Scars On Mars Fade … Sometimes / Comet-cluster Mashup


Curiosity descent and heat shield impact. Best heat shield images are at the end.

It’s only been a couple years, but the blast marks left by the descent stage that delivered the Curiosity rover to Mars as well as it heat shield that protected it have changed markedly in appearance. But not exactly the way you’d think.

This sequence of images shows a blast zone where the sky crane from NASA's Curiosity rover mission hit the ground after setting the rover down in August 2012, and how that dark scar's appearance changed over the subsequent 30 months. Image Credit: NASA/JPL-Caltech/Univ. of Arizona
This sequence of images shows a blast zone where the sky crane from NASA’s Curiosity rover mission hit the ground after setting the rover down in August 2012, and how that dark scar’s appearance changed over the past 30 months. Credit: NASA/JPL-Caltech/Univ. of Arizona

Curiosity was carefully lowered to the Martian surface in August 2012 by a powered descent stage that blasted away bright Mars dust to expose darker material beneath. Shortly before it landed, the probe ejected its heat shield which slammed into the crust some distance away. Once Curiosity landed, the descent stage or sky crane shot away and crash landed as well. Since that time, the winds crisscrossing the Red Planet have gradually re-coated the darkened areas with bright dust.

sequence shows where the rover itself landed. Curiosity disappears after the first two of the seven frames because it drove away. Its wheel tracks heading generally east (toward the left) can be seen in subsequent frames, and they also fade over time. Credit: NASA/JPL
sequence shows where the rover itself landed. Curiosity disappears after the first two of the seven frames because it drove away. Its wheel tracks heading generally east (toward the left) can be seen in subsequent frames, and they also fade over time. Credit: NASA/JPL

You might assume that accumulating dust would erase the scars, and this was true at first. Lately however, the process appears to have reversed itself.

“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,” said Ingrid Daubar, a HiRISE camera team scientist at NASA’s Jet Propulsion Laboratory who studied images of the blemishes taken by the Mars Reconnaissance Orbiter.

After fading for two years, the rate of change slowed with some areas re-darkening. Scientists are repeatedly checking the blast zones to compare their models against reality, revealing that we still don’ t fully understand how Martian dust is transported around the planet.

MarsBlast Heat shield
Five-frame sequence of the location where the spacecraft’s heat shield hit the ground. Credit: NASA/JPL-Caltech/Univ. of Arizona

Daubar’s work on this aids preparations for NASA’s next Mars lander, InSight, expected to launch in March 2016. The InSight mission will deploy a heat probe that will hammer itself a few yards, or meters, deep into the ground to monitor heat coming from the interior of the planet.

The brightness of the ground affects temperature below ground, because a dark surface warms in sunshine more than a bright one does.

Comet Siding Spring cruises past the bright globular star cluster M92 in Hercules on March 29, 2015. Credit: Rolando Ligustri
Comet Siding Spring cruises past the bright globular star cluster M92 in Hercules on March 29, 2015. Credit: Rolando Ligustri

Now that you’re brain’s completely flickered out after viewing three animations, let me share one additional photo from the weekend that has a Mars connection. It shows the comet C/2013 A1 Siding Spring passing very close in a beautiful way to the globular cluster M92 in the constellation Hercules. Siding Spring swept so close to Mars last fall it created a meteor shower in the planet’s atmosphere. Now it’s juxtaposed again, this time in the foreground of a star cluster that’s 26,700 light years from Earth.