Humans are getting a first glimpse of the tall sand dunes on Mars, and the photos are brilliant

After more than three years on the Martian surface, the car-sized Curiosity Mars rover is giving us a close-up glimpse of terrain unlike anything we've seen before: tall, ripple-ridden sand dunes like this one:

Satellites orbiting Mars have snapped photos of these sand dunes before, but never up close like this:

And NASA scientists are incredibly excited because it's the first time anyone has had the chance to study active sand dunes beyond Earth.

One of the first things they want to explore is the "grain size and morphology of different parts of the slipface," Lauren Edgar, a member of the Curiosity team and a USGS Astrogeology Science Center research geologist, wrote in a mission update.

The ripples on these dunes change over time due to Martian winds and mini avalanches. Notice in the picture below the breaks in the ripple pattern near the top:

These breaks happen after Martian winds deposit sand on the slope, where it gradually accumulates. Eventually, so much sand builds up that the sand underneath can't sustain the weight of the sand on top, and a mini avalanche occurs.

On Earth, this sort of thing usually happens on wind-protected slopes, leading NASA scientists to conclude the side of this dune, called Namib Dune, is also shielded from the wind.

For comparison, the wind-facing side of another nearby dune reveals a very different sand pattern:

Namib Dune is between 13 to 17 feet tall and is just one of many sand dunes located in the Bagnold Dunes field situated along the northwestern flank of the base of Mount Sharp, which forms Gale Crater's central peak.

Gale Crater is initially where Curiosity first touched down back in 2012. Here's a map of it's more than 7-mile journey from the crater (at the top) to the mountain (at the bottom):

And here's a better view of the environment, with Namib Dune on the right:

Mount Sharp is a 3.4-mile-high mountain that NASA's Curiosity team has been dreaming of exploring for a long time. They first snapped a photo of Mt. Sharp with Curiosity's Hazard-Avoidance camera in 2012 - that's Mt. Sharp in the distance:

Though NASA scientists haven't seen sand avalanches or ripple movement, yet, Edgar is hopeful:

"We'll be in the same location for a little while, so hopefully we'll have the chance to observe some sand movement!"

In the mean time, we can sit back and enjoy some amazing photos, like this breath-taking panoramic view of Curiosity's rover deck, Namib Dune in the middle, and Mount Sharp's peak in the background: