Curiosity’s view of life on Mars

It lugs around a formidable array of scientific instrumentation, but did you know NASA’s Curiosity rover also boasts 17 cameras? 

With seven on its mast, nine mounted on the body and one on the end of its arm – quite convenient for the odd selfie – Curiosity’s cameras have been busy snapping photos of the rover’s strange, other-worldly surrounds since August 2012.

In many of images, colours and white balance are adjusted to show us what the vista would look like under daytime light on Earth. The white balancing tends to overcompensate for the lack of blue on the planet. This makes the sky look light blue and sometimes gives a bluish tinge to dark, black rocks.

Here are some of Curiosity’s weird and wonderful finds.

Meteoritic find

Curiosity examined this dark, smooth object with laser pulses from its Chemistry and Camera (ChemCam) instrument to confirm it was an iron-nickel meteorite – a common class of meteorite found on Earth. 

They’ve been found on Mars before, but this is the first to be examined with a laser-firing spectrometer.

The meteorite is about the size of a golf ball. Iron meteorites usually originate as core material of asteroids that melt. They provide records of many different asteroids that left fragments on Earth and Mars. 

More analysis will determine how the Mars atmosphere has affected the iron meteorite. This photo was taken by the Mast Camera (Mastcam)

Celestial delights

They might look like the eyes of a strange alien, but this is an eclipse as seen by Curiosity’s telephoto lens camera of its Mast Camera pair (right Mastcam).

Three photos show the larger of Mars’ two moons, Phobos, passing in front of the sun. Each image is three seconds apart.

This eclipse happened near midday on Mars with Phobos nearly directly overhead. The timing made Phobos’ silhouette larger against the sun – as close to a total solar eclipse as you can get on Mars.

Crystal clear

Two merged images of a Martian rock, showing both colour and microscopic details. The rock bears elongated, light-coloured crystals in a dark matrix. Some crystals are up to a centimetre long. 

The elongated crystals are likely feldspars and the matrix is mostly pyroxene. This mineral pairing is typical of basaltic igneous rocks, so provides compelling evidence that Mars was once volcanic.

Remote Micro-Imager of the ChemCam instrument snapped the detail in the centre of the image. The right-eye, telephoto-lens camera of the Mastcam took colour information and wider context.

Sieved sand

Curiosity used electric lights at night to illuminate this scene of sand grains on the ground after being sorted with a sieve. The Mars Hand Lens Imager camera on the robotic arm took the image.

Dune, downwind

This image, images stitched together from shots taken with Curiosity’s Navigation Camera (Navcam), shows the downwind side of Namib Dune which stands about four metres tall. 

The winds on Mars cause the sand dunes in this region to migrate up to about a metre per Earth year. 

The downwind side of the dunes shows different textures from those seen on windward surfaces nearby. As on Earth, the downwind side has a steep slope called a slip face. 

Bagnold belt

The dark band in the lower section of this image, taken by Curiosity’s Mastcam, is the Bagnold Dunes, where the Namib Dune can be found. 

Mid-sized mystery

Some of the sand ripples on Mars aren’t seen on Earth. Both planets have large sand dunes and small sand ripples (less than 30 centimetres apart), but Mars also has an in-between phase of mid-sized ripples, about three metres apart.

Smaller ripples – called impact ripples – on Earth are generally cause by wind-carried sand grains colliding with other grains along the ground. 

But Curiosity’s Mastcam showed that the mid-sized ripples on Mars were unlike the impact ripples on Earth. Rather, they’re much more like sand ripples that form under moving water on Earth.

Researchers don’t necessarily think they were formed by water on Mars. Instead, they suspect Mars had a thicker atmosphere in the past, and that wind dragged sand particles the way flowing water does on Earth, creating these mid-sized ripples. 

This supports earlier evidence that Mars may have lost most of its original atmosphere early in the planet’s history. 

Earth gazing

The left-eye camera of the Mastcamtook this view of the twilight sky and Martian horizon, showing Earth as the brightest point of light in the night sky. 

The image is processed to remove effects of cosmic rays, but a human observer with normal vision could see Earth and Earth’s moon as two distinct bright “evening stars”. 

Petrified sand dunes

This Mastcam image shows the finely layered rocks within the Murray Buttes region on lower Mount Sharp.

Buttes and mesas that rise above the surface in this area are eroded remnants of ancient sandstone. The layering is called “cross-bedding” and indicates the sandstone was deposited by migrating sand dunes.

Ancient lake

This Mastcam view is from the Kimberley formation on Mars. The strata in the foreground dip towards the base of Mount Sharp, indicating water once flowed there before the mountain formed. 

Observations from this area suggest that Mars had a series of long-lived streams and lakes – between 3.8 to 3.3 billion years ago.