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From Mars, With Curiosity: How We Get Pictures From the Red Planet

6 minute read

When Curiosity celebrated its first Martian year on the red planet last month, it beamed back to Earth a selfie. Standing alone in a desolate landscape, with its companions Opportunity and Spirit standing on the other side of the red planet, Curiosity can feel good about itself. Some 100 million miles away, crowds of Earth-based creatures are following its every move and rejoicing at the hundreds of images it’s shared since landing on Mars on August 6, 2012.

“People feel for this robot,” says Dr. Mark Lemmon, an Associate Professor in atmospheric sciences at Texas A&M University and a member of the imaging team at Malin Space Science Systems (MSSS), a San Diego company tasked with controlling four of Curiosity’s 17 cameras. “It’s nice that people can take it seriously that way, and we certainly have those kinds of feelings, too—these robots are important for us. The idea that we managed to successfully communicate to the public not just what we’re doing but that we have a robot that’s exploring Mars for us, that’s extremely cool.”

His colleague at MSSS, James F. Bell, agrees. “People relate to these rovers because there’s been so much of an investment—not just in terms of money, but in people’s time and efforts. These rovers and the robotic work that goes on in space exploration is some of the best and most exciting and most successful stuff that NASA is doing right now.”

In just 10 years, Spirit, Opportunity and Curiosity have broadened and deepened our understanding of Mars, sending back to Earth thousands of images that have been closely studied by research centers and universities around the world.

Yet, capturing these images isn’t as simple as pushing a button, especially when your camera is millions of miles away. “It’s literally out of this world,” says Bell, who works on the imaging team at MSSS. “[We control] two color cameras up on Curiosity’s mast—we call them the Mastcams. There’s the Mars Descent Imager or MARDI, and the Mars Hand Lens Imager (MAHLI),” which is located on Curiosity’s robotic arm. “These cameras were built and are operated by MSSS in San Diego.”

As deputy principal investigator on the Mastcam and MARDI cameras, Bell is involved in day-to-day operations, making sure that they’re running properly and correctly calibrated.

“There’s a process that goes on every day,” he tells TIME. “We have briefings with all the different instrument teams where we plan [the rover’s activities]. Engineers will tell us how much power we have available, how much time we have with each instrument, and how much data we can send back. We will start with that resource envelope and then tactically figure out where we are and what we need to do.”

“Generally speaking, at the end of each drive, we use the one-megapixel Navcam [a navigational camera], which has a wide field-of-view, to give us a low-resolution picture of where we are,” adds Lemmon. As the different science teams study that image, they will make a list of targets for higher-resolution images. Is there an interesting rock formation on the left, some features on the crater wall on the right, or an interesting rock right in front of the rover? “That’s when we say we need a picture.”

This translates into a series of commands that will be beamed from Earth to NASA’s Mars Reconnaissance Orbiter (MRO) and the Mars Odyssey probe and down to Curiosity. “The camera command is a relatively simple line of instructions that tell the rover which camera to use [the two cameras on Curiosity’s Mast have different focal length: 34mm and 100mm], which filter to put on each camera, what focus position and what kind of exposure time it should use,” Bell explains. “Should we compress the data? If it’s a scene full of very fine details, we want it uncompressed. Or can we afford to compress the data, because the more we can compress, the more we can take. And then what priority should that get on the downlink? We can store an enormous amount of data on board, but can only downlink a small amount every day.”

The rover cameras are each fitted with 1MB of flash memory—equivalent to one raw image—while Curiosity itself sports “enough memory to store many days’ worth of data,” notes Lemmon. But that data has to make its way back to Earth, and with just a short window of 15 to 20 minutes of communications between the rover and MRO or Odyssey, only around 31MB of data can be transmitted each day.

The Jet Propulsion Laboratory at the California Institute of Technology then turns these zeros and ones into images. “This is raw data,” says Bell. “There are some artifacts that need to be corrected, like in your traditional camera, so we run those corrections, put a header and label on these images, describing as much as we can about them, and release them to the public. It’s in the spirit of openness and participation, but also acceptance of the fact that there are many armchair astronomers out there who like to play with data and put their own panoramas together. We’re exploring [a new world] and we don’t often know what we’ll see when we turn a corner.”

This openness has created an enormous amount of goodwill and interest from the public. When Spirit found itself stuck in a sand-filled crater, the Free Spirit movement was launched, with some arguing that NASA’s first human mission to Mars should strive to retrieve the beloved rover.

In January 2014, Spirit and Opportunity also became the stars of an exhibition at the National Air and Space Museum, with hundreds of the rovers’ landscape photographs on show. “I think it’s wonderful that we have the luxury of being able to take some beautiful pictures,” says Bell. “Sometimes we can come up with scientific reasons [for these photographs], but, to be honest, sometimes there are very weak scientific reasons. It’s just a beautiful picture of a sunrise, a sunset, or a self-portrait.”

Olivier Laurent is the editor of TIME LightBox. Follow him on Twitter and Instagram @olivierclaurent.

This view of the twilight sky and Martian horizon taken by NASA's Curiosity Mars rover includes Earth as the brightest point of light in the night sky. Earth is a little left of center in the image, and our moon is just below Earth.NASA/JPL-Caltech/MSSS/TAMU
This view from the left Navigation Camera (Navcam) of NASA's Mars Rover Curiosity looks back at wheel tracks made during the first drive away from the last science target in the "Glenelg" area. The drive commenced a long trek toward the mission's long-term destination: Mount Sharp. NASA/JPL-Caltech
The lower slopes of Mount Sharp appear at the top of this image taken by the right Navigation Camera (Navcam) of NASA's Mars rover Curiosity at the end of a drive of about 135 feet (41 meters) during the 329th Martian day, or sol, of the rover's work on Mars (July 9, 2013). NASA/JPL-Caltech
This image shows the robotic arm of NASA's Mars rover Curiosity with the first rock touched by an instrument on the arm. The rover's right Navigation Camera (Navcam) took this image during the 46th Martian day, or sol, of the mission (Sept. 22, 2012). NASA/JPL-Caltech
This image from the Navigation Camera (Navcam) on NASA's Curiosity Mars rover shows a sandstone slab on which the rover team has selected a target, "Windjana," for close-up examination and possible drilling. The target is on the approximately 2-foot-wide (60-centimeter-wide) rock seen in the right half of this view.NASA/JPL-Caltech
NASA's Curiosity Mars rover used the Navigation Camera (Navcam) on its mast to catch this look-back eastward at wheel tracks from driving through and past "Dingo Gap" inside Gale Crater. The gap, spanned by a 3-foot-tall (1-meter-tall) dune, is at the right-hand side of the horizon in this scene.NASA/JPL-Caltech
A chapter of the layered geological history of Mars is laid bare in this postcard from NASA's Curiosity rover. The image shows the base of Mount Sharp, the rover's eventual science destination. This image is a portion of a larger image taken by Curiosity's 100-millimeter Mast Camera on Aug. 23, 2012.NASA/JPL-Caltech/MSSS
This view of a Martian rock target called "Harrison" merges images from two cameras on NASA's Curiosity Mars rover to provide both color and microscopic detail. Curiosity inspected the rock's appearance and composition on the mission's 514th sol, or Martian day (Jan. 15, 2014).NASA/JPL-Caltech/LANL/CNES/IRAP/LPGNantes/CNRS/IAS/MSSS
This view of the rocky site "Darwin" was taken with the left eye of the Mast Camera (Mastcam) on Curiosity during the 390th Martian day, or sol, of the rover's work on Mars (Sept. 10, 2013).NASA/JPL-Caltech/Malin Space Science Systems
This view from the Mars Hand Lens Imager (MAHLI) on NASA's Curiosity Mars Rover shows the rock target "Windjana" and its immediate surroundings after inspection of the site by the rover. The drilling of a test hole and a sample collection hole produced the mounds of drill cuttings that are markedly less red than the other visible surfaces. This view is from the 627th Martian day, or sol, of Curiosity's work on Mars (May 12, 2014).NASA/JPL-Caltech/MSSS
This image from the Mars Hand Lens Imager (MAHLI) camera on NASA's Mars rover Curiosity shows a small bright object on the ground beside the rover at the "Rocknest" site. The object is just below the center of this image. The rover team has assessed this object as debris from the spacecraft, possibly from the events of landing on Mars. The image was taken during the mission's 65th Martian day, or sol (Oct. 11, 2012). NASA/JPL-Caltech/MSSS
NASA's Curiosity Mars rover used the camera at the end of its arm in April and May 2014 to take dozens of component images combined into this self-portrait where the rover drilled into a sandstone target called "Windjana." The camera is the Mars Hand Lens Imager (MAHLI).NASA/JPL-Caltech/MSSS
This patch of windblown sand and dust downhill from a cluster of dark rocks is the "Rocknest" site, which has been selected as the likely location for first use of the scoop on the arm of NASA's Mars rover Curiosity. This view is a mosaic of images taken by the telephoto right-eye camera of the Mast Camera (Mastcam) during the 52nd Martian day, or sol, of the mission (Sept. 28, 2012).NASA/JPL-Caltech/MSSS
This mosaic of images from Curiosity's Mast Camera (Mastcam) shows geological members of the Yellowknife Bay formation. The scene has the Sheepbed mudstone in the foreground and rises up through Gillespie Lake member to the Point Lake outcrop. The scene is a portion of a 111-image mosaic acquired during the 137th Martian day, or sol, of Curiosity's work on Mars (Dec. 24, 2012).NASA/JPL-Caltech/MSSS
This image from the Navigation Camera (Navcam) on NASA's Curiosity Mars rover includes a bright spot near the upper left corner. The sun is in the same direction, west-northwest, above the frame. Bright spots appear in images from the rover nearly every week. Typical explanations for them are cosmic rays hitting the light detector or sunlight glinting from rocks. NASA/JPL-Caltech
This view of Curiosity's deck shows a plaque bearing several signatures of US officials, including that of President Obama and Vice President Biden. The image was taken by the rover's Mars Hand Lens Imager (MAHLI) during the rover's 44th Martian day, or sol, on Mars (Sept. 19, 2012). The plaque is located on the front left side of the rover's deck.NASA/JPL-Caltech/MSSS

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