Mars is a fascinating place and it’s often been compared to our own Earth. So it’s no surprise that space images sent back from the Red Planet are always interesting to see.
NASA’s Mars Reconnaissance Orbiter takes gorgeous space pictures of the planet with its High Resolution Imaging Science Experiment (HiRISE) camera. These shots show everything from tumbling avalanches to skyscraping dust devils.
1. The Face
When the Viking 1 spacecraft flew past Mars in 1976, it sent back images that were instantly recognizable to people all over the world. One image, taken in Cydonia, a region of Mars’ northern hemisphere, showed a squarish mesa that looked like a face.
But while it was certainly an optical illusion, there were still a few people who thought that the face was evidence of advanced alien life. Smithsonian geologist John Grant says the face has always been difficult to prove either way, because the original pictures were very low resolution and the lighting geometry changed.
But high-resolution images from NASA’s Mars Global Surveyor, as well as 3D altimetry from the HiRISE spacecraft, have shown that the face is nothing more than a rocky mesa. So let’s take a closer look at this interesting landform.
2. The Hole
Mars is one of the most-explored planets in our solar system. It’s a fascinating place to visit and is teeming with amazing sights.
In fact, scientists and engineers have come a long way since the first close-up images of Mars were released back in 1965. Now, NASA has some of the most incredible pics ever taken from space, including some that are truly mind-blowing.
In one image, for example, you can see an unusual hole on the surface of the Red Planet that looks like it could be a home for life. It was discovered by chance on a series of pictures of the dusty slopes of Mars’ Pavonis Mons volcano shot by the HiRISE instrument aboard the robotic Mars Reconnaissance Orbiter.
3. The Worm
Scientists continue to search for signs of life on Mars, with multiple rovers and orbiting spacecraft examining the Red Planet’s surface for biosignatures.
One of the most interesting images in this series is a picture that appears to show a giant worm burrowing beneath the surface. That photo was taken by NASA a few years ago.
The worm-like rock formation is so small that it only has centimeters of total size, but the whole thing stands out as a distinct feature on the Martian surface.
This formation is found near areas where clay-heavy and sulfate-laden layers of rock have been eroded away, which may hint at water on the planet. It’s definitely a cool sight!
4. The Cracks
In early 2017, Curiosity rover sent back a photo of what appears to be cracks in a rock slab called “Old Soaker” that the mission believes are remnants of desiccation cracks in mud that once existed on Mars. If confirmed, these cracks would be the first mud cracks discovered on the planet.
These cracks appear to be a product of the drying and cracking of lakes that once filled Gale Crater 3.5 billion years ago. The results of the study are expected to help shed light on Mars’s ancient climate.
For example, sharp drops in temperature can cause ground to contract and fracture, forming thermal-contraction cracks that connect together and show polygonal patterns. These polygonal features are also commonly found in dried mud puddles on Earth, though the size scale of these polygons is far smaller than those found in the cracks on Mars.
5. The Ice Cap
Mars’ ice caps are located at the poles where winters get cold enough for molecules such as carbon dioxide to freeze. The frozen cap consists of two layers: a thin coating of water ice and a thicker layer of carbon dioxide ice.
This image, from NASA’s Mars Global Surveyor satellite, shows an orbital view of the polar cap, which is 621 miles across and contains many deep troughs. A large canyon, called Chasma Boreale, almost cuts the cap in half.
Scientists have long been puzzled by the south polar cap, which is offset three to four degrees from its symmetrical counterpart in the north hemisphere. It’s believed to be made of carbon dioxide ice, and data from ESA’s Mars Express spacecraft suggests it may also contain a layer of liquid water beneath it. However, until now, no one had independently verified this evidence.
6. The Dust Devils
Dust devils, also known as swirling vortices of dust, are common on Mars. They form when a difference between ground and air temperatures causes air to mix, causing dust and other particles to fly up into the atmosphere.
They can be incredibly strong whirlwinds that only last a moment and blow away everything in their path. They are a huge part of the planet’s weather, though they remain mysterious for various reasons.
Now, thanks to the Perseverance rover’s microphones and a bit of serendipity, scientists have captured the first sound of one on the Red Planet. The whirlwind swept over the rover last September, and was recorded by SuperCam’s microphone, along with its navigation camera and several sensors in its Mars Environmental Dynamics Analyzer instrument.
7. The Southern Hemisphere
For decades, scientists have puzzled over why Mars has two hemispheres that look so different. The north is flat and smooth, while the southern is dotted with craters and mountain ranges.
A new picture of the planet from the Hubble Space Telescope shows how those differences are actually a result of layers of layered material that have formed over time.
The material accumulating at the southern pole covers an area of almost a mile (1.5 km) wide and two miles (4.6 km) long. The photo also shows the dark streaks formed by wind blowing across the layered material.
Scientists say these ridges could be remnants of river systems and an ancient ocean floor. They also say the ridges are the densest collection of water-formed ridges on the planet. The study suggests that the Martian surface was once much more flooded with water than it is now.
8. The Dunes
Sand dunes are a common feature of the planets in our solar system. They record wind direction–like a free wind sock–and can provide information about planetary weather and climate.
They have also been identified on Earth, Venus, and Titan, as well as on Pluto and comet 67P/Churyumov-Gerasimenko. In particular, planetary scientists study dunes to infer wind speed and velocity on the smaller planets in our solar system.
The most recent discovery comes from Mars, where a team of researchers has identified hundreds of crescent-shaped pits that seem to be the remnants of ancient dunes. These dune impressions show that a Martian weather pattern was different billions of years ago, when the planet’s atmosphere was more like the one on Earth today.
9. The Crater
On Mars, craters last much longer than on Earth because of the thin atmosphere that erodes them more slowly. This makes them easier to study, allowing scientists to better understand the planet’s past climate.
To do this, Boatwright used high-resolution images taken by the Mars Reconnaissance Orbiter’s HiRISE camera. These showed features called inverted fluvial channels, which are a telltale sign that ancient water once flowed across a crater.
These channels formed after water deposited course-grained sediment inside the valleys it eroded. Over millions of years, the erosion whittled these channels away until they were left behind as raised ridges spidering outward from the crater floor. This type of channeling is a common geological sign that lakes once flowed on a planet, and it provides new clues about the early Martian climate.
10. The Ice Layers
In addition to polar caps, Mars has also been found to have several layers of ice that are buried beneath its surface. These layers could turn out to be one of the largest water reservoirs on Mars and may also help researchers learn about the planet’s history and climate cycles.
The layered deposits are believed to have been created over time by the Martian atmosphere, which deposited sand and dust on top of the ice. The ice then slowly melted and reformed over millions of years.
The ice on Mars is different than the ice on Earth, as it’s much thicker. It’s also able to survive warmer periods on the planet since only the upper sections of the ice undergo sublimation, where they transition from liquid to gaseous state.