Science

Why Do The Mars Rover's Images Look So Bad?

A lot of people are wondering why the first colour image from the Mars Curiosity Rover looks so murky. Or why the black and white pictures look so low-resolution and out of focus in some areas. Calm yourselves. They will look absolutely amazing soon, perfect and in high-def.

There’s a perfectly good reason why they look so bad now.

Today’s image — Curiosity’s first colour snap was taken by the Mars Hand Lens Imager (MAHLI), which, though clearly capable of photographing thehorizon, is really designed to take close up pictures of martian rocks and soil. MAHLI is part of a Swiss-army-ish gadget arm that has five more instruments.

Its colour sensor is 1600 by 1200 pixels in size — just a 2MP camera. More than enough to take close-ups of the objects that may get drilled by the other gadgets in the arm. Two megapixels is not that bad. In fact, it can capture plenty of detail, as the crop below clearly shows. So why does the image look hazy and murky?

Two words: dust cap.

Dust caps

All the cameras in Curiosity are covered with transparent dust caps. These were installed to protect the lenses during landing. Engineers knew that the landing operation, with the skycrane firing its rockets over the rover, would produce a lot of dust: particles that could fly around and damage the delicate camera glass.

So they placed protective covers on every lens on the vehicle to avoid scratches. They’ll pop the caps off in the coming days, when they’re confident that the lenses are out of harm’s way. Now, this being NASA, there are failsafes everywhere: To account for the off chance that the the pop-off mechanisms fail, the engineers made the dust caps see-through. Which is the cameras are still firing off images. Better to have blurry images than no images at all, right?

Once the caps get popped, all the images from all cameras will be crystal clear. In fact, that already happened with the Hazard Cameras (Hazcams). These were the cameras that beamed the rover’s first images to Earth:

Those top ones look terrible because the dust caps are full of particles. But check out how good they look without the caps:

Crispy and nice… except for the blurriness on the edges. The blur has an easy explanation too.

Hazard cameras

As the name indicates, Hazcams are used to detect potential hazards on the ground, so the drivers of Curiosity can avoid dangerous situations. Don’t expect spectacular images from the Hazcams.

The cameras are black and white, only 1-megapixel in resolution. They send images in 3D so both the Curiosity’s brain and her drivers have a perfect idea of what is going to go under the rover at any time.

The Hazcams also use super-wide-angle-hazard-spottin’ fisheye lenses, which is the source of the blurry edges: The image has been linearized so the public can see a “better” picture. This means that optical correction has been used to straighten out the distortion resulting from the use of these lenses. The process deforms, scales and stretches the original bubbly image, which results in the side blurring you can see.

We got thumbnails!

Another thing that has puzzled people are the tiny images that are shown by NASA in anticipation of the bigger pictures coming later.

These caused the biggest cheers at mission control last Sunday. Somebody shouted “We got a thumbnail!” and the crowd went wild.

That meant that Curiosity had beamed down a small version of the first image taken by the Hazcam. These thumbnails — which are 64 by 64 pixels in size — are like the icons for graphic archives in your computer, tiny previews that indicate the content of the bigger resolution image coming next.

The same happened with color video of its descent. That video is also made with thumbnails, the ones taken by Curiosity’s belly camera: MARDI, the Mars Descent Imager instrument. Those images are originally 1,600 x 1,200 pixel, so expect a full — and spectacular — high definition movie of the descent in the coming months, as the images get downloaded to JPL’s computers.

It takes a while, because, in case you haven’t noticed, the Rover is on Mars. Which is very far away. The Rover is doing its best to send the photos to us as quickly as possible.

The Really Good Stuff

That will be part of the really good stuff. Not that what we have now is not good. It’s amazing, because it shows that everything is working and fine.

Today we only got the first colour image, taken with an instrument that was not designed as Curiosity’s primary camera. But Curiosity has many cameras. Twelve, in fact. Some of them capable of capturing 3D. Each of these cameras has a different function.

There are Navigation Cameras: 3D black and white cameras used to drive the rover, mounted on the head of the vehicle. There’s MAHLI, which is more of a science camera. There’s the Laser-Induced Remote Sensing for Chemistry and Micro-Imaging, which is not a camera in the traditional sense, but one that will look into the composition of rocks with unprecedented detail and accuracy using a laser to vaporise rocks coupled with an spectrograph for analysis for the resulting plasma.

And then there’s Mast Camera, or MastCam for short. This is the one designed to capture the amazing colour images, panoramas, and video in high definition. There are two of them, in fact, because they are designed to create 3D imagery. And they have very powerful zoom lenses too.

These will be the real human eyes of the rover. They will give us the Really Good Stuff.