The High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter (MRO) made multiple observations on various dates of impact scars left by Curiosity. The scars have had two years to fade. Some scars did fade while others slowed and some even darkened again, according to a press release from NASA's Jet Propulsion Laboratory in Pasadena, Calif.

"Spacecraft like Curiosity create these dark blast zone patterns where bright dust is blown away by the landing," said HiRISE team scientist Ingrid Daubar, according to the press release. "We expected to see them fade as the wind moved the dust around during the months and years after landing, but we've been surprised to see that the rate of change doesn't appear to be consistent."

One reason for the monitoring of scars is to help scientists predict how long fading would take. The data will help Daubar and others prepare for NASA's next Mars lander, InSight, set for launch in March 2016. The InSight mission will install a heat probe a few yards, or meters, into the ground. The probe will monitor heat coming from the interior of the planet. The brightness of the ground affects subterranean temperatures, because a dark surface warms in sunshine more than a bright one does.

HiRISE is one of six instruments with which NASA's Mars Reconnaissance Orbiter has been studying Mars since 2006. NASA's Mars Science Laboratory Project has been using Curiosity to examine the Red Planet's terrain for signs of microbial alien life.

From the press release: "The University of Arizona, Tucson, operates HiRISE, which was built by Ball Aerospace & Technologies Corp. of Boulder, Colorado. JPL, a division of the California Institute of Technology, Pasadena, manages the Mars Reconnaissance Orbiter Project, the Mars Science Laboratory Project and the InSight Project for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, built the orbiter and collaborates with JPL to operate it."