See Mars Through Curiosity’s Eyes
by Emily Lakdawalla on August 23, 2012
Did you know that several NASA missions post the images shot by their in-space cameras to public websites in near-real time? These aren’t quite live video feeds from spacecraft, but it really is the next best thing.
Whenever the Mars Exploration Rovers, Cassini Saturn orbiter, or Curiosity rover data are received on Earth, they are usually posted to public websites right away. This happens fast; earlier today I saw a few Curiosity photos arrive on the Internet less than an hour and a half after they were taken on Mars.
Stop for a second to think about what has to happen for that to work. The rover shoots the photos on another planet. Then a Mars orbiter has to pass overhead (something that only happens two or three times each day) to receive Curiosity’s transmitted data. Then the orbiter has to transmit that information to one of the three Deep Space Network stations in Australia, California, or Spain. The data has to be sent to JPL, decoded into images, cataloged, and placed on a server. All of that happened within an hour-and-a-half span. Wow.
The way these images arrive on the Web every day has made these robots’ adventures in the solar system accessible to the world. You get to ride along with the rovers and Cassini as they go to new places at distant planets. Depending on what time of day you visit the website, you might even be seeing new pictures before the mission’s scientists and engineers do!
Here’s where to go for the photos:
- Mars Exploration Rover raw images site at JPL (sorted by mission day)
- Mars Exploration Rover raw images site at Exploratorium (sorted by date received on Earth)
- Cassini raw images site at JPL
- Curiosity raw images site at JPL (sorted by mission day)
- Curiositymsl.com (an enthusiast-maintained raw browser that’s better than JPLs)
- msl-raw-images.appspot.com (another better enthusiast-maintained raw browser)
And here’s a little field guide to Curiosity’s photos.
Curiosity has 17 cameras, of which 11 are in use at any given time. Of these, 6 are black-and-white engineering cameras used for navigational purposes; 4 are color science cameras; and 1 is the telescopic ChemCam (which I won’t talk about here). There are an additional 6 backup engineering cameras in case the first ones fail. Here’s a visual guide to the 7 cameras on top of the mast.
Images are usually returned to Earth first as very small thumbnails, which are quick to transmit and which provide a visual index to all the data waiting aboard the rover. Later, as bandwidth permits, most (but not all) are sent to Earth at higher resolution.
Navcam is short for Navigational Camera. Navcam images provide nice medium-angle views of the wide world around Curiosity; they provide context for everything else and are used by the rover drivers to plan their next moves. Therefore, they’re usually the quickest to arrive on Earth. To get panoramic views of the landscape, Curiosity takes a photo, rotates the mast 30 degrees, takes another one, and so on until there are 12 images making a complete circle around the rover. They may shoot more than one tier to add height to the panorama. There are right and left Navcams that are identical, giving Curiosity (and her ground controllers and the public) stereoscopic vision. Full-resolution Navcam images are 1024 by 1024 pixels; thumbnails are 64 by 64.
The rover also has two pairs of Hazard Avoidance Cameras, or Hazcams, one set mounted on the front of the rover’s body and one set in the rear. These are extra-wide-angle fisheye cameras useful mostly for examining the ground immediately around Curiosity’s wheels. Because of their fisheye lenses, the images are distorted, and a flat horizon appears to arch across the image. They’re paired to provide stereoscopic vision. They’re used by the rover for its autonomous navigation purposes (helping it — duh — avoid hazards). They’re also used by the rover drivers to plan how they will use the robotic arm and all its tools on the targets right in front of the rover. Like Navcam images, Hazcam images are 1024 by 1024 pixels in size, with 64 by 64 thumbnails.
- FLA_398919417EDR_F0030078FHAZ00302M_: A forward Hazcam image taken on sol 15 shows that Curiosity has been burning donuts in the Gale crater parking lot. (Credit: NASA / JPL)
The two Mastcams have different-size eyes because they have different focal lengths of 34 and 100 millimeters (different zoom levels). The right eye is zoomed in and the left eye zoomed out. The left-eye Mastcam is the one they use to shoot full-color panoramas; it takes 30 Mastcam frames to cover the entire 360 degrees, and 6 or more tiers to cover the landscape from the horizon down to the wheels. Here is an insanely amazing version of Curiosity’s sol 3 panorama, processed by Damien Bouic from the raw images.
The right-eye Mastcam will be used mostly for detailed views of nearby rocks and of faraway drive destinations. Both Mastcams are focusable, which means that occasionally the focus will not be set correctly (especially in the beginning of the mission) and an image will look blurry. Full-resolution images are 1600 by 1200; thumbnails are 192 by 144.
There are two more cameras. MARDI is the descent imager that shot the amazing video I’ve talked about before; it’s now staring at the ground and hasn’t been used since landing, but likely will be in the future to record how the soil changes from site to site. MAHLI is the arm-mounted camera, which they haven’t really used yet.
I hope this has been a useful tour of the images that are coming down from Mars every day, and that you’ll enjoy riding along with Curiosity as I do. Check those raw images pages from time to time to see how her landscape changes, and drive with her around Mars!
Here’s some links to some amazing amateur image processing work on Curiosity raw images:
- The definitive version of Curiosity’s first color panorama
- Curiosity sol 15 update: Wheel wiggles, arm flexes, and bad news about REMS
- Some fun with Curiosity MARDI images