A Needle in a Haystack on Mars

In 2006, a NASA spacecraft arrived at Mars and settled into orbit. The dragonfly-shaped Mars Reconnaissance Orbiter carried, among other instruments, the most powerful camera to ever leave Earth, capable of photographing rocks as small as three feet across, from about 200 miles up. The camera, known as High Resolution Imaging Science Experiment, or HiRISE for short, has provided scientists unprecedented views of the complex, textured Martian terrain. The detail is astounding: elaborate layers of bedrock, windswept sand dunes, rocky landslides and avalanches.

Then in August 2012, HiRiSE captured something not of this world: two bright objects hovering above the dusty landscape. A car-sized rover and its parachute, descending onto the surface. Curiosity had arrived.

HiRiSE has photographed Curiosity every few months since, tracking its careful slog across the planet’s surface. The observations are useful for scientists and engineers plotting the rover’s journey. They’re also reminders of just how alone Curiosity is out there.

The latest photo, at the top of this story, was taken on June 5 as the rover made its way toward its next destination, a ridge where scientists have spotted a lustrous, gray mineral called hematite from earlier observations. From this view, Curiosity is microscopic, a pinprick of intelligent life in a barren, alien world. It appears in blue because the colors of the photo have been enhanced to highlight the granular landscape. Without this adjustment, Curiosity would be nearly impossible to find, lost among the boulders and rocks. On Mars, it’s “a needle in a haystack,” says John Grant, a geologist at the Smithsonian Air and Space Museum who also works on the missions for Curiosity and Opportunity, another rover on the planet.

“The thing that’s most stunning to me is the isolation of the rover within the landscape that it’s traversing,” Grant says.

Curiosity has spent nearly five years exploring Gale crater and the three-mile mound in its middle known as Mount Sharp—and HiRiSE has been there to show us some of its milestones. Here it is, arriving:

A year after landing, Curiosity had made some progress, but not much. The rover’s top speed is about 1.5 inches per second:

HiRiSE periodically photographs Opportunity, the only other operational rover on Mars, located on the other side of the planet. The camera has also imaged other, now defunct NASA hardware, like the Spirit rover that arrived with Opportunity in 2004, the Pathfinder lander in 1997, and the Viking lander in 1976, the first robotic mission to Mars. HiRiSE has photographed Beagle 2, the British spacecraft that went silent after touching down in 2003, and Schiaparelli, the European-Russian lander that crashed on the surface last year. Each piece of hardware appears as a speck against the vast, desolate landscape.

HiRiSE has never found the Polar lander, which NASA dispatched to the planet’s south pole in 1999. Grant says years of migrating dust and ice may have camouflaged the spacecraft from view.

The Mars Reconnaissance Orbiter has enough fuel to last another two decades, barring any mechanical failures. Grant says he never tires of seeing HiRiSE images of the rovers.

“I think it reminds you that, oh my gosh, there really is a piece of hardware that we built and flew to another planet moving around on the surface of it,” he said. “I think it makes it real.”