mars Curiosity rover landing site, showing all the hardware that took it safely to the surface!
Coooool. Click to barsoomenate.
It’s like an episode of CSI: Gale Crater. You can see the Curiosity rover itself (labeled MSL for Mars Science Laboratory, the official name), sitting in a circle of dust disturbed by the landing rockets in the sky crane at final moments of descent. The sky crane impact site is to the upper left, several hundred meters away. The crane lowered the rover to the surface, disconnected the cables, then flew off to a safe distance. Note the plume of disturbed material pointing away from the direction to the rover, indicating the crane hit the ground at a low angle and not straight down (in which case the splash pattern would be more circular).
The parachute and backshell are off to the left. The backshell was literally that: a protective shell on the back of the rover and crane assembly to which the parachute was attached. That disconnected while the crane and rover were still well off the surface, to avoid getting tangled.
Finally, the heat shield is off to the lower right. That was the blunt capsule under the whole package that protected it from the heat of atmospheric entry; you can see it detach and fall to the ground in the descent video I posted recently.
These images are cool, but serve a solid purpose: they provide the engineers and scientists here on Earth evidence of precisely how the hardware performed. By looking at locations, dust patterns, and more, they can determine how well these devices did versus what was predicted. That’s important info for planning future missions, especially given how complex this landing sequence was. It really is a bit of forensics.
But it also says something else: we have hardware that made it to Mars! And we have photographic evidence of it!
The future. We are in you.
Image credit: NASA/JPL/University of Arizona
This is truly astonishing: the HiRISE camera on the Mars Reconnaissance Orbiter snapped what may turn out to be the Space Picture of the Year: Curiosity descending to Mars under its parachutes!
The rover is safely tucked inside the backshell, suspended underneath its huge parachute. This image was taken just moments after Curiosity’s speed had dropped from thousands of kilometers per hour to just hundreds. Shortly after that, rockets underneath took over the job of slowing it further, so that the sky crane could lower Curiosity safely to the Martian surface.
This took incredible skills in calculations, engineering, and a just a wee pinch of good timing. Engineers here on Earth knew just where and when Curiosity would be coming down, so they were able to aim HiRISE at the right place at the right time. It strongly reminds me of a similar picture taken in 2008 by the same camera as the Phoenix lander descended to the surface of Mars. I suspect MRO was closer to Curiosity than it was to Phoenix, allowing higher resolution. [Update (16:40 UTC): More info about the picture can be found on the MRO HiRISE wesbite.]
The simple and sheer amazingness of this picture cannot be overstated. Here we have a picture taken by a camera on board a space probe that’s been orbiting Mars for six years, reset and re-aimed by programmers hundreds of millions of kilometers away using math and science pioneered centuries ago, so that it could catch the fleeting view of another machine we humans flung across space, traveling hundreds of million of kilometers to another world at mind-bending speeds, only to gently – and perfectly – touch down on the surface mere minutes later.
The news these days is filled with polarization, with hate, with fear, with ignorance. But while these feelings are a part of us, and always will be, they neither dominate nor define us. Not if we don’t let them. When we reach, when we explore, when we’re curious – that’s when we’re at our best. We can learn about the world around us, the Universe around us. It doesn’t divide us, or separate us, or create artificial and wholly made-up barriers between us. As we saw on Twitter, at New York Times Square where hundreds of people watched the landing live, and all over the world: science and exploration bind us together. Science makes the world a better place, and it makes us better people.
It’s what we can do, and what we must do.
Image credit: NASA/JPL/University of Arizona
[I have a lot of astronomy pictures I've saved to my computer's desktop, so I've pledged to post one every day in an attempt to regain control of my machine. I call this my Desktop Project.]
Mars is a pretty interesting place. A lot of the surface is covered in dust and sand, and while the air there is very thin, it can move with terrific speed. That gives it enough momentum to push that solid material around. The small-grained dust is far easier to pick up and get blown around by that wind, and we see lots of clear (and gorgeous) evidence of that in pictures from Mars. But the bigger, heavier basaltic sand is harder to move. Until recently there was no evidence of bulk dune motion at all on Mars*!
But the fantastic HiRISE camera on board the Mars Reconnaissance Orbiter has found that evidence: the motion of a Martian sand dune that took nearly two years to see:
[Click to barsoomenate.]
The animation shows the barchan (horseshoe-shaped) dune on June 25, 2008 and May 21, 2010. During that time, the sand was blown a few meters, and you can see the difference. It’s most obvious in the crescent-shaped part, but if you look closely (especially at the embiggened picture) you’ll see the rippling has moved as well, sculpted by the moving Martian air.
This fantastic image brings home (so to speak) an important point. There are, broadly speaking, two kinds of planetary missions: ones that fly past their target, like when New Horizons will blow past Pluto in 2015; and ones that go to their destination and stay. Flybys give us a great opportunity to see other worlds, and aren’t as expensive — you don’t need to bring all that fuel to slow down (like Cassini did) or pack parachutes and a lander. But as great and important as they are, we only get a fleeting glimpse of the target.
But when we go to stay, we get a long, long view. Long enough, in most cases, to see change. Mars is a dynamic, ever-evolving planet. And sometimes that change is slow, so we need the time to see it. And when we do, we see dust devils, landslides, meteorite impacts, and the march of dunes across the Red Planet’s surface.
It’s more expensive, and it’s harder, but it’s worth it to go someplace and settle in. Otherwise, you might miss something really cool.
* There’s evidence that the ripples on dunes have moved, but not that the dunes themselves have been moving as wind pushes them.
Image credit: Image credit: NASA/JPL-Caltech/Univ. of Ariz./JHUAPL
In March, I wrote about a dust devil on Mars spotted by the Mars Reconnaissance Orbiter. It was 800 meters high, which I said was "huge".
Yeah. A week later, MRO spotted another dust devil… that was 20 kilometers high!
[Click to vortexenate.]
Dust devils form when air blows over warmer air rising off of the plains. If conditions are right, a vortex forms, becomes vertical, and you get a dust devil. It happens all the time on both Earth and Mars, and is common in the spring. It’s spring in the Martian northern hemisphere now, so there you go.
The folks at MRO put together a cool video to show what this monster would have looked like from the ground, and how it moved. Mind you, this is based on the image: shadows and sun angle give the height, and the shape of the shadow tells you the shape of the funnel. [You may have to refresh the page if you don't see the video directly below.]
What a sight! I’ve seen dozens of dust devils, including some that were clearly hundreds of meters high, and they’re mesmerizing and eerie. This picture is a reminder that as different as Mars is from Earth, there are also some striking similarities. And that just because Mars is smaller and has a thinner atmosphere, not everything it does is on a smaller scale than here.
Mars is a pretty incredible place. It’s way too easy to easy to think of it as a cold, dry, dead world, but that’s not really true: it has an atmosphere (though thin), it has seasons, and it even has weather.
Circling the Red Planet is the Mars Reconnaissance Orbiter, and with its HiRISE camera it has a fantastic view of the changing face of the planet. And it so happens that sometimes MRO is looking at just the right place, at just the right time, to capture astonishing events… like this magnificent twisting dust devil towering over the landscape:
Holy wow! [Click to barsoomenate.]
This picture is just amazing. Dust devils are wind vortices, like tornadoes, but generally not as violent. They form when sunlight warms the surface of Mars. The air just above it gets warmer and rises. If there is a crosswind, it can blow across the rising air and start it spinning like waves breaking on a beach. But since the air is rising, it can lift up vertically while still spinning, forming a dust devil.
I’ve seen them here on Earth all the time; driving across the American southwest one day I saw dozens, including one that was easily a hundred meters across. And so it happens on Mars too. But I’ve never seen one like this! Given the shadow and height of the Sun when this shot was taken, the devil must have been 800 meters high — a half a mile! That’s huge.
The dust devil actually was relatively vertical until a height of about 250 meters above the ground, where the wind caught it and swept it back into that serpentine shape. The path of the dust devil was actually fairly straight; it’s just the plume being whipped around that makes it look wavy (the shadow on the surface adds a wonderful depth to it as well).
usually commonly leave behind interesting tracks on the ground as well as they sweep away dust, which can be phenomenally beautiful and intricate. That’s not easily apparent in this closeup, but I’ve included a shot here that shows a much larger area — you can see the dust devil at the bottom for scale — and there are bright tracks all over the place, where earlier devils have swept up surface material.
As the folks at HiRISE point out, it’s interesting that these tracks are bright and not dark as usual. The area seen here has thick dust that is too heavy to be picked up by the devil’s winds, but there is lighter dust scattered around on top of the thicker material. It’s likely that after the dust devil moves, the lighter, brighter material swirls and settles behind the vortex, forming those tracks.
Dust devils are most common in the spring, when atmospheric conditions are best for them, and it happens to be late spring in this location on Mars. And having seen dust devils like this on Earth — where they are mesmerizing and fascinating — I have to wonder. Will my descendants someday put on a pressure suit and protective gear, walk out an airlock into a rusty landscape and butterscotch sky, and see a phenomenon like this towering above them?
I hope so. I surely do.
When I made my Top 14 Astronomy Pictures of 2010, it was really tough cutting some out. This is a gallery of the images that, for whatever reasons, I decided to leave off. They’re still spectacular and gorgeous, though! Click on the thumbnail in the slider to go to an image, use the arrows to navigate back and forth, and click on the big image displayed below to get more info and a bigger version if available.
Use the thumbnails and arrows to browse the images, and click on the images themselves to go through to blog posts with more details and descriptions.