When I last updated you on the excursion that the Curiosity rover has been making across the floor of Gale Crater on Mars I noted that the images it has been beaming back had been getting rather routine. But the rover has slowly been moving downhill toward what seems more and more likely to have been the location where a large lake once was. Along the way some more stream and river sediments have been observed but now it has arrived at an area that is certainly the most interesting and Earth-like yet seen by Curiosity so far. The martian air has also cleared in recent weeks allowing the walls of the massive Gale Crater to be more clearly seen looming in the horizon.
Above is the view from “dingo gap”. The sand dune in the foreground seems to have been produced by winds coming up this narrowing valley into this small gap. If you click on this image to enlarge you will find that the walls are made of broken up rocks that are clearly sedimentary in origin. This image was created by Emily Lakdawalla (Twitter @elakdawalla) who writes frequently at Planetary.org. This is quite an amazing view and tells us that there is going to be a lot to see when Curiosity finally makes it to the foot of the mountain in the middle of the crater.
I liked this close-up image of the dune at dingo gap. It looks so unbelievably perfect.
Above are some of the rocks along the wall of the valley. The darker rock has small rounded pebbles embedded in it suggesting it was laid down in moving water while the thin layers of fine sediment sandstone above them suggest a more placid water environment.
Another interesting feature has just become visible to the Curiosity rover. In the image above taken with the telephoto lens we can see a huge crater. The reason it looks much lighter than the foreground rocks is that it is a long way away. It is probably 20 miles or more from the rover and so the atmospheric dust is clouding the view. The map to the right shows the approximate position of the rover and the like crater in view here (arrow down). This crater is probably the result of a large impact that occurred sometime after the formation of Gale crater, itself a large impact crater. This inner crater is newer but as you can see is also greatly eroded. It may be responsible for some of the broken rock that is found strewn in the area that the rover is now traveling many miles away.
Nothing too significant about the image above. I just like the images of the wheels because they provide a sense that these pictures are real. Here you can see the sand on the wheels though the consistency of the sand is more like dust than sand grains.
Below is a picture taken by the Chinese Chang3 lander of the surface of the Moon. Its kind of cool to see the Moon like this but really it is quite boring compared to Mars. One big difference in Moon images is the lack of skyline. With no atmosphere the horizon just goes black. In addition the Moons surface is not nearly as interesting as Mars. There are many craters but because there is no atmosphere to burn up small pieces of space dust and rock every little thing hits the surface of the Moon breaking down the rocks on the surface into sand and dust. Some parts of the surface of Mars may be as old as the Moon but the Moon just looks older because it is so much more worn down.
Naturalis Historia 