Curiosity's Martian Playground Is Technically Located in Pasadena

The Jet Propulsion Laboratory has a specialized sandbox -- complete with beach sand, brick dust, and volcanic cinders -- that's meant to mimic Mars.

Seventeen miles from downtown L.A., on the campus of NASA's Jet Propulsion Laboratory in Pasadena, there's a small stretch of earth covered in beach sand, decomposed granite, brick dust, and volcanic cinders. The grainy layer, dotted with craggy rocks, is tinted a distinctive reddish brown. 

That's by design: The ground is meant to mimic Mars. The little stretch of land off the California coast doubles as a scientific sandbox, one that researchers at the JPL use to test robotic prototypes of the vehicles they send to the Red Planet. The box is located in the open air, to simulate robotic applications in natural light; its rock colors, sizes, and distribution are all meant to match the images that have been sent back from NASA's Martian missions.

The sandbox's official name? Mars Yard.

Here's JPL's description of its Imitation Martian landscape:

The rocks are several types of basalts, including fine-grained and vesicular, both in red and black. Rock-size distributions are selected to match those seen on Mars. Large rocks are not Mars-like in composition, being less dense, but easier to move for testing. In addition to rearranging rocks, other obstacles such as bricks and trenches are often employed for specialized testing.

Here's an interactive panorama of the yard as it currently looks. 

The Mars Yard of today is actually the third incarnation of JPL's ever-evolving rover playground. The first version -- located where JPL's fire station stands today -- was only about 80 feet wide by 60 feet long. (It was built for NASA's Viking landers, which were static.) The second was constructed in 1998, this version measuring 216 feet by 118 feet. And while that larger space was able to accommodate Sojourner -- more on that little guy, courtesy Alexis Madrigal, here -- the playground proved too cramped for the bigger, more powerful rovers that were to come. There simply wasn't enough ground for all the playing they were built to do.

In 2006, the JPL began renovations to accommodate the newer and larger rovers it was building. In 2007, an expanded Mars Yard opened for simulation. And its new capacity was demonstrated by a relatively large prototype ... of a rover that would be named, yes, Curiosity. (Planetary Society's Emily Lakdawalla has a great description -- featuring photos and videos -- of that unveiling.) This updated version of the yard, importantly, was not just larger than its predecessors; it was also hillier. It featured slopes that would allow engineers to test rovers' agility with Martian mounds. And that feature, of course, would prove especially essential for Curiosity, whose landing Monday morning placed it near the base of Mt. Sharp.

The Mars Yard, as a result of all this adaptation, is delightfully DIY in appearance. Some of the volcanic rocks the sandbox features as obstacles for its rovers are hand-me-downs from previous sites -- rocks collected, originally, from the Mojave Desert. The yard also uses specialized landscaping rocks, lightweight compared to their natural counterparts, to allow engineers to augment their simulated Marscape without the need for bulldozers or other equipment. Trailers stationed right next to the space itself -- housing computers, measuring equipment, and storage space for the vehicles being tested -- add to the decidedly earthly imagery. As does, the Pasadena Sun notes, "the deer-crossing sign and occasional weed popping up through the soil." 

And though the current sandbox area now features a viewing platform for visitors -- the better to watch testing activities without interfering with them -- the space's original incarnation came complete with some plastic deck chairs for from-the-ground viewing. Rocket science! 

And that's the point: the casualness and beta-ness of the whole thing. During missions, JPL staff alter the MarsYard's terrain based on what their rovers are expected to encounter during their rovings. After the twin vehicles Spirit and Opportunity slipped on unexpectedly flat rocks on the Martian surface, for example, flat rocks were added to the Mars Yard. And the area's contents and layout will likely be further adapted as Curiosity sends back images of the terrain it's encountering in its journeys. Martian crevices? Add them to the sandbox. Boulders? Throw them in. This is the MacGyver take on the Martian landscape -- an adaptable, affable stretch of earth that, with the help of human hands, takes the shape of a foreign planet.