Curiosity is a famous, car sized rover currently exploring Gale Crater on Mars. Famous because it has an impressive track record. Landing on Mars in August 2012, the rover was designed to last 687 days/668 sols (martian days) but was extended to indefinitely in December 2012. Although at the time of writing it is trying to wait out a dust storm that has forced Opportunity into a deep sleep, it is still going strong to this day, and has managed to even take a selfie while waiting for it all to blow over. That is over 2100 earth days, still functioning and completing chemical analysis on soil from 560 million km (350 million mi) away!
Even though this impressive piece of engineering has been collecting samples and completing scientific experiments for over 5 years, the rover still has time to take the occasional selfie. It has a 2.1m robotic arm, and a sophisticated camera (MHLI) mounted on the end of it. The obvious thing you will notice about the images is that you can’t see the arm taking the image. To many of the NASA sceptics and flat earthers this is conclusive proof that the rover is in a film studio somewhere in California rather than on our nearest neighbour planet. At first glance you can understand the problem, where is the arm? The first clue is that the arm isn’t in the picture at all, and when you see the images taken of it here on Earth you can see it is a very prominent feature.
The simple answer was explained by NASA/JPL when these questions came up after the first self shot. As the Curiosity camera has a limited view, it cannot get the entire rover into one shot, and even when it does, it looks slightly odd depending on the angle. This is also a problem that they have when taking images of the martian landscape. To get round it, the camera takes many images at differing angles. The images can then be stitched together in photoshop by engineers. They did something similar when putting together images of the moon taken by satellites. As the following image posted by NASA shows, the arm has to move during the changes in camera location, often moving out of frame. Even when the arm is slightly in an image they tend to cover it with another image, so it doesn’t confuse the people looking at it. The selfie would look odd if it had more than one arm showing.
Even though they take care to put together the images in a way that dont look like many stitched together there are still sometimes some inconsistencies. Notice that in the next image the shadow of the arm is still in the image, and there is a slight ghost of the arm below the rover. As you can see below this shot too 72 images stitched together to be made. 20 of those images, over 2 tiers just make up the horizon. Selfies are generally taken at each new drill site, as part of an overall effort to document the trip and of that site. The entire picture taking sequence has now been automated, and tested rigorously on the second identical rover that is here on Earth. If the rover were to take the multiple pictures from individual commands the process would be too long and drawn out.
There are at least 7 of these selfies taken over the years, all from a very similar angle. The big thing to notice is the difference in the rover itself. Over time it slowly gets covered in more and more dust, starting to blend in with the martian soil behind it. The saddest part to see is the slow deterioration of the wheels. There are small holes developing and getting bigger in the metalwork on the wheels, and in some images they can seem prominent. Either way, these selfies show a slight human side to the robot. There are many people throughout Twitter that anthropomorphize Curiosity and its predecessors, wishing them well on their journey.
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